VFD on a 19: bandsaw

**BobL** · 15th March 2015, 10:44 PM

I'm about to start on a project to upgrade the motor on my 19" carbatech bandsaw. The original 2HP motor has struggled on wider cuts so I have been on the look out for a suitable bigger motor. Recently I came across a never used good quality Italian 3P 3HP 1440 rpm motor on GumTree that should do the trick.
https://www.woodworkforums.com/f65/3p-motor-192985
This motor also has a independently powered quality high capacity 3P fan that runs at 2880 rpm but I will run it in parallel with the motor which means the fan will always be running at twice the speed of the motor.

A 4HP motor would have been better but using a 3HP means the saw will be able to run off a 15A socket and there is one of these in my shed about 2m away from the Current BS position.

I also happen to have 2 spare 4HP VFDs floating around my shed looking for something to drive.

Following a preliminary inspection this afternoon I realise there is going to be a fair bit of mucking around to fit this motor to the BS but, hey I'm retired and like these sorts of projects.
The main problem is the motor is not a flange mount but a foot mount so an adapter will be needed. A new pulley will have to be made to suit the motor shaft and fit in with my BS foot brake. I could get the VFD to do the braking but I will implement that at a much later stage so meanwhile I want to keep the foot brake in working order.

Even though it might sound dumb there is a question I wanted to the forum BS people.
VFDs enable a motor to be easily reversed in direction
SO
can anyone see a possible reason why at any stage it might be useful to run a BS backwards?
I do realise it will lift any work off the table and possibly end up jamming the work under the blade guides but there may be a reason for running in reverse for some other reason, that I cannot think of.
If no one can think of a reason I will not even enable reverse on this setup.

Speed wise, if the motor runs above 33 Hz the motor will still be able to develop 2 or more HP. From 50 to about 100Hz the motor should develop 3HP. I will be reluctant to run above 100 Hz as that means the fan will be doing 5760 RPM. For lighter cuts the saw should still be able to cut as low as 25Hz and not overheat the motor. This means the saw will have a speed range of about 4:1. Nothing fancy but it will be a wider range that is available on most other bandsaws.

I will post updates in this thread as they come up.

**pjt** · 17th March 2015, 12:41 AM

I can't think of a reason you might want to run the BS backwards, might be a safe option to disable that function.

Not sure if you have seen these pics Bob but I made a foot mount plate for my 3ph motor conversion
drive pulley and slot.jpg slot extention.jpg pulley on moter.jpg motor.jpg motor and mraket.jpg motor mount point.jpg
I used the same pivot/mounting and the same locking handle/nut system. I had to widen the motor shaft slot and lengthen it, I also had to lengthen the adjust slot, I had to do this to get enough movement to take up the slack belt, I used the same diameter twin groove motor pulley (I already had this on hand) for both drive wheel pulleys, if you do go with the VFD a single groove pulley aligned with the outer drive wheel pulley should alleviate a lot of the work I had to do and give you clearance on the drive wheel, I have none but hasn't caused an issue as yet. For ease of fitting a taper lock pulley and taper lock center will make fitting of the pulley a nice simple job, measure the motor shaft diameter and the key width, this should be a standard width for the shaft size, determine a pulley size and all good.
You might be able to get a flange mount for that motor, check with a motor supply place or the OEM. Not sure now why I didn't do that myself

Pete

**BobL** · 17th March 2015, 07:38 AM

Originally Posted by pjt

I can't think of a reason you might want to run the BS backwards, might be a safe option to disable that function.

Yeah I've been thinking about it and can't think of one good reason. I'f I ever think of one it will be easy enough to add on.

Not sure if you have seen these pics Bob but I made a foot mount plate for my 3ph motor conversion

Thanks for those - that's basically what I had in mind. Good to see it actually done by someone else.

I used the same pivot/mounting and the same locking handle/nut system. I had to widen the motor shaft slot and lengthen it, I also had to lengthen the adjust slot, I had to do this to get enough movement to take up the slack belt, I used the same diameter twin groove motor pulley (I already had this on hand) for both drive wheel pulleys, if you do go with the VFD a single groove pulley aligned with the outer drive wheel pulley should alleviate a lot of the work I had to do and give you clearance on the drive wheel, I have none but hasn't caused an issue as yet. For ease of fitting a taper lock pulley and taper lock center will make fitting of the pulley a nice simple job, measure the motor shaft diameter and the key width, this should be a standard width for the shaft size, determine a pulley size and all good.

I will have to probably custom make a pulley because I want to attach the brake disc for the foot brake to this pulley - same as I have now.

You might be able to get a flange mount for that motor, check with a motor supply place or the OEM. Not sure now why I didn't do that myself

I though of that but usually flange mountable motors have threaded holes in the end cap to attach the flange and this motor does not have any hole.

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