Foam rubber fabrication

mbalbritton

mbalbritton

#@$%!
Joined
Mar 22, 2005
Location
Lakeland, FL
Anyone know about making foam rubber gaskets? The kind for weather stripping on vehicles that seals your doors, trunk, hardtop mating surfaces.

There is a gasket on the half can hard tops for Jeep Commandos that no one makes anymore. There’s a small market for these and I’m working on 3D printing some. Unfortunately I don’t see a 3D print holding up very long and being that great of a seal. But if I could print the model and make a mold, what kind of material and how do I get it in a small enough quantity and form that I can use?

Anyone have experience or knowledge on this
 
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Not extruded. I would guess a 3-4 piece mold. These are the 3D print. Photo on the table is the 3D and the OE gasket.
 
If you want something simple, casting a 2 piece silicone mold from a properly surface-finished RP part (SLA or SLS and not FDM), and then making the parts from a soft 2-part urethane would be a simple way to go. Finding a tough, UV resistant black urethane or silicone of the proper (low) durometer would be the trick.

There's really no need to do any more than a 2 piece mold probably, because if the mold is flexible then the mold can flex to remove the part (minor undercuts or whatever are not a problem), and if the part is flexible then it's the same thing with the part being able to flex during removal from the mold. So a rigid mold with a flexible part can still be a pretty simple mold.

There are numerous seal and gasket companies that will do prototype and small quantity stuff with various molding processes and various elastomers. I think Apple Rubber does that for example. Depends on what you're looking for in terms of finished product quality and what you're comfortable with for investment to do a small manufacturing run.

What did you RP that existing part from, is that a flexible FDM (going by the really coarse layer resolution)? It doesn't look like something like polyjet. Speaking of polyjet, the Stratasys Agilus30 or Tango polyjet materials may be a good fit to make the parts directly, but that's going to be a decently expensive part with that amount of material volume and machine time probably.
 
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mbalbritton said:
I see under your screen name it says “Overcomplicator”

Yep, half that shit you just spouted off meant nothing to me. But some of it makes sense. Thanks
Click to expand...
let me translate.
You have 2 options for getting the mold to make the part.
Either 3d print the mold itself, this is the easiest but it yields a rigid mold, so fitment and ability to pry it out are an issue.
Or, 3d print an example part, make a silicone mold, then use that silicone mold for forming the part. That makes it easy to pry out.

But what you really want to know is, what material can you make the part from. Can do urethane as an option. Or even silicone. "Durometer" refers to the stiffness. You'd have to do some trial and error to find that out. You can buy all kinds of 2 part urethans from hobby sites.
Or, go to a gasket company and ask them to do it for you in a small batch. In some ways that's better b/c then you have a pro doing the work instead of you ;-).
 
mbalbritton said:
I see under your screen name it says “Overcomplicator”

Yep, half that shit you just spouted off meant nothing to me. But some of it makes sense. Thanks
Click to expand...

RP - Rapid Prototyping
FDM - Fused Deposition Molding
 
Found a flexible TPE filament. Looks rather promising. Hope we can get the model dialed in and the resolution increased. This basically the same material as foam gaskets are made from.
 
repro-rubber. two part non-shrinking rubber that you use to check dies with. mix it up, mate it up and it will stay pliable. it self lubricates and will come right out/off whatever you put it on. I use it all the time to measure things that you cant get into such as dies and molds.
 
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