"I can't grind a cutting tool with the right radius I need, so I'll build a toolpost spindle to cut the thread" is a level of knowing one's strengths and weaknesses I would love to achieve.
That's pretty much it. It seems so much easier to make a quick and dirty tool post spindle compared to standing at the grinder for an hour, burning your fingers and cutting facets on what is supposed to be a flat surface lol
@@TabletopMachineShop You can use a cutoff tool to rough off excess material much faster than grinding it all away when your blank is a lot larger than your finished tool.
Woo a new video! Love it :) Re: Stepper vs BLDC. it should be noted that hobby BLDC manufacturers wildly over-inflate their wattage because they assume perfect cooling. In practice, without forced air or water cooling hobby BLDC will give you ~50% their rated power before going into melt-down. That aside, both are technically brushless so the main difference is their pole configuration and how they're driven. Steppers try to maximize holding torque and precise steps, so have a very high pole count. Holding position over a pole produces essentially zero torque, so steppers compensate by pumping their max current through the coils to try and maintain position. This in turn limits power density since everything has to be designed to withstand continuous 100% current duty cycle (as well as things like environmental sealing, standardized NEMA body plan, etc). OTOH, hobby BLDC have low pole counts and the rotor always "lags" the stator, which produces maximum torque-to-current...but little position control. This gives them much better efficiency because it only needs enough current to overcome the opposing force, which in turn leads to better power density since it's assumed duty cycle won't be 100% max current. But with so few poles you can't control position easily and need an encoder to close the loop instead (thus turning the hobby BLDC into a servo motor). If you ever want to go _waaay_ down the rabbit hole of motor design, magnetics, etc check out: things-in-motion.blogspot.com/ Really great blog that dives into all the nitty gritty details.
Thanks for the info! It is a NEMA17 BLDC, not a stepper, but I imagine many of the same points apply when using them for precise motion control. The hobby motor got insanely hot in use, so I managed the duty cycle myself by taking a few cuts and then letting it rest for a bit. Thanks for the info as well, I'll make sure I have a look! Also, subscribed to your channel! I too enjoy breaking taps.
@@TabletopMachineShop Oh whoops, missed that one, critical detail :) You can ignore 90% of what I wrote then heh. FWIW, outrunner hobby BLDCs tend to be easier to cool (compared to those sealed inrunners) since they have open vents into the coils, makes it easier to point a cheapo fan down the bell. Can claw back some of the spec'ed performance without too much heartache :)
Precious Plastics is also putting together injection moulding machines with augers. Yours are much more automated and higher quality, but there may be something to learn from how their augers are machined.
look into oil extraction machine screws. there are these little desktop sized seed oil extractors that run off what essentially is a meat grinder. they have compression screws built in. Likely the motor on them could also be controlled with a SSR so you can eliminate the need for that big stepper, and control the whole thing with Marlin/arduino/ramps gcode
Hiya TTMS, thought I would chime in on your motor question. The difference in power between a NEMA 17 BLDC and am RC BLDC comes from the difference in the current one can take compared to the other, but that has to do with the principles of their operation. That NEMA BLDC in particular looks to be a decent sized stepper with an integrated servo driver, which allows it to act as a sort of BLDC. This integrated servo driver gives you exact speed control, and in turn, exact position control by allowing the motor to draw more or less current to keep up with changing applied loads, and also to increase speed to "catch up" back to its position that it needs to be at if the load exceeds the stall torque. All of this fancy current monitoring and high frequency driving however does not change the fact that the NEMA BLDC is still at heart a stepper motor, and as such operates using several coils that are used to advance the armature by a certain angular displacement each "step" of the coils. In order to achieve this kind of timing with so many small steps on the rotor, it requires relatively low inductance in each coil to be able to energize that coil in a short enough amount of time. This is why those smaller stepper motors typically have driver output voltages that are around 1V-3V, because any more voltage applied to the low inductance coils would send so much current that the windings would burn through their enamel coats very quickly. The hobby BLDC operates on a similar principle, namely switching the magnetic field of the stator in order to induce rotation via EM interaction in the rotor. However, rather than worrying about each individual step taken by the coil, it can hit the coil with the max output voltage the driver can handle, which is the same as the input voltage into the driver. Since we don't care about the time it takes to saturate each coil, again remembering that these time scales are definitely in the realm of "very small". This large driver voltage across a relatively small inductance coil results in massive current spikes, especially at start up when there is no back-EMF to drop the input current. Sorry for the essay, but little nuances take some time to explain. This project is fantastic by the way! Can't wait for the next installment.
Hi there, I work in plastics and I would advice you to make your screw at least 20 times longer than your diameter, and that it's maximum volume by weight to be at least 3.5 times the total shot weight but more to better but it's depends on the material. Also I would make a piston/screw combo with the ability to control the forward/reverse on the piston with it being charged via the screw, this would be ideal if you can't use a check ring. Injection mould takes alot more force than you would expect. If you ever need any advice please ask I've worked in the industry for 25 years making stuff like LDV, Rover, Dyson, Hozelock, Koito parts among other stuff. Good luck if you make another machine. Jim🏴🇬🇧
Just a small tip the flights in the screw should taper so the flights are smaller in the front and taller in the rear. This makes for better material feeding and melt compression. Also as a rule of thumb your part shot size should be about 30% of your barrel capacity.
Haha, yeah I'm sure a real machinist could make it work. I'm awful at grinding tools. I probably could have tried with a thinner tool, but that would have been way more grinding and I probably still wouldn't have been able to make it work lol
@@TabletopMachineShop This is why engineers and machinists should respect one another. Both have their own expertise and skills. Ideally they complement each other to make great products. At least you seem aware of this.
Congrats on the sponsorship! And I love your attitude towards making things. Even if you don't follow your steps for design lol. It's easy to get stuck in a design and reiteration loop (for me especially). I appreciate your videos, they're inspiring to me.
I seem to remember a oxtoolco video where he used some 3D metal printed parts for his Sensitive drilling attachment. He said they were reasonably priced. I think he mentioned the company in the video series. Maybe a good candidate for this part? Who is that Peter Stanton you mentioned in the video? Thanks!
Peter Stanton? I think he's just a myth. They say when there's a part with holes that are 40 diameters deep or integral internal keyways he appears... Actually I did quickly investigate 3d printed metal parts, the ones I found were pretty expensive, but a viewer actually offered to print and send me an oversized version. I think I'll do a video on cleaning it up as well, just to see how it machines.
@@TabletopMachineShop 3D printing a part like this is a bad idea. The thermal stresses and the forces associated with turning and pushing the plastic will cause it to have a much shorter service life that machined billet due to inferior grain. Not using a compression screw is also not a great idea as most of the heat that melts the plastic comes from friction. Were I doing this project I would sooner do 3-4 overnights at a fast food joint and pay to have it done right in china then do it wrong myself. Overall I like your design, but you will find the length of the screw and the lack of a compression screw to be major oversights. If it is not too late, those are things I would change.
Misumi > McMaster ReprapFirmware (Duet) > Marlin Not bad, sketchy live tooling setup....But if it works, it works. Experimental at best I'd say hits the nail on the head. Interesting. Wonder if it would've been easier to 3D print and cast that they have it like sand blasted or something, but live tooling is definitely a game changer. Been gone for a while, glad to see you've kept yourself busy!
