Custom bushings

[jman4747]

Originally Posted by David Guzman

A great material for bushings is UHMW (Ultra High Molecular Weight Polyethylene).

We used this extensively, not only on the robot but at work for many bearing applications. It is very easy to machine, has a very low coefficient of friction and can withstand significant loads for a plastic.

You can get rods from McMaster fairly cheap.

I would say +1 to UHMW, Delrin (Acetal Resin), or Nylon 6. All inexpensive all great bearing surfaces.

Another thing to consider if you can wait I would research different suppliers, Mc Master Carr is the fastest and arguably the best but not always the cheapest.

PS "All inexpensive" is a relative statement.

[asid61]

The thing is, the bushing looks pretty strange, and I can't really change the design at this stage (it follows an ultra-space-saving design that requires its weirdness). Basically I changed the design so it can use a smaller bearing, which is like 7/8" inner diameter and 1.125" outer diameter. However, it has a very large flange that's around 2" outer diameter. I'll look into using plastics for machining and cost without sacrificing strength. I've used UHMW in the past, but we tend to have a lot of acetal so I'll try that on aluminum too.

[highlander]

Originally Posted by asid61

The thing is, the bushing looks pretty strange, and I can't really change the design at this stage (it follows an ultra-space-saving design that requires its weirdness). Basically I changed the design so it can use a smaller bearing, which is like 7/8" inner diameter and 1.125" outer diameter. However, it has a very large flange that's around 2" outer diameter. I'll look into using plastics for machining and cost without sacrificing strength. I've used UHMW in the past, but we tend to have a lot of acetal so I'll try that on aluminum too.

In my experience Delrin machines really easily, while UHMW has a much lower coefficient of friction. However, UHMW is annoying to machine.

[colin340]

Originally Posted by DonRotolo

You could cast some Babbitt, but that's way old school.

props to don for going Hit and Miss style on CD old engines are cool.

What about junk yard parts or an ATV spindle.

[hrench]

Originally Posted by asid61

I looked into ball bearings in the 3" range, but they all cost more than $100. turret.

Ball bearings are just better than bushings and they're not expensive if you know where to look. just went to ebay and entered '75mm bearing' and here's two for $6.50 each.

http://www.ebay.com/itm/$@#$@#$@#-6215-2RSR-C3-Deep-Groove-Ball-Bearing-75mm-Bore-130mm-Outside-Diameter-New-/390838773352?pt=BI_Heavy_Equipment_Parts&hash=item 5affce6668

[asid61]

Originally Posted by hrench

Ball bearings are just better than bushings and they're not expensive if you know where to look. just went to ebay and entered '75mm bearing' and here's two for $6.50 each.

http://www.ebay.com/itm/$@#$@#$@#-6215-2RSR-C3-Deep-Groove-Ball-Bearing-75mm-Bore-130mm-Outside-Diameter-New-/390838773352?pt=BI_Heavy_Equipment_Parts&hash=item 5affce6668

Interesting. I never thought to check for metric sizes.
The problem is there are some holes machined in the flange of the bearing. The main bearing is 2" OD, but the flange is 3". I need the huge flange for mounting holes to other stuff.