Building a Stitching Clam
Some time ago another member of the IILG, Johan Potgieter, mentioned something he called "a stitching clam" during a discussion on sewing leather. Most people use a small stitching pony sold by Tandy or, if they are lucky enough to own one, a stitching horse. The idea being to have something that can hold pieces of leather tightly while you push the awl and needles through it. Since you need both hands to properly harness stitch it is imperative that the leather be held tightly without using your hands. (At least for those of us with only two hands.)
Since the stitching pony is small, limited in throat depth (The distance from the tip of the jaws to the first obstruction in the opening) it is only good for very small projects. I have trouble using one on a checkbook cover since the throat depth on the unit Tandy sells is less than 4 inches. A stitching horse has much larger jaws, will hold tighter (Since you use a foot pedal and strap to tighten the jaw) but is also large enough to qualify as a piece of furniture. They are also expensive for someone working on a hobbyist's budget.
The stitching clam (Clamp?) is different in that it is has a very long throat (no tightening mechanism), is small enough to store easily, and is inexpensive to make. (Mine cost just under $15 US to build.) To use it you spread the jaws apart and the natural spring of the wood holds your item in place. The clam itself is held between the knees while stitching. It is also extremely simple to build with a few basic hand tools. For this reason I ran down to my local home center and bought what I needed to build one.
Materials
The basic material of the clam is wood. I happened to find some beautiful, tight grained 1/2 inch hemlock at my home center. This is usually used for trimming around doors, door jambs and stops (The little strip that keeps the door from swinging past closed) and for some furniture. Since I like wider jaws I used a 6 inches wide piece. (Note: All lumber sizes are nominal, i.e. a 1 inch board is actually 3/4 inch thick. The exceptions are particle board, plywood, and my hemlock. It was sold as 1/2 inch.) I also purchased a hemlock molding strip 1 1/4 inches wide, 1/4 inch thick, and 6 feet long to make my jaw extensions. Since I really only needed about 2 feet of material I would have bought a much shorter piece, but 6 feet was the shortest they sold.
I chose Hemlock because that is what they had in the thickness I wanted. Common one by
(1 inch thick nominal) Pine would work (try to get it
with as few knots as possible) and so would thin Oak. I thought about using 1 inch Oak (3/4 inch actual thickness) to make it stronger, but I doubt I could
have spread the jaws to put my leather in it. Something softer such as maple, ash, birch, or my hemlock works very nicely. Just make sure whatever
you get has a good spring
to it. That's why you have to use regular boards and can't use plywood or finger jointed
boards. Although I have
thought of a variation that would let you use this material. More on that later.
The 8 foot long board I purchased was too long to fit in my car A very nice gentleman at the lumber counter offered to cut it for me. Since I only needed two pieces he cut it exactly in half. He also cut four pieces of the molding strip slightly longer than the board was wide. While I was at Eagle Hardware and Garden many home centers will do this for you since they cater to the "Do-it-yourself" clientele. Lumberyards that deal mainly with the building trades might charge you extra for cutting the material. While it saved me time and effort (and made the materials small enough to fit in my car) I could have easily cut all the materials with a simple hand saw and a few minutes work.
Hardware
The only hardware required for this project were a handful of wood screws. I used small flat head screws to hold the jaw extensions to the arms and 3/4 inch drywall or grabber screws to hold the base together. I also used liberal amounts of yellow carpenter's glue but plain old Elmer's white glue would work just as well. I also have some thin scraps of leather that I plan to cover the inside of the jaws with. That should prevent any marring of my projects as they are held in the clam.
