Servo Choices

[Wizcrafts]

So it looks like the SewPro is what I'll need to sew veg tanned straps on my old 111?...(BTW, great article on machines Wiz)...now I'm interested in what modifications should be made to it to sew leather better. You mention a 2" pulley and stiffer springs but I'm in the dark about presser feet. Mine has smooth feet but a grooved feed dog, should that be changed out?

Thanks,

joe

Sorry Joe, I don't know anybody who sells retail smooth feed dogs for upholstery grade walking foot machines. However, you could buy another feed dog and have a welder braze bronze in between the teeth, to just over the top of the peaks, then sand the top flat and buff it to a high polish.

[Wizcrafts]

I want to point out that I didn't buy the SewPro because I couldn't control the clutch. On the contrary, I have sewn on nothing but clutch motors until 2 years ago. I can feather a clutch motor to 1 stitch per second. But, keeping it at that speed, stitch after stitch, all the way around the oval holes in dozens of guitar strap tails, or all the way around the thick end of 40 rifle slings, is a lot easier with a servo motor. The SewPro 500GR has made sewing fun again, rather than stressful on my right foot.

I really like the analog pot on the back of this motor. I can easily reach in a dial it down between items, knowing that 12 o'clock will cut the speed in half. I have even dialed it down to just a couple stitches per second with the pedal down. It's like watching grass grow - how slowly the machine can be made to turn over with a touch of the toe, at that setting.It's not practical, but interesting. I could never feather a clutch down to one stitch every five seconds, repeatedly, for minutes at a time.

[amuckart]

Hi L.G.

Hello everybody ---- I'm having a hard time understanding what you guys mean by servo motor and especially about changing the speed on the motor .

Aren't the speeds to be found in the position of your foot pedal ( the farther you push it the faster the speed ) ? And also , don't these motors have a synchroniser on the fly wheel that you can adjust for the needle positioning system . When I push on the pedal and immediately release it the needle goes in to the preferred down position .

When I push with my heel the needle goes to the up position and all the speeds are to be found in the foot pedal . That box you see in the photo is in fact a computer the you can program all sorts of different parameters .

Technically, a servo motor is any electronically controlled motor that incorporates a feedback from the motor to the controller to control the speed. The Quick Rotan you picture is also a servo, but is a far more expensive (and capable) proposition than the type discussed here. It used to be that servos like Quick Rotan and Efka were the only ones available for sewing machines, but now there are simple cheap motors available that lack the power, needle positioning, and configurability but still offer big advantages over clutch motors. In my limited experience the cheaper motors lack the low-end torque of the expensive ones but for 1/8th the price that's an acceptable compromise for most people not doing production work.

Personally, on a machine as simple as most heavy stitchers I'd go for an SCR or PWM controlled high-current low-voltage DC motor. Current is what gets you torque in a DC motor, and there are 1HP 36V motors out there that'd drive the biggest machine through any material the needle is physically capable of penetrating and, controller included, still cost much less than a full-featured multi-input motor like your Quick Rotan. I'm slightly surprised nobody but Sailrite have gone down this track to be honest. They've gone for US-made, and the price reflects that but for the Chinese clone market you can get the same thing for a third of what they're asking.

[Gregg From Keystone Sewing]

Hi L.G.

Technically, a servo motor is any electronically controlled motor that incorporates a feedback from the motor to the controller to control the speed. The Quick Rotan you picture is also a servo, but is a far more expensive (and capable) proposition than the type discussed here. It used to be that servos like Quick Rotan and Efka were the only ones available for sewing machines, but now there are simple cheap motors available that lack the power, needle positioning, and configurability but still offer big advantages over clutch motors. In my limited experience the cheaper motors lack the low-end torque of the expensive ones but for 1/8th the price that's an acceptable compromise for most people not doing production work.

Personally, on a machine as simple as most heavy stitchers I'd go for an SCR or PWM controlled high-current low-voltage DC motor. Current is what gets you torque in a DC motor, and there are 1HP 36V motors out there that'd drive the biggest machine through any material the needle is physically capable of penetrating and, controller included, still cost much less than a full-featured multi-input motor like your Quick Rotan. I'm slightly surprised nobody but Sailrite have gone down this track to be honest. They've gone for US-made, and the price reflects that but for the Chinese clone market you can get the same thing for a third of what they're asking.

Amuckart,

Good stuff. I think the thing is, these types of high quality servo motors with needle positoer and all type of functions have been available for a long time now. The thing is that they were and still can be just under $1,000 in some cases for Efka, Mitsubishi, or Ho Hsing. This is a good thing. But, what it is now is that there is a new market for what I like to call the 'Sub $200 range' servo motors, that are highly energy efficient, offer great low end speed control, and in many ways are an improvement over a standard clutch motor.