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Introduction
I’ve always had the desire to make my own custom handgun grips.  I decided to start with 1911 grips because they’re somewhat flat and fairly simple to make.  Using CorelDRAW®, my CAD/CAM software BobCAD-CAM and my MAXNC 10 CL CNC hobby mill I felt I could design and create my own grips.

Jig

Before beginning the design work on my grips I needed to build a jig to hold the wood.  I purchased a piece of 3/4” x 3” x 12” aluminum from Online Metals.com to use as the jig.  I milled six holes along the center length of the jig; the two 0.201“ outside holes spaced 6.25“ apart I tapped for 1/4-20 bolts.  These are used to hold the scale for drilling holes.  The next two holes are 0.258” drilled completely through the metal with a 0.3752” countersink 1/4” below the top.  This holds a 1/4-20 set screw for T fittings that hold the jig to my mill table.  Finally the two inside 0.212“ holes spaced 3.074” apart I tapped with a 1911 grip bushing tap.  I install a 1911 grip bushing in these holes to hold the scale for final shaping by the mill.

After I milled the holes I took a 3/16” square end bit and milled a center mark on the jig.  This allows me to center the milling head each time I reinstall the jig.

Designing the Grips
I have the excellent book "The U.S. M1911/1911A1 Pistols:  A Shop Manual Volume 2" by Jerry Kuhnhausen.  Page 79 contains detailed measurements for 1911 grips which I used for my design work.  

I used CorelDRAW® to do my initial design work.  First I scanned a pair of factory grips then traced the outline.  I used the Kuhnhausen manual to adjust the dimensions and create the 3-dimensional profiles.  These 3-D profiles are located at either end of the grip outline.  The two red crosses at the bottom of each outline are used to help me locate the bottom profile after I get it rotated into the third (Z) dimension.  The small square below the left mounting hole of the right grip is for the gap for the right part of an ambidextrous thumb safety.  The line along the top of the left grip is for milling a notch to allow for the plunger tube.  The two mounting holes are exactly 3.074” apart along the center line.  The shape and 3-D profile of the grip is always with reference to this center line.

Next I exported each grip pattern as a drawing .dwg file, which I then imported into the CAD/CAM program.  The CAD (computer aided design) part of the program allows me to create a 3-D part.  I created all of the tool paths for the bushing and screws holes, cutouts and notches, and the final outline.  Because I could use a 3/16” square end bit for all of these cuts, the tool paths had to be offset by half of the thickness of the bit, or 3/32”.  

First I created the tool paths for all of the holes.  I did the bottom holes first; the countersink for the grip bushing, then the hole for the bushing itself.  At this time I also created the tool path for the cutout on the right grip for the ambidextrous safety, and the plunger tube notch on the left grip.  Next I created the tool paths for the top holes, which are for the grip screw heads.  In the above figure, the purple lines are the tool paths.

Now I created the tool path for the outline of the grip.  Again, this tool path had to be offset by half of the thickness of the 3/16” bit.

So far this has been fairly easy because I’m working with a flat, two-dimensional design.  But now I needed to create the three-dimensional shape of the grip.  I decided I didn’t have to create a detailed 3-D shape with all the notches and cutouts.  Instead, because I was going to cut the outline first I decided that I only needed to create a general 3-D shape that followed the contours of the grip.

First I rotated the top grip profile so it stood up straight; this is now the top 3-D shape of the grip.  I rotated the bottom grip profile upright so it leaned to the left by 45-degrees, then rotated it 12-degrees to match the bottom outline.  This gave me the bottom bevel of the grip.  Using the software I connected the two 3-D profiles and created a 3-D “skin” which was now the 3-D shape of the grip without all of the notches and cutouts.

I created the tool path for the 3-D shape based on a 5/16” ball end bit.  The tool path starts in the center of the grip and cuts in a radial pattern around the grip.  The 3-D pattern is a little bit larger than necessary because I designed the tool path to run off the edge of the grip and I didn’t want the edge of the bit to remove any excess wood.  I also set the individual tool tracks very close together so I could get a smooth grip with very few ripples, which makes it easier to finish.

Scales

Creating a grip begins with a blank piece of wood called a scale.  I found on the Internet some Brazilian blood wood that makes beautiful, bright red grips.  This is more of a soft wood, like pine, rather than a hardwood like walnut, but it has a very fine grain.  For 1911 grips I cut the blood wood into 3/8” x 2” x 4 1/2” scales.  I take one side of each scale and sand it flat on my belt sander using a fine-grit belt.  This is the inside of the grip that sets against the frame of the gun.

Step 1:  Milling the Bottom Holes and Notches

I position the scale in the center of the jig and hold it in place with brackets as shown in the photo.  I install the 3/16” square end bit and zero it to the top of the wood.  I run the program that mills the grip bushing and bushing countersink holes.  If this is going to be a right side grip, I also mill the ambidextrous safety cutout.  If this is going to be a left side grip I mill the plunger tube notch.

Step 2:  Milling the Top Holes

I remove the grip and install the grip bushings onto the jig.  This keeps the scale properly aligned for all the other operations.  I turn the scale over and install it onto the bushings and reinstall the brackets.  I then zero the 3/16” bit to the top of the jig and mill the two screw-head holes.

Step 3:  Milling the Outline

I remove the brackets and install grip screws to hold the scale in place.  I now cut the outline of the grip.  When this is completed I have a 3/8” thick grip that fits the 1911 frame, but it still needs to be milled to the proper shape.

Step 4:  Milling the Final Shape

I install a 5/16” ball end bit, zero it to the top of the jig, and start the final shaping program.  It takes about 90-minutes to mill the final shape of a grip, but this is because I wanted the tool paths to be close together so the result would be smooth.

Step 5:  Engraving a Design

Because I have a CNC mill I can etch designs into the grip.  As with the grip itself, I first create the design using CorelDRAW® then export the design to BobCAD-CAM.  With BobCAD-CAM I project the design along the curved surface of the grip.  This now becomes the tool path for engraving the design.

I use a 0.02” ball end bit to engrave the design.  Because this bit is so small I remove 0.0005” with each pass down to a total depth of 0.008”, and move it very slowly.

Step 6:  Final Finish

I mount a completed grip onto a small piece of aluminum onto which I have installed two grip bushings.  I hold this piece of aluminum in my hand so I can run the grip over a piece of 150-grit sand paper to remove any milling marks and make it smooth.  I final sand the grip first with 400-grit, then 600-grit sand paper. 

Now that the grip is finished I apply 3 coats of Birchwood Casey® Tru-Oil® to all surfaces and inside all of the holes.  I allow each coat to dry for 6 hours before applying another coat.

As you can see from the photo, the results are spectacular.  These are a set of grips I made for my son engraved with his initials.