Reach Shotgun - The molding process

[Brandon McClain]

So some of you might be wondering now that 99% of the rubber is poured, what is next? Well, next comes what I call backing boards. Even though I am using a shore 30 (moderately stiff, 10 is very soft/flexible, 70 being very rigid) it is still not stiff enough when using molds of these size to rotocast without some support. So what I do is cut pieces of 3/4" or thicker mdf to envelop the piece on either side. I cut the mdf so it has at least a 3/4" rim around the rubber. So say the rubber piece measures 8 1/2" x 3 1/2", I would cut two backing boards at 5"x10" (this leaves 3/4" all the way around. Once they are cut, I lay the rubber on them, mark where they sit, and then drill holes around the perimeter for bolts to pass through. Thus far on these molds I've used more than 50 6" bolts with two washer and a nut each. It adds up pretty quickly. The end result looks something like this:

And this:

One word if caution for those wanting to try this method: the molds are extremely heavy. There is a lot of rubber there, more than I care to think about really. They are not easy to rotocast. As a result I think I'm going to have to build myself a single axis rotocast machine.

 

[drack]

Are you not worried a single axis machine will make them a little thin in some spots? You know yourself when hand roto casting you have to turn those things in as many directions as possible to get the resin where you want it. You could make it so the base slightly tilts to ensure the resin is being moved on the opposite axis. This might mean you will need someone else to assist while turning it though.

 

[Brandon McClain]

Because the parts are narrow, and I only need to roto cast the initial layers (2 in smooth cast 65d, 2 in featherlite) the single axis is ideal. The parts are then filled with foam it 5, they are light but solid, and this negates the issue of possible thin spots. When your mold is 90 lbs you don't want to be turning it by hand. The single axis will be driven by a large electric motor

 

[drack]

Ah I see that makes sense. I didn't realise you fill them with a foam. You may have said some where but I must confess I have just been looking out for the pretty pictures

 

[Dystorted Props]

I just wanted to say, nice work Brandon! Any progress on casting so far?
Dying to see the results!

Thanks!

 

[Brandon McClain]

I know it has been a while since I had a chance to post here, but I happily have progress to report! I completed the pump mood and after finally working out most of the kinks in the various molds we now have this:

The first shows all of the individual parts, while the second shows its mostly assembled ( I left out the trigger and the housing on purpose). The entire thing is very light, roughly 5 lbs, and it is very well balanced. It is cast in smooth cast 65d, and feather lite. Most of the pieces are so light they will float in water.


I have a for sale thread going in the classifieds at the moment.

 

[CLOTHAR]

Really nice shotty you got there. Great job man!

 

[Dystorted Props]

Way to go Brandon! I cant wait till these are available! (If I decide to pick one up, hope so!)

 

[Brandon McClain]

Had some requests for closer shots. Here are all of the parts close up with flaws or seems pointed out. As far as bubbles and seam lines, I try and take care of most of them before I send out the parts. The biggest problem areas for bubbles are the hex nut details, though I should be able to mitigate most of those with future pulls (I've been in the process of tweaking my casting methods for each particular mold). The majority of the seam lines I tried to keep inside the parts, or in areas that were unseen. There were some small flaws in the pump and stock molds, issues between the print layer and subsequent layers, though most are easily fixed with very minor sanding. Here are the pictures (it's about to get a bit pic heavy):


Small bits: only a few very minor bubbles, and the seem lines are in unseen portions, and easy to clean up:

Upper receiver/rail: extremely small bubbles in the rails, some bubbles in the hex nut details. These should be mostly eliminated in your casting

One visible seam line, should be easily cleaned with minor sanding/file

Barrel assembly. Very very minor seem lines, few bubbles in the small screw details, once again, should be fixed in your pulls

Grip/lower rear receiver: very minor bubbles and seem lines, easily sanded

More to follow in next post

 

[Brandon McClain]

The buttstock: most imperfections, bubbles in hex nuts, heaviest seem line, and surface imperfections on one side. Easily sanded

Pump: some bubbles, one seem line at the back, and some surface imperfections on the grip. Easily sanded/filled, I used a small wood chisel on the larger bubbles of resin

Forward/lower receiver: minor seem line and maker mark from the master

And the whole thing together:

Holding up the flashlight, it screws in from inside the pump

Also, if you want to see other items I have available and other projects on the go you can check out my Facebook page: www.facebook.com/Incyte.117

 

[Chainsaw ninja]

How much do you plan to sell em for?????I want it!

 

[Mythosaur]

DEM MOLDS. As an avid mold-maker I have to say this thread made me drool a little (a lot). That is also quite possibly the most Mold Star I've ever seen in one place at one time. Props!

 

[Brandon McClain]

It is a lot of rubber to be sure. I really went overboard. If I remember correctly it is something like 9 gallons kits (each of which is a gallon of part a and a gallon of part b) between the shotgun mold and the pistol mold. They are very robust. Heavy as all get out as well. I will be taking a different approach as I mold the assault rifle in the coming weeks.

 

[Mythosaur]

It is a lot of rubber to be sure. I really went overboard. If I remember correctly it is something like 9 gallons kits (each of which is a gallon of part a and a gallon of part b) between the shotgun mold and the pistol mold. They are very robust. Heavy as all get out as well. I will be taking a different approach as I mold the assault rifle in the coming weeks.

Something like brushing on and using a mother mold? I did a pistol using the block method as well and while the material required is ridiculous, I just can't get over how sturdy and robust they came out. There's something so satisfying about a mold that substantial.

 

[saiko]

Wow, I love all of the crisp details you put on the master and were able to capture on your Reach shotgun. It's such a beautiful piece that I've just sat here scrolling back and forth to peek at every inch.
I've never tried molding and casting before but I like being able to catch a glimpse of your work-process and learning-process through this, particularly filling the rotomold with foam.

Great job and thank you for sharing

 

[TonnyT]

This is a true master piece. I can't get enough of all this amazing work.
I would love to purchase one.
How would I get in touch with you, other then the classifieds section?

 

[Brandon McClain]

You can get in touch with me via private message or on my Facebook page: www.facebook.com/Incyte.117

 

[Halo 1]

Brandon,

Nice to finally see it come together! Great tut bro! Now about that pistol......

 

[TonnyT]

Haha! I see I'm not the only one who's excited to see that!
Don't think we forgot.

 

[Brandon McClain]

Oh I finished molding the pistol ages ago!