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Thread: repro b/u lamp gasket
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straightrepu
Redlining
Posts: 232
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posted January 22, 2004 10:17 AM |
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Repro b/u lamp gasket
I`m starting to get some really good moulds from a NOS backup lamp lense gasket, the originals gaskets were made from an off-white rubber and seem to disinigrate after being exposed to the sun for a few years. I`d like to use a better quality synthetic white rubber, but everything I`ve found so far requires heat and injection moulding. I`d like to use something like devcon`s flexane a high quality synthetic, but it is black. Do you guys think that a white gasket is a must? Does anybody know of a synthetic white rubbber that may work?
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74 restorepu
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rotormunky
Redlining
Orlando, Florida
Posts: 424
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posted January 22, 2004 10:53 AM |
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Hey Craig,
I think you want to be looking into Dow Corning's silicone selection. White is an option and its pretty durable. Non-tearable tho I don't know what its UV resistance properties are but its pretty decent stuff.
I think Ken's using some kind of silicone for the rear gaskets.
Drop me a line sometime I'd like to talk to you about moulding techniques and stuff. Always good to pool our collective knowledge :)
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-Martin
Orlando, Florida
http://www.themonkeyhouse.org/REPU
'77 REPU (Some assembly required :)
'91 Cabrio (Battered and bruised, but she's still my baby.)
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straightrepu
Redlining
Posts: 232
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posted January 22, 2004 11:13 AM |
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Been there
Everything I found required heat and injection moulding, I need a mix and pour material.
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74 restorepu
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rotormunky
Redlining
Orlando, Florida
Posts: 424
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posted January 22, 2004 11:59 AM |
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I'd try the Dow Corning HSII. Its a multipart so you don't need heat or injection. Its pretty tough but soft and with good viscocity so you should be able to lay it in the mould and it should take all your details pretty well.
What's your mould material? Also what sort of mould style are you using out of curiosity? I've been messing with squish moulds mostly since most of the stuff I've been messing with is like your gasket, basically a ring of material without a center section, and I wasn't having too much success with pourable moulds but the casting material I've doesn't pour the greatest because I'm stuffing it full of aluminum powder.
Hopefully I'll have more success with the squish moulds tho.
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-Martin
Orlando, Florida
http://www.themonkeyhouse.org/REPU
'77 REPU (Some assembly required :)
'91 Cabrio (Battered and bruised, but she's still my baby.)
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nwaco
Redlining
Posts: 407
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posted January 22, 2004 01:34 PM |
 Edited By: nwaco on 22 Jan 2004 13:35 |
Devcons Flexane is not good for gaskets....
But it works great for some molds. Besides, it is too exspensive and must be mixed in too large of quantities to make it cost-effective enough to bother. Also, it is not flexible enough to compress to form a water tight seal. You would have to torque the screws too much to compress the gasket. That torque would probably damage the backshell of the light or maybe even break a lens.
I use an industrial silicone for my gaskets. I believe it comes in white as well, but I do not think white is a must for the gasket though.
As for the mold, I can't remember off hand, what the gasket shape is on a B/U light, if it has undercuts, then you would have to either have a multi-part mold or use a flexible proof to make a rigid gasket, and then get a flexible part out, but those molds are dificult to clean for long term casting. Multi-part molds are what I suggest for undercut part casting.
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Klaus43
Rotorhead
Posts: 1259
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posted January 22, 2004 04:31 PM |
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Black, White, Clear... who cares?
Any color is cool, just so long as it works, and lasts! Those who require a specific color gasket could always add a thin layer of paint...
I mean, I can understand why a white/light color would be best behind a clear lens, but it seems a minor point as versus the functionality.
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brad
Rotorhead
Posts: 1672
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posted January 22, 2004 07:56 PM |
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i'm with klaus
function over form; color in this instance.
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straightrepu
Redlining
Posts: 232
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posted January 22, 2004 08:39 PM |
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using casting plaster
This is all new to me, so I`m starting off with the simple gaskets, no undercuts and a smooth surface on one side.The casting plaster is cheap so if I make a lot of mistakes (of course I am) its no big deal. Martin the stuff from dow corning looks like a good candidate, have you used it? At $25 a pound its not much cheaper than the flexane but it is the correct color. I haven`t used flexane yet but from my research you can add a flexibilizer (flex-add) to change it from a medium hard rubber to a soft rubber suitable for weatherstripping or anything in-between. I also read that it has a short shelf life once opened, you can mix quantities smaller than the 1 pound package but its best to use it quickly. I can make a lot of moulds from plaster for cheap and want to have enough of different gaskets using different levels of hardness to use a package in a weekend.
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74 restorepu
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nwaco
Redlining
Posts: 407
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posted January 22, 2004 08:53 PM |
Edited By: nwaco on 22 Jan 2004 21:26
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Craig, I have three cases of Flexane....
and it is not a good candidate for gaskets. You can measure and mix smaller quantities, but it is a very expensive and tempermental material. It does deteriorate very rapidly when exposed to air prior to mixing.
I suggest if the mold does not require an under cut, that you use a temporary material to cast several gaskets. You take those several gaskets to arrange and make a mold that will use approx. 1 quart of material. Mix up a quart of flexane, to pour the multi-gasket mold. That way, you have a mold that will yeild four or more parts, wastes little material, and is cost-effective to make at least four gaskets at once.
Flexane is a very good urethane material best suited for final mold formation. It is too expensive and finicky for part manufacture IMO.
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mazdarx605
Redlining
Posts: 314
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posted June 13, 2010 07:09 AM |
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Wasn't there someone who made these gaskets years ago? I swear I bought some around the same time I bought the still unused tail light gaskets I have. I was changing the bulbs in the back-up lights,and looked all over for those gaskets,but can't find them. Is there any chance someone still makes these,and if so can I get a set?
Chris
74 REPU
74 RX-4
78 RX-7 x2
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