Tips on making your own delrin bushings?

[Sleepy_Steve]

I'm thinking of making a set of my own Delrin bushings for my sub frame and differential. I've got a lathe in my garage that can deal with stuff 6'' across, and about 24'' long, and this strikes me as a good opportunity to learn more about how to use it. I've also got lots of time while I look for a new job / wait for govt applications to not contact me and as I begin to consider hourly work.


But I do have a couple questions:

Where do I find this stuff for sale? Google lead me to this place (link), but I don't know of any others to compare to.

Is there a particular compound / flavor of the stuff I should be looking for? Is it even the right material for the job?

Does anyone know where one should look for dimensions of these parts? Infer from off the car measurements?

Every design of sub frame bushing I've seen that isn't metal on these cars has a metal core for the bushing. I'm going to assume this serves some functional purpose, and ask if anyone has suggestions on the dimensions and material to use for the center core?

[Jason M]

http://www.aircraftspruce.com/catalo.../delrinrod.php

You should make some sway bar bushings aswell and since you have soo much time on your hands I'll take a set for front and rear whitelines...

I think the metal core is to handle to the compressive forces from tightening the nuts onto the studs that locate the subframe.

[Def]

Try www.onlinemetals.com as well. You just want regular acetal/delrin(same thing, delrin is a tradename, acetal is generic).

The metal core is for compressive strength as was mentioned, and spreads out the radial loads more on the bushing. You could use some plain-jane 6061-T6 aluminum for this with at about a 3/16" wall thickness. Easy to machine, and cheap to boot.

I made some rear differential bushings for my S14 rear subframe out of aluminum - I'd suggest you use that as well. There's quite a lot of force on that part, and I think I ended up having about 1/4" of wall thickness on the back side where the nut bottoms out. As for dimensions, this is one of those times when you just need to break out your caliper and do a rough sketch and start machining. You'll probably suck at it if you've never designed or machined a part before, but they're all simple pieces so you'll pick it up quickly.

For subframe bushings just make them one piece and pull the subframe up to the body. I think you'll find acetal is expensive in that diameter, more expensive than aluminum. So I'd just make the subframe bushings out of aluminum really. Less hassle than having to make a separate sleeve.

[Matt93SE]

We buy raw material and machined parts for my work from Nationwide Plastics. We use the Houston office for obvious reasons, but these guys have several offices in the south and farm out the machine work to shops all over the country.

The Houston office is: 888-434-6593. My contact is Steve Downer.

for a chunk of raw material, definitely give him a call and they should set you up with a decent price. (Last week I bought a piece of 12" x 24" x 0.5" UHMW for under $20... It's listed for $28 +ship at McMaster and Onlinemetals.com)

[Sleepy_Steve]

Edit... skim reading got me again.

[Sleepy_Steve]

Honestly, I expected to see acetal as a bit less spendy than the cheaper alloys of aluminum. They are right around the same price in the sizes I'm looking at.

Time to go measure the diameter of my diff and subframe bushings I guess.

[Def]

The only benefit to acetal over aluminum in those sizes IMO is that a press fit has a much wider tolerance range. Probably on the order of 0.005-0.010" would work. Aluminum you're going to have a 0.002-0.003" window or so.

[Sleepy_Steve]

If thats the case, my decision may be made for me due to my limited skill with my old (assuming cheap Chinese harbor freight) lathe.

[Def]

I wouldn't say you can't make anything out of aluminum. I've made quite a few pieces on my Chinese mini lathe(7x14).

[cazman]

The easiest way is just to buy some ready made. Lol

[Equinox]

Do you even have any left? :P

I'm using mine to space out the foundations under my house at the moment.

[Tower240sx]

a press fit has a realistic tolerance of +.001/-.0 in Aluminum (and that's being nice) I think Def is assuming you are going to use heat and cold to install with those tolerances.

Delrin is much more conforming.

Your lathe will work fine if setup correctly, get a cheap DRO (digital Read Out) or some 0-1" travel indicators on magnetic bases setup to measure actual slide position this will help eliminate backlash inaccuracies in the diameter. make sure all the gibbs and ways are tight and use a good lube and you will be surprised what cheap $hit can do.

[Sleepy_Steve]

Well if I had a job and less spare time I'd buy some... But as it stands, this seems like a decent use of my time.

I think we've got a magnet mount run out gauge... Is that the same thing as a travel indicator? I'm very much a layman when it comes to using my lathe.

[Def]

a press fit has a realistic tolerance of +.001/-.0 in Aluminum (and that's being nice) I think Def is assuming you are going to use heat and cold to install with those tolerances.

Delrin is much more conforming.

Your lathe will work fine if setup correctly, get a cheap DRO (digital Read Out) or some 0-1" travel indicators on magnetic bases setup to measure actual slide position this will help eliminate backlash inaccuracies in the diameter. make sure all the gibbs and ways are tight and use a good lube and you will be surprised what cheap $hit can do.

Yes, I think a +.001/-.000 tolerance is unrealistic on a cheap home lathe, so cold + heat + BFH are your friends in "making it work." It'll still be closer than SPL's press fit stuff with some attention given to it. Although the larger aluminum stuff can usually do a +.002-.0025" press fit once you go over about 1.5".

The problem with cheap lathes is not so much making them tight(which is a necessary step, don't overlook this before you machine ANYTHING!), but that the bed, chuck, and ways are usually not parallel/perpendicular to each other. So you end up with slight tapers in every direction. It's not a problem for 90% of the parts you'd want to make on a homemade lathe, but it does present some big PITA issues when trying to do press fit pieces over "large" lengths.

[Tower240sx]

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