Motor for Rockwell Table Saw

[Ralph E Burns]

Hello Sawmill -

I have a 9" Rockwell table saw whose motor needs a little TLC. The saw was my late father's and his boss's before him, so it would easily be 60 - 70 years old. I put a Vega fence and Forrest blade on it last year. Using Dad’s tools brings me closer to the memory of his way of doing things. The saw motor does not always start, and sometimes needs a spin of the blade belt to get it moving. It's a big drive to an electric motor repair shop.

Question is to repair or replace and if to replace then with what? I can inquire about repair cost estimate tomorrow unless the vote is to skip the repair shop entirely and replace instead. It is rated 3/4 HP, but given “ratings inflation” I’d bet it’s more powerful than a 3/4 HP motor sold today. Yes, I sometimes wished for more power, as we all might.

Attached is a photo of the nameplate. I’m a hobbyist, but enjoy tools that do the job well!

Here's a link to the owner's manual (http://vintagemachinery.org/pubs/1141/1840.pdf).

- Ralph in Colorado
419475

[Mike Kees]

Ralph it may be cheaper to fix. However if you put a new motor on then you can go bigger (hp). I have run a contractors saw for the last 10-12 years as a carpenter,it rides in my tool trailer full time. My saws have been fine with a 1.5h.p. motor,currently I have a 2h.p. and wish I still had the 1.5. Honestly the bigger one just kicks breakers easier and it is heavier so puts more strain on the mounting bracket. It does however have a bit more oumpph.

[Ralph E Burns]

Just under $400 for a Leeson 1.5HP #110109... - what is the preferred brand around here?

[Doug Garson]

Assuming it runs fine once it starts two things to check out before you take it to a motor shop. One is the centrifugal start switch, pull the cover off and check for an accumulation of sawdust and the second is the start capacitor (if it has one), check for swelling or leakage. Here's a video that covers both of these issues. https://www.youtube.com/watch?v=4k4c998kLKc

[Ralph E Burns]

Copy Doug. It runs fine and will check those two things. Another note: the thermal overload button was fused / bypassed about ten years ago. The culprit of that one is me. I know that a stalled motor = toaster, so power off quick if that happens.

[Frank Pratt]

The saw motor does not always start, and sometimes needs a spin of the blade belt to get it moving.

It is rated 3/4 HP, but given “ratings inflation” I’d bet it’s more powerful than a 3/4 HP motor sold today. Yes, I sometimes wished for more power, as we all might.

Ralph, 'ratings inflation' is largely a myth. In fact, amp for amp, a modern motor will put put more power than one of the old guys. Where it's not a myth is with the '6.5 HP' vacuums and '3.5 HP' routers and other tools that use universal motors.

I had a newer version of that saw, a 9" Rockwell/Beaver that wasn't nearly as good as the one you have. I'd for sure go for a bigger motor, 1.5 or 1.75. I always found the 3/4 HP motor severely lacking for just about anything but sheet goods.

But the motor may not be beyond repair if you are handy with such things. It's probably just a bad capacitor or a centrifugal switch with dirty contacts. If it has to go to a motor shop, then probably not.

[Mike Henderson]

I agree with Frank. We've known how to measure HP for a long time and those old motors don't put out more power than a modern motor of the same HP.

From what you describe, that motor can probably be fixed. I'd get a new starting cap (they're not very expensive) and clean the motor and see what it does.

But long term, 3/4 HP is pretty weak for a table saw. If you're limited to 120 volts, I'd get a 1.75 HP motor (that's about the biggest you can run on most 120 volt circuits). If you have 240 volts, I'd go to a 2HP or even a bit larger. You get limited at some point by the amount of power the belt can transfer.

Good luck.

Mike

[Dick Brown]

I agree with both the start cap, dirty start switch, and more power posts. If you have been happy with the power, check out the capacitor and start switch. If you have been wanting more power, shop for a bigger motor but I would be very careful about adding to much weight to that old saw that was built for a 3/4 h.p. I have seen some TEFC 1-1/2 h.p motors put on old Craftsman saws that had (tagged)1-1/2 h.p. Craftsman motors and they were enough heavier that the blade tilt was over taxed to the point of failure.

[Doug Garson]

On the subject of motor HP I noticed the manual recommends a 1 HP motor so maybe the existing motor even though it is a Rockwell motor maybe isn't the original motor? In any case if all it needs is a cleaning and/or a start capacitor it would be a shame to scrap it or spend a bunch of $ on it at a motor shop.

