Needle cutter v2 lives!
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- เผยแพร่เมื่อ 21 ก.ค. 2017
- First v2 attempt failed pretty spectacularly. Still not sure why, but the flywheel/needle bearing got hot and melted the flywheel causing them both to go flying.
It is shaking quite a bit in the video because 1) I hadn't put in the screws that lock the quick change mount in place. 2) I haven't fully balanced the flywheel yet.
But now it's coming together. Still room for some improvements, but should be cutting foam later today!
Flite Test Forums thread discussing the needle cutter: forum.flitetest.com/showthread...!
Hello! Is it suitable for corrugated cardboard?
Totally awesome Idea! Thanks for the information!
I am little slow so here it goes :)
It got hot where the bearing is at top on cam is that correct? And got hot below in the needle guide? Thank you I am humbled at people like you and others on this post, smart peeps!
This looks excellent, I made a similar one (a TimSav variant) but the needles keep breaking, to the point where I've never used it because I can't finish a cut. How does the flywheel attach securely to the motor without a nut? I see that your motor stops slowly after you kill it, unfortunately my ESC brakes instantly so the flywheel tends to rotate out of the shaft...
How do you balance the flywheel? I don't see any counterweights.
The flywheel attaches with 4 tiny screws since the bell housing of this motor is tapped to accept a prop adapter. They're hard to see since they're countersunk into the face to clear the needle.
I balanced it by putting it on a prop balancer and adding/removing washers and a small screw on the backside.
I had a lot of problems with breaking needles at first as well - then I bought a cheap $13 tachometer and realized I was running it WAY faster than needed - since dialing the speed down I've only broken 2 needles. 1 while experimenting with cutting cardboard (it works...but you have to go REAL slow and it wears needles out fast) and one after 2 years of regular use.
@@jhitesma That's very useful, thanks!
The tach was really worth it. When I first started with the needle it was suggested to just do the math calculating RPM based on the voltage and kv of the motor then setting the "throttle" appropriately. But what I found is that all of the ESC's I had were decidedly non-linear so doing that didn't get anywhere near where I thought the RPM would be. Once I had an appropriate throttle setting figured out I configured a servo channel on the RAMPS and sent some manual gcode commands to dial it in just right - then once I knew the value to use in the gcode command I added that to my startup gcode so it all goes automatically.
@@jhitesma Hmm that makes sense, thanks. So 7500 RPM is a good speed to run it at?
Honestly...it's been almost 4 years since I had to think about RPM. So....if that's what I say or show in the video it's probably right. But due to some life changes my machine has been buried for 2 years now and I'd have to clear it out, fire it up and take a measurement to confirm.
I love your machine! I wonder, how often do your needles break? I am planning on .020" piano wire with a .030" tip. Too bad about the tip getting hot. Is there any negative effect other than possibly melting your PLA?
In almost 4 years of running it and a couple hundred sheets of foam I've broken 3 needles. 1 was when I was experimenting with cutting cardboard and pushed it to see how fast I could go. 1 was with an earlier crankshaft design that had tighter bends in the loop. The last was after about 80 sheets of foam when I knew the tip was getting dull and needed a bit of sharpening but I was lazy and kept putting it off. As long as you're careful to avoid creating stress risers (use round tipped pliers when bending the music wire and don't rebend the same spot) and keep them reasonably sharp they last a long time. Once I got the speed dialed in and added a small wad of cotton with a few drops of light oil I stopped having heat issues. The melting is the biggest issue with heat - and can cause the whole thing to jam up as the melted foam is pulle dup into the guide and then cools getting hard causing things to bind. I've done about half a dozen sheets back to back (about 2 hours of cutting) and the tip was still cool to the touch once I got it dialed in.
what do you use for the needle? It's kind of some music wire? like gita,or piano?
Yes, just hardened piano wire I get at the hobby store.
Are you controlling the esc by a servo tester or are you able to control it from the ramps board?
When I was recording this (and up until about a week ago) I was just using a servo tester. But I'd been planning on controlling it from the RAMPS before I even built the machine. Last weekend I finally tweaked my start/end gcode so it's now fully controlled by the RAMPS. It's not 100% ideal...since the RAMPS doesn't output any signal until it gets an M280 command I have to a "M280 P0 S0" then pause for 5 seconds to allow the ESC to initialize. Then I do a "M280 P0 S85" followed by another 5 second pause to allow the motor speed to stabilize. But...the S0 is only needed the first time I power up the machine so there's a 5 second pause at the start of most programs that could be eliminated if I modified Marlin to start outputting pulses at boot. And the second pause probably doesn't have to be 5 seconds. But even with a 10 second pause at the start it's so much nicer than setting the speed manually I'm not in a big rush to improve it. Deails on how I set it up here: forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle!&p=369010&viewfull=1#post369010
Nice! Thanks for the info.
What? I can't hear your motor over the commentary.😋
Just wait...full sheet cut video with the new cutter is rendering now ;) I don't talk quite as much on that one :D
fireworks