Wizcrafts

The throw and tension of the check spring also affects the quality of the loop. A longer throw and tighter action can overcome the tendency of poorly bonded thread to unravel. Furthermore, if the unraveling is due to excessive twistiness in the spool, wrapping in the opposite direction around the top post may offest the twist problem and keep the loop at the needle intact.

There are a lot of bottom feed sewing machines that will let you sew applicates onto garments. Top names in the industry include Juki and Consew, with Juki being more expensive. The video shows a straight stitch machine, with bottom feed only. A Juki DDL 8700 will do this job.

I split this post into its own topic. It is not proper etiquette to inject a totally unrelated post into an existing topic. This is a garment sewing machine. The topic the OP injected it into is about heavy duty 441 clones that stitch harnesses and holsters, not garments. This is, afterall, a leather sewing machine forum. We may have consider a sub forum to discuss garment and vinyl (non-leather) sewing machines.

I believe Bob was simply describing the collar with an arrow.

The Singer 15-91 is a domestic/home sewing machine; not industrial. It is definitely not a leather sewing machine! That's what's causing the confusion in the answers. I have owned a couple of them. I rebuilt and sold them in my leather and sewing shop as a sideline. I even wrote a web page devoted to the Singer 15-91. Now, as for the motor, it is a pod motor built into the head. These motors are old now and the wires and brushes wear out over time. You can replace the brushes yourself if the motor sparks when it runs. But, rewiring it is probably not worth the trouble. You are better off trying to buy a rebuilt pod motor online. As it is, it may draw power when not is use. So, unplug it it until you intend to sew. Plug it into a power bar with a breaker, in case the old motor decides to short out. Beware, you could become part of the AC circuit! Because of the way the 15-91 (and model 201) was designed, it is not practical to try running it on an external motor. If it runs erratically, or not at all, get rid of it or buy a rebuilt motor. You'll have to unplug it and carefully detach the old wires, then attach the new ones.

Facts only answer As the video demonstrated, it allows the operator to precisely stop with the needle either fully up or fully down, no matter the speed you were sewing at. This means that whether you are sewing 1 stitch per second or 30, pressing down with your toe or heel in the designated manner will cause the machine to come to a dead halt with the needle up or down. This would be a useful combination for an operator who lacks good foot control (medical or injury causes). Editorialized answer I have the same type of machine in the video; a Cowboy cb4500. It has a 3:1 speed reducer and an analog servo motor with a simple rotary switch to limit the top speed. It ramps up smoothly from zero to the maximum speed as set by the knob. I can easily operate my machine at less than one stitch per second, then floor it on straightaways to sew at 10 or 15 stitches per second. As I approach corners, turns, or the end of the stitch line, I simply back off the speed pedal until I reach the end, then either reverse into the previous few stitches, or move the stitch length lever to the zero movement position and double tap it to lock in the threads. In my learned opinion, there is absolutely no need for a normal user, with good foot muscle control, on this type of machine (Juki 441 clone), to install a needle positioner and more expensive digital servo motor if it has a 3:1 reducer between the motor and machine.

About a decade ago this was a major problem when the main leather machine companies began shipping digital servos. They started up at between 100 and 200 rpm with nothing between zero and starting speed. Leather Machine Company came up with a clever hack that let the motor start up controllably. It was a piece of clear plastic that was printed with a variable density that was placed between the light source and the photocell. One of those was connected to the speed control lever (I forget which). As the pedal was moved from the off position the density of the filter changed much more gradually than the original light beam shroud. It took a little manipulation to find the right spot to tape it down. Once that was done the motor would slowly speed up and was controllable down to under 1 stitch per second with a 1:3 speed reducer. I installed the filter on the servo motor that shipped with my cb4500 and left it in place for about 3 or 4 years. Then it began developing a dead spot and it had to go. So, I bought an analog servo motor, with a simple knob limiter. It is still on the machine after 6 years and lets me sew as slow as a 10th of 1 stitch per second. I have the same motor on a long arm walking foot machine. It has a 2" motor pulley, no reducer, and the balance wheel has a 5 inch diameter pulley. That machine sews as slow as 1/2 stitch per second if I keep my foot steady.

Hook timing on machines with reverse should be done with the stitch length position set to zero movement.

My 2700 stitch lever has a peg or stud in the end holding it together. I think yours did too when it was new. My wing lever moves over about 15 or 20 degrees.

This machine is a copy of a Consew 227R. I have one in my shop. I'll try to remember to look at the stitch lever when I get there. Any industrial sewing machine dealer who stocks parts will probably have what you need. My go to guy is Bob Kovar, at Toledo Industrial Sewing Machines. 866-362-7397

I don't intend to get into a debate about warranties and dealer services. I do want to point out that one of the purposes of this forum is to help people solve issues with industrial leather sewing machines. This is an excellent example of an unexpected part failure and how to replace that part. Had the OP purchased the machine used, with no warranty whatsoever, the same procedure would have to be followed to get the machine working again. The only difference is that the OP doesn't have to pay (full price) for the part. This is a learning opportunity in case someone else has a 441 clone that has a broken shuttle driver.

TIlt the head back and oil all of the moving components associated with the return lever. Clean out any grime in between shafts and bearings.

Please start a new topic about your particular machine. This topic from 2014 was about the Seiko 8bld, not the Juki LU machines.

No. That model is a domestic sewing machine with drop feed only. Not for any leather over about 4 ounces, with a slick top grain..

I spoke with one of our dealers and he told me that the shuttle driver is usually pinned to the end of the lower shaft. If that's the case, the entire lower shaft may have to be pulled out to remove the remnants of the driver and reinstall a new one (and its pin). All the components inside the arm will have to be stripped off the shaft as it is pulled out and secured in the proper order.The machine will have to re-timed after the new parts and bottom shaft are installed. This will be a thankless job. The best outcome would be if the shaft only has to be pulled out far enough to drive out the old pin, install a new driver and drive in the pin.