It wouldn't really make much sense to throw a duet on this setup. I'd probably just look at making a really simple ATMega based board with the necessary drivers, like one or two stepper drivers, a fet/ssr for the heater, and some sensing, and then have it run grbl or marlin (can't quite remember if grbl ever got temp control) You're not exactly doing complicated 3D moves that require lots of calculations, nor are you driving a load of axies, so a duet is pretty wasted on it.
@@dumle29 You're failing to think long-term though. Learn to Automate. Create passive income. Duet boards are servers, let's not forget that. Yeah, you wouldn't be leveraging the full potential of the board, you're absolutely right, but you'd still being networking and a lot of headers, fans, and the duet can run 24v with a few amps and ssr or you can use external motor drivers or just leverage some of the result configurable pwm control for stuff. Excessive? Perhaps. But you probably wouldn't need to do all that much coding and you could have start up routines and shutdown procedures.
I do have a duet kicking around... I think it would definitely make more sense if I were selling these, but since other people are interested in making them I would be concerned about how difficult it would be to convey the setup information. I seem to recall they're a little more difficult to setup. I might look into it a little more though, it would be nice just to wirelessly connect and run a few parts... You're a Misumi man? How could you? Actually I do like Misumi as well, I just dont like their website, I hate downloading zipped CAD with gibberish names, and I find sometimes the CAD I do get is super broken for some reason.
The screw should have a L/D ratio of at least 18 and the thread should have a compression ratio of at least 2 for the plasticizing to be good. With those values at least two thirds of the heat will come from the mechanical processing of the plastic. It will then be evenly heated and well mixed. Instead of using a straight screw you will probably get better results with a piston and a cylinder with a torpedo.
Yeah I think performance is going to suffer pretty severely for the sake of compactness. The piston cylinder may be the right answer, but I'm so close now I might as well fire it up and see what happens.
@@TabletopMachineShop Yes, of course you must try it. No matter what I think that you will get a result. In the worst case you have to wait a couple of minutes between every shot. It is also possible that for the first shot you will have to feed the screw a little at a time, with pauses between, to give the machine a chance to plasticize. I am sure that you will get something out of the machine. If you find out that you need better plasticizing you can make the screw and barrel smaller. Then you will improve the L/D ratio. And with a more shallow thread you will have more surface in relation to the volume of the melt, which will give you better plasticizing. Here is room for endless experimentation.
finally you are back. I am designing a similar toolpost grinder myself. but I got the same problem with the little torque. I am thinking of adding a plaetary geardrive.
Yeah that would certainly up the torque, I guess it depends on what speed you're aiming for. You could always try a brushed DC motor for more torque at lower speeds too. I was pretty impressed with this BLDC motor, even though I was starving it for current it would probably work quite well for easier metals like aluminum.
'The motor lacked torque at lower speed' ... That's why your average hobby motor can take that much more current and provide that torque from standstill to low rpm.
The power difference between nema17 bldc and hobby bldc is that huge because of heat dissipation. The efficiency of BLDC motor usually lies between 75% and 90%, so when you run 50 watt motor you probably waste ~10 watts to heat. Thats not a lot so aluminium body can dissipate it. But when you run a 1800 watt motor at max rpm and max torque, you'll have to dissipate ~360 watts, which is huge for this size. Hobby BLDC motors usually work being cooled by water around it (if its RC hobby boat, like in your case) or excess flow of air, like in RC planes. While nema17 BLDC is supposed to run in S1 mode (basicaly 24/7 non stop). 360 watt is enough to heat up 1 kg of water by 5°C in a minute. Thats not little.
Great to see an update up here! Been following along on Instagram. That screw is definitely quite an undertaking on a manual machine. Super cool to see the clever solution you came up with to get it done.
Awesome looking part 👍 having worked in injection moulding I’m surprised you got this close to a proper screw. Probably needs an off the shelf auger screw for hobbyists to reproduce this
Very cool and enjoyable to watch video. I see you figured out that a full profile form tool is too much for such a small part. Perhaps if you had used negative angle tooling the part wouldn't have protested so much. 😊 The end results is all that counts.
Thanks! Grinding tools is all witchcraft to me. I know the theory of it, I just suck at it. You're definitely right that the tool is way too wide, but the axial forces were pretty high so I didn't want to go too thin either... ah well.. more than one way to skin a cat :)
Other approach: First source a cheap extrusion screw, then build the machine around it: www.robotdigg.com/category/32/Extrusion-n-Injection That having said, by default extrusion screws are chrome coated.
You could have machined that screw with a single point cutting tool. Make it 3mm wide, when you reach full depth, progressively feed it along with the compound slide on subsequent passes.
The generalized power rule says that wattage = voltage * amperage, and the max amperage that a motor can handle will mainly depend on the thickness/length of the wire used in the windings (i.e. a thicker wire can handle more current without overheating than a thinner wire).
@@TabletopMachineShop The hobby BLDC motors usually have a number n of stator coil poles on the inside and n+2 permanent magnet poles on the outside, coupled to the shaft, which gives space for a higher area of windings per pole (not going to go into motor Kv) but gives the motor a higher moment of inertia. It comes at the cost of producing the most torque at a higher RPM and it's pretty low at lower RPM. The movement isn't very precise either and the position can be easily upset, even with good driver tuning, so it can't handle loads very well. Servo induction motors on the other hand (usually) have n+2 stator coil poles on the outside and n permanent magnet poles on the rotating shaft for a greater precision of movement with low moment of inertia and high holding torque, or at low speeds. Unlike BLDC, it comes at a cost of lower power for the same size motor and lower torque at higher RPM. The torque that can be produced has also quite a lot to do with how fast the coils can be magnetically saturated and the total magnetic reluctance of the system. Industrial servos often use very high voltages for this very reason, as it reduces the induced losses and saturates the coils faster, while hobby BLDCs can just get away with lower voltages and high currents; some well over a hundred amps for a motor fit for a small quad. A lot of heat being dissipated due to BLDC design and active cooling is key, while servos are often enclosed and passively cooled. Driving the motors is also different, with BLDC ESCs simply chopping up DC current into three phases, with timing being usually based on feedback voltage from the coils in an open loop, though some may utilize hall effect sensors. Induction motors on the other hand are driven with inverters that produce a chopped up approximation of a three phase sine wave, with timing being controlled similarly, but also with the additional aid of an encoder for more advanced closed-loop vector control in most cases, where positional accuracy and rigidity is needed, paired with a high holding torque. This needs some tuning on a per motor / driver pair basis to get it good enough and can be time consuming. More modern drivers may incorporate an auto tune process though, requiring few steps. BLDCs could also be vector controlled, but the cheap three phase bridge drivers on ESCs can't do that, at least out of the box and without some external logic hardware to interface an encoder. Not sure how e.g. ODrive does it, but it's one solution for using BLDC as a servo, with encoder feedback. Many camera gimbals also use them due to lower price, since the torque required to stabilize a camera isn't that great, usually.
