7-34 Motor recommendation ?

[DavidMillsSaddlery]

9 hours ago, tofu said:

well that's a different approach -- recommending a clutch over a servo..

Clutches worked fine for years long before the servo’s showed up... 

[tofu]

And treadles worked fine before clutches showed up. What's your point?

[DavidMillsSaddlery]

5 hours ago, tofu said:

And treadles worked fine before clutches showed up. What's your point?

And I still have a treadle that works fine... to each his own... just because some does something different than you do... doesn’t make them any less than you... 

[tofu]

1 hour ago, turbotexas said:

And I still have a treadle that works fine... to each his own... just because some does something different than you do... doesn’t make them any less than you... 

Did you even read what you originally quoted?  Point out where I said it was wrong or "less than" me. I literally said it was a different approach, as you just agreed with.

I don't care if you recommend two gerbils in a hollow flywheel  Get off my ass with this nonsense.

[Gregg From Keystone Sewing]

7 class machines need a lot of low end torque to get the handwheel moving.  The handwheel on a 7 class is 22lbs. or greater and required a lot of low end torque just to get the thing moving, and then we have to penetrate the material, that can be very or extra heavy compared to some leather or canvas jobs.  As far as speed, the large diameter handwheel slows the machine down a lot.  And you can get a Consew clutch motor from us directly or drop shipped, with any pulley size available that you want.

Most servo motors in the "$200" or range  are not up to this task at all, and even if working are not reliable under this load for production.  I could be wrong.  We pretty much to do same thing with skivers that we sell, clutch motor for them as well.

 

[Wizcrafts]

22 hours ago, tofu said:

Not sure why everyone jumps on the family sew bandwagon

I've used (and still use) a variety of sewing machine motors. Some of my machines have internal clutch motors, some have continuous run motors with external clutches, some are push-button servos, some are pot controlled servos and some multi-position rotary switch controlled servos. Of the servo motor types, I preferred and used to buy  Sew Pro 500GR motors. They had knobs on the left side to limit the top speed and worked awesomely once you got past the low torque setting. The advantage of these motors was that they began turning at zero and smoothly increased to top speed. But, they went out to lunch one day and never returned.

When Sew Pro went out of business I began buying push-button servos. They do have a lot of startup torque. The issue I have with most of them is that they usually start rotating, with a sudden jerk, at 100, 200, or 300 rpm. After getting past the starting point the speed transition is sometimes very abrupt. So, I bought variable density Cobra light filters and placed them between the bulb and sensor. The results were hit and miss with the filters and they still didn't start at zero.

When Toledo Industrial began importing Family Sew 550 motors I bought one and found that it had good low speed torque and started rotating at zero, with a smooth transition to maximum. I have 3 of them now. They are close to the Sew Pro in performance and are still in production. The important detail is the pulley diameter. It must be a 2" (50mm) pulley if you are going to want to sew in the neighborhood of 1 or 2 stitches per second flat out. The standard 3" pulley runs it too fast for precision sewing and makes it more like a clutch motor that has to be feathered to sew slowly.

Even with a 2" pulley, I found the need to buy a speed reducer for my walking foot post bed machine. This gives incredible slow speed torque for precision sewing.

NB: I can feather my clutch motors down to one stitch at a time, or hold the pedal steady at about 1.5 to 2 stitches per second. So technically speaking, I don't actually need a servo motor at all. But, they are quiet when not in motion and don't throw off heat in the summer like my clutch motors do. They draw less current at their typical slow speeds so the electric bills aren't as high as when I had nothing but clutch motors on for hours at a time.

[Mark842]

5 hours ago, Gregg From Keystone Sewing said:

7 class machines need a lot of low end torque to get the handwheel moving.  The handwheel on a 7 class is 22lbs. or greater and required a lot of low end torque just to get the thing moving, and then we have to penetrate the material, that can be very or extra heavy compared to some leather or canvas jobs.  As far as speed, the large diameter handwheel slows the machine down a lot.  And you can get a Consew clutch motor from us directly or drop shipped, with any pulley size available that you want.

Most servo motors in the "$200" or range  are not up to this task at all, and even if working are not reliable under this load for production.  I could be wrong.  We pretty much to do same thing with skivers that we sell, clutch motor for them as well.

 

Good to know as I'm slowing putting together me 7-31. Was thinking I was going to buy a servo motor. Guess when I get it all set up I'll try it with the 3/4HP Hercules clutch motor I have sitting around. I've just been spoiled by servo motors I guess.

[kgg]

23 hours ago, CowboyBob said:

FWIW ,the one we sell runs slower due to the 2" pulley Everyone else including Consew sells them w/a 3" pulley.

I know what you meant to convey in that by putting a 2" pulley on the drive motor it would cause the sewing machine pulley to run slower not that the drive motor runs slower by putting a 2" pulley on it.

kgg

[Mark842]

56 minutes ago, Mark842 said:

Most servo motors in the "$200" or range  are not up to this task at all,

Do you know of any servo motors that are up to the task if money wasn't the issue?

[Gregg From Keystone Sewing]

17 hours ago, Mark842 said:

Do you know of any servo motors that are up to the task if money wasn't the issue?

Seiko SLH-2B-FH-1 Demo with Efka DC1550AB321 with speed gate

Here is a setup I've done many times over at this point and offer.  It's a Seiko SLH-2B-FH-1 with an Efka DC1550AB321.  Motor provides needle positioning up and down.  I have a speed gate switch that will limit the upper speed limit to say 200RPM down from 800rpm so the machine will not get away.  This is the switch you see me using.  I also use a potentiometer for this as well giving it even more control, but not on this setup.  The Reverse is by foot pedal or hand lever, and works well.  What does not work well is the presser foot lifter pedal from a mechanical standpoint; you have to stand on the foot pedal and put lots of pressure.  This is where the air cylinder lift shines.  Heel back on the foot treadle at the end of the sewing run, and the needle and presser feet lift up so that you can easily remove the work from the machine, as well as stop with the needle in the work in the seam, lift the foot and turn the work with a half heel back.  Also, this has a needle cooler setup not demonstrated here that will run when machine is in operation and then shutoff automatically.

Edited May 23, 2019 by Gregg From Keystone Sewing