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AmyK

Servo motor still too fast

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I’m a newbie to the industrial machine game and I’m feeling really defeated. I have a Nakajima 341L (Juki 1341 clone cylinder arm machine) with a new Enduro  SM600-2P. I’m having the usual uphill battle with figuring out a new machine (I’ve owned several domestics and can sew fabric on those just fine) but I’m feeling like even adjusted all the way down (which I’ve done) I’ll never be able to keep up with this machine’s speed. I’ve read some peoples posts about welding speed reducers which is totally outside my wheel house. Do I look for one? Or a new motor? I don’t even know what I’d be shopping for. 
The man who sold it to me is incredibly nice and sells and services machines- he’s been out here once and didn’t even charge me, says he’s really invested in making sure it’s up and running- but I don’t know what to do. Do I keep trying? Throw some more money at this problem and buy another motor? There’s no returns it was a Craigslist purchase. I’ve got some serious buyers remorse. I want to love this but I’m mostly just cussing and stubbing my toe on it. 

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I have added 3:1 speed reducers to most of my machines. That usually does the trick for me and should for you too. The question is what type of reducer to buy and who is going to install it? Then there's the question about your motor. Does it start up with a jolt at a couple hundred rpm? If so, does it have pushbuttons to control it? That type of servo is very hard to control and I have removed any like that and replaced them with this type of knob controlled servo motor. This motor starts at zero and speeds up to the preset limit of the knob. Heck, you may find that you don't really need a reducer with this motor.

Note that when you change motor types, or add reducers, the v-belt length/lengths will change too.

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1 hour ago, Wizcrafts said:

I have added 3:1 speed reducers to most of my machines. That usually does the trick for me and should for you too. The question is what type of reducer to buy and who is going to install it? Then there's the question about your motor. Does it start up with a jolt at a couple hundred rpm? If so, does it have pushbuttons to control it? That type of servo is very hard to control and I have removed any like that and replaced them with this type of knob controlled servo motor. This motor starts at zero and speeds up to the preset limit of the knob. Heck, you may find that you don't really need a reducer with this motor.

Note that when you change motor types, or add reducers, the v-belt length/lengths will change too.

You have to crawl under the table and enter the setup mode to change speed and startup speed. I have the overall speed and the length of time the startup speed lasts turned to the slowest possible. There is no knob. It just seems like there’s no “play” in the pedal. It’s off or it’s ON. I think I could pay the guy I bought it from to swap it out, but I don’t even know what I’m potentially buying. Or how much of an investment I’m looking at. 
 

(Thanks Wiz, I always like to hear your thoughts on things) 

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I agree with, and have followed Wizcrafts advice, to great success. 

I went with the simple dial type servo.  It's sold under half a dozen trade names like eagle, family, new tech etc.

Then I changed the motor pulley from 70mm to 45mm.  That helped to slow it down, but I didn't have much power.  Especially if the speed was set really low.  So I added a box style speed reducer.  That got me where I wanted to be.  Nice and slow, and easy to control.  Plus gobs of punching power. 

So this brings us to your situation... since you already have a nice servo, just add a box style speed reducer.  They mount to the table using the existing holes.  Really easy to do.  Then, as Wiz pointed out, make sure to program your motor for slow take-off.  Most motor manuals are available online.  

That's what I would do... keep your servo for now, and get a box style reducer.

Worst case scenario, you have to swap out the servo down the road.       

Edited by Pintodeluxe

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The Enduro motors have no setting to adjust starting speed (just the initial time delay) and they do start at around three hundred RPM. I’ve had Enduro motors before and I don’t really like them. You can always sell yours on CraigsList again and get a better option.

The “Family Sew” style knob control motors mentioned above are decent, but old-school in terms of servo motor technology and not without their own problems. I personally don’t like the motor brushes that wear out, the useless motor brake pad that just gets in the way unless you remove it, and the motor torque (punching power) is rather low at slow speeds. These motor do really require a pulley speed reducers to work well for leather work. The motor plus pulley speed reducer will run over $300,  not exactly cheap. But it’s what the North American market settles for. It’s what’s readily available through dealers and Ebay here in the US.

There are modern servo motors available with full low-end torque and very good low speed control systems that allow you to sew at stitch-per-second speeds without requiring speed reducer pulleys. They also a support needle positioning, which apparently you either love or hate with no middle ground. Unfortunately, most of these motors are not sold in the US. The only exception I’m aware of is the SP1100 motor, sold by Keystone and SewPro. Of course EFKA motors are an option, but US consumers are generally unwilling to pay for that level of quality.

Personally, I’ve been buying my motors directly from manufacturers in China. Alas, that is not everybody’s cup of tea and requires a sense of adventure as well as self-reliance in terms of repairs. But I do love those motors and haven’t had a dud yet. 

If you need somebody to call when things go bump in the seam, settle for what’s available locally and buy from a dealer who offers support.

