Halo Reach M45 tactical shotgun - The Molding and casting process (PIC HEAVY)
- Thread starter Streetrocks
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Streetrocks
Active Member
Okay, small update. Laying out the rubber has taken a little longer than planned, but it's coming. Let me start by saying that I am in love withe the new moldstar30. It is sooo much nicer than rebound for making box molds. It self degasses and it is marvelous. Plus its such a purdy shade of blue! For anyone looking to make box molds, don't go with anything else. Seriously. As far as pictures, I will only be posting a teaser. I still need to mold the small bits, the pump and the barrel assembly. The full upper, lower and buttstock are all done being molded. The grip is a 3 part mold, I will have more pictures of that later. In the meantime here is a picture of the front lower receiver mold:
And another teaser, here is the next molding project once the shotty is completed
And another teaser, here is the next molding project once the shotty is completed
L05T V1K1N6
New Member
Oh my God yes! This is looking so freaking awesome man. Makes me really proud of my own work too 
Can't wait to see more.
-Gabe
Can't wait to see more.
-Gabe
SirNedKingsly
Well-Known Member
Do you have a price in mind for these?
Sent from my iPhone5 using mind control!
Sent from my iPhone5 using mind control!
Streetrocks
Active Member
I was thinking somewhere around $325 for a kit, it depends on how much resin and other material it takes to do the final casting. I've already spent and ungodly amount on rubber. In other news, some progress has been made in the molding process, which I hope to complete this weekend.
This is the mold for the grip. In this picture it looks like a standard two part mold, but there is in fact an insert that enables the interior of the grip to be hollow to hold the trigger, spring and etc.
These two pictures show the same side of the mold, the first with the insert in place, the second with it removed. I isolated the insert with clay, including the sprue on top when pouring the two halves. I then removed the clay and poured the insert.
The insert:
Next up is the buttstock:
After this all that is left is the pump, barrel assembly and small bits.
This is the mold for the grip. In this picture it looks like a standard two part mold, but there is in fact an insert that enables the interior of the grip to be hollow to hold the trigger, spring and etc.
These two pictures show the same side of the mold, the first with the insert in place, the second with it removed. I isolated the insert with clay, including the sprue on top when pouring the two halves. I then removed the clay and poured the insert.
The insert:
Next up is the buttstock:
After this all that is left is the pump, barrel assembly and small bits.
L05T V1K1N6
New Member
OH MY GOD. YES!!! That looks amazing Brandon! Keep it up, can't wait to see more
Weaselhammer
Sr Member
Outstanding work man, the gun looks amazing! good luck with the molds !
L05T V1K1N6
New Member
Thank you very much! I did the lettering with a 1/8" letter stamping set. For the design on the loading port on the top of the shotgun I just drew the shape with a pencil and kept tracing it, each time pressing a little harder into the soft wood, creating a groove. Hope that answers your question!
Streetrocks
Active Member
Hope y'all are ready for a lot of pictures... Got most of the prep work on the remaining pieces complete. I started with the pump, as it seemed to be the most complicated to me. It has a hollow center, as well as channels for the barrel assembly, which happen to connect, so I needed to find a way to separate the two rubber wise and keep the mold as simple as possible.
Here is how I went about it:
I began by blocking off the rear portion of the pump:
This will be covered later, but I wanted to ensure that if any rubber leaked past the block is would fill a small void and not the entire part.
Next I blocked off the front of the pump where the barrel assembly passes through. After blocking both the upper and lower holes, I made a registration key in each of them in order to ensure the rubber plugs would align properly.
I continued by blocking out any other portions that needed to be isolated such as the jog in the back of the pump.
The vertical piece of mdf serves as a spacer, rather than using a bunch of clay. The area that butts up against the mdf is that which was blocked out in the first picture.
Another shot:
Next I clayed in any small gaps between the part and the boards:
After that came the registration keys. I used the usual mix of magnets and cut up hot glue stick.
And finally the rim boards.
All that remains is to brush wax over the mdf and spray it down with release agent. I filled in the small gaps around the box mold with clay and hot glue to ensure no rubber leaked. With more viscous rubbers like rebound 25 you don't have to worry about such small gaps but with the moldstar30 it will sneak through any little gap you have and you will have a big mess and a lot of waste. Learned that the hard way the last time I poured. Lost almost a gallons worth of rubber through a couple little gaps in the various parts I was pouring.
Here is how I went about it:
I began by blocking off the rear portion of the pump:
This will be covered later, but I wanted to ensure that if any rubber leaked past the block is would fill a small void and not the entire part.
Next I blocked off the front of the pump where the barrel assembly passes through. After blocking both the upper and lower holes, I made a registration key in each of them in order to ensure the rubber plugs would align properly.
I continued by blocking out any other portions that needed to be isolated such as the jog in the back of the pump.
The vertical piece of mdf serves as a spacer, rather than using a bunch of clay. The area that butts up against the mdf is that which was blocked out in the first picture.
Another shot:
Next I clayed in any small gaps between the part and the boards:
After that came the registration keys. I used the usual mix of magnets and cut up hot glue stick.
And finally the rim boards.
All that remains is to brush wax over the mdf and spray it down with release agent. I filled in the small gaps around the box mold with clay and hot glue to ensure no rubber leaked. With more viscous rubbers like rebound 25 you don't have to worry about such small gaps but with the moldstar30 it will sneak through any little gap you have and you will have a big mess and a lot of waste. Learned that the hard way the last time I poured. Lost almost a gallons worth of rubber through a couple little gaps in the various parts I was pouring.
