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

I think you will be get better results with the airbrush. My basic procedure is oil / dye / oil and I don't use a top coat for my projects. You will need proper air pressure to drive the dye into the leather. From what I have seen on youtube people are using pressure settings in the sub 20 lb pressure range and then the dye is basically a top coating. Probably because most people are painting model figures/cars/nails/cakes/etc. I use a 30 lb pressure setting and am now moving up to 40 lb when applying the dye with multi coats in different directions to get a more even dying which I apply after the oiling process. My basic process is oil/dye/oil. Here is a link to two of my topics on airbrushing. I don't use NFO and can't speak to it's application with an airbrush. I use JoJoba oil and spray it on without any dilution. kgg

The Cobra Class 26 uses the system 135 x 16 or 135 x 17 needles which have a size diameter of about 1.0 mm (0.0394 inches) while the needles for a Class 441 machine the 794 needles are 2.5 mm (0.0984 inches). The Cobra Class 26, is the model number not the class of the machine and is a hybrid clone similar to the Juki LS-341 a Class 341 machine. The Cobra Class 26 like the Techsew 2750 and others model designations can be confusing but all are Class 341 machines. I agree with @Wizcrafts and as a note I don't use anything smaller then V92 in any of my machines. kgg

Very nicely done. It would also be good for hammering down the thread in seams. kgg

What I found too work the best whether it is chrome or veg tan is to apply one coat of contact cement let sit to soak into and dry. Then apply a second coat and when it has dried to the point of not being sticky to the touch put both pieces together, clamp or weight down depending on the size. My theory is the first coat seals the fibres of the leather and the second binds both pieces together. kgg