Is there a better way of mounting this 'speed reducer'?

[Fishyboy]

Hi all,
I am currently re-upholstering my 1950's Jensen. I have an industrial sewing machine (Image 1) and would like to slow the machine down to make some complicated sewing easier. I have made a speed reducer (a 45mm and 120mm pulley mounted on a pair of pillow block bearings) to sit between the motor (below the table - Image 2) and the sewing machine. There will be one belt from the motor to the speed reducer and a second one from the reducer to the machine (Image 3). I can only adjust the motor position (on its pivot) to tension the first belt I need to be able to adjust the lateral position of the speed reducer to adjust the tension of the second belt (from the reducer to the sewing machine).

Apart from drilling several different sets of 4 holes to mount the reducer bearing blocks is there a simple way of constructing something that will allow me to move and lock down the reducer in different positions to get the correct belt tension.

Thanks in advance.

Phil

 

[BrokenBiker]

think of a timing belt tensioner...a spring loaded arm, probably with an ilder on it, pressing on the belt between the pulleys...would be my go to with the limited space you have available

or buy a cheap VFD off ebay

 

[keithski122]

Another way to make it easier to control things is if you extend the arm on the pedal as much as you can and also extend the arm on the motor controller, you can only go so far before it hits the support between the table legs.I added some ali angle on mine.This should give more foot movement for the same motor action.
You might also be able to adjust the top speed of the motor down so the sweep of the pedal gives you a smaller range of speed for the same pedal movement.You should be able to one stitch at a time with just a tap on the pedal even without the speed reducer.
I did this with no alterations to my machine apart from those above.

 

[Fishyboy]

hi Keith

Thanks for the reply.

Impressive work.

I'll try extending the 'pitman arm' as mush as possible and the motor arm is already on its longest setting.

I can get the machine to do one stitch at a time with the needle position switched off without a problem. With the needle position sensor on and switched to 'down' every 5th, 6th single stitch is two stitches. When I've finished my car I want to make some wallets and feel that I need to have to needle positioner working, but also don't want a double switch just when I want to put just one stitch in. This was the main reason trying to slow the machine right down. This is where I got the idea of the pulley reducer from -

.
Phil

 

[keithski122]

I've heard that using speed reducers can cause issues with the needle positioner not working correctly. Sounds like something is wrong if its doing more than a single stitch with the needle positioner, mine will do a single stitch finishing in the down position then a dab of my heel will lift the needle up.I have also seen somewhere where someone made a rotary control so they could slowly move the needle using a finger to turn the knob.Where I work we have a different machine that stops with the needle up, I just give it a turn on the handwheel to get it where I need it.Another tip is as you move the needle down with the handwheel you can move the reverse lever to adjust where the needle hits the material so you can get it spot on where you need it.
A couple of pictures I've found on how I've extended the arms.

 

[frank horton]

I need a new suit.....lol....
oh so nice stitching.....

 

[jmp49]

My mrs has a industrial clone of a juki machine, but a cylinder machine rather than a regular that I made a flat table for so it can do both.
That like most of the juki clones from the far east arrive with a dc motor and a speed controller that you plug the needle position sensor into etc that looks a LOT like your on/off control box just with a speed display that can be altered. It goes down to crawl speeds & she uses it for her hobby of bag making and the odd bit of upholstery work for me when I can persuade her so its more than capable of stitching through multiple layers of leather etc even at slow speeds.

The speed controller for the clone and motor setups are on ali express etc, you might find you can just swap some component to give you wider ranged peed control range without any messing with idlers etc.