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

I should have used sticking rather then binding. (knee lift shaft is sticking.) Glad the machine works good with the knee lift. kgg

The case you have shown is very similar or the same as the ones made by Libertaz Leathers ( libertazleathers.com ) and here is a video of how they are made. kgg

Yes and No. My two cents: i) Looks like the cooling fan is incorporated in the motor pulley. So getting a smaller motor pulley with the cooling fans maybe limited. ii) Appears to be a 550 watt 6 coil brushless servo motor which would probably work. A 12 coil 550 watt would be better but would cost more (2X). iii) The start up speed could be as high as 500rpm which will give you startup jerk. A speed reducer would help eliminate that or go with a brushed servo motor rather then the brushless servo motor. iv) Make sure the operating manual comes with the setup. v) Like @AlZilla has mentioned the control box is going to be in a awful location under the table so you are going to be down on your hands and knees to change the settings. kgg

I really admire those that hand sew and tool leather but for me I don't have the temperament or the artistic ability. So for me it is all mechanically aided, sewing machines, presses, skiver, embosser, 3D printer, etc. kgg

I do agree with @Dwight but the grit of the sand paper selected has a lot to do with the speed of the machine. Too course a grit say 60 at slow speeds will tear chunks out while too fine a grid at high speed will burn. I use 120 grit on my machine which is a modified variable speed bench mounted buffer with a 4 3/4" long X 3"diameter sanding disk at 3400 rpm. kgg

I took another approach to punching oblong holes in leather belts. I 3D printed two simple jigs, one for the belt buckle holes and one for the other end. kgg

Here is a good threading video for the CB341 starting at about the 8:11 mark for the tension disc. You should really view it from the beginning just to cover off any other potential problems. kgg

Your threading of the top thread around the tension discs is incorrect, refer to your manual for the correct threading. kgg

I use an office chair with caster on all my machine without any difficulty. I have seen the foot lift to be more difficult then the using the rear presser foot lift lever for two reasons. 1) a missing washer on the pivot point of the the foot lift lever at the rear of machine and 2) the point of contact of the foot lift lever at the head needed to be adjusted / oiled where it made contact to lift the presser foot. You should check and see if the knee lift shaft is binding which maybe contributing to the hard lift when using the pedal to lift the pressure foot. Also: 1) The location of the cable to the foot pedal should be mounted to a bracket that is mounted to those two rear holes in the pedal. The closer you move that cable to the pivot point of the pedal the more difficult it is to operate. 2) Since you like using using a knee lift there should have been one come with the machine and it bolts to the shaft extending out of the base of the machine. 3) You should check and see if the knee lift shaft is binding which maybe contributing to the hard lift when using the pedal to lift the pressure foot. kgg

As a suggestion try doing a test piece and compare the result with your present method. Test piece i) Oil the top side of the leather by airbrushing (above 34 psi) first and then lightly oil the backside after letting the topside sit for a few minutes. Let the leather sit for 24 hours to soften and let the oil spread the leather fibres. ii) Then airbrush the top side of leather with the dye (50/50 mix at an air pressure of above 34 psi). Then lightly airbrush the dye to the backside. Let sit for 24 hours or longer then to allow the dye to spread and darker slightly. Then a final light coat of oil. Compare the result with your present method. kgg

I am assuming you are trying for something like the following photo where you have pouch attached to a shealth: You seem to be trying and fold under the bottom of the pouch during your wet molding. I would approach it using a form where the wet leather is placed over the shape form that has the side edges extending about twice the height of the form, place the wet leather over the form and clamp one side down, form the leather over that side and then move to one of the other sides and clamp. I would probably use a 2 inch "O" ring to shape the leather. Let dry for about 24 hours and then damp wet areas that need to be reshaped. This topic shows the shaping tool I would us. kgg

I prefer to use the single action airbrushes and the two main ones I use are the very inexpensive suction style at $21 CAD rather then the gravity feed type. Load up the dye bottle, push the button and you are spraying. If you are planning on using it indoors a regular compressor can be very noisy when it has to recharge the air tank and really is overkill for an airbrush. Keep in mind the dye will darken and spread in the leather after a few days. So you have an initial photo of the project so take another photo a few days down the road for a comparison.

If the item is going to be exposed a lot to UV rays or bleach type chemicals Bonded Polyester would be the better choice. Generally other items Bonded Nylon is a good choice. I mostly use Bonded Nylon. As a note: i) Bonded Polyester for a given thread size is a touch smaller then Bonded Nylon ii) Darker thread colours are stiffer then light coloured threads due to the dying process iii) I find that the 1 lb spools are better then the smaller spool sizes due to less spring memory as a result of being coiled onto the spools. iv) Only load up enough bobbins to complete the project. If left for more then a few days or less the bobbin thread comes off the bobbin looking like a coiled spring. v) Always buy good quality thread. kgg