Menu
What's new

new/old saw

Frank Fusco said:
No doubt I need a new motor. I tried ripping some 2 1/2" seasoned maple (mentioned this on another thread too) and it stopped the 3/4 hp motor dead, as in ded. Blade is recently sharpened. Having to dip into the emergency fund to get another motor. A friend will be picking up a 2 hp. 1 ph at Harbor Freight for me. Price is $149.99.
The maple will be ripped, in the meantime, by a friend with a 3 hp. table saw. I hope my investment pays off.
BTW, what little cutting I have done so far, the foot switch is proving to be a great choice.
Click to expand...

You want to double check that VERY carefully. According to the documentation on their website, the 2hp only spins at 1725rpm. To state the obvious, you need to roughly match the RPM of the new motor to the old or your blade speed is going to be way off. Adjusting pulley sizes can get your blade speed back up, but that's another can of worms.
 
David Agnew said:
You want to double check that VERY carefully. According to the documentation on their website, the 2hp only spins at 1725rpm. To state the obvious, you need to roughly match the RPM of the new motor to the old or your blade speed is going to be way off. Adjusting pulley sizes can get your blade speed back up, but that's another can of worms.
Click to expand...

My current 3/4 hp motor, that has difficulty cutting wet tissue, is 1725 rpm. Are you saying a 3450 is preferable? I haven't gotten the motor yet.
 
Most modern table saws are 3450 rpm so the 1725 rating jumped out at me.

The RPM of the motor doesn't really matter... it's the fact that the pulley sizes and motor rpm combine to get a certain blade speed. If your pulleys are sized for a 3450 motor and you put on a 1725rpm motor, your blade will be turning half as fast as w/ the old motor. So I was worried you were about to spend $150 on a motor that spun half as fast as you needed.

Since your old motor is also a 1725, you should be good to go. Just wanted to make sure it was taken into consideration. :thumb:
 
David Agnew said:
...Since your old motor is also a 1725, you should be good to go. Just wanted to make sure it was taken into consideration. :thumb:
Click to expand...

That's assuming the old motor/pulley combination was set up correctly.

Frank, I'd suggest measuring the diameter of the pulleys and comparing them to other similar saws. If your pulleys are the same size as those of most other guys who are running 3450 rpm motors, then I think you're gonna want to install a 3450 rpm motor. I'm wondering if the "can't cut wet tissue" problem might be the result of someone putting a too-slow motor on the old saw at some time in the past.
 
Vaughn brings up a good point. In general, if the motor pulley is bigger than about 2.25", it's designed for a low speed motor. In general, most saws want to spin a 10" blade at around 4000-4200 rpm (arbor speed; arbor RPM). A 3450rpm motor needs 2.125" on the motor and 1.75" on the arbor to get 4200. A 1725 motor would need something like 4.25" on the motor and 1.5" on the arbor. Those are just round numbers for you...

You can figure it out:

(Motor RPM * Diameter of Motor Pulley) / Diameter of Arbor Pulley = RPM of Blade.

If you plug in 1725 motor RPM and you're around 4000-4200 blade rpm, then you're good. If it's around 2000-2100, then 99% sure, you need a 3450rpm motor for those pulleys.
 
Love to see a bargain found! I too found a great used TS at a yard sale last year. JET 10" contractor saw with light rust on table surface. Bought it for $75 and the owner delivered it to my house! What a great saw and the price was terrific. I have also found super buys on a PC: biscuit joiner, Tiger saws all, and random orbit sander at another sale - total cost $45. I love yard sales.
 
Frank Fusco said:
Not yet. Friend going up next week to get motor.
Click to expand...

Have you determined if it needs to be a 1725 rpm motor or if it should be a regular speed 3450 rpm model? I still suspect some of the bogging you're seeing might be the result of a too-slow motor. Considering the saw's age and provenance, it's possible someone replaced the original motor with one that's the wrong speed. ;)
 
Vaughn McMillan said:
Have you determined if it needs to be a 1725 rpm motor or if it should be a regular speed 3450 rpm model? I still suspect some of the bogging you're seeing might be the result of a too-slow motor. Considering the saw's age and provenance, it's possible someone replaced the original motor with one that's the wrong speed. ;)
Click to expand...

The motor on it now is a replacement 3/4hp, 1725 rpm. Based on what you and others have said here I'll be getting a 3450 rpm, 2 hp. Looking forward to it.
 
Frank Fusco said:
The motor on it now is a replacement 3/4hp, 1725 rpm. Based on what you and others have said here I'll be getting a 3450 rpm, 2 hp. Looking forward to it.
Click to expand...

Sounds awesome. I hope it works out well. I've been tempted to do something similar myself. My saw is marketed as 1.5 hp, but it's a 13amp motor... 13amps at 120v gives 2hp at 100% efficiency; maybe it really is 1.5hp "real world"? Anyway, I'd been thinking up stepping up to a "true" 2hp or maybe 3hp 220v motor so I'm interested in how your experiment goes.
 
You must log in or register to reply here.
Top