If you haven’t already, please check out Part 1 of this series.
So you want to complete a Polymer80 80% Glock frame? If you’ve got access to a milling machine, lucky you. Completing 80% receivers will be an easy endeavor for you. Unfortunately, not all of us are so lucky.
But when Polymer80 released their 80% Glock frames not that long ago, I felt there was some potential that such a project might be in reach of the average tool owner. While completing a metal 80% lower such as an AR-pattern receiver would be a non-starter with something like a Dremel, the soft polymer of a Glock frame would be no problem for it. Many homeowners already own a Dremel tool – they’re pretty handy for all kinds of things around the house.
So here’s what you’re going to need:
- A bench with vice.
- A standard, everyday drill for making holes for the pins.
- Obviously a Dremel Rotary Tool.
- Ensure it’s a model that’s compatible with the Dremel Router Table, because you need that too. This adapter will basically turn your Dremel into a light-duty table router, which will make removing most of the excess polymer much easier than trying to freehand. It can be purchased on Amazon, or at most hardware stores for around $30.
- Finally, you’re going to need a few bits for your Dremel model. I grabbed a narrow (1/4 inch) sanding drum, as well as a standard short milling bit and this extended cutting bit.
Put on your eye protection and let’s get started! Good luck!
Step 1: Snap the 80% frame into the jig. My jig seemed a little warped in a few places, so I grabbed a little bit of painters tape to tighten things up. As directed by Polymer80’s instructions, we don’t want things too tight. Just ensure a snug fit.
Step 2: We need to drill the holes. This is pretty straightforward. Tighten the jig into a vice until it’s snug but not too tight. Use the included drill bits to drill the three holes needed. Do one side, then flip the jig around and drill the other side. Do NOT try to drill straight through from one side to the other.
Step 3: Mount your router table to a sturdy surface – a bench or work table will do just fine. The router table is made to be fixed to a standard 2×4, which can then be mounted to your desired surface using c-clamps. That way you don’t have to permanently attach it to anything. If you’re attaching this to a 2×4 for the first time, I recommend cutting the 2×4 to about 36″. I cut mine a little shorter, and find the c-clamps sometimes get in the way of my elbows. Obviously the surface size and shape of whatever bench or table you’ll be clamping it to will need to be taken into account.
Step 4: Install the short milling bit into your Dremel tool and attach the tool to the router table as per the instructions so the milling bit is sticking up through the hole.
Step 5: Turn your jig upside down and set it on top of the router table so that it’s close to the bit. The areas at the top of your 80% frame that need to be removed are exposed by the jig, so adjust the height of the milling bit so that it’s high enough to remove the extra polymer without cutting into the frame itself. Leave yourself a slight margin of error. Remember, you can always take more plastic off, but putting it back on is…a lot harder.
Step 6: Start the Dremel tool. I had found the sweet spot to be around 20,000-25,000 RMP. Slower, and it sometimes seizes-up on the plastic or cause things to jump around. Faster and I could smell the polymer beginning to melt. With the jig and frame still upside down, slowly move it so the milling bit contacts the exposed areas that we want removed. Repeat for each of the four sections of excess polymer that extrude from the top of the frame. Take your time. Slow and steady will get you better results, with less chance of a major oops. I left a tiny amount of plastic in place just to be sure I didn’t accidentally take too much off, with the intention of filing off the rest by hand.
Step 7: Once you’ve got the four sections removed, return the jig and frame to the vice and use a file or some sandpaper to smooth the ledges down so that they’re flush with the top of the frame. There you have it. That wasn’t too hard at all. Certainly a lot easier than trying to do it freehand.
Step 8: Now the hard part. We’ve got to clear out the channel to make room for the recoil rod and spring. There’s no easy way to do this other than putting the jig back into your vice and doing your best to freehand it. I started by using the drum sander on a low RPM setting. Once I had a good bit of the excess polymer cleared out, I switched to the longer milling bit. It takes a bit of patience, but after coming at it a few times from different sides and angles, I was able to get the channel sufficiently cleared without removing anything that shouldn’t be.
You’ve now got a finished frame that’s ready to accept Gen 3 compatible Glock lower parts and trigger. Polymer80’s website actually provides good instruction here, and there are plenty of how-to videos available on YouTube.