Belt specs vary

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StevenAyres
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Belt specs vary

Post by StevenAyres »

I'm relatively confident that someone on this forum has posted something like this before, but for the benefit of newbies like me: It matters where you buy your belts. Sources clearly have different ideas on the belt specs, particularly the V-belt.

Here's a comparison of two V-belts I bought via Ebay. The first I got was a no-name from Bandsaw Tire Warehouse, the second a Pirelli from a private seller with relatively low feedback. Both specified that the belts were specifically for the Smith. The BST belt came in 5/64 wider. It was a struggle to even get it on the sheaves, and it just felt wrong. I'm sending it back.
Belt compare.jpg
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JPG
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Re: Belt specs vary

Post by JPG »

StevenAyres wrote:I'm relatively confident that someone on this forum has posted something like this before, but for the benefit of newbies like me: It matters where you buy your belts. Sources clearly have different ideas on the belt specs, particularly the V-belt.

Here's a comparison of two V-belts I bought via Ebay. The first I got was a no-name from Bandsaw Tire Warehouse, the second a Pirelli from a private seller with relatively low feedback. Both specified that the belts were specifically for the Smith. The BST belt came in 5/64 wider. It was a struggle to even get it on the sheaves, and it just felt wrong. I'm sending it back.

Belt compare.jpg
Do NOT do that!

16 x 67.5 is VERY close to original SS design which was about 1 9/16 x 26.5. Indeed it is closer to anything else out there.

Be aware that most belt manufacturers design to metric dimensions. In addition they seen to think slightly narrower is "ok".

The belt width has a direct effect on the resultant speeds attained with the SS reeves drive.

It has been observed in the past that recent SS Inc belts are slightly narrower.
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StevenAyres
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Re: Belt specs vary

Post by StevenAyres »

JPG wrote:16 x 67.5 is VERY close to original SS design which was about 1 9/16 x 26.5. Indeed it is closer to anything else out there.
...
It has been observed in the past that recent SS Inc belts are slightly narrower.
I'm perfectly willing to accept that the spec numbers match. But in practice I can't get it installed, where the new Pirelli went on just fine and works as it should as far as I can tell.

I admit it's been a very long time since I changed a belt, so I tried the wide belt again this morning on the other headstock. I can get the belt on both sheaves, but so far I can't get the upper closed far enough to install the speed control.

I hate to rehash a topic that's probably long on this forum somewhere, but am I doing or understanding something wrong?

How much do you mean by "slightly," above? Is my Pirelli belt too narrow to make the right speed range?
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Re: Belt specs vary

Post by JPG »

You need to install the clip over the porkchop arm FIRST.(belt over idler pulley, but NOT tensioned to the motor pulley) with the speed control set to fast.

Then position the belt over the idler pulley and set the speed control to slow(ok to adjust with the belts NOT tensioned.) That will allow the belt to fall down into the idler pulley(small diameter thus providing more belt for the next step.

Manually pull the motor pulley open. (do NOT let the floating sheave slip and bang into the fan sheave).

While holding the motor pulley open, slip the belt into the motor pulley from one side. It will not go all the way on, but manually rotating the motor pulley will walk it on.

The belt starting onto the motor pulley will prevent the floating sheave from slamming into the floating sheave.

Doing it some other way can get frustrating. ;)
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Re: Belt specs vary

Post by JPG »

Not knowing the actual dimensions of the pirelli belt, I cannot say. Do realize that the reason for letters rather than speed calibration on the speed indicator dial is because there are so many things varying including the belt width being one of those things.

I dare say +- 20% would not be unusual especially with worn belts.

FWIW a narrow belt shifts the speed range upward whereas wider belts shift the speed range downward.

I really think you are better off with the BTW belt. As it wears the speed attained for a given setting will increase slightly and will be closer to 'nominal'. :cool:

P.S. all other things being equal, the BTW belt will ride higher in the motor pulley perhaps even slightly beyond the OD.

With narrow belts, the high speed limit setting becomes more critical, with wider belts less so.

High speed limit adjustment is not typically needed nor something to fret over. :)
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
StevenAyres
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Re: Belt specs vary

Post by StevenAyres »

JPG wrote: You need to install the clip over the porkchop arm FIRST ....
I'm pretty confident I'm doing what you describe, the standard procedure in the manual. I can get the belt onto both shafts, but only with both sheaves wide open, the motor sheave up against its spring limit and the idler sheave open beyond the range of the speed control. (Note: I'm doing this on the Mark VII, but my experience was the same on the 5, just with a couple more gears in the mix.) I can't see how to make this work.

Could the belt be the right width, but too short?
JPG wrote: Not knowing the actual dimensions of the Pirelli belt, I cannot say.
The Pirelli belt is 48mm (31/64"), same as the one running on my low-mileage VII.
JPG wrote: High speed limit adjustment is not typically needed ...
I notice there's a simpler provision for that on the VII, fwiw.
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Re: Belt specs vary

Post by JPG »

OK It ain't gonna work on a MVII. :( The belts are not the same length!!! The shaft spacing is different. You need a belt 4" longer IIRC.

Yes the HS stop is far simpler.

Yes I also have tried to put a M5 belt on a MVII before I recognized the shaft spacing differed.
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E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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Re: Belt specs vary

Post by JPG »

JPG wrote:OK It ain't gonna work on a MVII. :( The belts are not the same length!!! The shaft spacing is different. You need a belt 4" longer IIRC.

Yes the HS stop is far simpler.

Yes I also have tried to put a M5 belt on a MVII before I recognized the shaft spacing differed.
Case in point!!!! https://www.shopsmith.com/ss_forum/view ... 29#p159029
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
StevenAyres
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Re: Belt specs vary

Post by StevenAyres »

OK, bad test, doh!

I put the VII back together with the old belt (a nominal 51mm that's now about 49), and it's running at close to rpm spec.

Then I tried the BSW belt again on the brownie. I imagine that thanks to a couple days' practice plus the assurance that the much wider belt is correct, the procedure was less a struggle and it seems to have gone together OK. The head is running at around 400rpm at the low end. Yay!

Thanks very much for your patience and support!

Now: Can anyone tell me why "recent SS Inc belts are slightly narrower"? Is it due to differences between the older and current products?
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Re: Belt specs vary

Post by JPG »

StevenAyres wrote:OK, bad test, doh!

I put the VII back together with the old belt (a nominal 51mm that's now about 49), and it's running at close to rpm spec.

Then I tried the BSW belt again on the brownie. I imagine that thanks to a couple days' practice plus the assurance that the much wider belt is correct, the procedure was less a struggle and it seems to have gone together OK. The head is running at around 400rpm at the low end. Yay!

Thanks very much for your patience and support!

Now: Can anyone tell me why "recent SS Inc belts are slightly narrower"? Is it due to differences between the older and current products?
Not quite that 'simple'.

For starters belt manufacturers seen to have gone metric and substitute metric belts for near imperial measurements.

Secondly until very recently belts in 1/2" length increments all but disappeared.

Also SS does not have the engineers that did the original design and have made poor procurement decisions in the past(I believe they did learn from that). Recent belts from SS seem to be correct(slightly wider than 1/2").

FWIW, BTW is not the only one touting the metric belt(15x675 = .590x26.57).
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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