Small run Rubber parts

[Bill Stoneberg]

I have 2 seat pads on the Woodie that I cant find. The bolt to the floor and the seat rail sits on this rubber pad. So I need someone who does small run rubber goods. These are not going to big sellers, so that leaves Steele out. Besides Stelle is 8 or more months behind in their tooling. <BR>So do you all know anyone who can duplicate this part or is there a way I can make a mold and make them ? <BR>Thanks.

[1937hd45]

Check the Eastwood Catalog. I think they have a "one off" kit for small rubber parts.

[Guest]

Depending on the shape of the part you can take a rubber roller that they sell for boat trailers and grind to shape, I make my own body bushings out of these. If you need a bolt hole there is one already formed in these.<P>Rubber is easily ground with an aluminum oxide wheel turned at moderate rpm with lots of coolant. Parting off is accomplished with a knife shaped tool.<P>The Eastwood kit works well too if you make a mold.

[ronbarn]

Make a wood, metal, plaster (or whatever material you prefer to work) copy of the item you wish to replicate. Some of the pads are very simple. Then make a mold out of plaster-of paris or clay (both of these work better if baked). Or if you can envision and make a female mold directly, that also works.<P>While you are making the mold place an order for Devcon Flexane. You will have to make a decision regarding the hardness of the intended part. Flexane is available in a range from very soft to hard. Be sure to get the pourable type of Flexane.<P>Use a good release agent in the mold, carefully and precisely mix the two parts of the Flexane, pour it into the mold, let cure as specified in the directions, and remove the rubber part that you have now created. If the surface is not exactly like you wanted you can do what Chuck said, grind any unwanted material and or shape it is needed. I generally will leave the part in the freezer over night before I do any grinding to prevent the grinding wheel from digging in or loading up.<P>Have done this many times. Have had some failures which were easily traceable to sloppy work on my part. <BR>But most times I am successful. <P>Try to make your mold reuseable and make some spares for yourself and friends. Excuse me while I shut down here for a while and go to the barn to finish some 1927 Marmon Model L accelerator pads.<P>ps: There is a good book on molding rubber parts. Will pull my copy when I go to the barn and tell you the details.<p>[ 02-19-2002: Message edited by: ronbarn ]

[Bill Stoneberg]

Ron,<BR>Thanks for the information. I have looked the information up and will try to make some. I cant wait to hear about the book. Never can have too much information.<P>Chuck, Good idea and one I have used before for round items. This is a plate though so it wont work for me.<P>Eastwood has stuff or molding plastic, not rubber though.

[Guest]

Polytek has a number of different molding urethanes, RTV, plastics etc. and other types of rubber molding products. Sounds like you need their 2 part rubber product, add carbon black to get a black color. Here's the link;<BR> <A HREF="http://www.bare-metal.com/polytek_mold_materials_intro.htm" TARGET=_blank>http://www.bare-metal.com/polytek_mold_materials_intro.htm</A> <P>You can create a temporary mold by crazy gluing flat plates together in the shape you want. A syringe makes a good injector, make sure you make air relief holes in the corners or near hard to fill projections to ensure complete filling. This is a lot like casting steel so the techniques are the same. When your done just hammer the mold to break it.<P>Hope this helps.

[Bill Stoneberg]

Well I stopped on the way home and bought some plaster of Paris and played around with tonight. It went easier then I thought.<BR>I took an old part and made a mold out of it. About the only mistake I made was forgetting a mold release agent. I used PAM but made a mistake there too. I used the garlic flavored PAM instead of the normal. Now my part smells like garlic.<BR>But it mad a good mold that I am going to see if I can make a part off of. I figure Practice with this part I can replace easily as opposed to a part that I cant.<BR>I will look for the stuff recomended tomorrow.<BR>Thanks for the help.

[D Binger]

Bill,<P>Keep using the garlic PAM - - - it will keep the judges at a distance.<P>Dan

[Guest stude8]

Bill Cannon published a paper back book some years ago on how to cast your own parts in metal and rubber. He gives all the details on how to do it with suggested material suppliers. You should be able to get a copy through one of the auto book sources like Osceola, WI. Cannon published the Skinned Knuckles magazine and maybe they can supply a copy. It is a good investment at less than $20. Stude8

[ply33]

I'd have to go home to check for sure, but I believe the Cannon book was actually published by Tab Books. I bought my copy through <span style="font-style: italic">Skinned Knuckles</span> but I see that you can get it through <BR><a href="http://www.amazon.com/exec/obidos/ASIN/0830604146/qid=1014227381/sr=1-1/ref=sr_1_1/102-8504404-0572154">Amazon.com</a>.

[Bill Stoneberg]

Ron,<BR>I was looking at the Flexane and was wondering if it is better to us the Flexane 80 or the Flexane 94 ? If I understand it correctly, the 94 is harder than the 80.<P>Any opinions on this ?

[ronbarn]

What is the function of the part? One part I am making is the rubber pad for an accelerator pedal - not the normal type, but a round pad about 1 3/8" D and 1/2" tall. This is a pad you put your foot on and are constantly pressing - use the harder compound.<P>Have made several pads to go under cowl lamps, headlight brackets, etc. - not great compression, not constant deflection after mounting - use the spongier compound.<P>For a bumper pad which is what I understand you need - go for the harder compound.<P>By the way, the Bill Cannon book on molding small rubber parts is the one I was talking about. Keep us posted on your progress.