The stock machine is not able to sew 3/8 inch of anything. The foot mechanism isn't meant to clear that much while in action. If the lifted feet clear 3/8 inch, the maximum sewing thickness would by 1/4 inch because the feet need at least 1/8 inch to alternate. These machines were built to sew sails, Bimini covers, Sunbrella awnings and upholstery materials. The standard Sailrite portables have aggressive teeth on both feet and the feed dog. They will leave deep marks in leather. Sailrite has a version for leather workers that has knurled feet and feed dog. This greatly reduces the marks on the top or bottom. It is more expensive than the marine models and has a heavy balance wheel to punch through leather. No matter which model you get, it is limited to #92 bonded thread (polyester or nylon) If your customers are used to seeing belts sewn with .0258" (.655mm) 5 cord linen thread (w/ 53 pounds breaking strength), they will be disappointed by the thinner number 92 bonded thread that is only .0133" (.337mm) diameter and has just 14.5 pounds breaking strength. You can compare thread sizes and the corresponding needle sizes in this needle and thread chart. You would be much better served by a machine like a Consew P1206RB, which is a less expensive variant of the Consew 206RB-5.

In my previous lifetime I owned a very old Singer 29-4 patcher. It suffered from short stitches (~8/inch) and I started investigating why that was. It didn't take long to realize that the feed motion crank had too much slop.So, I disassembled the head and extracted the feed motion crank. It has a protruding "puck" on one side that moves inside the ring that moves up and down. My crank had about 3/32 inch of slop. I had some bronze brazing rods and a torch that I used to build up the density on the puck. Then I used a sander and a file to reduce the size until I got the best fit without binding in the feed motion ring (whatever). My final step was to polish it to a shine using green rouge on my buffing wheel. The results were amazing! I was getting over 5 to the inch instead of 8! If you can braze bronze rod and file and polish the puck to shape, you can restore the full stitch length for the cost of the propane and a brazing rod.

WOW! That was your hook driver!

Yes. I don't have nomenclature handy unless I did up a manual. I use common names that we use on Leatherworker.net. Sorry for any cornfusion.

A factory spec 29k only has enough slack in the feed motion cam to allow it to rotate over 360 degrees and cause the feed motion ring (which it revolves in) to move up and down. The stitch length is entirely dependent on this part having nearly zero free motion without binding. Replacements are available from the usual aftermarket sources. Make sure when you test for slack that the movable stitch regulator bracket and thumbscrew are in place somewhere along the extended arms above the foot.

The Singer 20U are bottom feed zig-zag machines meant to sew cloth. They can sew thin leather if the teeth can get a good grab on the bottom layer. The problem with sewing leather on a flat foot machine like this is drag. Leather, like Naugahyde (vinyl) tends to be sticky on the top grain side. It is also grabby inside and can really hold onto the needle as it comes up. If the leather lifts with the needle you will get skipped stitches. To counter the lift you have to crank down the pressure on the foot. This increases the drag on the leather, making it harder to feed it as you sew. It is a losing game. If the wallet interior isn't sticky or dense the machine will sew it with #69 bonded thread (no larger thread in that machine). Fur might slide under the foot better than veg-tan.

You're going to need a narrow cylinder arm walking foot machine with a synchronized binder. Then equip it with either a single or double fold attachment that produces the proper width on the folded edge. Pfaff and Adler binder machines are often used to apply edge binding. These machines are modified for this purpose.

I have a 107w3 and it can be set for a slightly wider zig zag, but the needle might hit the presser foot. I carefully position the throw so the needle just barely brushes the inside of the slot in the foot. It is over 1/4 inch, but not by much. The 20U has a much wider throw. As for the standard zig zag width, I once had a Pfaff 138 zig zag machine that had less that 1/4 inch width (I think 3/16", but metric).

Remove the needle clamp and stitch regulator clamp and screw above it. Then unscrew the two top and two bottom screws holding the head to the body and carefully pull it away and down from the body, leaving the needle bar attached to the top arm. Clean every part in there. There is a roller that needs to rotate freely on the back of the long sliding bar. The rotating foot parts include a ring and a feed motion cam. Remove them and clean off any junk. Now, examing the paddle spring on the needle bar. It sits above the needle clamp. It is supposed to hold onto the top thread as the needle does its up/down jog to form the loop for the hook to pick off. Those little paddles and the thin spring in the middle can get out of shape and cause binding. If there is any pressure problem with that spring the loop may dissolve before the hook can pick it off. Check (paddle shaped) springs are cheap. But, use a magnetized screw driver if you change it to a new one. Don't loose the two tiny screws. Also, keep them separated so you can reinstall them into the same positions they were in. The reason for this is that the factory usually files down the leading and trailing edges of the crew heads to prevent scoring the inside of the revolving head housing. If you replace them with new screws, get a narrow file to taper the edges after tightening them in.

I have a sewing room full of walking foot machines, including 1 Techsew 2700. Every now and then one of them decides to hang the presser bar when I lift it all the way. This happens because the bushings at the top and bottom can sometimes move, or get out of round. Or, the presser bar itself can bend slightly from stress and impacts. One way I found to fix this is by loosening the set screw for the upper or lower bushing (on the back side of the head), or both, with the foot lifted all the way. I play with the set screw adjustments until the presser bar move up and down freely, then liberally oil the raised bar to get the bearings lubricated. Also, open the faceplate and oil every moving shaft and bearing. If loosening the bushings doesn't help with a binding presser bar, buy a replacement. It is probably the same bar that was used in the Singer 111 machines.