Belt Help

[Ole South]

I just picked up a lightly used, early 70's Consew model 28 (Seiko Oem). Sews great. Seems to have the original Code 12 stand and all the paperwork. It's got a clutch with a 1/3 hp Westinghouse motor but no belt tension mechanism.

Here is the problem... the belt. 5/16" (8mm) top, 1/4"(~6-7mm) thick 46" long for the stock pulleys. I've made a smaller pulley (1 3/4 OD,1/2" bore) to reduce top speed but can't find a drive belt long enough. The one that came with it is stapled like a treadle belt; I'm guessing for obvious reasons..., no other way to tension. I've fabricated a temporary belt from paracord and clear 5/16ths vinyl tubing to test. Probably don't really need the paracord core as the vinyl doesn't seem to stretch excessively but I'll need a more permanent solution.

Any ideas where I can get a replacement belt? With the new pulley I'm looking at ~42" length. Does the Singer 78 use a similar belt?

As an aside: this machine has been stored for at least 15-20 years. While sewing it's really hard to feather the clutch to maintain a steady 20spm without holding the hand wheel. Do I need to disassemble and clean the clutch plate or just practice more? If I install a servo motor then I'm still going to have a belt issue as a standard belt (M-4x) rides extremely high in the handwheel and I'm assuming most modern servo's are going to have 3/8" or 1/2" wide pulleys with a 3/4" bore.

Thanks.

[Wizcrafts]

I don't know your setup, but the standard pulley and belt combination for industrial sewing machines and motors is 3/8 inch; Type 3L. 3L belts are available from every industrial sewing machine dealer in the World. In the USA they come marked in inch designations. In Canada and non-SAE countries, they are marked in metric notation.

Type 3L v-belts can be purchased in one inch increments, from the low 30s through the high 60s and beyond. I have a peg full of them in my shop, ranging from 38" through 59". If your previous 46" belt was too long after installing a smaller motor pulley, order a 44" 3L v-belt. Or, remove the C-clip from one side of your existing round belt, cut off the necessary amount to get a tight fit, punch a 1/16" hole about 1/4" in from the new end, push the open end of the clip through the hole and use your pliers to squeeze it down.

[SARK9]

When you look for v-belts on a website or catalog, you will see them listed as a "3L-390" or 3L-395". The -390 is a 39" belt, the -395 is a 39-1/2" belt. Be sure to get the best quality available for smooth, vibration free running. The guys on this site that have sewing supply shops probably have known good brands.

-DC

[Ole South]

Thanks for the quick reply Wiz. I picked up spare 46" from a local shop (Marked China EW V-Belt M-46). It fits fine in the new clutch pulley I bought from them but that pulley is 3/4" bore. I was impatient so I turned a smaller clutch pulley out of Maple yesterday. I don't want to shorten the working belt (I already took ~1/2" out to take up stretch) in case I needed to go back to the 3 1/2 OD Consew pulley.

3L belts must be 30deg chamfer like the old belt? The M-46 is definately 40deg and rides halfway up out of the pulleys, it would probably work but...

Do replacement servo-motors come fitted with a pulley?

[SARK9]

Specs for the 3L pulley:

Effective Outside Diameter in inches:

Under 2.2-- 32deg. width at full dia .360

2.2-3.19-- 34 deg. """"""""""""""""" .364

3.2-4.2-- 36 deg. """"""""""""""""" .368

over 4.2--38 deg. """"""""""""""""" .372

Depth of groove .406

-DC

[Wizcrafts]

Replacement servo and clutch motors all normally ship with type 3L pulleys. The Family Sew motors I got from Toledo Industrial Sewing Machines were fitted with 50mm (2") 3L pulleys. The shaft ID is about 1/2 inch, I think. Clutch motors usually have 3/4" shafts. But the pulleys I have are all for 3L v-belts.

[Ole South]

Thanks Sark & Wiz, exactly the info I was lacking.

I do short /intricate/stop-start runs (bags/purses etc...) do you think a servo will provide enough low end torque through 4-6oz leather? (chrome/veg).

I've used sewing machines all my life but sewing leather brings a whole new dimension to the craft.

[Colt W Knight]

You can order just about any shape/size belt you want from McMaster-Carr

http://www.mcmaster.com/#v-belts/=w0xi4i

Input your dimensions on the screen to the left, and it will tell you what type of belts are available. If you are not sure which type to choose, you can read the descriptions to see which brand/type fit your needs.

Looks about like an 8$ belt for your needs.

Edited February 22, 2015 by Colt W Knight

[Ole South]

Yeah, McM was my first look; unfortunately I was looking for a 5/16 top x 1/4 thick. Those only come in max 20-22" lengths it seems.

[Wizcrafts]

Yeah, McM was my first look; unfortunately I was looking for a 5/16 top x 1/4 thick. Those only come in max 20-22" lengths it seems.

Type 3L belts are 3/8 across the top, hence 3L designation. They are sold by industrial sewing machine dealers. You are unlikely to find them at auto parts stores that usually stock 4L (1/2 inch) belts for car pulleys.

But, I just remembered that you made your own motor pulley. Measure the motor shaft and order a 2" replacement with the correct inside diameter from an industrial sewing machine dealer, along with the new, shorter (3L) belt.