Reach Shotgun - The molding process

[Brandon McClain]

Hey everyone, Gabe (lostviking) had asked me to post up pictures of the process for molding the beautiful Reach shotgun he had made for me. I began by doing the layouts on 1/8th hardboard. I use tape to layout the borders around the parts and so I know how to cut the rim board.

The parts on the hard board, you can see the barrel shroud has two stripes of tape around it denoting where the registration keys will go.

Once the parts are all laid out I measure the length, width and depth of the parts. I make all of the measurements I write them all down so as to figure out the best way to cut them from the sheet of mdf.

And the final layout:

Some of the parts will be traced on the hardboard to facilitate when I clay up the parts. You will see what I mean shortly.

 

[TheReconSpartan]

wow this is looking good! you should make an Emile costume to go with the shotgun. that would look soo good!

 

[Brandon McClain]

Once I have everything laid out I begin to cut things out. I start by cutting out the parts that are traced onto the hard board:

I then measure out the side boards and write them all down so as to make sure that I dont forget any

I then cut out all of the hardboard panels, the backing panels and the side boards

Then its time to lay everything out. First comes the backing panels

I keep all of my spare chunks of mdf to use as spacers so as to keep the parts centered inside the space that the box mold occupies

Then comes the part

Once the part is in place I lay out the first two side boards

Then comes the hardboard that acts as a dam between the two sides

I finally lay out the remaining side boards and make sure that everything is glued in place.

I will continue to do this for each of the various parts that will have a two part mold. There are a couple that will be multi part molds and will be laid out a touch differently, but will take photos as I do so. Once these steps have been completed I will fill in the small gaps between the hard board and the part with chavant nsp soft clay and add in the registration keys.

 

[L05T V1K1N6]

Oh my... WOW! That is so amazing! I MUST SEE MORE!!
This is looking awesome, Brandon

(I miss you, shotgun! lol)

P.S. How did you trace all the parts to make the dams?

 

[Brandon McClain]

i just set the part on the hard board, and traced around it with a marker as best I could

 

[Brandon McClain]

Got the part clayed in. I use soft chavant nsp (non sulphur plasteline) to fill in the gaps between the part and the hardboard. Once that is completed I add the registration keys. In this case I used magnets and a few pieces of large hot glue stick that I cut to about 1/4 inch length.

Once the regsitration keys are in place, using a hard bristled brush i coat the mdf and hardboard in a light coat of wax. Once the light coat of wax is on the raw wood I spray everything down with mold release. This makes it so that the rubber will seal and coat nicely and will demold easily.

 

[ka5p3r]

wow man its looking awesome i cant wait to see it all molded

 

[L05T V1K1N6]

So freaking sweet! I'm interested to see how you mold the hole for the barrel. And of course the other side of the mold as well. Can't wait to see more, Brandon!

 

[Cereal Killl3r]

Very nice Brandon!
I've been waiting for a thread like this one.
Will be tagging along for sure!

Dave.

 

[Brandon McClain]

Just thought I would answer Gabes question. For those wondering what barrel hole he is talking about, at the front of the upper receiver there is a recessed slot that the barrel assembly fits into for alignment. Of you look closely in the picture where I have the part clayed in, you can see a big knob of clay. This block off the entire recessed area. I didn't want to have an undercut it the two sides, and this also acts as a makeshift registration key. When I pour the other half, this will be the first area poured and care will be taken so that no bubbles are trapped in the recessed area. Rubber will get poured today after work.

 

[Mstruvmgc]

Dude this is sick. subscribed

 

[drack]

Loving the tutorial/guide so far. I was just researching moulding a gun as going to attempt to make an MA5C from wood then make casts. +1 subscription

Keep up the good work,
Tom.

 

[Xarmymustang]

Im with tom and dave on this one very helpful on the molding process and also another subscription

 

[Brandon McClain]

Okay, made some headway on the rubber. I have some rebound25 left over and thought I would use some of it up before the new MoldStar30 shows up. I forgot how viscous rebound is, it takes for freaking ever to measure out of a 5 gallon pail. I grabbed my measuring and mixing containers, and some mixing tools.

I measured the initial batches at a liter per part (two liter total per batch). Each side took two and a half batches for a total of 5 liters of rubber per side. Yes, it is a bit excessive, but I dont want to have to redo this mold so I went a bit overboard. I made sure to give everything a fresh shot of release agent before pouring.

After the first batch was mixed thoroughly I poured a thing layer over all of the part using a tooth pick to pop any bubbles in the small recessed areas like the screw and bolt details.

I continued to mix and pour rubber until the part was completely covered to a depth of about 1/2 inch and let it cure overnight

Once the first side was completely cured i flipped it over, and removed the hardboard.

Once the hardboard was removed I began to remove the clay and make sure it was completely cleaned from the part so there will be a clean seam. This was particularly painstaking on the upper picatinny rail.

Once the part was completely cleaned up I brushed down the mdf sideboards with wax, and sprayed down the entire thing with multiple liberal coats of release agent so the two sides of rubber dont stick together.

You can see in the above picture that there is a recessed hole for where the barrel assembly slots into. When pouring the second half this is where I first pour the rubber, ensuring that there are no air bubbles trapped.

I repeated the same process for the second side mixing two and a half batches, popping air bubbles etc. Final side is curing currently. I must admit a small good on this one. I forgot to mark out the sprues (spot where the plastic is poured and the air is allowed to evacuate the mold) but I can cut those out later. I would usually lay them out with clay and just pour over them. I will ensure that I show this step as I continue the process on the other parts. More coming soon, once the rubber is cured.

 

[Toacrabman]

This looks like it could be the easiest method yet for beginners like myself. Thank you.

 

[Brandon McClain]

Yes, it's easy, but it uses a ton of rubber and isn't cheap.

 

[drack]

I agree with crabman. As I think I have said before this is exactly what I needed in a thread for when I attempt to mould my MA5C (when it's made ofc). Thank you for the indepth step by step

 

[Cereal Killl3r]

Looking great Brandon!
Man that's a lot of rebound! Expensive mold, would cry if three was a need for a do-over
But, doubt that's an issue of a pro!

Loving it!
Cheers,
Dave.

 

[Brandon McClain]

Definitely no need for a do over. It turned out spectacularly. I just need to pick up the bolts to hold it all together and I will see about pulling some casts. Im going to try and rotocast this bad boy. I guess I will let the pics speak for themselves. I just pulled off the side boards and the two sides came apart with zero issues. No bubbles, great surface curing, and everything is just as it should be.

The part comes out very easily, just a gentle coax and out she comes

You can see how well the details came out with the rebound. I was a little worried about cure inhibition and possible bubble entrapment due to the age of the rubber, bought it more than a year ago, but there was no problem at all. I do have mold star 30 coming in, and Im excited to give it a shot and see how it compares to the rebound. Rebound is seriously a monster pain to pour out.

Hope yall like it so far, Im stoked to give the casting a shot and see how she comes out. Need to make some headway on the rest of the parts too. Work is really getting in the way!

 

[TonnyT]

Loving the Shotgun!
I'm so jealous right now.