Direct Drive Servo Motor retrofit for vintage singer 491D

[JClif88]

Does anyone have experience with adding a direct drive servo motor to a vintage industrial lockstitch machine?

It seems as though the direct drive motors seen here...

https://www.aliexpress.com/item/4000188162454.html?spm=a2g0o.productlist.0.0.7b1e20faCglHc4&algo_pvid=55f99c43-5325-47c2-af78-38bd3defab7c&algo_expid=55f99c43-5325-47c2-af78-38bd3defab7c-0&btsid=2100bb4716050851459187891e49cf&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Should work but I want confirmation first, it doesn't seem like there is any local sellers (UK) and the only ones I can find would come from China, so I just want to make sure.

If anyone has any experience with them, I'd love to know what the speed control is like on them?

[Constabulary]

Why a direct drive motor and not a standard under table mount motor? I´m sure that would cause less trouble.

[JClif88]

Reduced Gubbins about, no need for a synchronizer, no belt losses, no belt wear and a lighter table overall.

 

Edited November 12, 2020 by JClif88

[chrisash]

But most likely a large problem to overcome fitting it to your machine. the pictures show it fitted to modern machines designed for it

Plenty of uk based sellers selling servo's at far lower prices which are far easier to fit under the table and out of the way

[Constabulary]

agree with chrisash.

1 hour ago, JClif88 said:

Reduced Gubbins - maybe true but lots of fiddling attaching it to the machine (depends a bit on your skills) if it is not a dedicated motor and it for sure is not.

no need for a synchronizer - yes, if you really need one - many do not - I don´t.

no belt losses - overrated IMO on a light duty machine like this.

belt wear - overrated, how often do you change  a V- Belt? 1x in 5 year or 10 year or maybe never.

and a lihter table overall - Lighter table? Not sure how much difference that is maybe 1-2KG or so? How often do you move your table that this matters?

my 2 cents

 

[Gregg From Keystone Sewing]

Intresting motor for sure, never seen that type. 

If you look, most are for specific model machines as a direct bolt on.  The Juki for example seem to mount off the where the original belt guard would bolt onto.  

Most direct drives moachines from the factory have built into the factory casting mounting for this or again is retrofitted as is here.

Personally, I would just get a belt drive motor and be done with it, otherwise you may end up with a mess on your hands.  

[dikman]

3 hours ago, Gregg From Keystone Sewing said:

Personally, I would just get a belt drive motor and be done with it, otherwise you may end up with a mess on your hands.  

My thoughts too. It would be an interesting exercise - but only if someone gave me the motor, I wouldn't buy one just to see if it would fit!

[DonInReno]

This type of motor motor set up is relatively new as a retrofit, not to mention there is no track record to go off of with that specific motor, so you are sailing in uncharted waters.    Do you feel lucky?   

In these cases I’m a fan of letting someone else take the risk - so I hope you get it, use the heck out of it and let us know how it goes!   

Edit:  After thinking about it a bit more the main thing I couldn’t live with is a lack of speed reducer.   

Edited November 15, 2020 by DonInReno

[JClif88]

Yes, this is a concern, I don't actually do lots of leather work so probably don't need a super slow speed but do want to work at a slower speed, I'm not sure how slow these motors can be tweaked to go and I'm hoping a bit of practice should be all that's required when it's tweaked right down.

On 11/15/2020 at 10:49 PM, DonInReno said:

This type of motor motor set up is relatively new as a retrofit, not to mention there is no track record to go off of with that specific motor, so you are sailing in uncharted waters.    Do you feel lucky?   

In these cases I’m a fan of letting someone else take the risk - so I hope you get it, use the heck out of it and let us know how it goes!   

Edit:  After thinking about it a bit more the main thing I couldn’t live with is a lack of speed reducer.   

 

[Constabulary]

Do what others did - that at least proven. I do not think these retrofit direct drive motors have a better speed control than other (proven) motor designs. But I maybe wrong. Super slow is better than a little bit to fast. IMO speed reducers have a lot of advantages. DIY speed reducers can be build fairly cheap. This is mine on the post bed setup I fished earlier this year:

https://leatherworker.net/forum/topic/91428-slowing-down-my-servo/?tab=comments#comment-626493

 

[DonInReno]

5 hours ago, JClif88 said:

Yes, this is a concern, I don't actually do lots of leather work so probably don't need a super slow speed but do want to work at a slower speed, I'm not sure how slow these motors can be tweaked to go and I'm hoping a bit of practice should be all that's required when it's tweaked right down

I do like how compact they are - as long as you aren’t expecting it to sew slower than other generic servo motors it seems interesting.

I was curious how these super compact servos attach and found a photo from a different servo that seems to show one as it comes out of the box.   On one end of the stator (spinny thing) there’s a bearing in the servo’s housing, but there isn’t a bearing on the other end - so I’m assuming the bearing supporting the machine handwheel serves as the output bearing of the motor.   The adaptor plate and shaft connector you will need to make up will probably have to be quite exact.

[dikman]

"spinny thing"......

 

[JClif88]

On 11/18/2020 at 2:22 PM, DonInReno said:

I do like how compact they are - as long as you aren’t expecting it to sew slower than other generic servo motors it seems interesting.

I was curious how these super compact servos attach and found a photo from a different servo that seems to show one as it comes out of the box.   On one end of the stator (spinny thing) there’s a bearing in the servo’s housing, but there isn’t a bearing on the other end - so I’m assuming the bearing supporting the machine handwheel serves as the output bearing of the motor.   The adaptor plate and shaft connector you will need to make up will probably have to be quite exact.

