Welcome back to my Leatherworking Journey. This month I continued creating tools for my new leather workshop. Here is a how to guide for creating a leather stitching clam. Similar to the Al Stohlman style leather stitching pony, this stitching clam is used to hold your leather pieces while you sew the item together. The stitch clam is longer, and works well for stitching lots of small items together. The stitching clam doesn’t require the use of your body weight for leverage, so you can quickly adjust positioning or change out pieces.
- Table or skill Saw
- Miter saw or hand saw
- Jig saw
- Dremel Saw (not required but helps)
- Drill with 3/8″, 1/2″, and phillips drill bits
- Tape measure
- Adjustable spanner wrench (aka Crescent Wrench)
- X-acto knife
- Sander or sandpapper block
- Thinnest plywood you can find 2′ x 4′. (I used 3/8″ thickness)
- 4’+ scrap 2″ x 4″ (2)
- Wood Glue
- 2″ 3/8″ carriage bolt (4)
- 3″ 3/8″ carriage bolt (1)
- 1″ radius 3/8″ washer (5)
- 1 1/2″ radius 3/8″ washers (5)
- 3/8″ locking washers (5)
- 3/8″ nut (5)
- 1/2″ wood screw (8)
- scrap leather (4″ x 8″ minimum)
- Craftsman contact cement
Step 1: Cutting clamp arm boards
I started my project by heading to my local hardware store. The thinnest plywood available was 3/8″ thick, and found in the limber flooring section. I asked a staff member to perform three cuts on the 4′ x 8′ sheet I was purchasing. Now, this is enough wood to create 4 clams, but a full sheet was the unit size available. I first requested the sheet be cut in half to create two 4″ x 4″ boards. I then requested each board be rotated and cut with the grain to create 2′ x 4′ boards, four in total. I then purchased the rest of my materials list and headed home.
Once home I used a table saw, and my father-in-law’s assistance to rip the 2′ x 4′ board into six 4′ pieces. Because of the width of the blade your six boards will be just shy of 4″ wide.
Step 2: Creating clam arm shape mold
Creating the mold is an easy, yet critical, step in the project. Your stitching clam will create force, to hold leather, by how the tips are shaped to extend past the base end’s depth. The image below is a better description than my words:
The first cut of the base was a table saw rip down the center of the scrap 2″ x 4″. We stopped the cut at about 2 feet. Next we hand sketched the remaining shape of the mold. Using a jig saw the curved shape was cut. You’ll want to save second half portion of the curve, so your clamps will have a stronger base to clamp onto.
Step 3: Gluing and molding the clam arms
The stitching clam arms are made by gluing three of the 4″ x 4′ plywood pieces together and clamping them to the mold for drying dry. The wood is thin enough to accept the shape, and the glue helps hold the shape. Take one board and apply a liberal amount of wood glue. Place the second board on top, and again apply a liberal amount of glue. Finally, place the third board on top. Position your boards onto the mold, and clamp the base first. We used small pieces of scrap wood under the clamp on the plywood side. This helps distribute the clamp’s pressure more evenly to the plywood. Next work your way to the end of the mold applying a total of four clamps. You can see in the image how we used the second half of the curve cut by placing it on top of the plywood and clamping. This provided the fourth clamp with a flat surface and reinforces the shape of the mold.
Repeat these steps to create a second arm, or allow arm one to dry for twenty-four hours, and then reuse the mold to create a second arm.
Pro Tip: Having helpers around is always fun!
My son enjoyed learning from Dad and Grandpa
Step 4: Finishing stitching clam arms
After allowing your clam arms to dry for twenty-four hours you are ready to finish their surfaces. I started by using a dremel saw to shave off the rough edges of the glued boards. Next, using a hand sander, I smoothed the surface and edges of the arms.
Note: if you plan on staining your stitching clam be very careful with how much you sand away from the surface. The top layers of plywood are very thin, and it is easy to expose the second layer with too much sanding.
After sanding the surface and edges you need to shape the tips of your arms. The goal is to sand the shape such that the tips press together is more surface area then just a sharp board edge. Take your time, and test the arms together until you like how your arms rest together.
Step 5: Drill holes for assembly
Hold your boards together as if the stitching clam were complete. Use clamps to hold the boards together. Now pencil two drill locations about 2 inches from base and 1 inch from sides. Using a 3/8″ drill bit create two side-by-side holes. Next use a 1/2″ drill bit to create countersinks on one side. The countersink with allow your carriage bolts to assemble flush with the board’s surface.
Install the base 2″ carriage bolts using the order: Bolt, 1 1/2″ washer, boards, 1 ” washer, locking washer, nut. This will hold your pieces together as you drill the other holes.
Your next holes are another pair for 2″ carriage bolts. Their location should be about 4 inches before the curves start on your clam arms. Once created you can assemble one bolt to help hold your boards together as you create the final hole.
The final hole is for your 3″ carriage bolt. The location needs to be eyeballed, and based on where the curves form around 2 inches of space. Using a pencil mark a drill location that is centered on the board. Now drill a hole with the 1/2″ counter sink. Drilling this hole is tricky because the curved wood creates a weird angle at rest. I suggest putting scrap wood under the base end, so the boards are level. This will help with drilling an accurate hole.
Now that all of the holes are drilled disassemble the boards for the next step.
Step 6: Leather covers for clam ends
The final pieces to craft are the leather covers for your stitching clam’s clamp end. Take your scrap leather pieces, and using an X-acto knife cut two pieces that are the width of your clam boards and a minimum of 8 inches long. Apply a liberal amount of contact cement to one side of the leather and to one side of the board. Position the leather so that when wrapped the leather will cover the same length of board on each side. Press the leather to one side of the board so the cement coated sides make contact. Anchor the leather down by screwing in the 3/4″ wood screws. Apply contact cement to the other board side and wrap the leather around the end of the board. Apply more contact cement so all of the area under the leather will be covered. Anchor the end of the leather with two more wood screws.
Step 7: Assemble the leather stitching clam
Install all four of the 2″ carriage bolts. Next place clamps onto the curved portion of the clam. Install the 3″ carriage bolt using the order: Bolt, 1 1/2″ washer, locking washer, boards, 1 ” washer, locking washer, nut. The locking washer will help the bolt assembly adjust to the curvature of the boards.
The purpose of the 3″ carriage bolt is to compress the curved boards together, and thus create pressure at the contact points of the clam’s tips. Use the clamps to compress the curves together as you gradually tighten the 3″ bolt. Tightening the bolt is how you’ll adjust the gripping strength of your clam.
Note: I initially drilled two holes for two 3″ carriage bolts, but I found that both bolts would have to be tightened exactly the same. If one was tighter than the other, then the less tightened bolt wasn’t contributing to the compression system. I eventually decide a single bolt design was best.
After adjusting the 3″ bolt to your desired compression remove the clamps, and your leather stitching clam is done! It’s now ready to hold your vegetable tanned leather, and assist you in creating some high quality handcrafted leather items. Thanks again for joining me on my leatherworking journey.
Cheers to the Journey,
Founding member, CFO
Origins Leather Company
Here are Origins Leather Company we’re striving to create a company that is founded on integrity and high quality business standards. Our handcrafted vegetable tanned leather products are a reflection of our passion for quality and integrity. Like our lifetime products, we hope to pass on our company to our next generation. We take pride in creating heirloom leather goods, and we hope our children will take pride in the work their fathers are doing. We look forward to the day when our children take the reigns of our company, and continue the traditions of high quality products and service that we are establishing today.