"Machine parts" should be a duty free tax code. Also there is usually a CNC threading cycles which should be able to cut a screw like the drawing you showed. You'd use a stout parting tool say 3mm wide and not much longer than the insert. You'd need a somewhat rigid machine for a 3mm wide bit and have to be somewhat brave to run it, so milling it is probably better for a hobbyist. The screw looked good to me.
Agreed. I might ask them to label my orders "birthday present" or something next time :P. Yeah the machinists in our shop said they'd hand program it with canned cycles and a live tool, but our cnc lathe is always pretty busy with production stuff
I'd like to add 2 items of critique. 1. When trying to turn the screw with a form tool you did not need a full width form tool. A much narrower tool run with more passes would have done the job. If you wanted to then you could have run a wider tool to smooth the root, but I suspect you would have found it to be unnecessary. 2. A machinist and machinery builder of your obvious ability should be able to build an adjustable taper attachment for your lathe in an afternoon. I have been following your build with great interest. I have need of a better plastic injection machine for testing myself. For now I just have a simple lever operated machine with very low volume. Eventually I'll need to get some setup for gun drilling water jackets too.
I accept your two critiques! Yeah the form tool was a disaster, I was never really expecting it to work, I should have used a thinner one and adjusted its position using the compound slide aligned with the bed. I suppose I even could have made a tool holder that held a parting tool at an angle for side clearance. Ah well. Unfortunately, the machine isn't my personal machine, so I would be hesitant to modify it in any way :(. Thanks for the suggestions!
@@TabletopMachineShop - I definitely did NOT want to convey anything as negative. Just offer suggestions if you need to redo the screw to make it longer in the future. I was not aware the lathe was not yours.
@@TabletopMachineShop Why not set it up between centers. Admittedly you may have to play around with the dog to prevent issues with your setup. What I am trying to say is when you are turning the dog is always loaded keeping the shaft indexed with the headstock. With a milling setup you would have to ensure the shaft can't move away from the drive dog to prevent your end Mill / part from self destructing.
Hi, nice project. First - the motor: - industrial grade motors are made to be running 20.000hrs - that hobby motor will maby last 200hrs, due to bearing overload and heat overload - it is designed so and serves well if taken care of (lubricating and replacing bearings on time, provide sufficient cooling) - power comes from thick wires and high currents To the screw.... On industrial IMM's length vs diameter is something like 20:1. Not going under 15 and over 25. It is related to residence time for plastic. Going under 1.5 minutes will give you bad melt with semi molten parts that tend to block the runners. Than going over 10 minutes - plastic starts to turn to oil again. Also - industrial machines use stroke of the screw to inject the plastic. What are you planning to use to inject?
Yup, the old 20khrs MTBF... Something tells me I won't be seeing 20000 hours out of this motor... it might have 2 or 3 left in it. Yeah, regarding the screw, i did a bit of research before the first video (and of course watched the engineerguy video), and that all agreed with your points. I guess what I'm doing is prioritizing compactness over performance. This has caused me problems before:P I think any mold I will use will be quite low pressure. I'll avoid using runners where possible, have lots of fairly thick vents, and be ready to clean things up with a hobby knife :P. The clearance between the screw and barrel is pretty small, so I think I'm hoping the near-static pressure downstream from the screw combined with a low pressure mold will be enough. After all, I'd be happy just molding bushings, screw caps, and perhaps the occasional bottle opener .. not lawn chairs :P As I mentioned, I'm considering making a plunger variant -- hopefully that will be able to deliver respectable pressure
@@TabletopMachineShop You will have at least a couple of hundred of hours out of your RC inrunner before bearings fail. Just do not overheat it. Babyplast is usind ancient double plunger system and it works pretty well. To do some reasonable molding - you will need at least some 450bar of melt pressure. Well - for lawn chairs you first need to upgrade the clamping unit to some 1.500 tones. Metric. :-)
Your channel is the nicest gem YT has come up with in a while. Thanks for the great content :-) BTW, the big difference between a hobby motor and an industrial one is duty cycle rating. Surely a you must know that?
Thanks! I knew there would be a duty cycle difference, and the RC motor no doubt is supposed to have a pretty solid airflow, I was more asking about the construction; the 50W for the BLDC is peak, so not a continuous duty cycle. Even if the RC motor is supposed to be run for short bursts, there's a huge power difference
Very cool. Question: Why not cut the auger using a narrow grooving/parting tool by incrementing the compound set parallel to work/spindle to increase the groove width?
I think that's probably the right answer. At the time I was concerned about being able to grind the tool (I'm really, really bad at grinding), and I also though I would be cutting a tapered root so I was worried about synchronizing multiple passes with that. The actual cut has a very high helix as well, so the tool would have to be thin enough to not chatter but thick enough that it could withstand some fairly serious Z direction force..
Wouldn't you want a smaller gullet at the end of the screw? I'm used to seeing large screws on 2000 ton machines where the ratio is very small compared to the diameter.
Yeah, you're absolutely right, real machines do. I struggled so much just getting the root cut I wasn't sure I would be able to pull off a taper. We'll see how it work, and if not, perhaps a plunger is the way to go :)
Oh lovely, another update, how long has it been. I want to know everything about this injection molding machine. Also I love your style and your explanations.
Если бы ты еще купил фрезу не с 90 градусным концевиком , а радиусным , то шнек твой был бы и крепче и лучше. Очень толстые кольца шнека , надо было 2-3мм оставлять. Вся энергия нагревателей уйдет на нагревание шнека ).
Wow, A MASSO sponsored video. Haven’t seen one of these in awhile. Are they around Anymore? I remember they had many G2 issues early in. Last post i saw on a G3 looked positive but that was three years ago. Since then I’ve not heard it mentioned until I ran into this 3 year old video. Compared to Linux CNC its very expensive wall art. Cant say I’ve had any issues using a PC myself but there have already been so many available online that work well to 6 axis for $500 or so. I almost pulled the trigger back than, but Im glad i decided to wait it out to prove themselves over time first. Must be a small market if still around. The G3 with touch screen is pretty. For $1400 though its still a hard pass.
Hello, I would like to know if you have this Injetora project for me to purchase. I saw that you have a website and that I need to pay $ 3 a month. Is the entire project on the site, or do you add one part of the project per month?
I suppose this screw is not your final one? It will not work properly because it has a uniform depth, but the channel in the screw will need three zones, the feed zone with an uniform depth (deepest channel) and needs to be cooled, then a compression zone with decreasing depth to be able to compact the resin once it starts melting and force all air out via the feed opening, and lastly a metering zone which holds the pressure to extrude or inject the polymer, it has an uniform or decreasing channel depth. In fact the screw will need to be twice at long to be able to locate these zones and to create enough pressure, probably there are going to be backflush problems when injecting the polymer. How are you going to inject the polymer into the mold? Just extruding polymer into the mold will not work, an injection moulding machine has a continous running screw which fills a chamber in front of the screw, then a hydraulic ram will force the screw forward a set distance to inject the polymer in that chamber into the mold. After the injection stroke the pressure on the ram is released and the screw will refill that chamber with new polymer and force itself back into the initial position doing so. I think also hydraulics will be needed to close the mold, I'm not sure if that actuator will be strong enough, as required injection pressures are somewhere between 40 to 160 bar (600-2400psi), holding pressure will be dependent on the surface area of the object to be molded. Injection has to occur quick enough to prevent short shots, this is polymer solidifying before the mold is full. It's a very interesting project however, and I'm curious to see how you gonna solve all the issues.
