$16.41 2.7:1 speed reducer

[DonInReno]

In the past I’ve suggested making an inexpensive speed reducer from the output bearing housing and shaft of a clutch motor, but had never tried it myself.  To see how inexpensively it could be done I ordered a few pulleys and stripped the shaft and out of a mid-70s clutch motor.  

The sewing machine pulleys were ordered from a Chinese company on EBay and were only $16.41 shipping included.    One is a 45mm and the larger is a 120mm with 15mm bores that happens to fit perfectly in place of the clutch disk. There are probably larger sewing machine pulleys for the big one, but that’s the max from this seller.  I’ll hacksaw off a bit of the hub on each pulley so they can be stacked together and still be held on with the nut.   The old output shaft stub isn’t used so I’ll hacksaw off that end to tidy it up. 

The 42mm (about 1-5/8”) round bearing housing will need to be epoxied into a hole in a piece of hardwood and bolted to a table in a way that allows it to be adjustable.  Hopefully I’ll have time to finish it sometime this week and give it a test drive  :-)

Edited January 17, 2021 by DonInReno

[dikman]

Always nice to see someone re-purposing old gear. When I've used those pulleys I had to drill and tap them for setscrews to tighten against the shaft. I also noticed that 120mm appears to be the largest most of those sellers have, once you start looking for bigger ones they're harder to find - and considerably dearer!

[DonInReno]

On 1/17/2021 at 5:30 PM, dikman said:

Always nice to see someone re-purposing old gear. When I've used those pulleys I had to drill and tap them for setscrews to tighten against the shaft. I also noticed that 120mm appears to be the largest most of those sellers have, once you start looking for bigger ones they're harder to find - and considerably dearer!

Access to speed reducers are such a common issue with those new to industrial sewing it’s been fun to figure some low cost ways to cobble one together.

A while back I picked up a couple of cheap pillow block bearings, a short section of rod and two cheap steel pulleys, and that reducer was over $40.   I figured there must be a cheaper way.

Edited January 19, 2021 by DonInReno

[Gregg From Keystone Sewing]

On 1/18/2021 at 9:56 PM, DonInReno said:

Access to speed reducers are such a common issue with those new to industrial sewing it’s been fun to figure some low cost ways to cobble one together.

This is the fun part, where we get to be creative. 

[DonInReno]

I finally found time to trim the hubs on those two pulleys.  For $15 this spindle/motor mount is available in all sorts of metric sizes and it looks more professional, but a block of wood would hold the bearing housing just as well.   At first I was going to simply add a hinge on one side and an adjustment bolt on the other to this block of wood and use that to adjust belt tension, but now I’m thinking a 2” wide hinged aluminum strap would look better. 

If it looks small, it’s because it is - visually it’s dwarfed by a traditional 3:1 reducer. 

All together I’ll have about $40 in it, but it looks great and the small size will make it much easier to fit under a table without moving the motor too far - I’m hoping to add a 4” wood spacer under the motor and move it about an inch to the right.

[councilman24]

A link for the spindle motor mount?  Not sure if I can find that.

Thanks.

[Constabulary]

Aren´t these linear bearing blocks? I´m not sure but don´t they have a "plastic sleeve" the balls are embedded in? So I´m not sure if they withstand the "pulling force" of the V-Belts on long term use... Don´t know for sure...

Edited March 2, 2021 by Constabulary

[DonInReno]

6 hours ago, councilman24 said:

A link for the spindle motor mount?  Not sure if I can find that.

Thanks.

https://www.ebay.com/itm/20-80mm-52mm-65mm-Diameter-Spindle-Motor-Mount-Bracket-Clamp-with-Screws-For-CNC/363048049399?ssPageName=STRK%3AMEBIDX%3AIT&var=632174603941&_trksid=p2057872.m2749.l2648
 

I’d definitely buy from them again.

When the order was placed the estimated shipping time from China was 5 weeks, but it arrived in 19 days.   This is similar to other small parts I’ve ordered from a Chinese address, but some have arrived within a week and two items have taken two months.

Edited March 2, 2021 by DonInReno

[DonInReno]

5 hours ago, Constabulary said:

Aren´t these linear bearing blocks? I´m not sure but don´t they have a "plastic sleeve" the balls are embedded in? So I´m not sure if they withstand the "pulling force" of the V-Belts on long term use... Don´t know for sure...

It looks similar to bearing blocks, but it’s just bare aluminum - very strong clamping force.

[Constabulary]

aaaaaah - that makes sense. I thought you did away with the old bushing and use a linear bearing block 

Edited March 2, 2021 by Constabulary

[DonInReno]

I don’t know why I find it so interesting to order parts from multiple suppliers just to see the variation in what is being sold, but I do!  I usually encourage people to buy twice as many as they need since odds are something won’t be quite right.  

The two “40mm” servo drive pulleys showed up.   Both are advertised as 40mm - a little smaller than I’ve seen advertised before. 

One measures 42.5mm - they wouldn’t be the first to round down or up to make the product sell better.  The other is nothing more than a 45mm pulley being sold as a 40mm.   It’s not even 44mm - measures a full 45mm.

These are clearly not made in the same plant.  The mold marks and design of the part are slightly different.   The aluminum alloy is different and the darker of the two has a much better finish and fewer little voids from how the metal flowed into the mold.  

The one that appears nicer also has an entire extra operation performed to the bore - a reamer has taken down about 25% of the surface to exactly .591” (15mm).   If someone was designing an injection molded part to not be reamed at all they’re cast it slightly larger - out of curiosity a quick check with gauge pins showed exactly that.   The one that cut corners in not only material quality, but bore size was 001” oversized and was $3 more expensive.

Once again I’d suggest that not all Chinese sewing machine pulleys (or machines, or anything else) are made in the same plant just because they look similar!  Lol

 

[dikman]

Keep up the good work, Don, you're finding out all sorts of things and saving us the trouble.