speed reducer

[Constabulary]

34 minutes ago, Sticks said:

 yes I agree about the servo,thing is I went to the shop in london to try out the one I can afford and it cuts in at 200rpm lowest setting.Too fast.

My servos also run at 200rpm min and thats what the speed reducer is for - reducing speed!!!! RPM on the motor does not mean stitches per minute except you have a 1:1 ratio (75mm pulley on hand wheel and 75mm pulley on the motor). With a speed reducer with 1:3 ratio you reduce the speed by 2/3 and that would be 1.1 stitches per second.

200 rpm / stitches per minute : 3 = 66.666 rpm / spm : 60 sec. = 1.1111 stitch per second

And when you add a smaller pulley to the motor its even slower.

You don´t have to cut the table you can put the reducer under the table. But you have to reposition the motor. Again - check the forum for Speed Reducer - almost everybody is using them and there are dozens of different solutions - thats the way to go!

This is how it looks on my table and and underneath.

Edited November 11, 2016 by Constabulary

[dikman]

Exactly which model servo are you looking at? My servos can be set to much slower than 200 rpm.

[Evo160K]

If you're wanting to slow down a digitally controlled servo motor without having to us a speed reducer, you might want to check the video in the first link.  It was originally posted in the LW topic, "Getting Control of Your Servo".  You can see how well that modification worked on my servo by checking the video I posted in that LW topic.

The video in the second link explains how to slow down a digitally controlled servo motor with a needle positioning system.

http://www.swflholsters.com/358/sewing-servo-motor-diy-smoother-speed-control-mod-paper-gradient/

http://www.swflholsters.com/434/sewing-servo-needle-positioner-eps-speed-mod/

Edited November 12, 2016 by Evo160K

[Constabulary]

I see no link but that does not work with servos from College Sewing as they have an magnetic accelerator unit.

[Constabulary]

I´m 99% sure it has a magnetic controller. This one also starts at 200rpm you have noticed that, right?

[Wizcrafts]

Sticks;

Have you read about the Family Sew servo motors? I have to believe that somebody in the UK sells this brand. This motor starts spinning at 1 rpm if you so desire. It doesn't have a lot of torque at the slowest speeds, which is why many users add a speed reducer. I have this motor powering a big Cowboy CB4500, through a 3:1 speed reducer. I can sew 1 stitch every 8 or 9 seconds if I had reason to do so. Once in motion it penetrates the thickest stack of leather (unless the belts slip).

The same motor without a speed reducer powers my long arm walking foot machine. I can hold it at a steady pace of about 1 to 1.5 stitches per second at the low end, with the speed limiter all the way down to 350.

[Wizcrafts]

20 minutes ago, Sticks said:

So the part is called the bobbin case opener. The is preventing the bobbin assembly from rotating fully.

 

Loosen the screw on the right end of the Latch Opener lever, push/pry the opener to the left for more clearance, then tighten down the screw. It should just pull back on the boon case as the top thread comes down and off the needle. Then it should begin to move left and release the case to pass the top thread as it goes over and under the bobbin case.

[SARK9]

When changing the stitch length on this type machine, I always unthread the needle before rotating the handwheel to engage the adjuster stop, as this prevents an occasional tangle in the hook area like you may have experienced.

Its the left button on the bed you depress to adjust the stitch length, the other one (safety clutch) will completely stop the handwheel from moving backwards, and will only ratchet when turning fwd.

 

-DC

[dikman]

16 hours ago, Constabulary said:

I´m 99% sure it has a magnetic controller. This one also starts at 200rpm you have noticed that, right?

You made the same mistake I did at first reading - it's 200 spm, not rpm, which equals about 3 rpm. Quoting spm, however, is meaningless as it all depends on the size of the pulley fitted to the motor and the size of the handwheel pulley. If it's a misprint, and is supposed to be rpm, then it's not a very good motor as a digitally controlled servo should be able to get much lower than 200 rpm. Really need the manual to work out what they really mean.

[brmax]

If I were not using a reduction setup, a small pulley is required in my opinion. Also a cogged belt may be beneficial in the smallest of pulleys.

I have seen on the net pulley calculation size programs and their rpms, may try to google and put your measures in!