Hi Tom, Thanks for the comment, I really do appreciate expertise :P. I guess what I'm hoping to rely on is a low-pressure requirement in the mold and a close fit between the screw and barrel. There's a bit of a space at the front of the barrel for plastic to accumulate, and I guess I'm hoping the static pressure in there will be enough to permit flow into the mold. I'm so close with this design I figure I might as well test it and see what happens. I certainly know there's a reasonably high risk of it not working, and if it doesn't I think I'll just switch to the plunger system I alluded to in the video. I really like experimenting and finding how things do and don't work myself, so I won't be crushed if I get zero static pressure and no injection :P. Thanks again for the comment and the great description of the process!
@@TabletopMachineShop Thanks, and I wish you success with the project, it might work this way with a very free flowing mould and a low viscosity resin, you can also play around with the temperature to lower viscosity, how far you can go depends on degradation stability of the resin used, it will be obvious enough if it's too high, you will get some yellowing and excessive smoke.
Good afternoon, I would like to know if you could help me since I would like to make a machine like yours. But I don't have plans, do you think you can help me?
You who may. It is possible that you manufacture one or more injection machines that I am watching the video of, just tell me where I can contact you so that you can send us a quote for them. Thank you. Gustav.
Well, looks like you are about to obtain your goal. Are the Solidworks files available and is this project going to be "open source". I would like to make some additions (mechanical or electronic). Please message me and let me know if this can be done. Thank you and best regards. "All we have is Time"
The files are available on my Patreon, except i haven't included any code or electronics -- I'm still working on something that doesn't rely on the sun being in the correct position on a prime numbered day of an even numbered month to work :P
what is the name of the material for the barrel material, sir? I had trouble finding the name of the Matrial to look for in a shop. sorry I also do not understand foreign languages. with google translation tools, hope to know. information please . Thank you very much sir 🙏🙏🙏🙏
The Python script controls the motors and heaters directly using Phidgets, so there currently is no G-code. In the future, I'll either use Arduino with a basic screen interface, or a 3D printer board that you could send G-Code to. Boards for 3D printers tend to accept G-code one line at a time over a USB serial port connection and send after each one is complete, so it would be pretty easy to write an easy interface that took molding parameters like shot size and cooling time, converted them to G-code motion commands and sent them to the 3d printer board.
I actually started using one but quickly destroyed it trying to press it into a sleeve for the bearings. I then decided just to make my own... it's only one part, how hard could it be?
Tabletop Machine Shop spoken like a true engineer! 1) try the easy route 2) break something in the process 3) try the hard route 4) regret vocation 5) produced part
Kids. Ha! How did people ever survive without computers? Ok, the easy way to make an auger with a tapered root diameter (aka minor diameter) on a manual lathe. Offset your tailstock center. A boring head works great for that. Just tap it in, nice and tight or make some sort of dog for it. You'll need a dog and dead center in the spindle. Use your milling attachment. Bob's your uncle.
That's a really good idea, that was totally off my radar haha. I had done that way back when I used my own Taig lathe to make tapered pins, I just totally forgot lol. Thanks for the tip!
@@TabletopMachineShop Glad I could remind you, although I'm sure you would have thought about it eventually. I'm looking forward to seeing your project completed.
![DIY Desktop Filament Extruder #6 [ENG] Bonus: Wood Drill vs. ( Plastic Screw / Compression Screw )](http://i.ytimg.com/vi/TkZ1h22KqbU/mqdefault.jpg)
![DIY Desktop Filament Extruder #6 [ENG] Bonus: Wood Drill vs. ( Plastic Screw / Compression Screw )](/img/tr.png)
![Filament Extruder from widely available parts [ENG SUBS]](http://i.ytimg.com/vi/NrexroHEQAc/mqdefault.jpg)
I've been in the injection molding business for 15 years. This project is great.
you must see this th-cam.com/video/yIDSmwjUcIA/w-d-xo.html
How I chose the dimensions secrew sir
"I can't grind a cutting tool with the right radius I need, so I'll build a toolpost spindle to cut the thread" is a level of knowing one's strengths and weaknesses I would love to achieve.
That's pretty much it. It seems so much easier to make a quick and dirty tool post spindle compared to standing at the grinder for an hour, burning your fingers and cutting facets on what is supposed to be a flat surface lol
@@TabletopMachineShop You can use a cutoff tool to rough off excess material much faster than grinding it all away when your blank is a lot larger than your finished tool.
MRP
Such a ridiculously underrated channel. Amazing work, keep it up! I've binged most of your videos btw and looking forward to more.
Hey thanks a lot, I really appreciate it! I've binged your channel a few times myself :P
Haha I'm currently re-watching his entire catalog (for probably the 4th time)!
Woo a new video! Love it :)
Re: Stepper vs BLDC. it should be noted that hobby BLDC manufacturers wildly over-inflate their wattage because they assume perfect cooling. In practice, without forced air or water cooling hobby BLDC will give you ~50% their rated power before going into melt-down. That aside, both are technically brushless so the main difference is their pole configuration and how they're driven. Steppers try to maximize holding torque and precise steps, so have a very high pole count. Holding position over a pole produces essentially zero torque, so steppers compensate by pumping their max current through the coils to try and maintain position. This in turn limits power density since everything has to be designed to withstand continuous 100% current duty cycle (as well as things like environmental sealing, standardized NEMA body plan, etc). OTOH, hobby BLDC have low pole counts and the rotor always "lags" the stator, which produces maximum torque-to-current...but little position control. This gives them much better efficiency because it only needs enough current to overcome the opposing force, which in turn leads to better power density since it's assumed duty cycle won't be 100% max current. But with so few poles you can't control position easily and need an encoder to close the loop instead (thus turning the hobby BLDC into a servo motor).
If you ever want to go _waaay_ down the rabbit hole of motor design, magnetics, etc check out: things-in-motion.blogspot.com/ Really great blog that dives into all the nitty gritty details.
Thanks for the info! It is a NEMA17 BLDC, not a stepper, but I imagine many of the same points apply when using them for precise motion control. The hobby motor got insanely hot in use, so I managed the duty cycle myself by taking a few cuts and then letting it rest for a bit. Thanks for the info as well, I'll make sure I have a look! Also, subscribed to your channel! I too enjoy breaking taps.
@@TabletopMachineShop Oh whoops, missed that one, critical detail :) You can ignore 90% of what I wrote then heh. FWIW, outrunner hobby BLDCs tend to be easier to cool (compared to those sealed inrunners) since they have open vents into the coils, makes it easier to point a cheapo fan down the bell. Can claw back some of the spec'ed performance without too much heartache :)
Precious Plastics is also putting together injection moulding machines with augers. Yours are much more automated and higher quality, but there may be something to learn from how their augers are machined.