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Streetrocks
Active Member
Next up was prepping the small bits for molding, there is the sight, trigger, trigger keeper and the flashlight. I laid down a base of clay and filled in around the parts. The registration keys were then added. All of the sprues will be added in between pours of the two halves.
Finally comes the barrel assembly. The procedure was much same with the other box molds. I had cut out the hard board the serves as a barrier between the two halves. The came filling the gaps with clay. I filled the back side first to provide a solid structure and good bass for filling in the gaps. This way no clay with pop out and let rubber leak. Once again, lessons learned the hard way. Once the back had all be filled, I cleaned up the front added clay in the gaps and using my sculpting tools I made sure that the gaps were smoothed out. All that remains is to cut the rim boards for the two molds? Wax and spray with release and they are ready for rubber. Once the rubber is down she is all done
Finally comes the barrel assembly. The procedure was much same with the other box molds. I had cut out the hard board the serves as a barrier between the two halves. The came filling the gaps with clay. I filled the back side first to provide a solid structure and good bass for filling in the gaps. This way no clay with pop out and let rubber leak. Once again, lessons learned the hard way. Once the back had all be filled, I cleaned up the front added clay in the gaps and using my sculpting tools I made sure that the gaps were smoothed out. All that remains is to cut the rim boards for the two molds? Wax and spray with release and they are ready for rubber. Once the rubber is down she is all done
tango down
New Member
man...you are really good. that thing looks awesome!
Streetrocks
Active Member
Okay, time for another update. Made some serious headway through the weekend and the week. Finished all of the prep and poured the rubber for the barrel assembly, small parts, and half of the pump mold. Here's the pics:
Completed box mold for the small parts:
The barrel assembly:
Sans registration keys
With registration keys. The usual glue stick bits were used for keys. You can also see the pouring sprues and vents.
Next I poured an initial pseudo print layer. This is less about preserving detail than it is about sealing around the part to prevent leakage. It locks the part in place and ensures that all of the cracks are closed up. I let it sit for an hour or two and then pour over top of it.
Just a shot of where I am working in my garage.
The initial layers on the pump and small bits. On the pump I made sure to pour over the front where the recesses were first to ensure that no large air bubbles were trapped.
What the work space looks like after a while of pouring rubber
After the first half was cured I pulled the clay barrier from the small parts and removed the hard board and the clay from the Sam on the barrel assembly. I then proceeded to spray down the whole thing with release agent being very liberal, you want to ensure that the two sides are not going to stick together, so you really can't use too much release agent. I then poured the initial layer, following it up by pouring the rest of the second halves for the barrel assembly and small parts.
So, once again, lots of pics, but I hope the process helps a bit. There is a ton of rubber in all of the various molds, once these are all cured I will get a shot of all of them together.
Once all of the rubber is cured I have to cut the backing boards for all of the parts, but that goes fairly quickly.
Completed box mold for the small parts:
The barrel assembly:
Sans registration keys
With registration keys. The usual glue stick bits were used for keys. You can also see the pouring sprues and vents.
Next I poured an initial pseudo print layer. This is less about preserving detail than it is about sealing around the part to prevent leakage. It locks the part in place and ensures that all of the cracks are closed up. I let it sit for an hour or two and then pour over top of it.
Just a shot of where I am working in my garage.
The initial layers on the pump and small bits. On the pump I made sure to pour over the front where the recesses were first to ensure that no large air bubbles were trapped.
What the work space looks like after a while of pouring rubber
After the first half was cured I pulled the clay barrier from the small parts and removed the hard board and the clay from the Sam on the barrel assembly. I then proceeded to spray down the whole thing with release agent being very liberal, you want to ensure that the two sides are not going to stick together, so you really can't use too much release agent. I then poured the initial layer, following it up by pouring the rest of the second halves for the barrel assembly and small parts.
So, once again, lots of pics, but I hope the process helps a bit. There is a ton of rubber in all of the various molds, once these are all cured I will get a shot of all of them together.
Once all of the rubber is cured I have to cut the backing boards for all of the parts, but that goes fairly quickly.
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Streetrocks
Active Member
I just posted an interest thread in the junkyard for those who had wanted a kit. You can find it here: http://www.therpf.com/f13/halo-reach-m45-tactical-shotgun-kits-186114/#post2913753
Streetrocks
Active Member
For the sake of preserving the purpose of demonstrating the dos and donts of the molding process let me show you my screw up:
If you notice, the pump is out of it's box, off to the side, covered in rubber. It was an expensive goof to say the least. In the case where you are pouring over a part, ensure that you have secured the part securely to the base over which you are pouring. I only tacked it down with hot glue. I should have glued it down more securely. The reason I didn't is that I was concerned that in removing the base to pour the rest of the rubber I would unseat the pump from the rubber which would create a lot of problems. (You almost never want to remove the part from the mold until all rubber has been poured, it never goes back in perfectly. There are tiny gaps that the rubber will find. Nightmare. Once again lesson I learned the hard way). The end result is that the pump floated off its base up through the 3/4 gallon of rubber I had poured over it. This could also have been prevented if I had left the initial/sealer layer cute longer until it was mostly hard. Sadly my impatience got the better of me. Now some might say why don't you just try glueing it down again and re-pour it: well, the rubber the cured against the mdf sort of seals the "pores" of the wood, and the glue won't really stick to it. How do I know that. Because silly me, like most other lessons learned, I tried it, and no dice. Now, one more lesson to learn from my screw up: the rubber isn't a complete waste. You can't cut it up and mix it with fresh rubber and it becomes a viable filler. Awesome when you are pouring large box molds like these. I was able to reuse pretty much all of my excess rubber from previous screw ups.
Streetrocks
Active Member
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.
