Replacement Pulley for Tapered Shaft

[friquant]

Where can I find a 45mm or smaller replacement pulley for a tapered shaft?

The shaft is about 11.5mm at one side of the pulley but tapers to 9.1mm at the other.

By the way this came with a new servo motor that looks very much like this one being sold on amazon

 

 

[kgg]

7 hours ago, friquant said:

The shaft is about 11.5mm at one side of the pulley but tapers to 9.1mm at the other.

The design of the servo motor you referenced has fins on the motor of the pulley probably for motor cooling as the control box blocks / restricts air flow into the motor.

Options:

i) If you can't find a 45mm pulley with the correct taper I would check with a machine shop or supplier. 

ii) have a 45mm pulley modified by either re-machining or by using a brass taper bushing. 

iii) If you got this off off Amazon I would personally return it and get a more conventional layout, one where the control box is mounted on the front underside edge. I think having to reach underneath the table to the far back of the table to change settings could be very inconvenient. 

iv) If you do find a pulley chances are it will not have the cooling fans which may affect the life expectancy of the servo motor. 

I think buying and installing a speed reducer would be the simplest solution. 

Based on the motor you referenced. The motor pulley is 3" in diameter and if you install a 3:1 speed reducer which typically has a 6" large pulley and a 2" small pulley you will reduce your speed at the sewing machines handwheel.  If my calculations are correct by 75 percent. 

Example:

i) servo motor 3" pulley running at 100 rpm 

ii) 3:1 speed reducer installed 

iii) 4" sewing machine handwheel pulley

The 4" handwheel will spin at 25 rpm.

 

kgg

 

[dikman]

I would say the chances of finding a pulley like that are pretty slim. Over the years I've bought several different (generic) servos and never had a shaft like that, they've all been straight and took generic pulleys. I'm assuming you can't return it for a different type so you have two options as I see it, either fit a speed reducer as kgg suggested or possibly replace the machine handwheel with a larger pulley.

[friquant]

Quote

If you got this off off Amazon I would personally return it

@kgg This servo motor I ordered through alibaba. It took two months to get here, so I may see if I can make it work. About half of the servo motors I'm seeing for sale on amazon and ebay now come with this reduced size / tapered pulley, but I have not seen anybody selling small diameter replacement pulleys for them yet. Perhaps they think the servo motor controller will handle all the speed adjustments we need? 🙄

In the spirit of experimentation, I decided to print one. I'm not sure how long it will last.

This is 3D (FDM) printed with PETG, which has better toughness than PLA or ABS. It's 35mm outer diameter.

[dikman]

That should work but longevity is going to be the issue. It has the advantage that you can print spares to keep handy, failure during a project may be a concern.

Worth a try.

[kgg]

2 hours ago, dikman said:

That should work but longevity is going to be the issue.

2 hours ago, friquant said:

It's 35mm outer diameter.

That may work but besides longevity the diameter maybe an issue with the bending ability of the belt around to such a small diameter and premature belt wear. It's worth a try but I would alter your design to add a larger diameter surface face on the motor side of the pulley with blades to help keep the motor cool while running. 

With that size of servo motor pulley (35mm) and a 4" (104mm) handwheel with the servo motor running at 100 rpm the speed at the handwheel will be reduced to 33.7 rpm.

The controller will handle the speeds but it's configuration on the motor was done to reduce the manufacturing cost with no consideration of easy access to the settings. You are going to be on your knees trying to change any setting.

kgg 

Edited May 27 by kgg

[RockyAussie]

6 hours ago, kgg said:

The controller will handle the speeds but it's configuration on the motor was done to reduce the manufacturing cost with no consideration of easy access to the settings. You are going to be on your knees trying to change any setting.

It looks to me that there is enough cable room to mount the control box at the front in the video they show on the Amazon link. I do think there will be issues with that small a pulley though and being plastic I suspect slipping may be a problem. May need a rubber band in the V in the pulley or something like that.

[kgg]

3 hours ago, RockyAussie said:

It looks to me that there is enough cable room to mount the control box at the front in the video they show on the Amazon link.

I agree the first video does show long cables but the second video shows the control box and servo motor as one unit with the wiring from the motor directly into the control box. Looks like two different servo motor setups being advertised.

@friquant which layout did you get?? The one with the long cables or the one with the on/off switch mounted to the front of the table???

Second related video in advertisement:

https://www.amazon.com/live/video/0b443a3824a2418a9770702b7017ddf6?ref_=dp_vse_ibvc1

kgg

Edited May 27 by kgg

[friquant]

14 hours ago, kgg said:

@friquant which layout did you get?? The one with the long cables or the one with the on/off switch mounted to the front of the table???

 

Mine has a 30 inch cable from the hall sensor to the control box. I mounted the gas pedal  and the hall sensor today, but waiting to see where the best location is for the control box after I get the rest of the table set up.

[kgg]

8 hours ago, friquant said:

but waiting to see where the best location is for the control box after I get the rest of the table set up.

Typical setup is on the right front corner area.

kgg