GerryR

You can run the 550 watt motor from the 750 watt control unit. The other way is not advisable (750 watt motor on a 550 watt controller) unless you know you won't exceed the 550 watt load.

In the system I have (AC-VFD), the motor is spec'd at 35-459 RPM, 10-90 Hz. That is the output from the 5:1 reducer (gearmotor). I have a 1-1/2" motor pulley going to a 7" drive pulley for another 4.67 reduction giving 7.5 RPM at the machine at 10 Hz (minimun specified operating frequency for the motor), which amounts to 0.125 revs.per second or 1 revolution every 8 seconds. But that is not the point. The point is that when I hit the pedal, and the motor starts to move, I am easily in the safe operating zone of the motor, 10 Hz minimum. It would be absurd to run the machine at 1 stitch every 8 seconds for any length of time. The idea is to keep the motor happy and stll be able to do some controlled slow stitching. Just my $.02

Keep rambling, good info!!

Yes, but that would defeat the purpose of a softer start, which you are trying to achieve.

Those optical filters are nice, but they defeat the purpose of starting the motor at the so-called required minimum speed, which is probably not necessary in most instances.

Yes, I stated that both motors would generate the same amount of heat and meant power; that is where the heat management comes into play, and like you stated, the choice of materials used.

Power is power, so if it requires a certain amount of power to pierce the leather, both motors, whether 9 coil or 12 coil, will generate the same amount of heat. It all depends upon the heat management of the motor design, so "should get rid of the heat better" is up for grabs until the longevity of the motor is proven. 12 coils will distribute the heat better, but it is still within the confines of the motor housing.

Torque from a motor depends upon current in the windings and the number of poles (basically, I'm not a motor expert) so without a speed reducer of sorts, the motor has to be very robust to maintain high torque at slow rpm and cooling is paramount. The speed reducer gets the motor rpms up where cooling is better, current is lower and torque is higher because of the gearbox. As far as the OP is concerned, I don't understand why he can't just tell us his new motor/system specs; why all the mystery?

I know, I just wanted him to say it. I still prefer VFDs with 3-ph gear motors over DC systems. JMO, YMMV.

So, you have a high torque, slow start-up speed motor, which means you have a special controller for it (?). What are the power requirements for it? How big is the motor? What are the output shaft dimensions? What are the mounting requirements for the motor and controller? Is the speed controlled by a foot pedal or a dial on the control box? Do you have provisions for a position stop (needle up-dwn)? These are just some questions I have for any new system I would consider. It sounds like your system already exists, so should be easy to answer.

Links to AC Drive Components: VFD good for up to 1HP 3-phase motor: https://www.amazon.com/dp/B0DFB57721/?coliid=I8NFU0YE5UPT8&colid=17LBFSFMFWW6H&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it Note: I bought mine through Ebay, but this is the same one. Motor: https://www.bodine-electric.com/products/ac-3-phase-inverter-duty-gearmotors-and-motors/42r-fx-parallel-shaft-ac-3-phase-inverter-duty-gearmotor/ Note: I was able to get model 2263, which has 58 in-lbs. of torque and 340 RPM at 60 Hz. You can choose outputs suitable to your needs and even get right angle output shaft versions. Just for comparison, the DC servomotor I was using was rated at 28.8 in-lbs. Foot Pedal Control: This is where I got a little creative. I took a TIG welder foot pedal and did a little rewiring. I got the unit off of Ebay: https://www.ebay.com/itm/176920994141?_skw=TIG+Welder+foot+pedal&itmmeta=01K01RR8XF07B0ETNHVT3SNZC6&hash=item293150215d:g:7KQAAOSwha9jZI28&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1cdg2dYapN7bLOj7QNBNYvFBgb9nYOw6ivyhEaLfbTDARnhlFmmmIvRE5v%2BmSHS6NHzBxmYRm%2FS%2FOUguxh4QASZ6dKnq4aAfCKcCK9LWjU5OyPxxvNKcH3CjV9WGIL7ylcLvGzb6%2Bdvpe9MAB418aLD72qlvGirmqZ2XNTPpOEnSdadqe%2BJUuU70vTyKzaCPmAPE85JgmuvVu3AwzJYH9iW5vfdQNC7nCE8q1Im3b6Kp6cynjjiIrNBiNTH1T%2Fur%2B7h1JYK8hs%2Bt5hyHSlK4eaNsbSQ%2FRi%2Bmrmp2OVY%2BjRpfg%3D%3D|tkp%3ABk9SR4CP4biAZg I rewired it so the knob-controlled pot limited the top speed so the foot controlled pot had full range to that limited speed. I put everything in a case: https://www.ebay.com/itm/165626696069 These are the basics. I added circuitry for a position sensor that worked off a jog button. I don't use the position sensor, but it is available if I ever want to use it. The jog is so slow that I can stop the needle anywhere I want. This should give you a good start. Feel free to ask any other questions you might have. Happy to help!

I realize that you already have the DC servo drive, but for future projects, you should consider an AC system with a variable frequency drive (VFD) and a 3 phase inverter rated gearmotor. As an example of the control you would have, a 3 ph, 3/8 HP, 5:1 gearmotor can be operated from 10-90 Hz giving an output shaft speed of 35-459 rpm. Any speed running with less than 60 Hz is in constant torque mode, and greater than 60 hz is in constant horsepower mode. The speed is controlled by a variable pot, not a link to an optical control and is easily top-speed adjustable, giving full range of the pot for control to the selected top speed. The VFDs are relatively inexpensive, but the motors are a little pricey depending on your source, but for control, I think they are better than DC systems. JMO, YMMV. P.S. Beautiful job on that machine!!

Good advice; sanding it is not a good option as it will just ball up and clog the paper; it needs to be shaved, not sanded. Is the back side in good shape? Can you just flip it over and use that until it needs refinishing, and then have both sides redone at one time?

I'm not familiar with the pneumatic foot controls so I'll assume (ass-u-me) they actually are piped in to the actuating cylinders and are pneumatic switches. If this is the case, then yes, it can be done using electrically controlled solenoid valves and electrical foot switches and an appropriate power source, depending on the valves chosen. If you want to replace the pneumatics completely, then that is more complicated.

Well, according to the way the OP responded to my post above, he claimed he achieved all the points I mentioned, which included a 5:1 gear reducer. Must be the language barrier, as I mentioned possibly using an AC servo control, and I doubt he has done that.