LumberJocks

Question for the Electrically Enlightened Members here.

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by Dusty56 posted 391 days ago 830 views 0 times favorited 12 replies Add to Favorites Watch
View Dusty56's profile

Dusty56

11605 posts in 2189 days


391 days ago

Topic tags/keywords: question unisaw table saw motors craigslist tablesaw

Hi , ” New 1.5H.P. 120v 1725rpm Equal to 3250rpm 3 H.P.” Quoted from a craigslist posting today for a Delta Unisaw.
1) Is this possible ?
2) why would we want a table saw blade to turn this slowly ?

http://westernmass.craigslist.org/tls/3699711051.html

thank you : )

-- When you arrive at my front door, please knock softly but firmly. I like soft , firm, knockers : )


12 replies so far

View AndyM1949's profile

AndyM1949

14 posts in 391 days


#1 posted 391 days ago

Hmmm don’t sound right to me. my blade turns around 3600 rpm. If you put a slower motor on you saw (less rpm) with less hp. Its not going to preform as well. The motor speed and size of the pulleys on arbor and motor shaft determine the blade speed. hope this helps.
Andy

-- Andy, SC

View sprucegum's profile

sprucegum

323 posts in 499 days


#2 posted 391 days ago

1.5 hp is not the same as 3 hp pure and simple. Table saw motors are almost always 3250 rpm, 1725 is too slow unless you use unequal size pulleys to speed it up ( big motor pulley to small arbor pulley).

-- A tube of calk and a gallon of paint will make a carpenter what he ain't

View amagineer's profile

amagineer

1383 posts in 1099 days


#3 posted 391 days ago

I contacted the owner yesterday about the saw. He said his brother in law fried the original motor and replaced it with the 1-1/2 hp motor. I agree with the pulley ratio to up the rpm’s. A 4” pulley on the motor and 2.18 pulley on the blade arbor will give the increased rpm. I decided not to buy the table saw, looked like to much work to restore.
-don

-- Flaws are only in the eye of the artisan!

View JamesT's profile

JamesT

102 posts in 414 days


#4 posted 391 days ago

Rockwell/Delta Unisaw made arbor and motor pulley sets for both 1725 and 3450 RPM motors. The blade would turn the same speed with both set-up’s But of course they are not the same power, 1.5 HP uses approx 1119 watt of power, 3HP approx 2238. If someone installed a 1750 motor without the correct pully set, the blade speed would be one half what it should be.

-- Jim from Doniphan

View runswithscissors's profile

runswithscissors

756 posts in 527 days


#5 posted 391 days ago

Not only that, but a large motor pulley to a smaller arbor pulley yields less torque at the blade. Burt it was typical many years ago to use 1725 rpm motors that way. I’m guessing 3450 rpm motors weren’t that common or were too expensive.

View unbob's profile

unbob

283 posts in 405 days


#6 posted 391 days ago

The very old Unisaws used a repulsion induction motor, of 1725 and apparently 1425rpm. Those old motors had plenty of torque, and run very smooth, with a larger motor pulley. One problem is, newer motors do not fit correctly, and the right hand opening has to be cut larger, or one can not get full 45 blade tilt.

View Dusty56's profile

Dusty56

11605 posts in 2189 days


#7 posted 391 days ago

Thanks for all of the info / knowledge , Gentlemen.
I knew it didn’t seem to be correct , but I had to check with you pros anyway : )
Very interesting to read about the pulley size changes , and I believe those old beastly motors were called Bullet motors due to their shape.
The condition of the saw doesn’t make it very desirable for that kind of money in my book , Unisaw or not.
Thanks again : )

-- When you arrive at my front door, please knock softly but firmly. I like soft , firm, knockers : )

View runswithscissors's profile

runswithscissors

756 posts in 527 days


#8 posted 391 days ago

Just looked at the photo for the first time. That is an “open, drip proof” motor, not good to use around sawdust, as on TS. Should be TEFC (totally enclosed fan cooled).

View Dusty56's profile

Dusty56

11605 posts in 2189 days


#9 posted 391 days ago

More good info . Thank you : )

-- When you arrive at my front door, please knock softly but firmly. I like soft , firm, knockers : )

View David Dean's profile

David Dean

452 posts in 1401 days


#10 posted 390 days ago

Your not realy thanking about buying that are you I still have my grand father’s table saw and the same motor that came with it like he siad you take care of your tools they well take care of you. Let the owner sale it for srape.

View Dusty56's profile

Dusty56

11605 posts in 2189 days


#11 posted 390 days ago

No , I wasn’t wanting to buy it , I was just wondering about his statement regarding the HP being equivalent.
Another Craigslist Cukoo for Cocoa Puffs moment !! LOL

-- When you arrive at my front door, please knock softly but firmly. I like soft , firm, knockers : )

View REO's profile

REO

542 posts in 576 days


#12 posted 390 days ago

in a word. No. it takes a given amount of force to remove a chip regardless of speed. In the case described here you will be able to make 1 1/2 HP worth of chips. this takes into account force, time and distance. You will only be able to do half as much. If you increase the speed with different pulley you will increase the speed but give away torque so you can only make a half sized chip. often the reason blades burn is not because they are dull but because they are not fed what they need to stay cool. When the proper feed rate is reached the chip takes the heat away and helps cool the blade as well. It really depends on whether you need to use 3 hp. Cutting 3/4 plywood you will be fine with 1 1/2 hp. Production runs of 6/4 oak and you will want the extra hp.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase