Shaping and Cutting Rubber Bushings

[Guest rsd9699]

Hi,

I need to replace the rubber isolation bushings on my 56 Oldsmobile factory air conditioning compressor brackets.

I have not found any replacements per say that just drop right in.

What I have found that are readily available are the front engine rubber bushings found on the mid to late fifties Chevy's.

They are are about the right diameter but are too thick. I was wondering what methods that I might use to make a fairly clean cut through the bushing to obtain two equal size parts.

My current thought is to mount it in a chuck with a bolt, spin it. and use either a hacksaw or a sharp knife to do this. But I wanted to see if others have a better way to slice and dice than me.

Ron

[Bhigdog]

Rubber is always tough to reshape. Without seeing the part, some options are to freeze the bushing in dry ice and alcohol and it will machine like hard plastic until it warms up. Use sheet rubber of the correct thickness from McMaster-Carr and cut the bushings out with a hole saw. I've done that a lot. The bolt/knife method is iffy but if you try it use a scalloped blade knife and soap lube.............Bob

[nickelroadster]

A band saw works well. Then clean up the cut with a power sander.

[Guest rsd9699]

You are right about needing some type of lubricant. Is that knife like a steak knife (ha ha). I don't have access to a bandsaw sadly.

Ron

[Dave@Moon]

My current thought is to mount it in a chuck with a bolt, spin it. and use either a hacksaw or a sharp knife to do this. But I wanted to see if others have a better way to slice and dice than me.

Ron

I remember years ago someone doing something like this (spinning a rubber part slowly by hand), cutting a small rubber part down using a very hot wire that had to be reheated occasionally with a propane torch. It stunk, of course, and had to be done outside for ventilation. Has anyone else tried using this method?

[auburnseeker]

I've used a right angle air grinder with coarse say 120 or coarser sanding disc on it. I had some think bumpers that needed to be shortened to allow something to close. I tried cutting them and that didn't work well. The grinder was the trick. If they are really different I imagine cutting it somewhat close and finishing it with the grinder would work well.

[Bhigdog]

No, but it's a very interesting concept. A short length of nichrome wire in a frame connected to a variable transformer would be the "hot" set up. One problem is the layer of carbonized rubber that would be left on the parting surfaces. Cutting a cylinder of anything on a bandsaw is problematic. A short rubber cylinder would be very dangerous without a set up to hold it from grabbing/spinning and pulling fingers into the blade. If you want to try the knife bit use a very sharp scalloped blade type knife. Band saw blades for rubber are scalloped not toothed. You might try using an electric carving knife but in any case use lots of liquid soap and be careful...............Bob

[Restorer32]

We cut rubber bushings on our bandsaw using a dowel thru the center to hold them, then follow up with sanding. You can even polish rubber a bit with compound on a buffer. We've done it many times. We have also cut them on a table saw.

[Guest rsd9699]

Hmmm,

They make a soldering gun blade that I see used at the hardware stores to melt (cut) the plastic ropes to your specified length?

I have also thought about the round hacksaw blades used to cut glass?

Ron

[Guest dstaton]

Ron,

How did it work? I am facing the same task.

How well did the Chevy bushings work as stock?

Thanks,

Doug

[Guest bofusmosby]

Over the years when I have had to re-shape anything rubber, I have used a bench grinder. Of course, you have to be careful, but it has always worked for me.

[Guest rsd9699]

I used a 3/8 inch bolt. Used two of the flat washers from my compressor mounting bolts and then sandwiched the rubber mount between them. I double nutted the bolt. I then chucked the bolt in a drill chuck mounted on my grinder. I used an hacksaw to cut the rubber as it spun.

Do this in a ventilated area as smoke is produced. Also some hot melted rubber is slung so be careful!!! I tried using knives but the hacksaw worked for me as the best tool.

I am reasonably pleased with the results.

Some pictures.

Ron

[Guest dstaton]

1/2" stock 6"x6" was $8 from local supplier.