How would you go about making a mould of this ?

[tiksie]

Hey guys,

just had a quick question in regards to a part that I have which I want to replicate.

This might seem like one of the easiest things to reproduce for some, but I'm in a bit of a pickle as to how I would go about making a mould of this so I can vac form it to reproduce it.

I made a gallery here to make it the thread more download friendly:
http://imgur.com/a/sQtC6

I was thinking of cutting out the bottom of the cup holders and the the tray from the bottom like so:


Then making negative moulds of each item out of plaster (I've only ever made moulds with plaster) then vac forming each item and gluing them together.

Is that a silly idea ? Or is there a better way ?

Cheers!

 

[19narvik40]

I guess it would depend on what you are trying to make.

 

[tiksie]

I guess it would depend on what you are trying to make.

I want to make the exact same thing so I can cover it in prepreg carbon fiber.

Only thing is, I don't want to do it on this as it's too hard to find! I don't mind cutting something up that could be put back together, but if I apply resin infused CF on this and change my mind later on, there's no going back Hence why I'm looking at reproducing the same thing.

Cheers

 

[19narvik40]

I want to make the exact same thing so I can cover it in prepreg carbon fiber.

Only thing is, I don't want to do it on this as it's too hard to find! I don't mind cutting something up that could be put back together, but if I apply resin infused CF on this and change my mind later on, there's no going back Hence why I'm looking at reproducing the same thing.

Cheers

Is it a difficult part to get? Have you tried the wreckers yard for one? Cutting it will permanently weaken the original and that plastic is difficult to glue back together.

 

[tiksie]

Is it a difficult part to get? Have you tried the wreckers yard for one? Cutting it will permanently weaken the original and that plastic is difficult to glue back together.

Took me quite a while to find this (it's a 25 year old part!) and quite expensive when I do find it.. Or else I wouldn't go to all this trouble

 

[19narvik40]

Okee dokee, got you friend. What are the dimensions? What vehicle is it from?

 

[clonesix]

May I ask why you want to replicate this? How many parts that you want to replicate? How exact to you want it?

I see its a car dash. Could you just order another part, or are you trying to replicate a lost part to a rare car?


Yes, this can be done. Yes, it can be vacu-formed. Now let's talk about the issues involved. 1st: if you were to mold this as a positive vacuform tool, and vacuformed over it, it would be larger than the original by the thickness of the material. This is not a problem until you get to the cup holders, which will be narrower by 2X the thickness of the material. i.e. if you use 1/8" sheet, the diameter of the cup holder becomes 1/4" smaller. 2nd: there is no taper to any of the sides, and that is likely to make it difficult to remove the pull from the mold.

Let's go the other way: suppose you make a negative mold from the front side. This would mean that you pour mold material onto the front side of the panel, and then vacuform over it. you would get a pull that looks like the picture above. There is still an issue with the fact that there is no draft angle on the cup holders, or the other boxes. this makes removing the part from the mold difficult, and maybe impossible.

for me this is the way to go. It gives you the best copy. It also involves a more complicated mold. In order to be able to remove the part from being locked onto the mold, the mold is made in two parts: A 1/4" silicone skin, and a gypsum backing. When you vacuform over it, and it is locked onto the mold, the two halves separate, and then the silicone is peeled out of the part, and replaced onto gypsum half of the mold.

Silicone can handle the heat very well, but I would suggest a high shore (stiff) RTV.

Does this sound like something that you want to try? Or just buy the darn part.

 

[19narvik40]

Does this sound like something that you want to try? Or just buy the darn part.

He stated it is a 25 year old part. Depending on which vehicle it is from and where he is located, it may be something that is too difficult to order especially because of the age.

 

[robn1]

I would skip vacuforming. I'd make a silicone mold of the outer surface and make the copy in fiberglass.

 

[clonesix]

I want to make the exact same thing so I can cover it in prepreg carbon fiber.

Cheers

I see that this was posted while I was typing my last answer.

That is a little different than vacuforming a piece. As such, I would concur with Robn1, make a silicone mold, and lay the carbon fiber into that mold. Done.