idahoderrick

7-34 Motor recommendation ?

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I bought a Singer 7-34 at an auction and I have no idea what type or size of motor that I should hook up to it.

I bought this machine for my brother that does leather work. He has never had a machine that is this heavy duty and also has no idea about the motor.

sew 7-34 singer.jpg

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@idahoderrick Moved yourpost to leather sewing machines.  You'll get responses here.

Tom

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I would put a servo motor with the highest HP that I could find. I would be looking at digital speed controller rather then the turn the knob speed controller having the lowest start-up speed and the highest startup torque. Some servo motors claim to have a start-up speed of 100rpm, others at 300rpm and others don't readily list it. Finding the start-up torque may also take some research as suppliers generally don't list the value but a general rule of thumb would be the higher the HP the greater the available torque. I would also prefer a brush-less servo motor over one with brushes. Most suppliers rate their motors in watts (1HP is approximately 745 watts).

My top two choices if I were in the market for another servo motor would be:

1. Brushless Digital 12-coil DC Servo motor Sewquiet 6000sm from Reliable (550 watt, costing $169 US or $232 Canadian)

2. Brushless Digital ??-coil D.C. Servo Motor from the Leather Machine Company (600watt, cost ??)

kgg

 

 

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I bet you did Not pick that up and carry by yourself to your truck ...LOL . Did you get a table set-up with it also ? or just the Head by itself ?

Class 7's are a BadAss , ever see one sew through silver dollar ?

.

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2 hours ago, kgg said:

I would put a servo motor with the highest HP that I could find. I would be looking at digital speed controller rather then the turn the knob speed controller having the lowest start-up speed and the highest startup torque. Some servo motors claim to have a start-up speed of 100rpm, others at 300rpm and others don't readily list it. Finding the start-up torque may also take some research as suppliers generally don't list the value but a general rule of thumb would be the higher the HP the greater the available torque. I would also prefer a brush-less servo motor over one with brushes. Most suppliers rate their motors in watts (1HP is approximately 745 watts).

My top two choices if I were in the market for another servo motor would be:

1. Brushless Digital 12-coil DC Servo motor Sewquiet 6000sm from Reliable (550 watt, costing $169 US or $232 Canadian)

2. Brushless Digital ??-coil D.C. Servo Motor from the Leather Machine Company (600watt, cost ??) 

kgg

 

 

Thank you

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nylonRigging:

A funny story about moving this thing... A very well built and very nice gentleman picked it up and handled it like it was a tinker toy and I thought to my self "it must not be that heavy", I on the other hand could not even get it more than 2 inches off of the ground by myself. I used an engine cherry picker to get it out of the truck and into my shop. I got the head only with this machine.

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5 hours ago, Northmount said:

@idahoderrick Moved yourpost to leather sewing machines.  You'll get responses here.

Tom

Thank you

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I would use a 3/4HP motor, good common example is a Consew NS-614 (P24) CLICK HERE for their product page.

The 6000SM is a motor we work with, and NOT a good fit for this machine, at all in this case for this machine.

Edited by Gregg From Keystone Sewing
info@keysew.com

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4 hours ago, Gregg From Keystone Sewing said:

I would use a 3/4HP motor, good common example is a Consew NS-614 (P24) CLICK HERE for their product page.

The 6000SM is a motor we work with, and NOT a good fit for this machine, at all in this case for this machine.

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

 

As far as servos, i tried the Rex version of the family sew that everyone recommends from Toledo -- didn't like it (thank god for amazon return).

Bought the sewquiet and it's perfect.  Better pedal control and i can do stitch by stitch without messing with additional pulleys.

Considered the consew because i like having separate controller for top mounting, but the reviews i read on it were pretty bad, so I didn't bother.

 

Not sure why everyone jumps on the family sew bandwagon, but to each his or her own. Maybe it varies based on machine.

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1 hour ago, tofu said:

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

 

As far as servos, i tried the Rex version of the family sew that everyone recommends from Toledo -- didn't like it (thank god for amazon return).

