What to watch out for when up-sizing Table Saw motor

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Blog entry by Kevin May posted 07-07-2012 11:36 PM 9485 reads 0 times favorited 12 comments Add to Favorites Watch

I have an old Craftsman saw that does OK for me except when I start ripping 8/4 hardwoods like Walnut, Hard Maple or Jatoba. I’m thinking I could just up-size the motor. This wouldn’t be a big job at all (assuming I can find a motor at a decent price).

My question; is there anything to look out for that I’m not thinking about? (OK, I know to get the same speed motor and to get a single phase 110/220v motor.) Will the increased horsepower cause any problems with other parts of the saw?

Thanks in advance for any valuable input you could provide.


-- Kevin May "Making wood useful and fun!"

12 comments so far

View knotheadswoodshed's profile


225 posts in 2941 days

#1 posted 07-08-2012 12:31 AM

bumping this up for you.
I would like to see peoples input on this as well.

-- Randy - "I dont make mistakes, I make design change opportunities"

View Roger's profile


21030 posts in 3573 days

#2 posted 07-08-2012 12:53 AM

I don’t think it will hurt anything else. I have an old ‘50’s Craftsman model and the motor on it is actually setup for either 110 or 220. I would like to wire it for the 220 also, but haven’t done it yet. It runs really good the way it is. One thing I might try if I were you is to rip those thicker boards in a few passes, instead of hoggin out all that wood at one pass. That’s bout all I can say. Good luck with it. Work safe.

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed. [email protected]

View davidroberts's profile


1027 posts in 4255 days

#3 posted 07-08-2012 01:30 AM

As Clint Goodwood said “A tablesaw got’s to know it’s limitations”. Thought it needed repeating. Nah, I just like saying it. But seriously, without knowing your Cman model, and taking a stab, most tablesaws are designed for more than one motor size. Manufacturers typically offer at least two HP options for the same model saw. Of course this is all within reason. I assume you are using an cap start motor motor, with a belt drive, verses universal. I wouldn’t know where to begin with a universal, except forgetaboutit.

Cman may have started the “developed” HP back in the day, or maybe B&D, I digress. Bottom line, if you are running a true 1.5 to 2 hp, as measured in amps pulled – 10 amps at 110V (120V) is roughly 1hp depending on motor efficiency. Cut the amps in half for 220V (240V). More HP means more amps, so you should check the circuit you plan to run a higher HP motor. Also the breaker. As for the integrity of the TS itself, as in trunnions, gears, belts, bearings, etc, if you stay within 50% or so of what you have now, going from a true 1hp to a 1.5 or even 2.0hp should not affect the stability of your tablesaw. No one would hold it against you if you called Cman technical support about your particular saw.

One other thing, electric motors are designed using “frame sizes or numbers”. It is a NEMA standardization related to motor interchangeability based hp and manufacturer. I won’t dwell on it here. The internet is full of this info. Bottom line is the placement of the mounting holes may be different for a larger motor. A different HP motor will be a different frame number and you will likely need to drill out some new mounting holes, or buy a new pre-drilled mounting plate.

I’ll also assume that you are currently using a thin blade verses 1/8 thick Forrest-type blade. A thin kerf blade will effectively increase the HP you already have. You may have thought about all these things and I’m just reinforcing what you already know.

I would probably slow down and get expert advice if you wanted to go from a 1 to 3, or 3 to 7hp. Besides at 3hp and up, 220V (240V) is highly highly recommended. There are probably some 3hp motors wired for 110V, but I can’t think of any offhand.

-- Better woodworking through old hand tools.

View JuniorJoiner's profile


497 posts in 4209 days

#4 posted 07-08-2012 02:08 AM

if ripping thick hardwoods is the problem, why not use a bandsaw?
I use a cmt multi-purpose thin kerf blade on my tablesaw, solved my underpower issues.
best regards

-- Junior -Quality is never an accident-it is the reward for the effort involved.

