Best way to mold this.....????

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yaris

Sr Member
So this is the off my pump action airsoft shotgun and I want to silicon mold and cast in resin a copy....while I've done some molding and casting before, I'm not sure if just a tube around it and pour the silicon...will I be able to get the master and replica out of the mold...???...maybe a two part mold...???

Anyway if you've done something tricky (for me anyway) like this before please let me know the best way how.

Thx in advance.
 

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TazMan2000

Master Member
IMO that would be very difficult to mould, unless you partially fill the cavity up with clay and machine out the resin afterwards.

A better option would be to scan it in 3D and put a hole all the way through.

TazMan2000
 

swgeek

Sr Member
If it were me, I'd make a 3 piece mold. First split would be at the top of the pump handle then I'd split the second half into two parts, such that there's a seam in the middle and each half pulls toward each end of the handle.
 

Duncanator

Sr Member
If you're intent on molding it, swgeek's advice is about what I would have recommended.

However, JediDade may be right depending on the cost of a replacement part. You could end up $150-200 deep in silicone, casting resin and assorted materials by the time you get a good casting out. Just food for thought.
 

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yaris

Sr Member
Thx all for the input.

We're I live you can't buy the part seperate, I can buy a cheap version of what I have and use the slide, but it may or may not be worthy, most likely won't fit and probably substandard material....when I say Airsoft, I mean GelBlaster...in my country AS is not allowed, but GB is....in certain regions

I consider a three piece mold is the best advice (thx) and as I have the product it won't be that expensive.

swgeek...I presume you mean all splits are as per a cross section...as if the part is standing on it's end, then it's sectioned into three..??

Thx to all who repsonded, I appreciate it and have a great day.
 

swgeek

Sr Member
No, I meant split as the pump handle would be on the shotgun, so horizontal. The one big piece would be the exterior of the handle and the split pieces would be the interior of the handle.
 

edspaged2

Well-Known Member
I’ve made a mold where I’ve had to make a hole for a tube to pass through. It’s small but I imagine it could work for you on a bigger scale? All you will need is a tube that is the same size OD as the gun barrel. I’ll get back to you with pics.
 

yaris

Sr Member
No, I meant split as the pump handle would be on the shotgun, so horizontal. The one big piece would be the exterior of the handle and the split pieces would be the interior of the handle.
Ummm...ok, I don't understand that.....
I’ve made a mold where I’ve had to make a hole for a tube to pass through. It’s small but I imagine it could work for you on a bigger scale? All you will need is a tube that is the same size OD as the gun barrel. I’ll get back to you with pics.
Please share with pics if possible thx.....I'm strugging to understand it at all....
 

swgeek

Sr Member
If you take the pump handle in your first picture and turn it 90 degrees, so that the grip is facing down and the open side is up. That's how I would orient the handle. For the mold I would make one part so that it was flush with the top of the handle and flush with each end. Then the other part of the mold would be two pieces that meet in the middle of the handle and extend past the end by a couple inches. So that they cap the ends of the mold. The lower piece of the mold covers the exterior of the handle and the two other parts would cover the interior of the handle. Excuse the crudity of my drawing.
20201228_000427.jpg
 

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division 6

Master Member
What about a 2 piece mold with it keyed to have a greased pipe down the middle.
May even get away with it being a 1 piece cut down the side.

Did something like that years ago for MG34 parts.
 

edspaged2

Well-Known Member
This is what I was talking about. Bear in mind that this is a much smaller part. Once the resin has set, I often have a hard time removing the resin component even after I’ve sprayed mold release on the pole. I just use an 8mm short threaded rod with a machined washer to extract it out and to break the bond that the resin has made against the brass tube.

I’ve tried wrapping baking paper around it and that was easily removed, but the baking paper increases the OD of the tube and I want a snug fit with later. But it could work for you?
 

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yaris

Sr Member
Thx to all who have responded...greatly appreciated.

I still don't really understand how to do it.

It's not so much molding it....it's getting the piece out of the mold that makes my brain hurt.

I think it can be done in a one piece, then slit it up to release.....I think having a big base will assist with the release as I draw it out...??

Pulling the silicon core out in one piece (as part of the outside connected silicon mold) is a pressure thing, so I think where a solid big base of silicon will assist with leverge as a base attachment...?

Maybe a release agent will be a great asset to the release....??

I've thought about 2, 3 piece molding and of course keying them, but keying inside the structure will be a challenge I think.

It would be way easier if i could just buy another piece, but that's not an option where I live and while there are much cheaper whole weapons (gelblasters) they're still $100+ and from what I've seen they may or may not be suitable both in size and quality.

Thx for reading and again...thx for all your opinoins and advice....greatly apprecited.
 

edspaged2

Well-Known Member
If you had a silicone core going through instead of a solid pipe/tube or shaft, that would work easier pulling it out as it will elongate and stretch causing the silicone core diameter to become narrower. BUT, the only problem with that is the silicone core will flop about the place and you will have a hard time keying it back up. If you were using a higher shore rated silicone it may work but you will get a better result by using a solid tube.

personally, if I were attempting to mold that pump grip, I would wrap some baking paper tightly around the same diameter tube that passes through the grip with some masking tape sealing the tape so as no resin can get between the sheet and touch the tube. You can spray a bit of mold release or thinned down Vaseline onto the outside surface area of the baking paper. Once the resin is poured and sets, the tube should be much easier to pull out leaving the baking paper semi adhered to the resin. The baking paper can then be pulled away.
 

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