Oh cool, I'll have to check them out, thanks!
look into oil extraction machine screws. there are these little desktop sized seed oil extractors that run off what essentially is a meat grinder. they have compression screws built in. Likely the motor on them could also be controlled with a SSR so you can eliminate the need for that big stepper, and control the whole thing with Marlin/arduino/ramps gcode
A video through the gauntlet of the holidays? Impressive.
Heya Calvin! It's sort of funny, this was the first free time I had to make a video :P
Hiya TTMS, thought I would chime in on your motor question. The difference in power between a NEMA 17 BLDC and am RC BLDC comes from the difference in the current one can take compared to the other, but that has to do with the principles of their operation. That NEMA BLDC in particular looks to be a decent sized stepper with an integrated servo driver, which allows it to act as a sort of BLDC. This integrated servo driver gives you exact speed control, and in turn, exact position control by allowing the motor to draw more or less current to keep up with changing applied loads, and also to increase speed to "catch up" back to its position that it needs to be at if the load exceeds the stall torque. All of this fancy current monitoring and high frequency driving however does not change the fact that the NEMA BLDC is still at heart a stepper motor, and as such operates using several coils that are used to advance the armature by a certain angular displacement each "step" of the coils. In order to achieve this kind of timing with so many small steps on the rotor, it requires relatively low inductance in each coil to be able to energize that coil in a short enough amount of time. This is why those smaller stepper motors typically have driver output voltages that are around 1V-3V, because any more voltage applied to the low inductance coils would send so much current that the windings would burn through their enamel coats very quickly. The hobby BLDC operates on a similar principle, namely switching the magnetic field of the stator in order to induce rotation via EM interaction in the rotor. However, rather than worrying about each individual step taken by the coil, it can hit the coil with the max output voltage the driver can handle, which is the same as the input voltage into the driver. Since we don't care about the time it takes to saturate each coil, again remembering that these time scales are definitely in the realm of "very small". This large driver voltage across a relatively small inductance coil results in massive current spikes, especially at start up when there is no back-EMF to drop the input current. Sorry for the essay, but little nuances take some time to explain.
This project is fantastic by the way! Can't wait for the next installment.
This is what ToT looked like when he was younger... love your videos, keep 'em coming. And Merry Christmas, etc.
Thanks Aaron!
Hi there, I work in plastics and I would advice you to make your screw at least 20 times longer than your diameter, and that it's maximum volume by weight to be at least 3.5 times the total shot weight but more to better but it's depends on the material. Also I would make a piston/screw combo with the ability to control the forward/reverse on the piston with it being charged via the screw, this would be ideal if you can't use a check ring. Injection mould takes alot more force than you would expect. If you ever need any advice please ask I've worked in the industry for 25 years making stuff like LDV, Rover, Dyson, Hozelock, Koito parts among other stuff. Good luck if you make another machine. Jim🏴🇬🇧
you can use an auger bit for wood for the screw, you can find them long and cheap
The humor alone is worth the sub. Great video!
Thanks!
I used a brushless rc motor for live tooling on my lathe too. Good, cheap power source.
Waiting anxiously for the next videos.
Amazing, I start my self injection molding business
For now i own JSW 85 ton unit it is difficult and needed to know a lot about processing
Just a small tip the flights in the screw should taper so the flights are smaller in the front and taller in the rear. This makes for better material feeding and melt compression. Also as a rule of thumb your part shot size should be about 30% of your barrel capacity.
Yeah that came up in my research. Some of the smaller machines I've seen also seem to have straight screws so I'm hoping I can get away with it :p
make more videos! I check your channel often for new content. keep up the great work!
Thanks Ben! 2 videos are on the way!
As a manual machinist who likes to chuckle at engineers, thank you for this: 2:30
Haha, yeah I'm sure a real machinist could make it work. I'm awful at grinding tools. I probably could have tried with a thinner tool, but that would have been way more grinding and I probably still wouldn't have been able to make it work lol
@@TabletopMachineShop This is why engineers and machinists should respect one another. Both have their own expertise and skills. Ideally they complement each other to make great products. At least you seem aware of this.
wow live tooling on a mini-lathe I've been looking for a video like that and there's nothing, you should do a video on that, could go viral.......
Muchas Bendiciones...
*¿Cuando viene la Parte #3?*
Congrats on the sponsorship! And I love your attitude towards making things. Even if you don't follow your steps for design lol. It's easy to get stuck in a design and reiteration loop (for me especially). I appreciate your videos, they're inspiring to me.
Thanks Justin! My cnc mini lathe has been in a design loop for like 2 years now :P. Oh well...
This is fantastic stuff, you're a likeminded man. Designing a small scale injector myself.
I seem to remember a oxtoolco video where he used some 3D metal printed parts for his Sensitive drilling attachment. He said they were reasonably priced. I think he mentioned the company in the video series. Maybe a good candidate for this part? Who is that Peter Stanton you mentioned in the video? Thanks!
Peter Stanton? I think he's just a myth. They say when there's a part with holes that are 40 diameters deep or integral internal keyways he appears...
Actually I did quickly investigate 3d printed metal parts, the ones I found were pretty expensive, but a viewer actually offered to print and send me an oversized version. I think I'll do a video on cleaning it up as well, just to see how it machines.
@@TabletopMachineShop 3D printing a part like this is a bad idea. The thermal stresses and the forces associated with turning and pushing the plastic will cause it to have a much shorter service life that machined billet due to inferior grain. Not using a compression screw is also not a great idea as most of the heat that melts the plastic comes from friction. Were I doing this project I would sooner do 3-4 overnights at a fast food joint and pay to have it done right in china then do it wrong myself. Overall I like your design, but you will find the length of the screw and the lack of a compression screw to be major oversights. If it is not too late, those are things I would change.
Fantastic, what a great design. Thanks for sharing...!
Misumi > McMaster
ReprapFirmware (Duet) > Marlin
Not bad, sketchy live tooling setup....But if it works, it works. Experimental at best I'd say hits the nail on the head. Interesting. Wonder if it would've been easier to 3D print and cast that they have it like sand blasted or something, but live tooling is definitely a game changer.
Been gone for a while, glad to see you've kept yourself busy!
It wouldn't really make much sense to throw a duet on this setup. I'd probably just look at making a really simple ATMega based board with the necessary drivers, like one or two stepper drivers, a fet/ssr for the heater, and some sensing, and then have it run grbl or marlin (can't quite remember if grbl ever got temp control)
You're not exactly doing complicated 3D moves that require lots of calculations, nor are you driving a load of axies, so a duet is pretty wasted on it.
@@dumle29 You're failing to think long-term though. Learn to Automate. Create passive income. Duet boards are servers, let's not forget that. Yeah, you wouldn't be leveraging the full potential of the board, you're absolutely right, but you'd still being networking and a lot of headers, fans, and the duet can run 24v with a few amps and ssr or you can use external motor drivers or just leverage some of the result configurable pwm control for stuff. Excessive? Perhaps. But you probably wouldn't need to do all that much coding and you could have start up routines and shutdown procedures.
I do have a duet kicking around... I think it would definitely make more sense if I were selling these, but since other people are interested in making them I would be concerned about how difficult it would be to convey the setup information. I seem to recall they're a little more difficult to setup. I might look into it a little more though, it would be nice just to wirelessly connect and run a few parts...
