Questions re: DIY box style speed reducer

[shelr1]

fibersport sorry I just now saw your question.

I got most of my parts on Amazon

When I was researching I determined that shaft size is the key decision, mainly due to availability of pulleys with the correct diameter and bore size, and bore size of the pillow block bearings. I used 1/2 Inch shaft size. 15mm and 5/8" are other common choices.

6" Dia. Pulley Congress 1/2" bore

1.75" Dia. Pulley Terre Products 1/2" bore

1/2" bore Jeremey pillow block bearings

I sourced the shaft locally. 

The belts are size 3L,  3/8"wide, they are listed for automotive applications and work perfectly for sewing machines. There are lots of lengths available on Amazon. I needed a 46" and a 24".

I built the support frame from stuff I had laying around my shop.

Note: 3L belts will work on a 4L pulley, it will change your ratio slightly as it sits slightly lower in the pulley.

If I recall correctly I have about a 3.5 to 1 reduction.

[fibersport]

No problem.  I ordered my parts from ebay, they're coming in on a slow boat from China as they say so I'll have to be patient.

One other question:  is your reducer mounted on a hinge or something?  It looks like there is a pivot towards the outside of your frame.

Edited July 18, 2023 by fibersport

[shelr1]

fibersport, I used a bunch of stuff I had on hand to make the frame. I was trying to make it adjustable for belt tension, I found brackets for the ends that act like a hinge, but when I got the belts on simply moving the entire assembly up and down worked fine, and I fine tuned the short belt with the motor adjustment.  In retrospect it didn't need to pivot but it worked well.

The picture shows one of the end brackets, it attaches to the end of the table legs vertically. I'm not sure what the bracket was intended for maybe a garage door roller bracket.

[fibersport]

I really like your design, it has given me some great ideas for making mine.  I'll be sure to post some pictures when I get it done.  Thank you (and everyone else on this thread) for your inspiration!

[fibersport]

Here are a couple of pictures of my version of a speed reducer using information from this thread - thanks to all!  Pulley sizes are 120 and 40 mm with a 15 mm bore.  I welded up a U shaped frame out of 1-1/4" angle.  The frame pivots on the leg of my table and is tucked in so it's out of the way.  A spring keeps tension on the belts.  The motor mount is used to fine tune the belt tension on the belt between the motor and large pulley on the reducer.  Belt selection is kind of critical, I used a belt length calculator to pick my belts which worked well.  I would like to slow it down a little further as the lowest speed of my servo motor is a little too fast for my liking although I need to do some sewing to see if I can adapt to the slowest speed.  My options are a larger diameter large pulley, a larger balance pulley on the machine or a servo motor controller that has a lower intial speed.  Overall I'm very satisfied with it and really like the simple design.  I ran it without the spring and it worked OK until I tried to sew 4 layers of vinyl which cases the small pulley on the speed reducer to slip.   Adding the spring worked great, it actually rises up a bit on startup but there is no slippage on multiple layers of vinyl.  I don't have much tension on the spring, if it did start to slip all I would do is pull it down a little more.  I do need to cut the shaft down and paint the frame but until I spend a little more time with it I'll call it almost done!

 

Edited August 10, 2023 by fibersport
add pictures delete multiple post

[AlZilla]

@fibersport, I'm not seeing any pictures ...

[fibersport]

It wouldn't let me upload them even after resizing, trying it again.

Doesn't seem to be working, I see them after I pick them and watched as they were uploaded, they are both around 500 kB so well under the 1.46 MB limit.  Anyone have any suggestions?

Edited August 10, 2023 by fibersport
more information

[Wizcrafts]

4 hours ago, fibersport said:

It wouldn't let me upload them even after resizing, trying it again.

Doesn't seem to be working, I see them after I pick them and watched as they were uploaded, they are both around 500 kB so well under the 1.46 MB limit.  Anyone have any suggestions?

Disable any ad or script blockers you have running.

If you are using a computer to manage the forum, but the photos are on your phone, and the phone is plugged into a USB port to open its files, download the photos to a folder on your computer, then upload them to the forum. I often run into this problem when I try to upload photos that are still on the phone, while using my computer. If you are going directly from the phone to the forum, and the filesizes are under the limits, try sending just one photo. If successful, add another after the first one appears in your post. You should have enough time to edit the post several times.

[fibersport]

They were on my phone but I sent them to my computer via email and then resized them to around 500 kB and then saved that file to the computer - phone font size is way too small for these older eyes!  

I am uploading them again but have moved them to the C drive on the computer rather than my Microsoft365 drive, maybe that's the problem.  It was not, I clicked on "insert other media" and they appeared.  Must have been user error ....

Edited August 10, 2023 by fibersport

[AlZilla]

I appreciate you making the effort. Straightforward design. I can see where getting the belts just right might be ticklish but tensions are pretty forgiving on these things.

Looks like the axle shaft just floats? The belts should keep it from walking sideways.

Very nice.

[dikman]

Very nice job! Simple and effective.

[fibersport]

Thanks for the compliments.  Belt tension does take a little effort but not too much, I found setting the longer belt first since the only tension is set by the spring.  The smaller belt is then adjusted using the motor adjustment as if there were only one belt.  The bearings have two set screws each which prevents the shaft from going side to side.  I had to drill and tap the pulleys for a set screw which I used a regualr screw for now along with small flat spots filed into the shaft and also a little Loctite retention compound.  It is simple and might not hold up to 8 hours a day use but I think it will suit my needs just fine.  All total I think I paid about $57.  I had the angle iron laying around, I could have saved a few bucks had I used a shorter shaft but I wasn't sure how my final design was going to need.  

[Burkhardt]

Looks simple and cleanly done, if only everything turned out like that.

[fibersport]

Well even this had its issues, had to redrill the holes in the leg to get them straight using my drill press instead of my hand drill which even after measuring still didn't drill the holes lined up!  Even the simple things throw you curve balls -

[Kfd518]

@shelr1, that is a national hardware #500-30000 garage door step plate. They unfortunately are out of production now. I’m working on a similar setup but went with a much larger large pulley @10” HA HA by my math I should be able to run 1 stitch every 2 seconds if I so choose. 

[Jonnyh]

On 5/11/2023 at 9:27 AM, AlZilla said:

I don't have a design for you but I do have a caution. I've been working to reduce a 111w153 by putting a bigger hand wheel on it.

One thing I've learned is that hardware store pulleys aren't really very well balanced.

I'm probably just going to end up with a servo. I could probably balance those pulleys well enough by using the same process we used decades ago to "balance" motorcycle tires.  But it's reached the point of more work than I care to put into it.

I know exactly what you mean and that was my first concern with putting a bigger hand wheel on my leather sewing machine, believe it or not I had luck with taking a pulley off of a gas-powered air compressor. It's a little over 10 in in diameter and also balanced and it's nice and heavy duty cast iron, just look around for the old compressor pumps with the good size flywheel on them and they are most likely balanced.