A Guide to Building a 1911 Frame at Home – Part 2 (Cutting)
Drilling is out of the way. For many, drilling the frame is surprisingly the more difficult of the two tasks in our project. Cutting your 80% 1911 frame is a much slower and more controlled process. Let’s continue with our Guide to Building a 1911 Frame at home – Part 2: Cutting.
Secure the Jig and 80% Frame in a Table Vise
Once you’ve drilled both holes, grab the cutting car (hand plane) provided in the kit. Use the smaller Allen key provided in the kit to loosen the car’s frame rail cutting blade adjustment screw, found on the side of the raised cutting block. Set the depth of the blade so its edge is flush with the surface of the cutting car by gentling pressing it, then re-tighten the adjustment screw.
Set the Cutting Blade Depth and Control Knob
Now you can install the cutting depth control knob on the opposite side of the cutting car, where it is recessed. Simply screw it into the pre-threaded hole, tightening it until the cutting blade begins to move. Once the blade begins to move (so it is protruding past the cutting car’s surface), loosen the adjustment screw, make the blade flush once more, and re-tighten the adjustment screw. You’re now ready to set your “zero”, or depth at which the blade begins cutting, by rotating the adjustment knob further.
Install the cutting car’s handle in the pre-threaded hole immediately next to the adjustment knob. Run the blade across the surface of the frame by seating the car’s cutting blade inside the oval slot on the side plate. Move the car forward to feel whether the blade is cutting (lubricate the cutting area and all contacting metal surfaces first; do so liberally). Make slow passes and be sure to continue cleaning debris and lubricating while you cut.
Continue test-cutting and adjusting the knob with slow passes until the blade begins to touch and cut the frame. Once you begin to feel resistance and cutting force being applied, mark the adjustment wheel and the surface of the cutting car. This will be your starting cutting point on the adjustment knob, or simply, your “zero”. As you make passes, you’ll rotate the adjustment knob. Each tick mark surrounding the adjustment knob represent 1/10th of a turn. You will need to continue cutting until you’ve rotated the adjustment knob a total of 1.9 turns.
Cut the Frame Rails
Now you can begin cutting your 80 percent 1911 frame’s side rails. Make slow, consistent passes. Only cut in the forward direction, lifting the cutting car and blade away from the frame. Keep cutting until you no longer feel cutting friction.
At this point, you will turn the adjustment knob to continue cutting. Repeat the cutting process until you’ve made approximately 1.9 full turns. Check your cutting depth with a micrometer until you measure 0.061” of cut depth.
Once you’ve cut the first frame rail, remove the jig from your vise and remove the raised block. Flip the jig over and place the raised block in the recess on the opposite side plate. Seat your jig once more, find your cutting zero, and cut the other frame rail to depth.
Set up the Jig to Cut the Barrel Seat
Once you’ve cut both frame rails, remove your jig and remove the raised block. Take your larger Allen key and remove the set screw from the side plates. Remove the frame from the jig. Some force may be needed. Ensure your slide stop pin and hammer pin are still seated in the frame.
Locate the two holes in the RH and LH side plates that are only half-drilled and seat the slide stop and hammer pins in those holes, sandwiching the frame between both side plates. Reinstall your set screw to keep the assembly together, ensuring there is no space between your jig and frame. Secure your frame and jig in your vise, with the barrel end of the frame pointing toward you.
Set up the Cutting Car to Cut the Barrel Seat
Remove the handle from the cutting car and reinstall it in the threaded hole immediately to the left of its current location behind the adjustment knob. Remove the adjustment knob from the recessed slot, and reinstall it in the lifted, threaded slot immediately in front of the handle. Tighten the adjustment knob until the larger barrel seat blade begins to move.
Flip the cutting car over and press the larger barrel seat blade so it is once again flush with the car’s surface. Grab the smaller Allen key and tighten the set screw for the adjustment knob and barrel seat blade.
Cut the Barrel Seat
Place the cutting car atop the frame, making a test pass to set your zero at the minimum cutting depth. Again, mark the adjustment knob and car with a marker and be sure to oil the car, frame and jig while cutting.
Make slow, consistent passes while cutting, adjusting the adjustment knob as needed to continually remove metal from the frame. Make cutting passes until you’ve cut a depth of .077”, or approximately 2.4 passes.
Once you’ve finished cutting your barrel seat you can celebrate – you’ve just become the proud owner of a legal-by-definition 1911! Your completed frame is now ready for final assembly using the components in your 1911 Build Kit, though you may need to lap the slide during assembly. Lapping the slide involves installing it and gently tapping it across the frame rails, in order to remove metal and eliminate binding – we talk about how to lap your slide in more detail here.