Thread: Another Vertical Bandsaw mod to cut Metal

I bought a Carbatec Vertical Bandsaw ( 345C )recently and could not justify the cost I variable speed model as it cost me $1800 as it was.
I am not thinking of modifying it so I can cut differnt metals as well as wood.

My first thought was to use a DC motor and speed control due to DC motors having very good lower speed torque. (They are expensive and would take alot of moding to fit. Also ,none S/H locally )

But then I thought if I could keep the motor speed closer to 50Hz at metal cutting speeds, then a 3 phase motor would have enough torque.

I could do this by fitting a 4 pole 3 phase motor and VFD and then run it at higher frequencies for cutting wood.

With a 2 pole motor, presently the blade speed is 880m/min.
If I fitted a 4 pole 3 phase motor, that would reduce to 440m/min ( still a bit fast?)

So if 440m/min was when running at 50Hz,

Getting back to 880m/min ( not really required, I think ) I would need 100Hz.
300 m/min would be 34 Hz, and
200 m/min would be 22 Hz.


I'm thinking that would probably work OK. 22Hz is not *too* slow, I think. I may not even need to go that slow...not sure yet.

Will try to get a 3 phase 4 pole motor that bolts straight up and get a cheap VFD off Ebay. Shouldn't be too expensive.

Steve

Cutting Speed Calcs.jpg

Have a look a the VFDs on Aliexpress (half price of eBay - around $60 delivered to Australia).

I have a 6 pole motor here I plan to use for a large disc sander.
960 rpm same as a Wadkin 30” disc.
These are not easily obtainable like 4 pole but might be worth keeping an eye out for.
H.

If you want to cut anything other than aluminium, you're still going to be running at least 3 times too fast for bimetal at 22hz, and even more so for carbon steel...

https://austechsaw.com.au/documents/Speed%20Chart.pdf

Always the downfall of converting wood saws, you usually need two steps due to the amount of speed change required - in other words, you'd need to combine a pulley swap with your motor change.

Originally Posted by Jekyll and Hyde

If you want to cut anything other than aluminium, you're still going to be running at least 3 times too fast for bimetal at 22hz, and even more so for carbon steel...

https://austechsaw.com.au/documents/Speed%20Chart.pdf

Always the downfall of converting wood saws, you usually need two steps due to the amount of speed change required - in other words, you'd need to combine a pulley swap with your motor change.

OK..thanks.

I might be sunk....Just got a quote for a new motor....$500! Not as cheap as I thought. I bought one a couple of years ago and it was no where new that.
Time to fall back and regroup....lol

I just spotted an obvious mistake on my part.....which makes all this moot.
My motor is already 4 pole, as it spins at 1440 rpm. I'm a bit rusty and the motor doesn't have a name plate.......grrrrr

A 4 pole 3 phase motor won't improve things. I will need more pulley speed reduction than what I have, as mentioned, by others.