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Discussion in 'Workshop Tips and Secrets / Tools' started by FritzW, Dec 18, 2016.
I'm in no hurry. Just summarize on 6th grade reading level and post here when done. :gig:
I believe there are some really tough nylons (nylon 6?) and then maybe not so tough. Bearing design is not trivial, but as a guess I would think bearing strength Fby and wear are the important factors. The fiber reinforced plastic should wear better.
Yes, I do. And for me printing real parts (structural) that will go in a real airplane, if it ever happens, is a looong way off. But you can't test a part unless you can print it. This is just the very beginning of a never ending educational process. ...and I gotta start somewhere
Obviously, but it's probably the strongest material I can print with my humble little printer, and the most chemical resistant (PLA and ABS won't work for that reason).
For rudder bushings on our p40 I looked at 3d printed setups for a brief minute, but ultimately, using a sleeve of Acetal tubing is so cheap @ around $8/ft, that we went with that as the solution.
I pretty much only will be using 3d printed bits on the P40 for fairings and small details in the cockpit.
The plans call for Teflon but most folks use Nylon or Delrin. The plans also call for them to be glued in, no bolts (ever try gluing something to Teflon?)
I've made several sets (machined, not printed) for myself and the guys on the VP newsgroups. The loads are very low and very well understood. And the most likely failure mode would be wearing out and not a catastrophic failure, even if one broke.
The scarry thing would be using a CF impregnated bushing on an aluminum tube (they don't get along). But my next VP rudder tube will be CF and the interface between the mating surfaces will be Teflon so that's not a problem.
...but this is a printer build thread and I'm waiting to see some of TF's build pictures
This is exactly what i need, i designed the parts for my design and am trying to figure out how to print them out without spending a fortune.
This is what we have so far. Will try and attempt a "test" print after dinner:
Nice.You already have a bunch of parts I still need to print (belt tensioners etc...)
Unless your P-40 has a full flying rudder and a 2" rudder tube, I'm sure it's a completely different animal than what I'm talking about.
exploded view, red part is a strip of .040 PTFE (Teflon)
...it'd be tricky to make these out a piece of Acetal tubing
How many hours do you get out of the PTFE? against that other plastic probably lots, nice design
Belt tensioner on x axis broke when we tightened it up. Had a large internal void so I don't know if that's why it broke or not. I glued it back together with epoxy.
Bummer. Was it printed in the right orientation? ie. did the layers break apart or did it just break?
I tried to take a picture but the break doesn't show up very well.
Here is the first print - a 1cm cube
The parts you have printed look pretty good. I don't think you should be too concerned about difficulties printing nylon. I found it easier to use than ABS. I think the trick is to dry out the filament before printing because nylon absorbs water from the atmosphere and the water will boil off in the print head causing bubbles in the print. The photograph shows a part I make from nylon which would be difficult. or at least expensive, to make by any process other than printing - it's the operating screw for an adjustable air vent. The screw is nylon, chosen for it's flexibility, while the nut is PLA. The thread is 12mm x 6mm pitch double start.
BUT, the only structural part I make by printing is a flap stop (see http://www.ansoneng.com/sample-page/products-summary/adjustable-flap-stops/) and those are only loaded in compression so the bond strength between layers is not so important.
I probably wouldn't run away immediately from 3D printed bushings for a plane depending on where and what they're used for.
I had a friend who was experimenting with Delrin and another thing he called POM and he printed quite a few things that have held up amazingly well.One of them was a spherical rod end for shifter in a VW I had.After about 2 years of daily driving it was still solid when I sold the car.He also did some strut top bushings and sway bar bushings for me to test out and they also held up really well and considering the strut tops were a big problem on those cars I was surprised.
I'm not saying that I'd use them in a position that if they failed it would cause a serious issue.But most bushings are used in places where they could completely disintegrate and you would still retain functionality although not for long without serious damage.Most cases they're considered a wear item and you'd most likely notice any excessive wear long before they'd become a real safety issue.
So if someone didnt have access to a lathe or needed a odd shaped bushing in a noncritical area I think it could be a viable application.
One thing I should add is he did have a pretty advanced printer that could use filament or pellets through a hopper and the Delrin came in pellets.So that very well may have had a lot to do with the quality of the parts that he made for me.
The 3D platform has my brain in high gear! I already want to put a router in place of the extruding nozzle and start cookie cutting some wing ribs!
I want to go the other way and add an extruder to my cnc machine and make a 4'x8' printer
Update on the flap handle:
It's in, worked great. It took a little massaging to get it on but now I know to print PLA scaled up a little, ~100.4%
I also printed a little switch "background". It's mostly for looks but it does ensure the fuel site tube (when it's mounted) can't interfere with a switch.
And finally, a little table to hold the printer:
I have to get it finished and get the printer off the dining room table before the Memsahib get's home. ...and the garage is too cold for the glue to setup
I just stumbled on this and figured I'd share it here.
Needless to say I was quite surprised and to be honest with a little bit of optimization I probably wouldnt hesitate to run one on a little back bay/lake boat.I actually mangle quite a few props yearly on my skiff crabbing and at $60 a pop they add up pretty quick.
But if they'll hold up there who knows what else we can do.
Wow! that was an eye opener. The order I guessed they would finish in was just about opposite of how they really did (good thing I wasn't betting on a horse race :gig. It's too bad they couldn't test the Nylon prop.
That's it in a nutshell. Reliable, hobby level, 3D printing is still kind of new. I wonder where the technology will go in the next few years?
Free/cheap CAD software and $200 3D printers... I think some really clever ideas are about to start popping up all over the place.
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