I've spent a lot of time researching the original roller timers, and I can't find a solution. Is there a material that can be used to rebuild the insulator ring inside a roller timer? I've read that some people suggest garolite, but after searching on some machining websites they say to avoid this product at all costs due to the dust created in the machining process and the damage to the tooling. Does anybody else have a suggestion? I've got a couple timers sitting in my junk pile and thought I'd like to give rebuilding them a shot. I'm just curious as to if it's possible.
I always thought it was some sort of hard fiber. Could pthat be used? I have had this bookmarked for a while for info purposes. They are in Australia. However, they say the material can be machined to make gears, so I would think it can resist the wear fairly well in a roller timer.
Howard Cascia (RIP) used to rebuild Ford roller timers. The material is a hard Micarta or Phenolic.
I find that Ford roller timers can be found for $1 - $5 each in pretty decent condition either on eBay or at swap meets. If they have minor wear I chuck them in the lathe and resurface the inside. If the wear is more than about .010" then I look for a better candidate. Pack them with grease and they will not wear out. The Ford roller timers give excellent service and very accurate spark event timing.
Maintenance instructions here:
From what I understand, Garolite is a brand name for a phenolic impregnated glass fibre, imparting the finished product with outstanding structural integrity.
I know that some machine shops are reluctant to machine any phenolic material because of the mess, but I also know a guy in San Francisco that specializes in making custom Phenolic parts and has no problem doing it. His machines are equipped with dust collectors and he uses special carbide and diamond tipped tooling. For one or two rings I wouldn't hesitate using Garolite, but I would use carbide tools, and fit a shop vacuum to suck up as much dust as possible.
I don't understand folks not wanting to machine phenolic. I kind of like the smell. It makes dust similar to cutting wood. It's not obnoxious at all.
I don't think any special tooling is necessary beyond what you use to cut steel. I use carbide bits on everything I do on the lathe, so that is not any problem for any ordinary machinist.
Glass reinforced phenolic will generate some silica dust when machined. You need a good dust mask if you machine it. If I were to make an timer insulator then I would use linen based phenolic. You won't get silica dust and you will get the wood like smell Royce is talking about.
And would this linen based phenolic still be a hard wear surface? I've never heard of it, but anything has to be better than what I've heard about garolite. Between the burning up tooling and creating dust that ranges somewhere between nuisance and health hazard, I'm willing to hear other options. I've heard of Micarta, but I'm not sure where to get it. Anybody know? Is Howard Cascia the only one who rebuilt original Ford Timers?
Phenolic or micarta (they are two words referring to the same product) sheet is what you want. I've worked with it for decades, it is not any sort of hazard at all. Anyone who says that is simply unaware or has never used the product. Like Ted says, a dust mask is the only thing you would need, same as any wood shop project. In the aircraft industry we only use grade LE phenolic, which is linen based.
Here is one source that I found by using the magic of Google:
Here is a place that stocks all grades of phenolic / micarta. They also would machine the parts for you if you are not capable:
Thanks for the help, Royce. I've never done any work in plastics, so this is all new to me. I haven't quite figured out how to machine the insulators yet, so I'm not in any rush to start building them. I just thought I'd do some research into it. I have three engines and all three have Ford Roller Timers on them. The one that's running does so quite well, so I figure they can't be all bad. I was mainly just curious about whether or not a home shop would have the ability to rebuild one. I know repops and decent originals are abundant, but it might be handy information all the same.
Don't use a paper based phenolic. They can be quite hard but chip pretty easily.
In this application what would make them chip?
Turning them on the lathe. Milling the notches for the shoes. Fitting the shoes. If you going to the trouble to make them use a good material, linen base phenolic. At least that is what I wood do, others may do as they wish.
I would suggest that most timers could be rebuilt with new shoes in the existing insulator.
They could be compression molded in a fiberglass based material with minimal tooling cost if you could find a plastics or rubber molding shop with a sympathetic ear.