Dumbing down a Cowboy CB4500 or other 441 clone
Most people who buy the large harness stitchers, known as 441 clones, use them to sew holsters, knife sheathes, saddles, harnesses and saddle bags. They normally come preloaded with #277 bonded nylon thread, on top and in the bobbin and are adjusted and sewn off with this thread (at least they are by our member-dealers), with the test piece under the feet. The most common brands and models discussed on Leatherworker.net include the Cowboy CB4500, the Cobra Class 4, and the Techsew 5100 (they and all other advertisers are supporting us and the server expenses with their paid ad banners).
Nowadays, it seems that every leathercrafter who has worn out their hands with hand sewing their goods wants to buy that one sewing machine that does it all. They want it to sew wallet interiors, chaps, knife sheathes, tow straps, harnesses and extra thick gun holsters. I see them posting questions about which machine should I buy (to do all this), or similar wording. Respondents usually point out the fact that the typical upholstery grade walking foot sewing machines cannot sew thick holsters or use heavier thread than medium weight #138. The buyer will have to look at a more substantial machine, like a Cowboy, Cobra or Techsew, etc.
Most advice given is to buy more machine than you think you will need. So, the newbie to machine sewing shells out between $2000 to $3000 for a 441 clone (or $6000 for an actual Juki 441) expecting it to sew everything from wallet interiors to hand gun holsters. It sews the holsters just fine, but not the wallets or other thin projects. The knots are too big to hide between the thin leather layers. Pretty soon, they begin posting requests for help getting their (insert brand name and model) 441 super heavy duty stitcher to sew thin stuff. That's when they are told that they need to buy a lesser machine for thin work. Say what? I thought y'all said to buy more machine than I needed!
Some folks can and some can't afford to buy a second industrial sewing machine and table for thin work. Their other half (or they themselves) may own a domestic sewing machine, but they found it horrible at feeding and sewing leather, even wallets. They can't justify spending another thousand dollars for a lesser walking foot machine right now. What can they do if all they own is a 441 type machine? In these cases it is possible to "dumb down your machine" to get it to sew thin leather with thinner thread than it was built for. Here's how.
I'll use my Cowboy CB4500 as the reference, since that's what I currently own. Let's see how to dumb it down to sew thin stuff with thin thread.
First, buy some #19 (or even #20) needles in System 7x3. These are not leather point but are a good fit with #92 thread. There aren't usually any leather points available in System 794 under size 23/160. This is both a matter of economics and the tendency of these extra long needles to bend too easily below size 23/160.
Also buy #92 bonded nylon thread in the colors you intend to use (two spools of each color - one for the bobbin and one for the top thread). I usually get bobbins, oil, needles and thread from the dealer who sold me my machine. Order some extra bobbins if all of yours are already loaded with thick thread.
- Install a #19 or 20 needle (with the scarf facing to the right). Any other size will be either too tight or too loose for this thread.
- Thread the top with #92 bonded thread, but don't loop it around the top post. Feed it through just one hole. The extra tension from wrapping the thread around two holes in the top post could make it impossible to sink the knots effectively!
- Wind an empty bobbin with the color of #92 thread to be used on the bottom of the wallets or interiors, or chaps, etc.
- The bobbin spring will be way too loose if the last bobbin had #207 or larger thread in it. so, tighten it down to get a decent amount of tension of the bobbin thread, but not so much that the thin leather puckers on the bottom.
- Note: you may have to first loosen the long bobbin tension locking screw before the tensioning screw can be turned.
- Set the stitch length to about 6 or 7 stitches per inch.
- Run a test stitch line on a stack of the same thickness of leather/material as the interior, or whatever you are going to sew.
- Back off the top tension adjuster until the knots move down. You may also have to back off the bottom tension thumb nut so the bottom roller turns with the thread wrapped around it.
- If the knots still won't drop between the layers, you'll need to loosen the tension on the check spring. This spring is normally set to high tension action to work with the much heavier #277 or #346 thread that the machine was built to handle.
- Loosening the check spring action requires one of the open ended metric wrenches (11 or 12 mm?) that came with your CB4500 to loosen the nut on the back of the left end of the head, where the check spring shaft is fastened. This is a tricky tight fit and may require dinking with the position of the wrench to loosen that nut.
- With the locking nut backed off a thread or two, use a screwdriver blade on the front side to turn the bottom roller/check spring shaft counterclockwise until the spring loses some of its tension. Find a position where the spring travels all the way up and just makes it all the way down to the bottom travel stopper, then tighten down the locking nut. The check spring should have enough range of motion to hold the top thread taut until the needle has fully penetrated the leather.
- Sew some test stitches again. If the knots are still too close to the top surface, either back off the top tensioner all the way, or tighten the bobbin spring a little more, until they are submerged between the layers. Make sure that your top thread is feeding freely to the top tension disks!
These are the basic steps needed to dumb down a big Cowboy, Cobra, Techsew, Juki 441, or any other brand name 441 clone.
It is possible, even after you do all these steps, that the huge needle hole in the feed dog and oversize rectangular slot in the standard throat plate may let the thin or soft leather get pushed down inside the plate, or the feed dog itself. This might ruin your work, or cause gathering and tiny stitches. There is a solution though. If your machine came with an accessory flat throat plate with a narrow slot, you can remove the standard plate and feed dog and instead, use just the slotted plate. It is much less likely to allow the leather to be pushed into it. However, since you are taking the bottom feed dog out of the equation, your stitch length will change and reverse stitches may not hit the same holes unless you play with the stitch length lever as you sew backwards. If you didn't get this plate with the machine, you can order one from the dealer who sells that brand and model (to avoid possibly mismatched mounting holes).
I have done this temporary conversion many times, and it is always a PITA. Whenever possible, I use a different machine that is already setup with #69 or #92 thread and has shorter needles that don't deflect as easily.
Dumbing down your 441 machine to sew thin projects may earn you enough money to buy a proper upholstery grade walking foot sewing machine (the type that maxes out at 3/8" and #138 thread). Having more than one machine will greatly expand your sewing possibilities.
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