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- เผยแพร่เมื่อ 14 ก.พ. 2020
- Bit of backyard casting of an impeller I designed using the lost PLA method. They had a few imperfections from plaster entering the PLA part so I will need to cast these again. Hopefully printing them slower will seal the print better.
wow that really looks great. So smooth the casting come out great.
Thanks Doc 🤙
Skilled man 💪💪
Nice work
Thank you for sharing.
Thanks for watching.
Mixing sand with the plaster helps keeps the mold from cracking. I did not do this here and this is the reason these impellers failed.
Thanks for sharing your files man, not everyone does that willingly, I checked your impeller design and one thing I've noticed is that you might need more fillet where the blades meet the hub, other than that you did an amazing job
@@Eden_M Thanks for the feedback :). Hopefully I can get back to this project soon!
Nice Work. I'm considering the same techniques now to refurbish a 1980's stand up Jetski that has an impeller in very poor condition. Similar design to your 3 blade impeller. What did you use for the 3D modelling ?
Hi @trkclark, I use Solidworks. You could also use Fusion 360 which it's free. Since you have the old impeller there to copy it shouldn't be too hard to model it as you've got all the dimensions. If you do cast it make sure you make the dimensions of the 3D printed part around 2-2.3% larger to account for shrinkage of the metal. Also you will want to make the diameter slightly larger so that it can be turned down to spec in a lathe. Good luck.
Hi, thanks a ton for this video. I'm building a Schreckling's microgas turbine and was looking for methods and experiences of people on how to cast impellers. Mine is 68mm in diameter. I built a DIY furnace last year and 3D printed some impellers out of PLA with a blade thickness of 5 to 10mm.
What's the thickness of your impeller blades? And what minimum thickness do you think the mold can take before PLA melts and mold collapses?
My university doesn't have a 5axis CNC, and they're expensive to use to make one or two impellers.
Hello Vinith, impellers were around 2-3mm depending on the model. The only problem with using these with a gas turbine is imbalance might be an issue.
Good luck
That's true. Full throttle translates to around 120,000 rpm, the vibrations can destroy the shaft assembly too. Thanks, I'll keep that in mind.
What's the max rpm your impellers bear? And could you describe your methods or make a video for resolving imbalances in your castings?
@@vinithkaradi1104 I don’t think this casting method would be suitable but hey if you have the tools it wouldn’t hurt to try.
These impellers are designed for 10k - 16k rpm.
Could you repurpose a turbo charger impeller and turbine? It would be a centrifugal type turbine.
هل هذا القالب مصنوع من الجبس العادي
Hi Adam, could you share those 3d files of impeller and nozzle assembly?
Hi Abdul I certainly can. I have lost time to complete this project as I am back are University. Hopefully I can start working on it again at the end of the year.
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The slip on type pump was my current style I was designing.
Hello Adam, that’s cool! What diameter impellers are these? And did you print the wax model yourself? Thanks, Hendrik
Hi Hendrik, these impellers are 92mm and printed in PLA. I use the lost PLA method to cast these. Another option which might be easier is to mold them in carbon fibre.
Adam Gow molding them in CF might be difficult as the blades overlap somewhat making for an intricate mold-design. Personally I like the aluminum solution, aspecially in the prototype stage. Do you have a machine shop available to machine the impellers to final size in order to fit smoothly on driveshaft and in intake/stator-endbearing etc? They will probably end up being a bit smaller than 90 mm after machining due to material shrinkage during the cooldown. Nice work Sir!
@@hjl4004 Thanks! I've got a small lathe but I'm a novice and need more practice. The impellers that I had casted before the ones shown in the video have a high degree of accuracy and only needed facing to remove the sprues. I was going to 3d print a nylon or some other suitable material wear ring which can be adjusted to give the desired clearance been the impeller and housing.
Adam Gow that’s great work; especially the 3-bladed design seems to have ample space between the blades for picking up and pushing enough water into the pump. I’m not sure about the 4-bladed one, this might work better with a bit longer hub. But you’ll test that anyway and probably prove me wrong😁. I’d do a bit of work on finishing them: balancing them is key to keep everything in one piece when the rpm’s go up, aspecially since they’re made of relative “heavy” aluminum as opposed to CF. And sanding all “wet” surfaces that are in contact with the waterflow inside the pump to a fine grit should increase flow efficiency a bit and might help against cavitation as well (considering your impeller design is okay, which it seems). Heck, you might even polish them like they do with metal high rpm RC boat propellers! Turing down the outer blade edges on the lathe to make a perfect circle will ensure a snug fit inside the wear ring (0.3-0.5 mm space) this will definitely further improve your pump efficiency. And finally I’d make absolutely sure both front- and stator-bearing align perfectly. Running the pump with poorly aligned bearings will surely break the driveshaft and ruin your pump’s internals. Are you going to cast the stator+housing as well? Btw use PEEK rather than Nylon as nylon will take up water and swell gripping your impeller. With PEEK you’ll be able to run a much snugger fit. Cheers, HJ
@@hjl4004 Thanks for the info. I have already casted the stated housing for a smaller impeller (83mm) but realised this is probably too small. I've seen people use stainless pipe and weld up a stator housing so that could be an option too. My pump will use phosphorous bronze bushes so axial movement will not be contained by the pump. I was going stop the axial movement by either using an outrunner motor like the 12090 from alien systems or some sort of petrol motor like an outboard power head.
Also I forgot to mention I print my models 2.3% larger than required to account for shrinkage which seems to be pretty spot on for the material I am using ( aluminium car wheels).
Here are the cad models if you are interested.
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Very good Dadá dies 🤔 🖒
You did not explain the whole way Well done anyway
kwee kwee kwee kwee kwee kwee kwee... sort of miss fake ducks... except when broody. lol, they arent ducks. and they arent geese, either... they are what they are. muscovy!
erm. each to their own. very nice work, but "lost wax" techniques are... messy and expensive. only worth it when the design is complex... learn to greensand.
thats a really easy design to split up into two patterns, cope and drag... include the risers... just CAD it out and print the two patterns, ram up, pour.