The pictured unit looks like the ones they sell for Overlockers, but I suspect they are the same internally.

I've not actually used a servo motor yet but I'm hoping, bringing the speed down as far as possible on the control unit (around 400-500 RPM) should give me a usable range.

I contacted a US supplier about the Yuma motors and they've stated they have fitted them on to a Singer 591 so the shank on my 491 should be suitable, I just need a way of stabilising the motor which will require drilling and tapping my machine or fabricating some other mounting system.

It also seems that they supply converters with the units to adapt the servo to many common shank sizes (I think mine is 14.7mm)

I'm also interested in whether I can modify the controller to have better speed control via the optical sensor as shown on this forum which would be great.

[dikman]

13 hours ago, JClif88 said:

I'm also interested in whether I can modify the controller to have better speed control via the optical sensor as shown on this forum which would be great.

IF it uses an optical sensor. It appears that most, if not all, of the generic servos use Hall-effect sensors, not optical now.

[DonInReno]

I’ve also tried some things not all that traditional, and while tried and true is almost always the way to go, sometimes it’s worth it just fast a learning exercise.    I also like a more compact form factor, but there is no way I’d go without a 3:1 reducer.

My preferred setup so far is a planetary reducer directly coupled to the motor and one short belt.  I’ll bet eventually a company will offer a servo mated to a planetary reducer.

[dikman]

That's neat, Don. I would imagine the only reason it hasn't been offered is cost? Plus, of course the bog standard servo is a straight swap for either a clutch or another servo motor, no messing around.

[Constabulary]

For a while I have been playing with the idea of an NEMA planetary gearboxes like this:

https://www.ebay.de/itm/Planetengetriebe-Drehzahlminderer-Nema17-23-34-Getriebekopf-3-5-8-20-30-40-50-1/264861653607

But when putting approx 120€ for a 1:3  planetary gearboxes + tinkering in relation to a DIY Speed reducer the DIY version was the winner.

 

Edited November 21, 2020 by Constabulary

[dikman]

Another advantage of a home-made reducer is you can tinker with the ratios by changing pulley sizes.

[DonInReno]

12 hours ago, Constabulary said:

For a while I have been playing with the idea of an NEMA planetary gearboxes like this:

https://www.ebay.de/itm/Planetengetriebe-Drehzahlminderer-Nema17-23-34-Getriebekopf-3-5-8-20-30-40-50-1/264861653607

But when putting approx 120€ for a 1:3  planetary gearboxes + tinkering in relation to a DIY Speed reducer the DIY version was the winner.

 

If a sewing servo had a NEMA nose so it would simply bolt up to a NEMA reducer it would be much easier! Lol

My current project is a Wittgenstein Alpha 3:1 reducer off eBay and SP-1100 servo from Keystone Sewing.  It seems these reducers are available in a huge range of input and output sizes, as well as base adaptor measurements, both metric and inch.   This one is 5/8” input, 7/8” output, with 70mm x 70mm holes in the base.  The servo hasn’t made it here yet, but an adapter plate between the two will need to be made, or at least new holes drilled in the reducer base.

Other than the compact size there is no noticeable benefit over using a 3:1 pulley reducer.    

[JClif88]

13 hours ago, DonInReno said:

If a sewing servo had a NEMA nose so it would simply bolt up to a NEMA reducer it would be much easier! Lol

My current project is a Wittgenstein Alpha 3:1 reducer off eBay and SP-1100 servo from Keystone Sewing.  It seems these reducers are available in a huge range of input and output sizes, as well as base adaptor measurements, both metric and inch.   This one is 5/8” input, 7/8” output, with 70mm x 70mm holes in the base.  The servo hasn’t made it here yet, but an adapter plate between the two will need to be made, or at least new holes drilled in the reducer base.

Other than the compact size there is no noticeable benefit over using a 3:1 pulley reducer.    

This is really interesting, so in theory, could a planetary gearbox reducer be found to link a servo motor directly to the shaft?

It's good to know if I find the direct drive motor too fast, I might be able to use a planetary gearbox reducer to slow it down.....

[DonInReno]

I can’t picture it.

[JClif88]

pardon my ignorance....

don't these gearboxes have a driver input and the output shaft?

I'd imagined you could just have a motor->gearbox->sewing machine?

 

[DonInReno]

With the direct connect servo being fairly wide, adding another 7”-8” for an in-line reducer puts the handwheel waaaay over there.  I can’t imagine it would be very enjoyable to sew with.

[JClif88]

On 11/22/2020 at 4:52 PM, DonInReno said:

With the direct connect servo being fairly wide, adding another 7”-8” for an in-line reducer puts the handwheel waaaay over there.  I can’t imagine it would be very enjoyable to sew with.

true,

 

Anyway, I have a DD motor coming, got it for about £70, will be interesting to see how well it works, I'm quietly confident that it will mount ok as I've heard they have mounted to Singer 591D's in the past. So just a case of trying to work out how to stabilise it which should be possible which a bit of angle steel.

[JClif88]

So I finally got this and fitted it, I'm pretty pleased with it tbh, very easy to install, just needed some bracing fixing to the table to stop the motor spinning. Great control options, much neater than a belted setup and the lowest setting (200 rpm) is fine. Hopefully the quality is up to scratch.

It's a 750W motor and seems strong (I can't stop it with my hand). It also behaves like a stepper motor as it doesn't run smoothly, rather runs in stages. Also it has a nice Led light and single stitch button and also passes power through to an external lamp. 

Edited December 24, 2020 by JClif88