You're a Misumi man? How could you? Actually I do like Misumi as well, I just dont like their website, I hate downloading zipped CAD with gibberish names, and I find sometimes the CAD I do get is super broken for some reason.
Very interesting. You do a great job of explaining things.
Thanks John!
The screw should have a L/D ratio of at least 18 and the thread should have a compression ratio of at least 2 for the plasticizing to be good. With those values at least two thirds of the heat will come from the mechanical processing of the plastic. It will then be evenly heated and well mixed.
Instead of using a straight screw you will probably get better results with a piston and a cylinder with a torpedo.
Yeah I think performance is going to suffer pretty severely for the sake of compactness. The piston cylinder may be the right answer, but I'm so close now I might as well fire it up and see what happens.
@@TabletopMachineShop Yes, of course you must try it. No matter what I think that you will get a result. In the worst case you have to wait a couple of minutes between every shot.
It is also possible that for the first shot you will have to feed the screw a little at a time, with pauses between, to give the machine a chance to plasticize.
I am sure that you will get something out of the machine.
If you find out that you need better plasticizing you can make the screw and barrel smaller. Then you will improve the L/D ratio.
And with a more shallow thread you will have more surface in relation to the volume of the melt, which will give you better plasticizing.
Here is room for endless experimentation.
Thanks for the Masso tip, just what I needed.
Sweet tool post spindle! Shars gets me with there shipping cost also and I'm in the US. Always over priced- they make $ on the shipping as well...
its a shame because their tools have gotten better over the last couple of years... oh well
@@TabletopMachineShop I just bought a bunch of stuff on black Friday from them because they had a discount code that basically = free shipping.
finally you are back. I am designing a similar toolpost grinder myself. but I got the same problem with the little torque. I am thinking of adding a plaetary geardrive.
Yeah that would certainly up the torque, I guess it depends on what speed you're aiming for. You could always try a brushed DC motor for more torque at lower speeds too. I was pretty impressed with this BLDC motor, even though I was starving it for current it would probably work quite well for easier metals like aluminum.
'The motor lacked torque at lower speed' ... That's why your average hobby motor can take that much more current and provide that torque from standstill to low rpm.
what an awesome vid! keep it up
The power difference between nema17 bldc and hobby bldc is that huge because of heat dissipation. The efficiency of BLDC motor usually lies between 75% and 90%, so when you run 50 watt motor you probably waste ~10 watts to heat. Thats not a lot so aluminium body can dissipate it.
But when you run a 1800 watt motor at max rpm and max torque, you'll have to dissipate ~360 watts, which is huge for this size. Hobby BLDC motors usually work being cooled by water around it (if its RC hobby boat, like in your case) or excess flow of air, like in RC planes. While nema17 BLDC is supposed to run in S1 mode (basicaly 24/7 non stop).
360 watt is enough to heat up 1 kg of water by 5°C in a minute. Thats not little.
That is really cool!
I love the live toolpost you made
Thanks!
Great to see an update up here! Been following along on Instagram. That screw is definitely quite an undertaking on a manual machine. Super cool to see the clever solution you came up with to get it done.
Thanks Josh, great to hear from you!
Awesome looking part 👍 having worked in injection moulding I’m surprised you got this close to a proper screw. Probably needs an off the shelf auger screw for hobbyists to reproduce this
Thanks! I think a plunger-style system will make this a lot more achievable for hobbyists.. It may even work better
Very cool and enjoyable to watch video. I see you figured out that a full profile form tool is too much for such a small part. Perhaps if you had used negative angle tooling the part wouldn't have protested so much. 😊 The end results is all that counts.
Thanks! Grinding tools is all witchcraft to me. I know the theory of it, I just suck at it. You're definitely right that the tool is way too wide, but the axial forces were pretty high so I didn't want to go too thin either... ah well.. more than one way to skin a cat :)
Yay! New video! Happy to see from you again. 👍
Thanks!
Other approach: First source a cheap extrusion screw, then build the machine around it: www.robotdigg.com/category/32/Extrusion-n-Injection
That having said, by default extrusion screws are chrome coated.
Wow those are inexpensive... hmmmm... I wish I'd have known about them sooner :P
Is there a reason you didn't use something like a concrete drill bit? They're already hardened steel and very heat resistant
You could have machined that screw with a single point cutting tool. Make it 3mm wide, when you reach full depth, progressively feed it along with the compound slide on subsequent passes.
Yeah someone else suggested that too. That's probably the right way of doing it, but I suck at grinding tools, so I avoided it.
any chance you could give further description or point me to additional resources on what exactly the geometry of such a tool would look like?
I was wondering ...if you can make that type of screw, how can we buy it ?
It would be great if you can tell us how
I'm interested for buying one
Is there a part 3 for this?
The generalized power rule says that wattage = voltage * amperage, and the max amperage that a motor can handle will mainly depend on the thickness/length of the wire used in the windings (i.e. a thicker wire can handle more current without overheating than a thinner wire).
Makes sense. Big beefy wire, more current, moar power.
@@TabletopMachineShop The hobby BLDC motors usually have a number n of stator coil poles on the inside and n+2 permanent magnet poles on the outside, coupled to the shaft, which gives space for a higher area of windings per pole (not going to go into motor Kv) but gives the motor a higher moment of inertia. It comes at the cost of producing the most torque at a higher RPM and it's pretty low at lower RPM. The movement isn't very precise either and the position can be easily upset, even with good driver tuning, so it can't handle loads very well.
Servo induction motors on the other hand (usually) have n+2 stator coil poles on the outside and n permanent magnet poles on the rotating shaft for a greater precision of movement with low moment of inertia and high holding torque, or at low speeds. Unlike BLDC, it comes at a cost of lower power for the same size motor and lower torque at higher RPM. The torque that can be produced has also quite a lot to do with how fast the coils can be magnetically saturated and the total magnetic reluctance of the system. Industrial servos often use very high voltages for this very reason, as it reduces the induced losses and saturates the coils faster, while hobby BLDCs can just get away with lower voltages and high currents; some well over a hundred amps for a motor fit for a small quad. A lot of heat being dissipated due to BLDC design and active cooling is key, while servos are often enclosed and passively cooled.
Driving the motors is also different, with BLDC ESCs simply chopping up DC current into three phases, with timing being usually based on feedback voltage from the coils in an open loop, though some may utilize hall effect sensors. Induction motors on the other hand are driven with inverters that produce a chopped up approximation of a three phase sine wave, with timing being controlled similarly, but also with the additional aid of an encoder for more advanced closed-loop vector control in most cases, where positional accuracy and rigidity is needed, paired with a high holding torque. This needs some tuning on a per motor / driver pair basis to get it good enough and can be time consuming. More modern drivers may incorporate an auto tune process though, requiring few steps.
BLDCs could also be vector controlled, but the cheap three phase bridge drivers on ESCs can't do that, at least out of the box and without some external logic hardware to interface an encoder. Not sure how e.g. ODrive does it, but it's one solution for using BLDC as a servo, with encoder feedback. Many camera gimbals also use them due to lower price, since the torque required to stabilize a camera isn't that great, usually.
