Foo - other materials besides delrin to consider?

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phantomcow2
02-13-06, 07:18 PM
I am considering using delrin as a linear bearing. It would be drill rod maybe 1" diameter, with delrin bored to something like 1.001". I have machined delrin a lot, but never used it for anything except leadnuts.
THis would be a reasonably high speed application, moving probably about 350 inches per minute max. Are there any other materials i should consider before going through with this? Or is gold old delrin #1?


Rev.Chuck
02-13-06, 07:49 PM
I know guys that use delrin for bushings, but not bearings. Seems like high speed would be better suited to a cartridge bearing.

phantomcow2
02-13-06, 08:16 PM
it would not be for a radial bearing, but a linear bearing.


slvoid
02-13-06, 08:28 PM
Sapphire.

Namenda
02-13-06, 08:33 PM
I suppose cheese would be out of the question...

MERTON
02-13-06, 08:54 PM
what's delrin?

slvoid
02-13-06, 09:55 PM
It's the blue stuff they make jeans out of.

Stacey
02-14-06, 04:21 AM
Have you thought of sintered bronze?

slvoid
02-14-06, 04:33 AM
Try oilite.

sngltrackdufus
02-14-06, 04:37 AM
hmmmm...
maybe Babbit could possibly used as a bearing material.

Rev.Chuck
02-14-06, 07:58 AM
That explains the 350 inches per minute. I think (but don't know for sure) that it would work fine for that.

Chimera
02-14-06, 02:17 PM
Ertalyte would be another possibility.

DannoXYZ
02-14-06, 02:20 PM
cast-iron?

bennyk
02-14-06, 02:35 PM
nougat?

iamlucky13
02-14-06, 07:27 PM
What kind of load and how much bearing surface area?

Is it feasible to use a roller setup, instead? Ultra-high molecular weight poly-ethylene or Nylon might also work (I believe the former works better for this sort of thing). Generally, when using plastics for a bearing surface, you don't want to oil it, because this attracts dust which acts as an abbrasive.

sngltrackdufus
02-15-06, 12:09 AM
Monel might work

phantomcow2
02-15-06, 02:31 PM
What kind of load and how much bearing surface area?

Is it feasible to use a roller setup, instead? Ultra-high molecular weight poly-ethylene or Nylon might also work (I believe the former works better for this sort of thing). Generally, when using plastics for a bearing surface, you don't want to oil it, because this attracts dust which acts as an abbrasive.

Shaft would be 1" diameter, maybe 1.25. Length of delrin (or whatever other material i decide upon) would be 3" long, but two of them spaced 8" apart.
These ones would have a 40-50lb load resting ontop

What i am doing now is using roller blade bearings (abec 7 with 8mm bore) rolling right on polished conduit pipe. This is very smooth, very smooth indeed. But I am not satisfied with two things:
Since the outer race of the bearing is rolling on the conduit, i need a mechanism to preload the setup, basically pushing it against the pipe. This is all fine, i have suchg a mechanism created already using threaded rod. However due to the mechanical advantage of the threaded rod, and the nature of the the RADIAl bearing, the axial load capacity is very easily exceeded. This produces a "lumpy" feeling.

Its kind of a pain to make all the parts, and mount it. Where if I had a linear bearing, i could just make an aluminum pillow block with nice pretty mounting holes and off I am.

MDF dust is going to be all over the place, I like how the plastic linear bearing is unaffected by this. BUt i dont think the roller blade bearing setup will be much affected either, so theres one thing./

iamlucky13
02-15-06, 10:52 PM
Dang...there had to be a round shaft on top of it. I don't have my machinery's handbook with me, and I don't remember the formula for contact stresses of round objects, but my gut says this application will be fine under the load you're talking about. Alternately, is there any way to use a leafspring to keep preload on the roller skate bearings?

Looking over materials properties, I think nylon or delrin are roughly even for applicability. I know my boss used some sort of graphite laminate for a pretty high load (well beyond what you're doing) bearing surface in a recent test, but I think it would be kind of spendy and he was pushing it with hydraulics, so friction wasn't really a big deal, just wear resistance.

DannoXYZ
02-16-06, 12:04 AM
If you are loading a bearing axially, why don't you just add another bearing at 90-degrees to the existing one?

sngltrackdufus
02-16-06, 12:12 AM
I think a Muffler bearing might be a good application for that :o

sngltrackdufus
02-16-06, 12:17 AM
I know guys that use delrin for bushings, but not bearings. Seems like high speed would be better suited to a cartridge bearing.
would it be effective to use Delrin as bearings in bicycle wheels?

TexasGuy
02-16-06, 06:53 AM
I'm not sure if somebody has suggested this but I think cheese or Duct Tape could hold up real wel

klondike300
02-16-06, 08:44 AM
Oilite works great. Just machine it at a low speed or else all the good stuff flies out. If you have the right machine and abillity. You can also put grease grooves on the inside of the sleeve/bearing. My former job as a machinist we made quite a few of them.