- Joined
- Dec 23, 2019
- Messages
- 1,138
Evening!
I'm looking for a bit of knowledge, discussion and collective noodling regarding some aspects of single phase mytors that don't seem to get much airtime...
Circumstances:
I'm building a Quorn tool and cutter grinder. As designed, it uses a ~2800 rpm 2 pole 1/6hp motor from Parvalux (though the brand is unimportant).
The conundrum(s):
I could buy new and be done with it. But they're not an insignificant amount of money. 2800rpm single phase motors that size are almost impossible to get hold of second hand - I assume because there's not much call for high speed/low torque. Most get geared down down way anyway, so what's the point?
Brushed motors alone are not an option as they rev their t*** off when unloaded. Not cool with an abrasive wheel that may explode.
My thoughts:
It's round belt drive (though I've not invested anything in parts design or construction of the pulley system at this stage), so easy enough to gear up from motor to spindle. My lowest rated wheel, I think is over 4000rpm, so that's the spindle speed I'm aiming for. 2.75:1 is not a completely stupid pulley ratio assuming a 1450rpm motor. I also have reservations (that may be unfounded) about the smoothness or lack thereof of a 2 pole motor. Is this actually an issue? Does a 4 pole give smoother torque delivery than a 2 pole? If so, is this negated in any way by gearing up through the pulleys
Other options:
3 phase motors are available cheaply second hand, but then I'd need a phase inverter/vfd, which seems rather heavy handed and more expensive than just buying a new 2800rpm motor.
Use a brushed universal motor from a vacuum cleaner and a closed loop speed controller. This does have compactness going for it.
Rewire a 4 pole to a 2 pole? I've successfully internally rewired 2 Dahlander configured 3 phase motors to standard delta, so that's not particularly scary if it's indeed possible. Though I was told by t'internet at large that rewiring a Dahlander motor without rewinding it was impossible. Pffff. Watch me!
Another option is to make a speed increasing gearbox, which I'm quite capable of doing.
And fill in the blank...... Talk to me, Goose.
I know, I know: just buy the high speed motor and save the bother... But I wouldn't be a hobby machinist if I wasn't always half engaged in finagling some crazy scheme to save precious tool money at the expense of dozens of hours, would I?
I'm looking for a bit of knowledge, discussion and collective noodling regarding some aspects of single phase mytors that don't seem to get much airtime...
Circumstances:
I'm building a Quorn tool and cutter grinder. As designed, it uses a ~2800 rpm 2 pole 1/6hp motor from Parvalux (though the brand is unimportant).
The conundrum(s):
I could buy new and be done with it. But they're not an insignificant amount of money. 2800rpm single phase motors that size are almost impossible to get hold of second hand - I assume because there's not much call for high speed/low torque. Most get geared down down way anyway, so what's the point?
Brushed motors alone are not an option as they rev their t*** off when unloaded. Not cool with an abrasive wheel that may explode.
My thoughts:
It's round belt drive (though I've not invested anything in parts design or construction of the pulley system at this stage), so easy enough to gear up from motor to spindle. My lowest rated wheel, I think is over 4000rpm, so that's the spindle speed I'm aiming for. 2.75:1 is not a completely stupid pulley ratio assuming a 1450rpm motor. I also have reservations (that may be unfounded) about the smoothness or lack thereof of a 2 pole motor. Is this actually an issue? Does a 4 pole give smoother torque delivery than a 2 pole? If so, is this negated in any way by gearing up through the pulleys
Other options:
3 phase motors are available cheaply second hand, but then I'd need a phase inverter/vfd, which seems rather heavy handed and more expensive than just buying a new 2800rpm motor.
Use a brushed universal motor from a vacuum cleaner and a closed loop speed controller. This does have compactness going for it.
Rewire a 4 pole to a 2 pole? I've successfully internally rewired 2 Dahlander configured 3 phase motors to standard delta, so that's not particularly scary if it's indeed possible. Though I was told by t'internet at large that rewiring a Dahlander motor without rewinding it was impossible. Pffff. Watch me!
Another option is to make a speed increasing gearbox, which I'm quite capable of doing.
And fill in the blank...... Talk to me, Goose.
I know, I know: just buy the high speed motor and save the bother... But I wouldn't be a hobby machinist if I wasn't always half engaged in finagling some crazy scheme to save precious tool money at the expense of dozens of hours, would I?
