Are Matched belts still a thing? What to get?

[Mark Gottesman]

I am getting down to the last few items on a TS restore. It uses a two belt pulley(2.25" diam) with 3/8" x 43" belts driven at 3450 by a 1HP motor. Since the TS is probably close to 70 years old are matched belts still a thing. This is my first multiple belt rig. Last one used a single and I put a Link belt on that, but they are to wide for this pulley. The belts it came with are "Gates7740 Extra Service K123 H"

I've done a bit of reading and opinion is all over the place. Some say absolutely needed others say just go to the auto parts store. Others say change over to a automotive ridged belt ala a serpentine belt. That is probably going to cost more that I want with 2 new pulleys and belt.

I look forward to your thoughts on the matter.

 

[scsmith42]

Mark, modern belts are manufactured so precise that matched belts have almost become a thing of the past. If it were me, I would simply buy a pair of automotive belts that were of similar age / packaging, etc.

 

[Willemjm]

I purchase over the phone at VBeltsupply.com and they don't make matched sets any longer, but they do make sure that the belts come from the same batch, roll, production run when I ask them before committing to the order.

 

[allisnut]

I'll throw in the opposite opinion - I work in a textile factory, and anywhere I can I buy bonded back belts. They are simply single belts that are sold in two, three, four, or whatever multiple you want before they are sliced apart into individuals. For example, I have machines that run 4 individual small belts. I started buying 4 bonded together because it eliminates the 'flop' if one belt is incrmentally longer than another. I order some through a local carquest. Motion industries and bearings and Drives are two other vendors with regional offices all over the place.

 

[Mark Gottesman]

OK, just to mix it up some more, what about this idea. I have been running the same motor on a contractor tablesaw with a 1/2" link belt running on machined pulleys. Would there be any downside on running that setup vs. the two belt pulley with 3/8" belts? Is one setup "better" at power transmission?

 

[scsmith42]

I'll throw in the opposite opinion - I work in a textile factory, and anywhere I can I buy bonded back belts. They are simply single belts that are sold in two, three, four, or whatever multiple you want before they are sliced apart into individuals. For example, I have machines that run 4 individual small belts. I started buying 4 bonded together because it eliminates the 'flop' if one belt is incrmentally longer than another. I order some through a local carquest. Motion industries and bearings and Drives are two other vendors with regional offices all over the place.

Adam, I have not been able to find bonded back belts in dimensions short enough for my woodworking machinery. The last time that I checked my supplier they were only available in longer lengths for industrial equipment, and this is greater than what my tablesaw and shop equipment requires. II tried to purchase some for my slabber. Can you check with your supplier to find out what the shortest lengths / belt widths are that they have available?

Mark - Adam is absolutely correct that the Bonded back belts eliminate the flop between the belts and they are the *best* option if they are available in your size / length. If not, then Willem's source may be best.

 

[allisnut]

The shorter ones we buy are metric, I'll get a size off of one for you and find out where we get them.

 

[mkepke]

OK, just to mix it up some more, what about this idea. I have been running the same motor on a contractor tablesaw with a 1/2" link belt running on machined pulleys. Would there be any downside on running that setup vs. the two belt pulley with 3/8" belts? Is one setup "better" at power transmission?

Not inherently.

Your current 2-belt set up is primarily limited by the small diameter of the pulleys, then the cross section of each belt (narrow). Your current saw compensates by usiny two belts.

Your link belt is probably a fractional horse power design (but could be something else), but since it is wider, it is inherently capable of higher xmission than a *single* one of the 3/8 belts.

But the key is the size of the 1/2" pulleys. Provided they have a pitch diameter of, say, 3.25" or larger, then the single link belt can xmit more power than the two 3/8 belts together. Which is a moot point, since either set up can xmit the 1hp of the motor.

It works the other way too..if you have 1/2 inch pulleys less than about 3" dia, then that set up will be less capable than the 2 belts set up, in scale with the diminishing size of the pulleys.

-Mark

 

[Mark Gottesman]

I will have to stay with the 2.5" pulley if I want to get a full depth of cut from the saw. So, I think I'm going to take a trip to K'ville and see what Motion Industries has to offer. Will inquire about the "bonded Back" belts, but I am guessing that I will endup with two separate belts.

Thanks for the education.

 

[mkepke]

I will have to stay with the 2.5" pulley if I want to get a full depth of cut from the saw. So, I think I'm going to take a trip to K'ville and see what Motion Industries has to offer. Will inquire about the "bonded Back" belts, but I am guessing that I will endup with two separate belts.

Thanks for the education.

Yes, I was guessing that the manufacturer used a two-belt set up BECAUSE the saw's design required small diameter pulleys.

How are the belts tensioned ? If by gravity, like most Contractor's saws, I would just buy two identical belts from the same rack in a local store - ideally belts with matching lot-numbers - and assume gravity will eventually make them the same length.

I wouldn't over-think it.

-Mark

 

[KenOfCary]

I try to match my belts to my shoes. Sorry, couldn't resist. But I digress, interesting discussion.

I would think it does matter more for an industrial machine running 8x5 or 24x7 than it would for a TS with limited run time.

 

[Mark Gottesman]

Yep, I'm overthinking it. Saw is 60 years old and belt tech is a lot different re: tolerances. Belts are tensioned by motor weight. I'm just going to get it up and running with the Gates belts that came with it and get new ones if I see any problems. 2 x 3/8" link belts would be pricey so that probably won't happen.

Right now I'm wondering if going up a bit on the motor pulley size to get a slight faster SFPM is worth the effort. Right now it is at 9,032 SFPM and Iv'e seen a rule of thumb that 10,000 is a good working speed. Not sure if the slight increase brings anything to the table for light use. A lot of the blades I have state a max RPM of 7000, so a small increase would not be a hazard..