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Tools The tools required are few and should be in any moderately well stocked tool box. A measuring tape or ruler and a small square to mark the boards for cutting (You want them as straight as possible). I also used a drill with 1/8" and 1/4" bits to predrill and countersink all my screws. That way the heads are out of the way, won't mark the leather, and it looks nicer. When working with thin material is it important to predrill the holes to keep the wood from splitting. A screwdriver of the proper type for your screws, spring clamps, or c-clamps, to hold pieces together while marking and drilling (masking tape works if you don't have clamps) and a small paintbrush or your finger to spread the glue. Use a damp rag to clean up any excess glue as it squeezes out of the joint. It's much easier to clean up before it gets hard! While I used a small block plane and wood shaver to shape the angle on the jaws a rasp would work well also. Sandpaper to touch up any rough or sharp edges. |
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The Parts
The arms are the long pieces that act as both springs, and jaws. I made the jaw extensions to give me more room to hold a project and to get
the proper jaw
type curve without cutting the arms out of a much larger timber. The jaw extensions made it easy to use straight material without
bending or heavy woodworking. While I have not yet built it, I am contemplating a base assembly to hold the clam upright. That would allow me
to use my big feet to hold it down instead of my weak knees. Until I get some more experience with the clam I won't know if I really need it.
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Assembly Taking two of the small molding strip pieces I placed them flat sides together then offset the top piece so that the top edge stuck up 1/4 inch above the top of the second piece. I then positioned the strips on the end of one arm, again offsetting them so they stuck up 1/4 inch above the end of the arm. Marking the pieces in case anything moved, I held them together with a spring clamp and measured and marked my screw holes. Repeat to create the second jaw. |
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I spread glue on both strips and the arm with a small paintbrush and my finger, being very careful not to get glue on the strips where they did not overlap, and put the whole mess back together. Holding everything in place with a pair of spring clamps I screwed the jaws onto the arm. Once the screws are in the clamps can be removed. The screws will hold everything nice and tight until the glue sets. Remember to set the screwheads well below the surface of the wood. We have to plane a slight angle on the jaw face so the top edges will close tightly. |
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After the glue dried (About 60 minutes for yellow glue, 4-6 hours for white) I shaped the profile of each jaw to a rough 45 degree angle. This will allow my hands and awl to have clearance and easy access to the very tip of the jaws. I also used a wood shaver and sandpaper to slightly round the corners on the outside of the jaws. I could see no reason to leave them sharp when undoubtedly I would end up skinning my knuckles on them. The face of the jaws was then planed at a slight angle, removing wood from the bottom of the jaw, so the tips would come together tightly when the clam is used. If you don't do this the spread of the arms will force the bottom of the jaws closer together than the top. This will result in marks on a project and the clam will not hold tightly. See the picture of the jaw profiles to understand what I'm saying. |
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When the jaws were complete I measured up 3 inches from the lower end of the arms and marked a line. That would be the limit of my glue area. I aligned the jaws and arms, went back to the plane to correct the jaws where they didn't line up, then aligned and clamped everything in place again. I admit I went a bit overboard screwing the base together. I marked three rows of screws, 3 in the first 1 inch from the bottom, 4 in the second row, 2 inches up, and 3 in the last row, 3 inches from the end of the arm. I don't want it ever pulling apart. Remember, there is a LOT of pressure there. Screws are cheap and you can't go wrong using a few extra for security. I drilled and countersunk for the screws then glue was spread on both arms up to the line using my fingers. The brush was just too slow. Then I carefully realigned the arms and jaws, clamped, and screwed the arms together. Then I let it set for a day to completely dry. |
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Variations
If you can't get good hard wood you could make something very similar to a clam using plywood or wood with very little spring to it. Essentially what you would be building is a very large stitching pony. Cut two arms the size you want. The jaws would be made the same way as for the clam, but could be angle cut with a table or circular saw instead of planed. At the base you would have to include an amount of material, the same thickness as the jaws, between the arms. You might also want to cut one arm near the base and hinge it to the base. Next you would need some kind of tensioning device to clamp the jaws closed. A C-clamp or bar clamp would work, but could be unwieldy. A strap clamp would also work. A long bolt with a wing nut could be mounted about half way up the arm, but that would cut the throat depth in half.
UPDATE! 4-3-98
I've been using the clam for a while now and I've found that it just isn't quite stout enough to hold small projects tightly. It works great on the larger
items, but the small stuff tends to move around. The half inch thick wood works well, but has a bit more spring than I really need. To correct this I put in
two short wood screws half way up the clam. It tightened things up nicely. I'm thinking about drilling a series of small holes up the length of the clam. Then
putting a short bolt with a wing nut on it would allow me to customize the amount of tension I need for each project. A small C
clamp would also work.
Over all I have been very happy with my new toy... er... tool!