Bought the sewquiet and it's perfect.  Better pedal control and i can do stitch by stitch without messing with additional pulleys.

Considered the consew because i like having separate controller for top mounting, but the reviews i read on it were pretty bad, so I didn't bother.

 

Not sure why everyone jumps on the family sew bandwagon, but to each his or her own. Maybe it varies based on machine. 

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

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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... 

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

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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... 

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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.

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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.

 

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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.

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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.

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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

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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?

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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 by Gregg From Keystone Sewing

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Greg, could one not use a solenoid ( electric ) foot lifter ? I have an EFKA speed controller NPS on a Juki DLU 490-4 , the machine also has a separate solenoid mounted under the table to activate the foot lift ("heel back" on the foot pedal activated for the foot lift solenoid ) and a small "paddle control" just to the right of the needle to activate reverse as well as the usual second smaller pedal ( next to the speed pedal ) reverse system ..( There's load of stuff in the way or I'd take a photo ) ..Makes a definite "click" when the solenoid fires for up or down, but less noisy than having a compressor running for air controls..

It is an old EFKA unit ( looking for information about it and the machine was what brought me to leatherworker.net..Eric kindly pointed me towards the mechanic's manual for the machine, as you know top and bottom differential feed ..He figured that from my description of the noise from the EFKA that it is tired :) ..but as I only use it occasionally I am in no hurry to change it..As you say, EFKAs can be dialled down to run very slow, I added "bump stops" under the speed pedal to limit the top speed by limiting the pedal "travel", and a child's inflatable ball to give air resistance under the same pedal to allow a more progressive throttle..

It isn't quite as slow as running a servo with a reducer ( like my Singer 211 set up ) but is easily controllable..although EFKAs are more expensive, I see many more people in Europe using them on the older machines..

I know that Tor swears by Efkas, and he runs some heavy machines..could well be a good controllable set up for the 7-34.

Edited by mikesc

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2 hours ago, mikesc said:

Greg, could one not use a solenoid ( electric ) foot lifter ? I have an EFKA speed controller NPS on a Juki DLU 490-4 , the machine also has a separate solenoid mounted under the table to activate the foot lift ("heel back" on the foot pedal activated for the foot lift solenoid ) and a small "paddle control" just to the right of the needle to activate reverse as well as the usual second smaller pedal ( next to the speed pedal ) reverse system ..( There's load of stuff in the way or I'd take a photo ) ..Makes a definite "click" when the solenoid fires for up or down, but less noisy than having a compressor running for air controls..

It is an old EFKA unit ( looking for information about it and the machine was what brought me to leatherworker.net..Eric kindly pointed me towards the mechanic's manual for the machine, as you know top and bottom differential feed ..He figured that from my description of the noise from the EFKA that it is tired :) ..but as I only use it occasionally I am in no hurry to change it..As you say, EFKAs can be dialled down to run very slow, I added "bump stops" under the speed pedal to limit the top speed by limiting the pedal "travel", and a child's inflatable ball to give air resistance under the same pedal to allow a more progressive throttle..

It isn't quite as slow as running a servo with a reducer ( like my Singer 211 set up ) but is easily controllable..although EFKAs are more expensive, I see many more people in Europe using them on the older machines..

I know that Tor swears by Efkas, and he runs some heavy machines..could well be a good controllable set up for the 7-34.

Singer 7-31, -33 and -34 do not have a foot pedal operated foot lift, only the hand lever.  We have put some cylinders for presser foot lift, but it's not pretty but has worked.  Electronic solenoids work well, up to a point.  See link for video of  24V solenoid with SP-1100 motor

These solenoids can be of course used with the Efka motor's 24V output for foot lifting.

As for speed control, I make up these speed control dials mounted external from the control box.  I can set the machine from say 50rpm up to maximum 800 and everything in between to limit the upper limit of maximum speed of the motor.  Speed control example video

Edited by Gregg From Keystone Sewing
info@keysew.com

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