Thread: Upgrading Motors on Machinery

Hi Steve

The closest I can advise is how I recently went about replacing the motor on my tablesaw: https://www.woodworkforums.com/f153/upgrading-motor-contractor-tablesaw-187499

Regards from Perth

Derek

I am thinking of downgrade the motor on my sander lol it's 25hp. Am at the border line of my power if it's switched on with the extractor and compressor lol

Upgrading can vary from easy to a PITA depending on the machine and the motor.

A simple straight swap requires

a) Enough space to locate the replacement motor.
Not all motors are the same size and may not physically fit in the space provided.
The easiest arrangement is where the motor is on the outside of the machine so space is not as critical.
If the motor location position has to be moved longer (or shorter) belt(s) may be needed and belt tensioning arrangements allowed for.

b) The motor mounting holes to match
If not new holes may need to be drilled in the machined motor mounting plate or an adapter plate to be constructed .
Motors that use "feet" are much easier to swap out than motors (such as on bandsaws) that are flange mounted although it's impossible to make adapters.

c) The old pulley to match the new motor shaft.
1HP motors tend to use 16/19 mm shafts, 2HP motors tend to use 19/24 mm shafts and 3HP tend to use 24/28 mm shafts.
It's not always possible to bore out the holes in pulleys as it may leave too little material behind and most 3HP motors would use keyways so that would need to be cut (i.e. not easy)
A simpler alternative is to purchase a new pulley but this may not always be possible e.g. pulley is specialised such as on a DP or BS.

d) The switches on a machine may need to be changed if they cannot handle the higher currents.

My experiences are
MW lathe: motor changed from 1/2 to 1HP, straight swap but had to purchase a pulley with a larger bore.
WW lathe: motor changed from 1/2 to 1HP, the HP was a bigger motor and would not physically fit in space so had to mount it underneath the bench and use a longer belt. a completely new motor mount and tensioning mechanism was needed. This lathe used a special 6 position V-groove pulley and I could not bore out old 16 mm diameter pulley to fit new 19 mm motor shaft - in the end I turned a completely new pulley
Drill press: motor changed from 1 to 1.5HP, straight swap but new motor had a 16mm shaft and had to make an adapter to fit the 19mm bore DP pulley.
Compressor: 4HP motor changed to 5HP. Motor mounts were different and new motor shaft was shorter so made an adapter plate to short motor so the pulleys lined up better. 28 mm Pulley was easily swapped.

Switch gear was not an issue on any of these as I completely rewired these to run through VFDs.

Other issues you might come up against;

3HP motors need dedicated 15A outlet and circuit, while 2HP will work on a normal 10A outlet on a shared domestic circuit provided that the circuit is not already heavily loaded.

Check the drive belt arrangement on the selected saw. Induction motors have a max speed of 2900RPM or thereabouts for 50Hz mains. 10-12 saws have an arbour speed in the range 3800-4500RPM, so the drive system has to use a step up pulley and belt system. Because of space considerations the pulleys are small diameter and have a small belt contact area, so often multiple V belts are used. At 3HP, a dual belt would be a minimum because of the small diameter pulleys, and some use a triple pulley system. The issue is that if you need to add an extra belt, you need to get pulleys to carry it, and it may not be easy to match diameters, shaft bores in a multi belt format. You also need to get matched belt sets so all belts are doing equal work, they tend to come in matched sets for particular applications, and may not be easy to find for a custom application. Saws might use a serpentine style belt system which may even harder to update.

Thanks Guys,

some good information to think about, just so you know I was looking at a bandsaw in particular so to me it seemed a simple idea (famous last words) to swap a motor to a more powerful version.

I figured since they make a model with a more powerful motor but don't bring that model to Australia I could just purchase a bigger motor and bob's your uncle


life should be so simple.

Steve

For a bandsaw, you tend to larger drive pulleys, so a single belt is possible, bypassing some of my points above.

However, if the unit is sourced from China, and uses a sheetmetal frame rather than a solid cast one, it is possible that there are non obvious variations between the 2HP and 3HP frames, like additional bracing or a heavier gauge of metal in the frame. There is a possibility that upgrading a 2HP frame to 3HP may increase frame flex etc as I assume that you work the unit harder to get the benefit of the extra power.

Another possible issue is that if the unit uses a Reeves drive to achieve limited variable speed, it may be virtually impossible to adapt the drive to a larger shaft size or obtain a similar unit for the shaft on the upgraded motor.

Hi Steve, I changed my bandsaw motor from a 2hp 1phase to a 3kw 3phase(4hp), I had to deal with some (all?) of the points made above; remake a motor mount plate, I used the existing pivot, shaft slot and locking bolt (that worked out well!) and new switchgear/wiring.
Previously I could stall it on a deep cut and blade speed was tooo slow.

Another point to look for is the frame size of the motor, for e.g. 90L this describes the physical size and things like bolt hole position so for you see if you can find a frame size on your existing and then see if the size up (3hp?) that you want is the same frame size, it does happen, you never know you might get lucky, alternatively this sort of detail is also available from motor suppliers so google single phase motor and you should be able to find your existing motor and start to make some comparisons.


Pete

Pete from memory yours is a 19" generic blue taiwanese BS - is that right?

Originally Posted by BobL

Pete from memory yours is a 19" generic blue taiwanese BS - is that right?

Yep, same breed yours.

Originally Posted by pjt

Yep, same breed yours.

I was thinking about upgrading the motor power on my BS but when I added a brake to my BS I noticed how small a diameter the shaft of that motor was (I think it was a 5/8" or 16 mm shaft?) and was concerned about this. When you upped the motor what did you do about the bore in the pulley. Did you note out the existing pulley or did you replace the pulley?

Originally Posted by BobL

I was thinking about upgrading the motor power on my BS but when I added a brake to my BS I noticed how small a diameter the shaft of that motor was (I think it was a 5/8" or 16 mm shaft?) and was concerned about this. When you upped the motor what did you do about the bore in the pulley. Did you note out the existing pulley or did you replace the pulley?

I think my original shaft size was 19mm, but I just replaced the drive pulley, used a taper lock with a 28mm bore and somewhere about 110mm twin sheave, this then allowed me to use both sheaves on the drive wheel for a fast and a not so fast speed, the problem with this tho is the outer sheave runs very close to the lower wheel, the motor has to be set lower to move the pulley away from the wheel (a longer motor/adjust slot) I just get away with it as it is, an alternative is to just use one sheave and forgo the other speed which is pretty much what I do or I could turn the outer sheave down to a smaller diameter somewhat like the original, the taper lock limits how far unless I used a smaller size taper lock or when I fit a VFD to the BS I'll just go to one sheave and have all the benefits including dynamic braking, at some later date......


Pete