[Frank Pratt]

The caution about motor weight should be heeded. That saw doesn't have particularly stout trunions & I wouldn't want to hang anything too heave off it.

[Bill Dufour]

I would at least try a new start cap and blow dust out of the centrifugal switch. A start cap off ebay would be under $5.00. hardest part will be reading the numbers on the old cap. If illegible look for standard micro farads chart online. Make sure voltage is at least 170 or 350 for 240 acv. Any motor is worth saving for some use even if you upgrade to more hp on saw.
Bill D

[Ralph E Burns]

Hello, hello hello - and thanks for the replies!

Opened up the motor: no signs of trauma on the start capacitor, but my Fluke 87III can only measure up to 5uF. We can only assume that the capacitance has faded. There are $6 ones on eBay, tho looking on Amazon not all get stellar review ratings. I can get TemCo (https://temcoindustrial.com/sc0014-motor-start-capacitor-216-259uf-110-125-volt.html) or NTE (https://www.nteinc.com/capacitor_web/pdf/motor_start.pdf) labelled ones for $13, and Amazon has a drone circulating my house right now with one for delivery tomorrow (https://www.amazon.com/NTE-Electronics-MSC125V216-Electrolytic-Capacitance/dp/B007Z7MJV4/). Sadly, the surplus electronics supply shop around here went bust a few years back.

The centrifugal switch looks good and not tons of sawdust, although I blew it out sometime in the last ten years. I struggled to remove the end bell from the shaft bearing, so stopped disassembly.

I probably ought to replace the overload protector switch. Mine is marked Klixon D511, and I'm guessing from scant web info that it's 8.7A. I've emailed a supplier (http://www.carbonbrush.com/klixonphenolicold.htm) to see how that rating jives with my 10.4A motor.

My motor weighs in at 26#, and a Leeson 1.5hp motor specs at 34#. Sure, more power is always handy... if the saw can handle the weight. On the flip side, it's $400 for a new motor, and I could put that money towards a router table or Router Boss. Besides, I'm sentimental about using Dad's old tools because it's something we did together when I was a youngster.

[Ralph E Burns]

Something went wrong. I replaced the starter solenoid and thermal protection switch with new parts and now the motor won't start, even with a manual push. Took it in to the motor shop, and there the original capacitor measured in spec.. The guys at the motor shop said that a motor "only hums when it doesn't know the words". It'll take them a few days to look into it.

[Ralph E Burns]

The motor shop quote to fix the old motor comes in at $200, so the question is to repair or replace with a larger, although heavier motor.

Old motor = 3/4hp @ 26#, frame 56C (although I don’t see a “C” face), $200 repair
Leeson #110109 = 1.5hp @ 34#, frame 56, $360 from Northern and junction box will barely fit
Baldor L3513 = 1.5hp @ 41# = very heavy! $470

[Frank Pratt]

I know that the saw has great sentimental value to you, but...

I'd not spend $200 on repairing a motor that is under powered to start with. The Leeson would be an attractive alternative, but the extra weight may be an issue. I don't think it would break anything, but the extra weight may cause flexing & alignment issues. And there's the cost. The $360 could go a long way towards buying a far more capable used 10" contractor or cabinet saw.

Do you know what model that saw is, and is it a Rockwell, or a Rockwell/Beaver?

[Ralph E Burns]

The saw is a Rockwell, per the manual linked on post #1. After putting on the Vega fence last year, I'm not in a big rush to send it to the dump. I'm not as offended by the 3/4hp as many of you, and will simply tolerate a slower feed rate. Which is fortunate because I shopped around and cannot find a new 1.5hp or 1hp motor frame that will stay below the table when the blade is tilted 45-degrees (printed out several full-scale templates to prove it to myself, and was trying ODP-style for reduced size). It's the least brain damage to use what I already have, so decided to fix the motor (I could get a vintage Rockwell 1hp off eBay, but given the fuss I'm going to pass on that for now).

The smallest ones that still didn't fit was a Leeson 1.5hp 110161-700B, or 1/2" shorter 1hp 110160-650B and Marathon C704 and C1477A, which are all open frame just like the original motor. For all of those, I'd have to relocate the start capacitor. The TEFC are all way too fat at the fan end.

Thanks everyone! Fingers crossed!

[Frank Pratt]

Sorry, I missed the manual link. If the 3/4 HP is okay with you, then spend the $200 to fix the old motor. Sometimes it's not just about the economics of a thing that's most important.