kgg

I'm glad you had good success with the dealer. Seems strange, you should contact them or Alder directly for a solution. Ah, you should bought a Juki. kgg

My take: i) Lower startup speed is determined by the amount of bottom end torque it was designed for and how good the electronic closed speed loop controller. Even if you can change the startup parameter to something less then 500 rpm the motor you will introduce some annoying things like stalling, surges and poorer rpm regulation. ii) The cheaper servo motors have 6 internal coils while the better ones have 12 coils which will typically provide better lower startup speed that is more consistent and smoother not just because of the added coils but chances are of they will have better electronic controls. I could not find any information on that particular servo motor but it would be a safer bet to assume it has 6 internal coils or call / email the manufacturer. iii) The only way of getting a reliable slower, smoother startup speed with the brushless servo motors is to install a speed reducer or buy a better servo motor. Getting the 1 stitch per second is probably equal to about 60 RPM. This I think is a bit unrealistic. If you really need that low a speed you would have to build an 8.33 to 1 speed reducer and probably change the servo motors shaft pulley. Keep in mind that an off the shelf speed reducer is 3 to 1 which will give you about 166 rpm. iv) to properly determine a realistic sewing speed you would need to do a pulley calculation knowing the size of the sewing machines handwheel and the size of the servo motors pulley based on the minimum startup speed. kgg

This wouldn't have been my first choice of a machine mainly due to the hole it would punch through the material, 2.5mm diameter unless you are sewing items above 1/2"(12.5mm) in thickness or saddles. I would have probably gone with a Juki LS-1341 or clone with a speed reducer as it would use a smaller diameter needle the system 135 x 16 x needle size for leather. My understanding is the 969 is a class 441 machine that takes the system 7x 3, 794 or 1000 needles (Schmetz). There are needles available for 7x3 or 794 from #19-#27 (120-220) for V92 to V415 thread. I would talk to the dealer to track down the needles if you are going to keep the machine and maybe discuss exchanging the machine for something like a 869 which would take the system 135 x 16 needles . kgg

That is very true there are situations where you just can't get the bobbin thread. Nice tip for machines without reverse. kgg

Thank you Everything in moderation. The aim is two fold. Even tension and to prevent any excess bobbin thread on the underside of the leather or fabric that would cause a problem. kgg

The very basics of getting a good seam are: i) correct machine threading ii) correct top & bobbin tension iii) correct needle system for your machine iv) correct orientation of the needle v) correct needle type (ex. 135 x 16 for leather and 135 x 17 for fabric) vi) correct size of needle to handle the top thread vii) This next step is where people seem to be having a problem. Getting the seam started. You really need to hold both the top and bobbin thread as you start your seam. That can be a royal pain grabbing and holding those threads particularly with smaller sized thread like v69 and v92. If you don't hold both together weird things can happen like jams, bird nesting, skipped stitches, etc. A quick solution is: Tie both threads together by a simple knot. Chances are now you will be able to grab the threads and put consistent tension on both threads at the same time. viii) Locking the threads a) Typical method is sew forward 3 or 4 stitches and then reverse to lock the stitches then continue with forward stitching. b) More Advanced Method is start your stitching 3 or 4 stitches in and reverse sew back 3 or 4 stitches. The seam threads will be locked when you sew forward but with less thread bulk in the needle holes. kgg

To start off. i) Which clone?? ii) What are you trying to sew, Fabric or Leather and how thick? If the machine has a walking foot then the simple answer is a roller foot will Not work. Can you give a little more explanation of your curve / turning woes. A couple of photo's of your setup would help considerably. Also what thread and needle combo are you using??? kgg

Why??? To help speed up the bobbin winding process even further is to have a bobbin being filled while you sew. I always have a second spool of thread in the color and size setup that is dedicated for winding the bobbins. i) install a empty bobbin on the winder, ii) thread the bobbin, iii) engage the winder. iv) bobbin fills as I am sewing v) bobbin winder disengages went the bobbin is full When the bobbin in the machine runs low or is empty replace I replace it with the newly filled bobbin. Rinse and repeat. kgg

I came across a youtube video which I think should be a must view for anyone that uses a sewing machine, domestic or industrial. It helps eliminate the black magic of how stitches (chain-stitch and lock stitch) are formed with a history of the development of sewing machines in very simple terms. Ever wonder why the long grove is on needles?? kgg

What I'm seeing: First photo: i) Stitch length seems different The stitch length seems to be smaller on the right then on the left. ii) Loose stitch on the left. iii) skipped stitch on the right side. iv) Distance to the edge of the binding fold over varies slightly. This probably is being cause by the leather piece either not having a straight edge, not being feed into the binding folder just right, a slight downward pull being applied as the item goes over the backside of the cylinder arm causing a slight shift or a pressure foot slightly off. Are you holding both threads when starting the seam??? Are you using a table top attachment while binding?? It would help in feeding the leather into the binder. As a note I set my binder so it is just leaves a very small space, a couple of mm, between the forward position of the pressure foot and the binding attachment. Any photo's of your binding setup may help. kgg

Couple of questions: 1. How thick is the leather you are trying to bind with?? 2. How thick is the leather you are trying to put the binding over?? 3. What is the total thickness of the edge including the binding. 3. Are you using a 90 degree binder or an inline?? I suspect the problem is that there isn't enough space within the binder attachment to allow for the 5 layers of leather, the edge of the article and 4 layers of binding leather. I have seen this happen when using a basic inline binder and the problem was easily fixed by bending the the top part of binder up slightly and opening the exit end up. If you are using a 90 degree binder the exit end is fixed which I don't think can be modified and the largest opening I have seen is like 6mm. I think using a inline binder would work better or have a 90 degree binder custom made. The problem with the inline is that there are not any that I know off that can be mounted directly to a cylinder arm and none of the table top attachments allow for accessories to be mounted to them like edge guides or binding attachments. Me being me and a cheap geezer I 3D print my own table top attachments to allow for this. kgg

The photo with the nameplate info appears to be for the motor which was made in Croatia. The wording "tvornica elektricnih strojeva subotica" converts to say "Electrical Machine Factory, Subotica". I would send your photo's to USM ( https://usm-americas.com ) and see if they could match up something. kgg

I would like to see the path of the top thread starting from the spool of thread on the thread stand following it as it passes through each thread guide or tensioner to the eye of the needle particularly the tensioner assembly. kgg

Could you post a few photo's of your top thread from the spool to the eye of the needle. I think this is a fairly easy problem to solve. kgg

You probably get better help if you listed the manufacturer of the machine. kgg