shelr1

Nice job, I enjoy seeing the variety of designs for speed reducers.

Redbeeerd, You may already know this, Handstitched mentioned Seiko machines. There are many Japanese machines (and Chinese clones) that are essentially copies of Singer models, in some cases the parts may even interchange. Many of us look for older used machines that are available at reasonable prices, since price is often the limiting factor for enthusiasts.

I purchased a 6" OD 1/2" bore pulley from Amazon, 22.20 including tax.

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 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.

I got the belts installed, happy with the way it turned out.

I have spent a little over $50.00 so far, add to that new belts about $9.00. I appreciate the servo motor option, I also really like the challenge of designing and implementing a mechanical reduction.

RockyAussie, the belt will clear , it is a little hard to tell from that angle. Thanks for the input.

kgg, 1. it is a Pfaff 545, I recently purchased it. The clutch motor had a small pulley installed by the previous owner, so there was some speed reduction already. 2. Shaft dia. is 1/2", large pulley is 6" O.D. the small pulley is 1 3/4" O.D. These are rated for either 4l or 3l belts, I think I am close to a 4:1 reduction using a 3L belt.

I'm making progress. This is pretty close to kgg's design.

kgg, thank you for the info. Yes it is the vertical tension between the hand wheel pulley and the small pulley I was asking about. I do like your idea of the cantilever arrangement for the shaft/pulley. I am putting this on a flat bed machine, just need see how that fits my machine. I do like the easy access to the belts on your design. Garyak, I appreciate your design idea, it reminds me of a belt tensioner on a car, and pretty easy to adjust.

The 2 pulleys I am using for this speed reducer are straight bore, common bore sizes are 1/2" or 5/8" or 15mm depending on the shaft that is selected. They can be keyed or set screw but typically a taper bore is not used in this application. If using a quality shaft and pulley the fit is not a problem as far as run out or balance is concerned.

I would like to build a DIY "box style " speed reducer. I understand the concept pretty well, I am thinking of a 3:1 reduction using a 6: OD and 2" OD pulley. My first question is, if you use 2 fixed pillow block bearings to support the shaft, how do you allow for adjusting the belt tension between the reducer and the sewing machine? I thought of use a 2 bolt flanged bearing and making one of the mounting holes slotted, would need to have same setup on both bearings does that seem like it would work? Also, I see a lot of 6" pulleys rated for 4L belts and I want to use 3L, can a 3L belt work well with the larger 4L pulley? I have seen some pulleys rated for 3L and 4L that's what I'm hoping to do.