Swapping clutch motor to servo motor, please assist

[Ana1234]

Ok thanks for all info, appreciated! I will discuss all options with the technician guy (currently on holiday). Perhaps he has parts in his shop! I'll run all of this by him. 

Info on servos is super helpful. 

So if I got it right - 

- i either get a speed reducer (already built) and then I only need to attach a smaller pulley (45mm) on the shaft (or what ever it's called) of the servo. 

- or I build the system from scratch (cheaper option for parts but I guess I need to pay the technician a handy fee instead) with a larger pulley on handwheel and also the smaller 45mm on servo.

A lot depends on the price of installation. If I go ahead to do it myself I'll be ready to sew in a couple of months 

 

 

Edited July 2, 2023 by Ana1234

[kgg]

2 hours ago, Ana1234 said:

So if I got it right - 

- i either get a speed reducer (already built) and then I only need to attach a smaller pulley (45mm) on the shaft (or what ever it's called) of the servo. 

That would be you least expensive option if you are going to pay a labor rate for someone to install it. To keep your labor cost down have the technician do the full install all at the same time. It will involve i) removing the old motor with a new servo motor ii) removal of the factory 75 mm pulley on the servo with a smaller 45mm pulley iii) installing a speed reducer and iv) installing the two new pulley belts, one belt from the 45mm pulley to the large pulley on the speed reducer and one belt from the small pulley on the speed reducer to the hand-wheel pulley on the sewing machine.

This is not a difficult task but does involve removing the sewing machine from the table and tipping the sewing machine table over so the old clutch motor which is heavy probably around 25kg or so can be more easily and safety lifted off the bottom of the table top. Even the new servo is probably going to weigh around 10 kg.

2 hours ago, Ana1234 said:

A lot depends on the price of installation. If I go ahead to do it myself I'll be ready to sew in a couple of months

This would be the cheapest option by far. Waiting for the parts to arrive is probably going to take awhile due to shipping to your location. Once you have the parts you are probably looking at a couple / three hours of work to remove the old motor, install the new servo motor and speed reducer. It would be much easier and safer if you have someone to help with the heavy clumsy lifting. Once the motor and speed reducer are installed all is left is getting the right size of belts to install on the pulleys.

kgg 

Edited July 2, 2023 by kgg

[AlZilla]

@Ana1234. if you have any level of mechanical expertise (as in you can change the oil in your car or hang a picture straight), swapping out a motor will be easy.  As stated, the weight of that old clutch motor is probably the biggest issue.  You'll have to locate where the speed reducer will sit and drill the holes.  Belts are always my bane on something like this No matter how much I measure, I always seem to miss it by a half inch and make another trip to the store ...

[Ana1234]

Ok super grateful for all advice I feel confident now to pick the needed gear. This was a crash course into speed reduction!! 

I will report back how all of this turned out. Probably in August after holiday season. All the best! 

Just one more thing, with everything fitted and I've achieved that slow stitch how fast will I actually be able to go after that? I don't need top speeds but sometimes I get upholstery work and I am sewing curtains for TV commercials so I'd like to take it up a notch for those projects (now and then). 

Will the extremely slow speed set up be a stress on the machine somehow if I turn the speed up a bit? 

[kgg]

6 hours ago, Ana1234 said:

Will the extremely slow speed set up be a stress on the machine somehow if I turn the speed up a bit? 

The main stress will be caused by putting too thick / tough /sticky of material under the presser foot. I am going to go on the bases your machine is rated for 2000 stitches per minute (spm) in lighter thickness material. If you exceed what the machine is rated for ( sewing capability or speed ) then chances are you are going to have a problem and bust something. The speed reducer will provide both slower speed and more torque ( punching power ). The torque if you exceed the limits of your machine mostly in thickness and type of material being sewn that is when nasty things are going to happen. Keep in mind you do not have a safety clutch on the sewing machine to prevent the bottom end of the sewing machine from being damaged. Speed reducers are like a double edged sword, providing slower more controllable sewing speeds and with that you get more available torque which can damage the sewing machine internals if not cautious.  