[RoadsterRich]

Ron and other knowledgeable folks too...<P>I am facing numerous 'rubber' parts I will need to find, many of which appear to be darn near impossible to find, or if they are available are massively expensive. Would this material work for things like motor mounts (In my case about a 2x3 square roughly 3/8" thick with hole in the middle with some other small shapes to it), and what about the shock absorber mount rubber, mine are big blocks of rubber the end of the springs sit in, the rubber is encased in a metal housing (housing I have, rubber I don't), the one quote I got for them was $85 each and there are 8 of them and at that they will still have to be trimmed and shaped to fit. I guess the question is, would this material be strong/safe for these types of uses? <P>Perhaps a more generic question might be what types of applications on an automobile are appropriate for these cast rubber parts?<P>Thanks,<P>Rich

[ply33]

I will pass on a little what I remember from Bill Cannon's book. (You should get a copy.)<P>Flexane (and other equivalent products) are very resistant to petroleum products. This is good for engine compartment parts. The Flexane will resist damage much better than the original rubber.<P>It was my understanding from the book that Flexane has excellent bonding to metal. It also has a very high shear strength.<P>I would have thought that simply cleaning up the metal parts of the mount and roughing the surface some with a disc grinder would provide sufficient adhesion. The mounts on my Plymouth all have the rubber loaded in compression, so I don't think there would be a problem with shear or tension in the Flexane or with the bonding to the old metal core(s).<P>Chuck has more experience on this than I, but I don't think you will have a problem with this application.<p>[ 02-26-2002: Message edited by: ply33 ]

[ronbarn]

One important point must be made at this time - Flexane is NOT made by Devcon for antique automotive hobbiests! It is made for critical industrial maintenance and repair functions with rigid standards. The last time I was at my favorite machinery supply shop, I picked up a Devcon brochure on the product, and would you believe, absolutely no mention of making pads and parts for old cars!<P>This is one of those marvelous products made for other applications that works great for us. You might call this piggy-back technology. Although it is not cheap, the fact that we can get it at a reasonable price is due to it's demand in industry. If Devcon relied on the demand from us, they would probably cease production and significantly increase the price.<P>I would feel very comfortable using it for the applications mentioned. By the way Rich, don't want to change the subject, but did you ever get the hubs off of your car?

[Bill Stoneberg]

I have poured my first parts tonight using the Flexane 94. It was easy to use but noxious (but not as bad as my dog).<P>I will let it dry and see how the pad looks tomorrow.<P>Rich, I was able to get the Flexane pretty reasonably at WW Grainger.

[Guest]

Rich, I have had excellent results with any of these types of products. They are as durable as any rubber product you will find, I have found the harder compounds more useful and I finish cure them in a 200F oven just to ensure they are fully hardened. For producing motor mounts you would have to come up with a retention scheme so that the rubber isn't in unsupported shear or tension. What I mean is the rubber itself will not adhere as stongly to a substrate as vulcanized types. So if your motor mounts are two parallel flat plates this rubber cannot be used as is, it will unbond from the plates, now if you weld some large headed bolts to the plates and then embed the bolts in the rubber to help "key" it to the plates, that would work. It's kind of hard to describe in words but I think you get the picture.

[Guest Curt Fouse]

This is the first time I have looked over the forum in quite a while. 2 evenings ago I made 8 door bumpers for a 30 Buick 4-door, and 8 pads that the window rests on when in the down position. I had some 1"X4"<BR>and about 2 feet long rubber. I had gotten it at a surplus flea market. This material band sawed well, and sanded to a nice finish. My son-in-law commented that the last time he made rubber parts, he made a mold, went to the local recapping shop and got some of their uncured rubber. The rubber is forced into the mold and put in the oven at 350 deg. to cure. Probably none of this is of interest, but it will sent the thread to the top. I have a number of parts to make yet, and if it requires machining on the lathe or milling machine, I freeze it with dry ice first. At one time I picked up a piece of semi tire cap from along a highway to get the rubber to work with. Now is that frugal or what? Also, flexane is not supposed to have long shelf life once opened, but I have some that has kept over 2 years. Good luck with all the oldies.<P>Curt

[ronbarn]

Curt, You are correct about the "short life" claim on the Flexane container. I had some about seven or eight years old and still made a good part. Of course, if you try it and it is no good, then you just get a fresh batch.<P>Had not thought about a local vulcanizer for using a mold that I make. May try that with the next larger item. Thanks for the tip.

[Guest]

Biil I was reading my GT Restorations catalog and they do revulcanizing for motor mounts.As far as price the one listed was around $80.00pr. I think I would have motor mounts done so that they are guaranteed,any other parts I would do myself.Their website is <A HREF="http://www.gtrestorations.com" TARGET=_blank>www.gtrestorations.com</A><p>[ 06-07-2002: Message edited by: dnomyar47 ]

[George Rohrbach]

I posted this on the Studebaker Fourm, but you might not have seen it. This was for myself....I don't make them for sale.<BR>The new rubber spring bumpers are finished. They came out great! I used Flexane 94 by Devcon. It is a pourable, two part urethane rubber, that cures at room temperature. First built the old wrecked one up with wax to the correct shape and made an indexed mold with dental die stone (sort of a very<BR>hard plaster). Then took off old broken down rubber from the mounting plate, sandblasted the plate and used 2 special primers that make the Flexane bond to it. Mixed and poured the rubber and reindexed the metal plate in the mould.<BR>The pic shows the two moulds and two of the finished bumpers. They are about 2 1/2" by 1 1/2" by 1 1/2".--<BR> <p>[ 06-09-2002: Message edited by: George Rohrbach ]