"Machine parts" should be a duty free tax code.
Also there is usually a CNC threading cycles which should be able to cut a screw like the drawing you showed. You'd use a stout parting tool say 3mm wide and not much longer than the insert.
You'd need a somewhat rigid machine for a 3mm wide bit and have to be somewhat brave to run it, so milling it is probably better for a hobbyist. The screw looked good to me.
Agreed. I might ask them to label my orders "birthday present" or something next time :P. Yeah the machinists in our shop said they'd hand program it with canned cycles and a live tool, but our cnc lathe is always pretty busy with production stuff
I'd like to add 2 items of critique. 1. When trying to turn the screw with a form tool you did not need a full width form tool. A much narrower tool run with more passes would have done the job. If you wanted to then you could have run a wider tool to smooth the root, but I suspect you would have found it to be unnecessary. 2. A machinist and machinery builder of your obvious ability should be able to build an adjustable taper attachment for your lathe in an afternoon.
I have been following your build with great interest. I have need of a better plastic injection machine for testing myself. For now I just have a simple lever operated machine with very low volume. Eventually I'll need to get some setup for gun drilling water jackets too.
I accept your two critiques! Yeah the form tool was a disaster, I was never really expecting it to work, I should have used a thinner one and adjusted its position using the compound slide aligned with the bed. I suppose I even could have made a tool holder that held a parting tool at an angle for side clearance. Ah well. Unfortunately, the machine isn't my personal machine, so I would be hesitant to modify it in any way :(.
Thanks for the suggestions!
@@TabletopMachineShop - I definitely did NOT want to convey anything as negative. Just offer suggestions if you need to redo the screw to make it longer in the future. I was not aware the lathe was not yours.
Hi! you are a genious! (capo total!) Can you tell me more about the motor characteristics? Power, torque and rpm? Thanks and cheers from Argentina!
what did you mean when you talked about junior engineer accidentally made through holes not blind?
What is the milling spindle attachment on your cross slide? It’s really cool, I would totally implement it on my lathe. Thanks.
If you want your screw at an angle, all you need is a lathe with a taper attachment.
Yup, no luck there though :(
@@TabletopMachineShop Why not set it up between centers. Admittedly you may have to play around with the dog to prevent issues with your setup. What I am trying to say is when you are turning the dog is always loaded keeping the shaft indexed with the headstock. With a milling setup you would have to ensure the shaft can't move away from the drive dog to prevent your end Mill / part from self destructing.
offset the tailstock...
@@SuperAWaC basically what I was trying to get at
Hi, nice project.
First - the motor:
- industrial grade motors are made to be running 20.000hrs
- that hobby motor will maby last 200hrs, due to bearing overload and heat overload
- it is designed so and serves well if taken care of (lubricating and replacing bearings on time, provide sufficient cooling)
- power comes from thick wires and high currents
To the screw....
On industrial IMM's length vs diameter is something like 20:1. Not going under 15 and over 25. It is related to residence time for plastic. Going under 1.5 minutes will give you bad melt with semi molten parts that tend to block the runners. Than going over 10 minutes - plastic starts to turn to oil again.
Also - industrial machines use stroke of the screw to inject the plastic. What are you planning to use to inject?
Yup, the old 20khrs MTBF... Something tells me I won't be seeing 20000 hours out of this motor... it might have 2 or 3 left in it.
Yeah, regarding the screw, i did a bit of research before the first video (and of course watched the engineerguy video), and that all agreed with your points. I guess what I'm doing is prioritizing compactness over performance. This has caused me problems before:P
I think any mold I will use will be quite low pressure. I'll avoid using runners where possible, have lots of fairly thick vents, and be ready to clean things up with a hobby knife :P. The clearance between the screw and barrel is pretty small, so I think I'm hoping the near-static pressure downstream from the screw combined with a low pressure mold will be enough. After all, I'd be happy just molding bushings, screw caps, and perhaps the occasional bottle opener .. not lawn chairs :P
As I mentioned, I'm considering making a plunger variant -- hopefully that will be able to deliver respectable pressure
@@TabletopMachineShop
You will have at least a couple of hundred of hours out of your RC inrunner before bearings fail. Just do not overheat it.
Babyplast is usind ancient double plunger system and it works pretty well. To do some reasonable molding - you will need at least some 450bar of melt pressure.
Well - for lawn chairs you first need to upgrade the clamping unit to some 1.500 tones. Metric. :-)
Your channel is the nicest gem YT has come up with in a while. Thanks for the great content :-) BTW, the big difference between a hobby motor and an industrial one is duty cycle rating. Surely a you must know that?
Thanks! I knew there would be a duty cycle difference, and the RC motor no doubt is supposed to have a pretty solid airflow, I was more asking about the construction; the 50W for the BLDC is peak, so not a continuous duty cycle. Even if the RC motor is supposed to be run for short bursts, there's a huge power difference
Very cool. Question: Why not cut the auger using a narrow grooving/parting tool by incrementing the compound set parallel to work/spindle to increase the groove width?
That's how I would have tried to do it. Maybe he has a reason. Or maybe he's just a masochist?
I think that's probably the right answer. At the time I was concerned about being able to grind the tool (I'm really, really bad at grinding), and I also though I would be cutting a tapered root so I was worried about synchronizing multiple passes with that. The actual cut has a very high helix as well, so the tool would have to be thin enough to not chatter but thick enough that it could withstand some fairly serious Z direction force..
@@Loebane ...the second one...
any updates on this project?
Wouldn't you want a smaller gullet at the end of the screw? I'm used to seeing large screws on 2000 ton machines where the ratio is very small compared to the diameter.
Yeah, you're absolutely right, real machines do. I struggled so much just getting the root cut I wasn't sure I would be able to pull off a taper. We'll see how it work, and if not, perhaps a plunger is the way to go :)
Ive seen these sold on alibaba. Not aliexpress. You have to email to place an order.
Oh i see. Someone just sent a link for Robotdigg or something like that... they carry some nice cheap screws too... oh well, too late now :P
Hey you. I like what you do. Keep doing it.
Thanks!
Awesome.
Thanks!
Oh lovely, another update, how long has it been. I want to know everything about this injection molding machine.
Also I love your style and your explanations.
Hey thanks! Yup it's been a long time, but hopefully updates will be more frequent now!
Hello sir. You are using Solidworks for 3D models how with g code. Do you have post processor for masso ? In solidcam or other program you are using?
I'll never complain about Shars shipping prices again.
*like my short extruder screw😅
Если бы ты еще купил фрезу не с 90 градусным концевиком , а радиусным , то шнек твой был бы и крепче и лучше. Очень толстые кольца шнека , надо было 2-3мм оставлять. Вся энергия нагревателей уйдет на нагревание шнека ).
Wow, A MASSO sponsored video. Haven’t seen one of these in awhile. Are they around Anymore?
I remember they had many G2 issues early in. Last post i saw on a G3 looked positive but that was three years ago. Since then I’ve not heard it mentioned until I ran into this 3 year old video.