Depending on the servo motor you purchase the minimum startup speed rating will be probably be 200 or 300 rpm's with a maximum speed rating of 3000 to 5000 rpm's  

With a 45mm small pulley installed on the motor and a speed reducer with a large 150mm pulley and a smaller 50 mm pulley here is what you can expect as far as needle speed goes. So you can see for doing thinner items you will never come close to exceeding the speed rating of the machine but be cautious on how thick and type of material you plan on putting under the presser foot because of the addition torque available. These sewing speeds would probably drive an experienced production person nuts at how slow they are.

These are based on a hand-wheel pulley size of 85mm.

Motor speed (rpm ) setting --------------------------------------- Needle speed (SPM)

200 rpm ------------------------------------------------------------------------35

300 rpm ------------------------------------------------------------------------53

400 rpm ------------------------------------------------------------------------71

500 rpm ------------------------------------------------------------------------88

600 rpm ------------------------------------------------------------------------106

700 rpm ------------------------------------------------------------------------124

800 rpm ------------------------------------------------------------------------141

900 rpm ------------------------------------------------------------------------159

1000 rpm ----------------------------------------------------------------------176

2000 rpm ----------------------------------------------------------------------353

3000 rpm ----------------------------------------------------------------------529 

Edited July 2, 2023 by kgg
Forgot to add size of hand-wheel pulley

[AlZilla]

5 hours ago, Ana1234 said:

Just one more thing, with everything fitted and I've achieved that slow stitch how fast will I actually be able to go after that?

I went to the pulley calculator and entered in my setup on the 2 set calculator. At 200 rpms it says I should have 57 rpms at the hand wheel. I counted 52, so close enough. Then I raised the motor speed to 5000 on the calculator and it says I should have 1429 rpms.

I'd be pretty confident in 1400 or so top speed, based on that. There's a real world data point for you.

[kgg]

23 minutes ago, AlZilla said:

I'd be pretty confident in 1400 or so top speed, based on that. There's a real world data point for you.

I think the slight difference between actual vs the program is the program numbers are based on the inside diameter of the pulley rather then the outside dimensions. I did edit my previous post to show I assumed a 85 mm diameter hand-wheel pulley.

kgg

[dikman]

Regarding top speed, servos have various parameters that can be set in the control box. One of them will be setting top speed. When sewing leather most will set this lower, as high top speed is generally not a consideration, but if you feel you need a higher speed at some time you can set this parameter higher and then drop it back after. With a reducer fitted it still won't be super-fast but may be sufficient for your needs. If you only have one machine then setting it up will always be a compromise.

I have fitted my motors from underneath, once you have the clutch motor removed it's pretty easy. BUT be careful removing the clutch motor, they are very heavy! Stick with a reducer, like kgg linked to, it will be the simplest option. Forget about building your own reducer and/or replacing the handwheel for now, I only mentioned that to show what options are available, they're not for the beginner. If you're getting the tech to do it then fitting a servo and that reducer should be a pretty easy job.

[AlZilla]

4 hours ago, kgg said:

I think the slight difference between actual vs the program is the program numbers are based on the inside diameter of the pulley rather then the outside dimensions. I did edit my previous post to show I assumed a 85 mm diameter hand-wheel pulley.

kgg

Well, especially with my 3.5" hand wheel, which I laid a ruler across and eyeballed. I thought 57 vs 52 was pretty close.  Any of those pulleys could be slightly off exact claimed spec.  These are really not precision parts we're playing with.  I think with all the data in this thread, anybody could get a very close estimate with high confidence.

Edited July 2, 2023 by AlZilla

[xnikolaos]

I'm a bit of a latecomer but I'll share my experience. I have bought three 750watt servomotors from AliExpress, duty free, and I was pleased. Company VEVOR on alliexpress. It has two pulleys 45mm and 70mm and an automatic needle positioner. You need someone with basic DIY knowledge to install. 120€. I live in Greece.

Edited July 3, 2023 by xnikolaos