 

 

 

 

  

 

 

Edited by Uwe

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5 hours ago, AmyK said:

I’m a newbie to the industrial machine game and I’m feeling really defeated. I have a Nakajima 341L (Juki 1341 clone cylinder arm machine) with a new Enduro  SM600-2P. I’m having the usual uphill battle with figuring out a new machine (I’ve owned several domestics and can sew fabric on those just fine) but I’m feeling like even adjusted all the way down (which I’ve done) I’ll never be able to keep up with this machine’s speed. I’ve read some peoples posts about welding speed reducers which is totally outside my wheel house. Do I look for one? Or a new motor? I don’t even know what I’d be shopping for. 
The man who sold it to me is incredibly nice and sells and services machines- he’s been out here once and didn’t even charge me, says he’s really invested in making sure it’s up and running- but I don’t know what to do. Do I keep trying? Throw some more money at this problem and buy another motor? There’s no returns it was a Craigslist purchase. I’ve got some serious buyers remorse. I want to love this but I’m mostly just cussing and stubbing my toe on it. 

I don't get it. All the established gurus seem to promote the box type reducer which is beyond the ability of most people and takes a considerable amount of time to gather the components and put something together.

On my Durkopp 239 and my Adler 69 all I did was change out the standard handwheel for a much larger pulley and a smaller pulley on the servo motor. The result gives more torque and I can do a stitch at a time. Once you have the pulleys it takes around 1 to 2 hours to do and costs no more than  a third of the cost of a box type or less.

Perhaps someone will say what's wrong with doing it this way?

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Nothing wrong with installing the smallest possible pulley on the motor (usually 45mm or 50mm) - I order my motors with the smallest possible pulley to start. A larger hand wheel or a large pulley to replace the hand wheel may be a little trickier to find, depending on the machine. If that puts your machine in the speed comfort zone, you’re good.

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"No play in the pedal" doesn't sound right, pedal movement should move an arm on the motor controller that will vary the speed. Can you post a couple of photos? Replacing the hand-wheel with a larger pulley works well BUT it isn't usually an easy option as it requires some mechanical nous. A box reducer, as mentioned, will be the simplest to fit as it is a fairly simple job but may require new belts.

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1 minute ago, dikman said:

"No play in the pedal" doesn't sound right, pedal movement should move an arm on the motor controller that will vary the speed. Can you post a couple of photos? Replacing the hand-wheel with a larger pulley works well BUT it isn't usually an easy option as it requires some mechanical nous. A box reducer, as mentioned, will be the simplest to fit as it is a fairly simple job but may require new belts.

What I think is meant is the motor doesn't ramp up to speed. 

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4 hours ago, Uwe said:

There are modern servo motors available with full low-end torque and very good low speed control systems that allow you to sew at stitch-per-second speeds without requiring speed reducer pulleys. They also a support needle positioning, which apparently you either love or hate with no middle ground. Unfortunately, most of these motors are not sold in the US. The only exception I’m aware of is the SP1100 motor, sold by Keystone and SewPro.

Uwe, when I look at you link to Keystone, I guess the motor got a minimum constant speed of 100 RPM. And I have not seen brushless servo motors with a lower speed than that. Have you seen lower speed than 100 RPM?

 

5 hours ago, AmyK said:

. It just seems like there’s no “play” in the pedal.

For some years ago a problem with some servo motors with this issue were debated. It may be this problem you see:

https://leatherworker.net/forum/topic/41916-having-problems-with-servo-motor-speed-control/ 

 

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1 hour ago, Uwe said:

Nothing wrong with installing the smallest possible pulley on the motor (usually 45mm or 50mm) - I order my motors with the smallest possible pulley to start. A larger hand wheel or a large pulley to replace the hand wheel may be a little trickier to find, depending on the machine. If that puts your machine in the speed comfort zone, you’re good.

The pulley can be any size Uwe, it's the taperlock that goes on the shaft and these can be got in any size. I've attempted a video showing the taperlock bush in the center.

I've also included the bill for the pulley, the taperlock bush and the new belt. The 4omm pulley on the servo I already had.

IMG_20201016_002924.jpg

 

 

Edited by toxo
Wrong photo.

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sigh. My machine guy replied to my text:

“you don’t need a speed reducer with a servo motor” 

um. I think I’d be the one to know. Maybe not how to slow it down but that it’s too fast for me. I feel like I’m getting “now see here little lady”ed. 
 

anyone wanna buy a cylinder bed machine - Atlanta area. Not completely joking ☹️

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@AmyK Don’t give up on the machine head, it’s the motor control that’s causing you grief. That poorly implemented speed ramping control on the Enduro motors is a real problem. Speed control is done via a light sensor and speed varies depending on how much light hits the sensor. The factory combo of sensor and light blocker is WAY too sensitive, jumping between full light to zero light with the tiniest of pedal movements. I also ended up making a special triangular light blocking “flag” to get any sort of real world ramping of speed. The motor is indeed capable of graduated speed control, just not with the factory bits. Whether you want to bother modifying the speed control on your motor is up to you.

@toxo thanks for the demo and details on your hand wheel pulley. That speed control looks just about perfect to me, sweet! I’m very much in favor of this pulley-as-a-hand-wheel solution. I really don’t care for the in-between pulley speed reducers.  

