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Forum topic by dyermaker8 posted 08-24-2010 11:08 PM 4019 views 0 times favorited 5 replies Add to Favorites Watch
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dyermaker8

5 posts in 2432 days


08-24-2010 11:08 PM

Hey guys,

I’m rebuilding an atlas 3021 8” table saw. It came with a non-oem motor attached and i’m thinking the pulley might not be correct. Does anybody have a clue as to what the original motor pulley size might have been. I’ve looked at all the available docs on OWWM but they don’t reveal the size.

Thanks,
Dan


5 replies so far

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dyermaker8

5 posts in 2432 days


#1 posted 08-24-2010 11:34 PM

on second thought I may be able to answer my own question,. somebody correct me if i’m wrong.
The saw still has the original double v-belt arbor pulley. The original motor was of the 3450 rpm varity and the motor currently installed is 1725 RPM. I’m of the impression the current motor pulley should be double the size of the original to maintain proper rpm at the blade.

Which brings me to the new question,. should the original motor’s(3450 rpm) pulley have been the same size as the arbor pulley,.aka a 1:1 ratio?

thanks,
Dan

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EEngineer

1061 posts in 3081 days


#2 posted 08-25-2010 01:08 AM

You can find the manuals for your saw on OWWM. But they won’t do much good. Nowhere do they mention saw blade speed.

The last time I dealt with this was with my old Craftsman 8” table saw. The manual for it (103.22161 if you want to check for yourself – manual at owwm) listed blade speed as 4500 RPM. I had a 1750 RPM motor and the arbor had a 2 1/2” pulley. So i used a 6” pulley on the motor giving me (6 / 2.5) * 1750 = 4200 RPM. Used it for years like that. My brother is still using it like that.

-- "Find out what you cannot do and then go do it!"

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dyermaker8

5 posts in 2432 days


#3 posted 08-25-2010 01:36 AM

Ah,. good,. so my equation was right. If the pulleys are the same size the motor speed is roughly the same as the blade speed. Does 3450 sound like it would be about the ideal blade speed for a machine like this? Using a bigger pulley to get higher RPM would translate to a loss in torque wouldn’t it?

Thanks for the assistance! , much appreciated!
Dan

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EEngineer

1061 posts in 3081 days


#4 posted 08-25-2010 06:51 AM

Most of the blades I have are marked something like 7000 max RPM. If I hadn’t found the rated RPM in my Sears manual for the saw, I might still be looking for some indication of what the right speed is. My 10 inch saw, by the way, seems to run 1:1 on the pulleys with a 3450 motor.

Using a bigger pulley to get higher RPM would translate to a loss in torque wouldn’t it?

Hmmm, lemme think about that a minute… from Physics, power = torque X rotational speed. Can’t create power, so with no belt slippage, motor HP = blade HP so , yeah, I gotta assume that as blade speed goes up, torque goes down. However, doesn’t there have to be some minimum speed that the blade runs at to cut effectively? No idea what that would be, just the note from my old Sears manual. You might want to err on the low RPM side.

-- "Find out what you cannot do and then go do it!"

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RCT

89 posts in 3219 days


#5 posted 07-06-2012 12:58 AM

I know this is late but for others hear it is

-- "Ya but what does he know anyhow?"

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