Compared to Linux CNC its very expensive wall art. Cant say I’ve had any issues using a PC myself but there have already been so many available online that work well to 6 axis for $500 or so. I almost pulled the trigger back than, but Im glad i decided to wait it out to prove themselves over time first. Must be a small market if still around. The G3 with touch screen is pretty. For $1400 though its still a hard pass.
What should be the clearance between extruder screw and barrel diameter
Hello Man, If you could be able to sell it (Mini extrusion screw) What it would be the cost for ?? Thanks / Greetings
Forgot to say when I said no check ring you would use a ball-bearing instead.
Hello, I would like to know if you have this Injetora project for me to purchase. I saw that you have a website and that I need to pay $ 3 a month. Is the entire project on the site, or do you add one part of the project per month?
The entire project is up, so $3 will give you access to all of it!
@@TabletopMachineShopwhen i want to unsubscribe, will that $3 not pay more?
Hurrah!!!!!!
Do a video on that spindle!!!
On the way!
Don't blame Canada it's the US boarder !!!
Just when I thought you gave up and was about to give it to me ;p
Never!
I suppose this screw is not your final one?
It will not work properly because it has a uniform depth, but the channel in the screw will need three zones, the feed zone with an uniform depth (deepest channel) and needs to be cooled, then a compression zone with decreasing depth to be able to compact the resin once it starts melting and force all air out via the feed opening, and lastly a metering zone which holds the pressure to extrude or inject the polymer, it has an uniform or decreasing channel depth.
In fact the screw will need to be twice at long to be able to locate these zones and to create enough pressure, probably there are going to be backflush problems when injecting the polymer.
How are you going to inject the polymer into the mold?
Just extruding polymer into the mold will not work, an injection moulding machine has a continous running screw which fills a chamber in front of the screw, then a hydraulic ram will force the screw forward a set distance to inject the polymer in that chamber into the mold.
After the injection stroke the pressure on the ram is released and the screw will refill that chamber with new polymer and force itself back into the initial position doing so.
I think also hydraulics will be needed to close the mold, I'm not sure if that actuator will be strong enough, as required injection pressures are somewhere between 40 to 160 bar (600-2400psi), holding pressure will be dependent on the surface area of the object to be molded.
Injection has to occur quick enough to prevent short shots, this is polymer solidifying before the mold is full.
It's a very interesting project however, and I'm curious to see how you gonna solve all the issues.
Hi Tom,
Thanks for the comment, I really do appreciate expertise :P. I guess what I'm hoping to rely on is a low-pressure requirement in the mold and a close fit between the screw and barrel. There's a bit of a space at the front of the barrel for plastic to accumulate, and I guess I'm hoping the static pressure in there will be enough to permit flow into the mold.
I'm so close with this design I figure I might as well test it and see what happens. I certainly know there's a reasonably high risk of it not working, and if it doesn't I think I'll just switch to the plunger system I alluded to in the video. I really like experimenting and finding how things do and don't work myself, so I won't be crushed if I get zero static pressure and no injection :P. Thanks again for the comment and the great description of the process!
@@TabletopMachineShop Thanks, and I wish you success with the project, it might work this way with a very free flowing mould and a low viscosity resin, you can also play around with the temperature to lower viscosity, how far you can go depends on degradation stability of the resin used, it will be obvious enough if it's too high, you will get some yellowing and excessive smoke.
Hello sir... do you use nema stepper motor or servo motor...?
Good afternoon, I would like to know if you could help me since I would like to make a machine like yours. But I don't have plans, do you think you can help me?
I want to buy this device
to have access to this project on your website, do i need to pay 3 dollars a month always, or do i stop paying whenever i want?
I usually encourage people to hang around and support the channel, but you can just stay for a month and download what you need!
You did not need to go that far. You could have bought a off the shelf oil extraction screw for low cost online. It is a compression screw.
Yeah actually those do look promising, good tip. I'd have to find a really small one though
I order castable ceramics from the US. Importing is expensive.
You who may.
It is possible that you manufacture one or more injection machines that I am watching the video of, just tell me where I can contact you so that you can send us a quote for them.
Thank you.
Gustav.
That hobby motor's giant rating assumes it is a) mounted behind a propeller and b) not going to live very long anyway.
Agreed. It got unbelievably hot. Still sounds fine (well, the same as when I got it,) but I wouldn't be surprised if this screw was its last hurrah
What is the locking pressure?
is there any chance you can share hardware cad files and code file
The auger is always the hardest part....
Agreed
can you work on marlin system please ? so it can be easy to us to make it
Do u describe these machine catalog?
I want SDL file for 3d printing
Sell the DWG plans?
hi,i also make a mini type injection machine with full electric units,it seem your melt gear wheel ratio is too small..
That's quite possible. If it turns out to be a problem I'll find a motor with a planetary gear drive. Thanks for the advice!
Hello. Did you make a working car or stop building it?
Well, looks like you are about to obtain your goal. Are the Solidworks files available and is this project going to be "open source". I would like to make some additions (mechanical or electronic). Please message me and let me know if this can be done. Thank you and best regards. "All we have is Time"
The files are available on my Patreon, except i haven't included any code or electronics -- I'm still working on something that doesn't rely on the sun being in the correct position on a prime numbered day of an even numbered month to work :P
what is the name of the material for the barrel material, sir? I had trouble finding the name of the Matrial to look for in a shop. sorry I also do not understand foreign languages. with google translation tools, hope to know. information please . Thank you very much sir 🙏🙏🙏🙏
Sir, Now I'm also looking for the same
i need the file of this project
he sells that for 1$/month
How I chose the secrew dimensions
Hello. Small Injection Molding Machine. How much for it?
Hey, sorry, I don't sell them :(
Great!! I would like to know band of lathe machine.??
band?
sir tell more about python and cad and gcode and how you did it
The Python script controls the motors and heaters directly using Phidgets, so there currently is no G-code. In the future, I'll either use Arduino with a basic screen interface, or a 3D printer board that you could send G-Code to. Boards for 3D printers tend to accept G-code one line at a time over a USB serial port connection and send after each one is complete, so it would be pretty easy to write an easy interface that took molding parameters like shot size and cooling time, converted them to G-code motion commands and sent them to the 3d printer board.
Hi hello I was thinking, are you electronic engineer or mechatronic engineer.
I went to school for mechanical engineering
why not just use a modified wood auger drill bit?
HomeDistiller because that would probably be too easy!
I actually started using one but quickly destroyed it trying to press it into a sleeve for the bearings. I then decided just to make my own... it's only one part, how hard could it be?
Tabletop Machine Shop spoken like a true engineer!
1) try the easy route
2) break something in the process
3) try the hard route
4) regret vocation
5) produced part
Kids. Ha! How did people ever survive without computers? Ok, the easy way to make an auger with a tapered root diameter (aka minor diameter) on a manual lathe. Offset your tailstock center. A boring head works great for that. Just tap it in, nice and tight or make some sort of dog for it. You'll need a dog and dead center in the spindle. Use your milling attachment. Bob's your uncle.
That's a really good idea, that was totally off my radar haha. I had done that way back when I used my own Taig lathe to make tapered pins, I just totally forgot lol. Thanks for the tip!
@@TabletopMachineShop Glad I could remind you, although I'm sure you would have thought about it eventually. I'm looking forward to seeing your project completed.