@Gymnast the 100 RPM starting speed is the lowest I’ve seen on the motors I’ve researched.

 

Just for reference, this is the kind of speed control I’m getting with my servo motor and a standard hand wheel:

 

Edited by Uwe

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This is a video, that in my opinion shows good speed control of a leather sewing machine and with an available servo motor.


This is a video of speed control, with a DIY solution on a domestic sewing machine. I think it have got exceptional good speed control. It have got a very fast responsive foot pedal, and it have got a factor 70 between lowest speed and highest speed. If I was a manufacturer of a servo motor for leatherworkers, the performance should look like this: 

 

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I have a Consew 255-rb3 with a family sew servo motor. I had the same problems as most, the motor had no torque at the first or second position but was to fast for me at position 3 or <. I added a 45mm pulley to the motor and a box style speed reducer, problem solved. Brought it all from Toledo, the speed reducer was a simple remove motor bolts and place reducer in place them bolt motor to the reducer. I used a piece of rope to get a belt length and bought that at Autozone.   

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Gymnast- Yes. This is what I want. I have no idea how to make it happen. 

Edited by AmyK
Clarification- quote was left out

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I need a book called “So you just want to sew slowly and don’t understand motors or pulleys” 

also what’s this about occluding the light to slow it down? It was referenced in a linked thread but I’m having trouble understanding how putting a sticker on it is the solution to any problem??

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Yes,we used this type of servo years ago & stopped after so many complaints,the ramp speed & lack of low end torque topped off by the boards burning out in 2-3 out of 10 we discontinued buying them & switched to the type with brushes.

We have tested & even have the 1100 watt servos for sale BUT have found that it lacks the punching power @ low speed & won't run as slow as our little FS550 servo does with a speed reducer on it,the brush type of motor also seems to have more low end torque.We stopped using the electronic servos years ago & have had alot less problems do to their simplicity,they also seem to have a long brush life.

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There are various factors that determine how precisely you can control motor speed input.

One factor is the mechanical linkage between the foot pedal and the speed input lever on the motor controller. Depending on how close to the pivot point you connect the linkage rod to the pedal and to the lever on the motor controller, you can either exaggerate the pedal movement, or you can minimize the effect of pedal movement on controller input. For maximum control, you want a large pedal movement to cause a small speed input lever movement. 

On your Enduro motor the second factor is how much pedal movement does it take to make the sensor go from receiving full light to zero light. Full light means stop, no light means full speed. It’s like looking at a flash light and moving your hand in front of the flash light to adjust how much light hits your eye.  

A small movement of your hand covers the flashlight completely. (That’s how the Enduro works out of the box)

Instead of just  your hand,  you can hold a clear strip of plastic with a gradient in front of the flash light. That plastic strip is going from clear on one end to black on the other end, with increasingly darker shades of gray in the middle (or increasingly dense sharpie pen lines). The longer that gradient strip is, the easier it is for you precisely control how much light hits your eye.(that’s the video above)

Instead of the gradient plastic strip you can also hold a pennant shaped piece of cardboard and move it leading with the pointy end in front of the flash light. This also makes it easier to change precisely how much of the flashlight you cover. (That’s what I did)

Modifying the Enduro is not very hard to do, but it does take some fiddling and experimenting.

 

  

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Lots of interesting information guys! Thank you all so much! 

I've slowed it down quite a bit, and the torque drop off was helped somewhat by turning off the slow start (it wasn't helping much anyhow), but in order to get me into where I want with the speed, I'm still getting some stalling out. 

Sounds like the easiest thing for the non-mechanically inclined might be to replace the hand wheel. Unscrewing a couple wheels and replacing the belt seems doable. Unfortunately, my guy doesn't have any idea how to get a new hand wheel or servo motor pulley. 

I've got a Nakakima 341L (I'm lead to believe its a Juki 1341 clone) and a Enduro SM600-SP. Can anyone recommend a dealer who might have these parts? 

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AmyK, unless you're into tinkering with things changing the handwheel may not be a straightforward project. You will not find a larger replacement handwheel, what you have to get is a large pulley with the same shaft diameter as the machine and then ensure it can be locked to the shaft. I have had to drill and tap more than one pulley to lock it to a shaft.

If you're not keen on messing around with the gradient strips in your servo controller I think your best bet will be to sell the servo and buy a new one (I'm not aware of any newer ones that use the optical gradient control like yours). Even if you buy one of the inexpensive generic servos on ebay it should work better than the one you've got, and if you fit a box speed reducer you'll be able to make the needle crawl.:) If you can handle a screwdriver and spanner you should be able to fit the reducer, or get a friend with a little mechanical ability to help.

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Does anyone know the shaft size of a Nakakima 341L?

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AmyK,

Is it Nakakima or Nakijima?

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1 minute ago, shoepatcher said:

AmyK,

Is it Nakakima or Nakijima?

Nakajima- though I call it Bruce because I keep saying Nakatomi by accident. 
 

(Die Hard. Nakatomi Plaza. Bruce Willis)

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