Friction disc recommendation, huge old GE camelback drill?

I have recently acquired an ancient and huge Gould & Eberhardt camelback drill... 37" swing, powerfeed and backgears etc. I'm currently in the process of getting it mechanically operational, prior to a clean & brighten phase. I now have all the feeds and speeds working to the spindle, and even the power up/down to the drill head itself, but the remaining weak link is the friction disc in the variable speed arrangement for the powerfeeds/power traverse for the drill head.

I've found some discussion of similar friction discs- some are made of paper from what I can gather, although this one looks perhaps to have been a rubber type material. At any rate, it's worn down to the level of the surrounding steel hub and needs to be replaced with new material.

My options, as I see them: some type of hard rubber, in sheet form, which I'd cut and stack.
Heavy leather, cut and stack discs.
Or, use some paper or canvas phenolic block to turn a new disc from (I have both)

What would you guys think is best to try first?

Here's an original GE flyer for the drill, followed by a terrible quick phone video of the drill (apologies for the vertical format, low resolution, and noise level etc.)

Thanks for your input.

I made a friction disc out of a plastic called red pattern board I got from a forum member.
It seemed very similar to Delrin.
The original was some kind of paper phenolic or leather material.
The plastic disc works great.

Interesting... that pattern board appears to be a species of high durometer, dense polyurethane sheet. In small pieces I'm finding it available through McMaster, but looks as though smaller, cheaper salvage pieces yet can be found on Ebay, black 90A durometer polyurethane sheet. I may pursue that, as it looks as if it has the properties of a rubber with high wear resistance, which seems good...

I would go with leather.

Older small riding lawn mowers and other light power garden equipment used a very similar friction drive arrangement to give variable speeds as well as reverse gear. I believe these drives used a rubber-edged friction disc.

Enginebill makes a good point in recommending the use of leather. In early automobiles, and on some lineshaft and machinery drives, leather-faced cone clutches were used. Leather is an excellent friction material- if it were not, flat leather belts would never transmit power. If a thicker disc is required, cutting leather discs and laminating them together should work. Cutting a stack of discs and gluing them with "Barge Cement" would be one way to laminate them together. Barge Cement is an old product used by leather workers, as well as for sticking gaskets where they belong on large joints.

The friction disc has to have the right combination of friction plus some small amount of slippage. Leather discs, sandwiched between two steel plates with a bit of leather projecting beyond the circumferences of the plates, seems like a good substitute for the original paper disc. Some rosin on the leather will increase friction if need be.

At the powerplant, we used to have to make replacement insulating mechanism parts for high voltage air circuit breakers. The material used was a laminated paper product. It was a hard material and we used to machine it to the required geometry using regular machine tools and HSS cutters. It was too dense to cut with a circular saw, so we used to cut it to rough size with a bandsaw. It drilled and tapped with no problem. It had a grayish color and the laminations could be seen in the edges of the material. We used it because it was what the OEM of the breakers had used. We were going for dielectric strength as well as mechanical properties. The parts used to wear out from a combination of mechanical wear and arc flash/burn. We kept it in stock at the powerplant for as long as we had those air circuit breakers. We phased them out a few years before I retired, in favor of "SF 6" (inert gas atmosphere) circuit breakers, and I've been retired 6 years.

I never learned the name of the material. I think that while it is a commercially available product, it might actually be a bit too hard and not have a high enough coefficient of friction for a friction drive application. The stuff is so strong that we used to cut up the scrap and mill it to make blocks for use in fixturing work on the machine tools. I do not know the name of the product, but, like anything else, I am sure that the manufacturers are on the internet. It's worth a shot to look into it.

Joe, the material you speak of sounds a lot like paper micarta or phenolic. Being a knifemaker, I use phenolic from time to time, in linen, canvas, and paper versions... it's great stuff for handles. As you describe, it machines readily and is very useful for other things around the shop such as fixtures. I think you are probably right though that these materials may not be grippy enough for my application here. It's true that one has to imagine back to when this machine was designed, and think of what materials would have been used at that time... leather does seem likely, and I'm saving that as a backup method (last night I went ahead and ordered some 1" thick 90A durometer polyurethane sheet to make a friction wheel from.)

Thanks for all the responses fellas, and I'll report back with a general report on the drill soon, including the friction plate assembly.

If all else fails You could always try these guys. They may have a pattern that is close enough.

home

I have drill press envy.

Does the disc running dry or in an oil bath (my situation) make a difference in material choice ?

Joe Michaels said:

At the powerplant, we used to have to make replacement insulating mechanism parts for high voltage air circuit breakers. The material used was a laminated paper product. It was a hard material and we used to machine it to the required geometry using regular machine tools and HSS cutters. It was too dense to cut with a circular saw, so we used to cut it to rough size with a bandsaw. It drilled and tapped with no problem. It had a grayish color and the laminations could be seen in the edges of the material. We used it because it was what the OEM of the breakers had used. We were going for dielectric strength as well as mechanical properties.

I never learned the name of the material. I think that while it is a commercially available product, it might actually be a bit too hard and not have a high enough coefficient of friction for a friction drive application. The stuff is so strong that we used to cut up the scrap and mill it to make blocks for use in fixturing work on the machine tools. I do not know the name of the product, but, like anything else, I am sure that the manufacturers are on the internet. It's worth a shot to look into it.

Click to expand...

Could have been paper Micarta. Micarta - Wikipedia

I worked repair in a large stamping plant and we would replace the brass ram gib liners with Micarta.


Cheaper than brass and seemed to outlive it, too, when kept oiled.


Mike

If it were mine I'd check with your local small engine shop. Snow blower, lawn tractors all use friction wheels for transmissions.

44dwarf said:

If it were mine I'd check with your local small engine shop. Snow blower, lawn tractors all use friction wheels for transmissions.

Click to expand...

The old Snapper riding mowers that they built for many years used a metal drive disc, with a rubber band around the outer edge.............Ariens did too for a while. Changing speed was just sliding the disc across an aluminum plate on the motor shaft.

I only had trouble with one that was on an Ariens mower, needed a new drive disc, put a new one on and it didn't last any time...........changed the tension on the wheel and as far as I know, it did ok.

With machines of that age, it is very likely to have had a common material used. You have to love that.

If you need a thick, large piece of rubber a good source is truck mud flaps. I mean big trucks for a large one.
And the best part is you can find them by the side of the road all the time.
I use one for a bench mat. Very durable and oil resistant.
It also has a raised border that keeps small pins, springs, and screws from rolling off the bench.
Just as an interesting drill, here is a Willey drill on Cape Cod Mass CL.
It uses a friction disk for the spindle drive.

Willey Electric Drill Press - tools - by owner - sale

rustytool said:

Does the disc running dry or in an oil bath (my situation) make a difference in material choice ?

Click to expand...

In oil bath, cork works great and lasts a long time.

Automotive clutch liner material is a good choice in dry applications. The aftermarket performance shops can identify all sorts of options. The friction disc does NOT need to be monolithic. Just place the sections "close enough".

Thanks for the continued input, guys! I received a nice chunk of 1" thick 90A durometer polyurethane rubber sheet in the mail the other day... I'll be machining a new friction disc from it when time permits. Currently though I'm in a time crunch, getting ready for a chef knife show in Chicago next weekend so it won't be until after that! I'll post when I get the new material fit and trial run...

You reject a couple hundred years of useful application experience for some "plastic" that has nothing behind it.

Good luck.

I run leather band saw tires. have done so for more than 50 years. those new fangled rubber ones don't hold up to coolants and oils. ;-)