Floyd

[torrbuidhe]

On Saturday November 12, 2016 at 6:29 PM, Wizcrafts said:

Sticks;

Have you read about the Family Sew servo motors? I have to believe that somebody in the UK sells this brand. This motor starts spinning at 1 rpm if you so desire. It doesn't have a lot of torque at the slowest speeds, which is why many users add a speed reducer. I have this motor powering a big Cowboy CB4500, through a 3:1 speed reducer. I can sew 1 stitch every 8 or 9 seconds if I had reason to do so. Once in motion it penetrates the thickest stack of leather (unless the belts slip).

The same motor without a speed reducer powers my long arm walking foot machine. I can hold it at a steady pace of about 1 to 1.5 stitches per second at the low end, with the speed limiter all the way down to 350.

This looks like the Family Sew motor here - http://www.anglosewing.co.uk/anglospeed.html

No price though

 

Neil
 

[dikman]

The smallest pulleys I've seen are 45 mm (that's what I use). I'd fit the smallest pulley I could to the motor, regardless of whether or not a reducer is fitted.

[dikman]

Yeah, most sewing machine pulleys tend to be 15mm. I had to sleeve one for a reducer I made so it shouldn't be too much of a problem. I drilled and tapped the pulley to take a couple of set screws 'cos I couldn't use the keyway to lock it in place.

Edited November 16, 2016 by dikman

[Constabulary]

I just have checked the last Jack Servo I bought from CS it has a 15mm shaft but that is the 750W w/o NPS, the other with NPS I bought has a 12mm shaft as well - don´t know why that is. Just wanted to have it mentioned.

[gigi]

Finally we managed to have a potentiometer pedal, using scrap material around the home. It is not the best but it serves the purpose. There is plenty of room for improvement. . The control of the machine is much better now. Locked the clutch on engaged position and now the motor is permanently connected to the machine. (The VFD is stopping the motor; after that motor is turning freely). 

Second video shows the setup is working also with veg-tan leather 7 mm with 138 thread (20 metric).  (It's just a test: the machine is not a heavy duty subclass.)

 

 

[brmax]

Excellent!

? curious what is the signal voltage 5? to the treadle switch

Seems it has to be different and reduced for the electronics

 

Floyd

[gigi]

Thanks! Pedal provides variable voltage 0-10V, 10mA max to the VFD.

[TinkerTailor]

That is a winner.

[Constabulary]

Mad electric scientists!

[dikman]

Well done! Now that you've proven the concept works you can make a better pedal.(Maybe ).

[MikeC5]

I thought I would share the set up I just completed on my 111.  It's an 8" large pulley and 2" small for a 4 to 1 reduction.  I tried it first with the original clutch motor but it was still hard to go as slow as I wanted.  I installed the servo motor and an quite happy with the set up. 

[catskin]

On ‎9‎/‎8‎/‎2007 at 9:05 PM, Art said:

Hi Pat,

Servo Motor produces full motor power at any speed since you can have a closed loop and Variable Frequency Drive and the Hall sensor to allow for as much or as little current as required to maintain the desired speed.

AC motors only have their power when running at the rated motor speed e.g. 1725 or 3450 rpm. Clutch motors run at rated speed and engage through a clutch when you push the pedal down. You can "feather" the clutch a bit like a car (except they work in opposite directions) but basically when the clutch is fully engaged the machine is running at full speed.

To way overly sinplify (and incorrectly to boot)

Servo = Automatic Transmission

Clutch = Manual Transmission.

The basic home sewing machine motor is (or used to be) an AC motor with a potentiometer foot control of various designs that varied the voltage. The only time you get full power is when the pedal is to the metal, anything under that drops the voltage and hence the power (power that you need for leather), it scrubs this power off as heat and that is why your foot control gets hot when you run the machine slow. This would not work well in an industrial situation and that is why industrial machines have a table with the motor underneath and full speed motors with plenty of power.

Since the 80s, you will occasionally see computer controlled DC motors on the higher end home sewing machines.

AC motor home machines just don't develop the power at lower speeds and are only really good for 6oz or less at slow speeds. Constant use on heavy leather (even if the machine head is built like a tank) will eventually toast the motor though. If you have one of those baklite button controllers, sew with your shoes on because slow speed running will get that thing hot enough to blister your tootsies.

Art

Art , I think your comparison might be even closer if it were  Clutch= manual transmission and  Servo = hydrostatic  transmission.  I wrote this before I read all 5 pages but still think some might understand what I mean.

Edited February 12, 2017 by catskin
Had not read all 5 pages before writing