Best material for modeling a part?

azredhawk44 · May 24, 2007, 02:39 PM

So... say I want to make an AR mag well insert for a caliber and magazine conversion.

What material lends itself best to a casting that can then be altered to accept springs, latches and pivot pins? A plastic? Epoxy? Some sort of resin?

I basically need to make a bunch of "blocks" about the size of a 20rd AR-15 magazine that has room to hold a 1911 magazine inside of it, and tweak each one to find the best depth for the magazine to insert, for reliable feeding. I will then take that plastic model and look into a CNC metal (probably aluminum) solution that is more stable and rugged.

Scorch · May 24, 2007, 03:35 PM

I have seen plastic mock-ups of AR mags. Maybe you could modify one of those? If not, an aluminum block could be machined to fit the mag well very easily.

choochboost · May 24, 2007, 03:48 PM

I'm not sure what you're trying to do but this company may have a suitable product: www.smooth-on.com

5whiskey · May 24, 2007, 04:09 PM

I GOT IT!!!

Is this an attempt at a CA legal AR with detachable magazine? What's the rule there, cannot accept in any way any magazine over 10 rounds? I'm not sure, but shooting from the hip it sounds like where this is going. Of course, I've been terribly wrong before.

As for what you're trying to do here's my suggestion. Take bondo, yes bondo and thin it with acetone. Remove the magazine release completely and tape up those holes from the inside of the mag well, don't want any epoxy to seep in. Tape off the top of the mag well completely, and then spray the inside very liberally with pam cooking spray. Make sure you use the kind that has olive oil. That will be the release agent. Then mix up your thinned bondo and slop it in. You will need to work the stuff in pretty good to get rid of the air pockets, and you will still have very small ones. Get a little wooden dowel to pack it in well.

In about 6 hours you will have a near perfect cast of your mag well that should be able to hold the springs, pivot pins, etc. as long as it's just a prototype. I wouldn't bank on it working forever but it should work long enough for you to experiment with and develope the specs to build something more permanent.

Bondo cures pretty quick... but thinning it plus making a solid block this big will probably take much longer to cure. I think I'd wait a day before I pounded it out. Just make sure you coat very liberally with release agent.

azredhawk44 · May 24, 2007, 04:30 PM

Quote:

I GOT IT!!!

Is this an attempt at a CA legal AR with detachable magazine? What's the rule there, cannot accept in any way any magazine over 10 rounds? I'm not sure, but shooting from the hip it sounds like where this is going. Of course, I've been terribly wrong before.

There's another good use for it... except I think there ARE 1911 mags that hold more than 10rds... big stick mags about 18" long.

Nah... screw California.

I just want an AR in 45acp that takes 1911 magazines, and I'm willing to put in some sweat and elbow grease to get it done. Once I have a functional plastic prototype, I'll look into milling a more permanent Aluminum solution and a possible patent or copyright, and maybe some sales later.

But for right now, I want a new 45acp carbine that takes 1911 mags, for me.

Slopemeno · May 24, 2007, 08:08 PM

Delrin is easy to work with, though expensive if you are paying retail.

That Bondo idea is interesting though. Put some release agent wherever the Bondo touches...I prefer butter flavored Pam myself.

Cowart · May 25, 2007, 05:00 PM

It seems to me that it would be much more practical to make a block that attaches to the magazine rather than the gun. It would be shaped to imitate an AR magazine, including the opening for the magazine catch.

This is the method that Oly uses for their own 45acp upper, which uses modified UZI magazines. See pictures at http://www.olyarms.com/?rootView=bro...dtl&ids=K45-UR

Slopemeno · May 25, 2007, 09:38 PM

..then you have to make a bunch of them. This way he only has to make one.

T. O'Heir · May 27, 2007, 12:05 AM

It's been done, but not with 1911 mags. http://www.cncguns.com/projects/AR45lower.html

May 24, 2007, 02:39 PM	#1
azredhawk44 Junior member Join Date: September 28, 2005 Location: Mesa, AZ Posts: 6,465	Best material for modeling a part? So... say I want to make an AR mag well insert for a caliber and magazine conversion. What material lends itself best to a casting that can then be altered to accept springs, latches and pivot pins? A plastic? Epoxy? Some sort of resin? I basically need to make a bunch of "blocks" about the size of a 20rd AR-15 magazine that has room to hold a 1911 magazine inside of it, and tweak each one to find the best depth for the magazine to insert, for reliable feeding. I will then take that plastic model and look into a CNC metal (probably aluminum) solution that is more stable and rugged.

May 24, 2007, 03:35 PM	#2
Scorch Senior Member Join Date: February 13, 2006 Location: Washington state Posts: 15,248	I have seen plastic mock-ups of AR mags. Maybe you could modify one of those? If not, an aluminum block could be machined to fit the mag well very easily. __________________ Never try to educate someone who resists knowledge at all costs. But what do I know? Summit Arms Services

May 24, 2007, 03:48 PM	#3
choochboost Senior Member Join Date: October 15, 2005 Location: orange county, ca Posts: 610	I'm not sure what you're trying to do but this company may have a suitable product: www.smooth-on.com

May 24, 2007, 04:09 PM	#4
5whiskey Senior Member Join Date: October 23, 2005 Location: US Posts: 3,652	I GOT IT!!! Is this an attempt at a CA legal AR with detachable magazine? What's the rule there, cannot accept in any way any magazine over 10 rounds? I'm not sure, but shooting from the hip it sounds like where this is going. Of course, I've been terribly wrong before. As for what you're trying to do here's my suggestion. Take bondo, yes bondo and thin it with acetone. Remove the magazine release completely and tape up those holes from the inside of the mag well, don't want any epoxy to seep in. Tape off the top of the mag well completely, and then spray the inside very liberally with pam cooking spray. Make sure you use the kind that has olive oil. That will be the release agent. Then mix up your thinned bondo and slop it in. You will need to work the stuff in pretty good to get rid of the air pockets, and you will still have very small ones. Get a little wooden dowel to pack it in well. In about 6 hours you will have a near perfect cast of your mag well that should be able to hold the springs, pivot pins, etc. as long as it's just a prototype. I wouldn't bank on it working forever but it should work long enough for you to experiment with and develope the specs to build something more permanent. Bondo cures pretty quick... but thinning it plus making a solid block this big will probably take much longer to cure. I think I'd wait a day before I pounded it out. Just make sure you coat very liberally with release agent.

May 24, 2007, 08:08 PM	#6
Slopemeno Senior Member Join Date: January 19, 2007 Posts: 2,663	Delrin is easy to work with, though expensive if you are paying retail. That Bondo idea is interesting though. Put some release agent wherever the Bondo touches...I prefer butter flavored Pam myself.

May 25, 2007, 05:00 PM	#7
Cowart Senior Member Join Date: March 15, 2007 Posts: 247	It seems to me that it would be much more practical to make a block that attaches to the magazine rather than the gun. It would be shaped to imitate an AR magazine, including the opening for the magazine catch. This is the method that Oly uses for their own 45acp upper, which uses modified UZI magazines. See pictures at http://www.olyarms.com/?rootView=bro...dtl&ids=K45-UR

May 25, 2007, 09:38 PM	#8
Slopemeno Senior Member Join Date: January 19, 2007 Posts: 2,663	..then you have to make a bunch of them. This way he only has to make one.

May 27, 2007, 12:05 AM	#9
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	It's been done, but not with 1911 mags. http://www.cncguns.com/projects/AR45lower.html