3d printed a smaller pulley

[jimi]

Here is the pulley for the jack servo motor. 

50mmpulley.stl

[Gregg From Keystone Sewing]

23 hours ago, jimi said:

Here is the pulley for the jack servo motor. 

50mmpulley.stl

Looks great, that is an odd size.  We hosted a an exchange student from Salamanca over two summers, and then went to stay with his family, in Salamanca for two weeks.  We had their old apartment, and they were more than accommodating.  It was a great two weeks they took us everywhere and treated us like family.

Edited March 16, 2020 by Gregg From Keystone Sewing

[jimi]

2 hours ago, Gregg From Keystone Sewing said:

We hosted a an exchange student from Salamanca over two summers, and then went to stay with his family, in Salamanca for two weeks.  We had their old apartment, and they were more than accommodating.  It was a great two weeks they took us everywhere and treated us like family.

Yes, Nice place Salamanca, and sounds like you had a good time over here Gregg. 

Sorry Stor...

Edited March 16, 2020 by jimi

[8dsf]

Hello, I realise this is old topic but I wonder how long "Stor's" 3d printed pulley survived. I would like to 3d print it as well but from PETG or later from stronger nylon if this actually makes any sense :). Probably custom made pulley would be the best solution. I also wonder what is the size limit for the needle positioner if any.

Adam

 

 

[Matt S]

3 hours ago, 8dsf said:

Hello, I realise this is old topic but I wonder how long "Stor's" 3d printed pulley survived. I would like to 3d print it as well but from PETG or later from stronger nylon if this actually makes any sense :). Probably custom made pulley would be the best solution. I also wonder what is the size limit for the needle positioner if any.

Adam

Hi Adam,

It'd be interesting to find out how long Stor's pulley lasted but I'd be concerned about concentricity and vibration, especially long-term -- however I tend to run my motors at 4500RPM a lot so your mileage may vary. Sewing machine pulleys are normally cast from aluminium, the bore reamed, keyway broached and the V-groove cleaned up on a lathe, which eliminates most of the wobble and gives a wheel that you can be very sure won't distort over time or spread shrapnel around the place. All for £5 retail.

As to size limit, and assuming that you're aiming for as slow a speed (high reduction) as possible, I guess it depends on the motor. I'm currently running a 40mm motor pulley to a 80mm handwheel (standard/common with upholstery weight machines) on a Jack 511 and a 513, both with the standard needle positioner, neither of which has ever missed a stitch. 40mm is probably the smallest commercially available size and has problems at times with slippage (not much arc length in contact with the belt). I don't think I'd want to go any smaller just on the slippage issue alone.

In the past I've gone with higher reduction ratios on other servo motors and found that issues tend to crop up with needle positioners when going above a 1:2-3 ratio, but it really does depends on the motor. It's also my experience that so long as you don't have one of the absolute dog toffee servo motors that starts at something like 500RPM a 2:1 ratio is plenty slow enough when you've got a needle positioner installed -- you can just tap your toe down and get a single stitch quite reliably.

Out of pure idle nosiness, why do you want to 3D-print a SM pulley? Is it curiosity, or is there a problem you're trying to solve?

[8dsf]

Matt, I am planning to buy the JK 563 and after reading all the topics on the forum looks like there is a problem to source a 40mm replacement pulley with 13mm bore. So my plan was to print one and ask friend to fabricate one for me which would take time for sure... By any chance would you know where to get 40 or 50mm pulley for JK servo motor  in the UK?

Thanks 

Adam

[Constabulary]

I have two JACK servos one came with a 13mm shaft one with a 15mm shaft. Back then someone milled a pulley for the 13mm shaft (did not find any 13mm bore pulleys back then). An easier task is using a tube with 15mm outer diameter and 1mm wall an make a sleeve for the shaft. I did that on a different project - works perfect. If my next JACK servo has a 13mm shaft I will use the sleeve workaround again. Just my 2 cents.

[Matt S]

15 hours ago, 8dsf said:

Matt, I am planning to buy the JK 563 and after reading all the topics on the forum looks like there is a problem to source a 40mm replacement pulley with 13mm bore. So my plan was to print one and ask friend to fabricate one for me which would take time for sure... By any chance would you know where to get 40 or 50mm pulley for JK servo motor  in the UK?

Hi Adam,
I've not used a 563 but both of my smaller Jacks have the awkward 13mm shaft, which is also a little shorter than I would like. The ~70mm pulleys that came on them are thinner than the usual ones. It's a real shame that College doesn't just sell a compatible range of pulleys... or Jack switch to a more common shaft size!

Constabulary/Folker's method looks really neat, quick and doesn't need a lot of tools -- if you can get the right size of tubing. I suspect that you'd still need to reduce the length of the boss on the more commonly available 15mm bore pulleys to fit the shaft though.

What I did is took a 40mm tapered shaft pulley (11mm tapering to 15) and drilled it out to 13mm. That gives a good tight fit for most of the length with a little slop at one end, but with the key installed and the nut snugged down it's very solid. The only thing is that the shaft is a little short so I had to shorten the non-pulley end so it would fit. I used a grinder on the first one, which worked with a little care, then a few passes with a facemill in my milling machine for the second and third ones, which worked better. I've done this 3 times so far, works well.

If you have a 3D printer and the skills to run it, rather than traditional workshop tools and skills, maybe it is a better option than adapting a commercial one. I don't know if I'd hire someone to print one though -- I doubt that it'd be cheaper than hiring someone to make an adapter sleeve or bore out an existing pulley. Probably cheaper than hiring someone to turn one from scratch, unless you know a bloke. I'd still be leery about running a 3D printed wheel at 4500RPM at crotch height for very long though... 

[8dsf]

Hi Matt. I think I will give it a go knowing that guys here use Jack without problems other than adapting a small pulley.  I have just printed  half of the pulley with 0.1mm resolution in PETG from the stl project someone has shared here but I would prefer pulley in one piece so I will have to make own sketch. I agree with you that running on high RPM would most likely deform the 3d printed pulley due to running temperature.  Maybe nylon would survive longer as it has higher melting temperature but printing it brings some difficulties as well.

I have reached JK representative in Europe and somehow they were surprise why would I need to change the pulley as there is speed regulation per design... 

 

Edited June 27, 2020 by 8dsf

[Matt S]

Quote

I have reached JK representative in Europe and somehow they were surprise why would I need to change the pulley as there is speed regulation per design... 

To be fair to them the desire to slow down an industrial sewing machine is pretty rare when taking into account the world market. They may be thinking that what you want to do is limit the top speed of the machine, which with a clutch motor is often achieved by changing the motor pulley but of course with a JK servo is just a menu setting. I presume though that this isn't what you're trying to do?

Your pulley half looks good. Not knowing much about 3D printing I guess you'd have problems preventing the overhanging flange from sagging while printing the full thing? What machine are you running, and how long did that print take? I'm kinda tempted to buy a 3D printer, mainly for making jigs and layup tools, but I don't know how much use I'd actually get out of it.