View woodman71's profile


182 posts in 4093 days

#5 posted 07-08-2012 03:11 AM

One more thing to keep in mind to is if this is belt drive which it i think it is. Cutting 8/4 with belt drive you will lose no matter how much horse power you have craftsman’s saw don’t do well in my opinion because of slipping. You can up grade your belt and pulleys. You will lose power because of slipping cause the blade to slow and burn . Don’t get me wrong a big motor will help but it will come down to getting the belts pulleys to also work with the new motor and getting the slipping down when cutting 8/4 or for that matter 8/4 hard maple.Good luck

View vipond33's profile


1405 posts in 3266 days

#6 posted 07-08-2012 03:19 AM

There is no substitute for power, get as much as you can. 3HP will allow you to work with ease and without slowing down which is where all the trouble starts. Take the opportunity to increase your RPM’s at the arbor at the same time. Most saws run much too slow, a 10 inch blade is rated as high as 6500 rpm and what you are concerned with is chip load per tooth. The smaller the better. Having said all that, a new 3hp motor is a very expensive thing, you might be better off buying a used tool already so equipped.

-- [email protected] : dovetail free since '53, critiques always welcome.

View tomd's profile


2218 posts in 4539 days

#7 posted 07-08-2012 05:13 AM

I have a 1985 Craftsman that I bumped up. It came with a 1HP motor and I increased it to a 2 HP motor and it has worked very well the last 8 years. One thing to be aware of is the motor shaft size increases from 1 HP to 2 HP. You will have to replace the pulley. I put on the 2 HP motor changed the pulley and used a link belt. Also the 2 HP motor fit right into the old support no changes necessary.

-- Tom D

View Bob Kollman's profile

Bob Kollman

1798 posts in 3960 days

#8 posted 07-08-2012 06:18 AM

If you own a contractors saw I think your limited by pulley slippage. I own a rigid 3650 contractors saw and find myself limited to 6/4 stock with a WWII blade. Any 8/4 stock I have to take to the band saw. I would imagine that you’ve probably out grown your contractors saw if cutting 8/4 stock is something you are going to be doing frequently.

-- Bob Kenosha Wi.

View benchbuilder's profile


285 posts in 3219 days

#9 posted 07-08-2012 06:46 PM

One other thing to look at is the newer size motor is much heavier and if its the type that is mounted on a hinge type mounting, the extra weight and stress on the blade shaft may be too much after a short time. Check the bearings and try to not over stress the shaft. Try to use a motor of the same frame size as the old one. check the name plate on the motor for info.

View Kevin May's profile

Kevin May

74 posts in 3084 days

#10 posted 07-09-2012 01:08 AM

Thanks for all the input.

Follow up info: saw is labeled full marketing BS as “CRAFTSMAN 3HP max developed”, with the motor clearly marked as 1-1/2HP. It is a belt driven saw, with the motor hanging on a pivoting mount to allow the motor to move as the arbor is moved. I’m using a Freud thin kerf 24T ripping blade.

(As for the band saw, I just picked up a Rigid 14” saw with 3/4hp motor in need of repair. The parts needed to repair are on order. I’ll give it a try when it’s running.)

Following the post by David Roberts I had to re-think the belt slippage possibility. I had the mindset that the belt was not slipping, due to me not noticing any sound or smell caused by a slipping belt. Goes to show that my mind being set is not a good thing. As the weight of the motor is all that provides tension, to test if more tension would help with belt slippage, I took the brute force route to add tension to the belt, I hung a 15lb hunk of steel off the back side of the motor via a small rope loped over the capacitor.

Following the high tech modification, the saw was tested on 6/4 maple and walnut. Not the same as 8/4, but I noticed a significant difference. I’ll post the outcome on 8/4 next weekend when I’m able to get back in the shop.

Thanks again to all who posted.


-- Kevin May "Making wood useful and fun!"

View Bearpaw's profile


264 posts in 4489 days

#11 posted 01-17-2013 09:31 PM

I just came across you page, mainly because you and I live close to one another. I have an older Craftsman saw that I installed a 3 hp motor on and it has made my cutting so much easier. It was bought from Harbor Freight for about $150.00 new. You have to make sure that it fits the frame support. The other thing I did was to install a segmented belt from Harbor Freight. I did a lot of research on the different manufacturer of that type of belt. HF is green and the other is red from Rockler and other stores. There is no difference in them except the price. But the best advice is to use the proper SHARP blade. I cut a lot of plywood and you may want to look at the in feed table I built for my saw. That has made cutting large sheets safer.

-- "When we build, let us think we build forever." John Ruskin

View Kevin May's profile

Kevin May

74 posts in 3084 days

#12 posted 01-18-2013 03:37 AM

John, Thanks for the info

-- Kevin May "Making wood useful and fun!"

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