Kuhn315

Table saw motors/safety concern

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I have an old 8" craftsman table saw that I bought awhile ago for $30 on craigslist. I eventually got around to building a 4'x8' table around this small 22" x 22" table saw. It works great and couldn't be happier the way it came out. However, I did all this work when I was just getting into woodworking and didn't bother looking at HP of the motor or what would work. I had no problems cutting all sorts of material with this table saw, and as I'm getting more skillful in woodworking I wanted to get a dado blade for it. 

 

Problem: Table saw motor is only 3/4 HP and the dado blades I see require a minimum of 1 1/2 HP motors. I have a brand new craftsman 2HP motor off a bench mortising machine that I bought (off craigslist) for $50. I was thinking of just replacing the old 3/4 HP with the 2 HP but second guessing putting something more powerful on an old but good working machine. Anybody switch out bigger motors to replace a smaller motor and have any problems? I'm worried about the more powerful motor doing damage on bearings or something bad going wrong!

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I am by no means an electrical engineer, so take this with a grain of salt. But I wouldn't worry about the increase of HP causing problems. I would be more worried about the RPM of the new motor being adequate. I have a feeling the RPM for a mortising machine is much slower than a table saw motor. But that all is just an Uneducated guess.

 

And if by any chance I am right, then if you talk to someone a lot smarter than me, you could probably figure out different pulley arrangements that could increase the RPM necessary to use on a table saw.

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I would personally put this in my screw that, too dangerous category.

You may well find the table saw arbor is not long enough to hold a dado stack anyway.

If it were me I'd save to upgrade the saw and find another way to do the cut I want the dado blade to do. Usually there's a way to do it with a router if you have one?

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Yeah I just looked, rpm wouldn't be adequate, the Arbor for the table saw is long enough for a dado stack, the thing is, they did sell dado stacks for this model, however I can not find them since it's pretty old. So I was thinking if they made dado blades for this machine why wouldn't I be able to use newer dado blades? I might just buy the dado blades and try it with the 3/4 Hp.

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They used to rate motors a lot more conservatively.  If it's old enough, that 3/4 hp motor might have more guts than a new imported 1-1/2 hp.  It'd probably be happier with a 6" dado than an 8".  It's also not a pass/fail situation.  Maybe you can't take a 3/8" deep pass with a full stack, but it could do it in two passes and most other cuts in one.

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Thanks krtwood I think I'll go with the 6 inch stack, and for right now I just need 1/4" x 1/4" dados

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I used to cut dados with a 6" stack on an old craftsman 8" direct drive bench top saw. With a moderate feed rate, it would do half by quarter dados it oak ply, no trouble. You should be fine.

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They used to rate motors a lot more conservatively.  If it's old enough, that 3/4 hp motor might have more guts than a new imported 1-1/2 hp.  It'd probably be happier with a 6" dado than an 8".  It's also not a pass/fail situation.  Maybe you can't take a 3/8" deep pass with a full stack, but it could do it in two passes and most other cuts in one.

++++1 On this.  My table saw has an old industrial motor that is rated at 3/4 HP.  From experience it is most definitely as powerful as most of the new motors rated at 1/5hp.  Give the dado stack a go, you may be surprised at how well it works.

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++++1 On this.  My table saw has an old industrial motor that is rated at 3/4 HP.  From experience it is most definitely as powerful as most of the new motors rated at 1/5hp.  Give the dado stack a go, you may be surprised at how well it works.

I agree. The motors rated at 3/4hp from even up to the 1960's were most likey rated for a lower duty cycle. A lot of times these motors can handle the same jobs when compared to say a newer motor rated even at 1hp to 1-1/2HP. Its really all about how you use the motor and it life expectancy. The older motors are made with larger guage wire which will be able to handle more current load when compared to a motor these days rated at 3/4hp. So these motors won't be effected as severely with increase loads. Thats one reason why you still see those fridges from the 1950's still kickin. The compressor motor is over built compared to the motors they make now.

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Your pulleys & belt on the existing 3/4 HP set up will probably not support the torque from a 2HP motor.  You would need to look at speed and torque to do this kind of conversion.  New pulleys, different belt, etc... to allow for the increased torque in the new set up.

 

Brian

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I have an old 8" craftsman table saw that I bought awhile ago for $30 on craigslist. I eventually got around to building a 4'x8' table around this small 22" x 22" table saw. It works great and couldn't be happier the way it came out. However, I did all this work when I was just getting into woodworking and didn't bother looking at HP of the motor or what would work. I had no problems cutting all sorts of material with this table saw, and as I'm getting more skillful in woodworking I wanted to get a dado blade for it. 

 

Problem: Table saw motor is only 3/4 HP and the dado blades I see require a minimum of 1 1/2 HP motors. I have a brand new craftsman 2HP motor off a bench mortising machine that I bought (off craigslist) for $50. I was thinking of just replacing the old 3/4 HP with the 2 HP but second guessing putting something more powerful on an old but good working machine. Anybody switch out bigger motors to replace a smaller motor and have any problems? I'm worried about the more powerful motor doing damage on bearings or something bad going wrong!

 

The arbor and mechanicals need to be designed for a dado blade. The motor does play a role but the saw itself has to be build to take a dado blade. If your saw will not take a FULL dado stack it is not designed to use a dodo blade of any width.

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They made dado blades for this model just hard to find, the newer dado stacks say minimum 1 1/2 Hp but it looks like I can get away with using 3/4 Hp with 6" stack

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PB's spot-on...

 

Think of it like a pick-up truck... The motor is only one component of the drivetrain... You have the pulleys/belt (drive shaft), trunion (transfer case), arbor/bearings (differential/axle)... OK, it's not perfect, but you get the idea...

 

To increase to towing capacity, you can't just change engine...

 

Folks are spot-on, modern HP specs tend to be inflated...

 

When you say that they made dado stacks for this saw, were they 6" or 8". Where they full-width or narrow? etc?

 

If you post some model numbers, we could help a little more...

 

As for the 1&1/2 HP full-width dado stack... I'd be careful... You would have to take very shallow passes...

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They made dado blades for this model just hard to find, the newer dado stacks say minimum 1 1/2 Hp but it looks like I can get away with using 3/4 Hp with 6" stack

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

If your saw arbor is not long enough to take the whole 13/16 stack you should not be using any at all not even 1/4. This means it is not designed for a dado period.

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Because as of right now I don't have a fence system, so what I do now is measure from the blade to a home built fence to make a cut, it's not accurate but I've been getting away with it, I just ordered a fence from vsctools.com the t square. I have a 4'x8' foot table that I put the table saw in, I love it but I really needed a fence system but kept putting it off, but now that I'm getting more things I need to build the time has come to put in a nice fence system and I think it will work out great, just waiting for it to be delivered and I still have to get an 8 foot rail for it to sit on. I'll post pictures when I get it installed.

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@particleboard I didn't measure it but it looks to be about inch and a half to 2 inches long, I'll definitely measure it before buying a stack.

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They made dado blades for this model just hard to find, the newer dado stacks say minimum 1 1/2 Hp but it looks like I can get away with using 3/4 Hp with 6" stack

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

This isn't a 1/2 arbor saw is it?

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