GraemeVW
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This is what I thought I'd read before.
Am I right in thinking you can wire the motor for one speed and then use one?
- Thread starter GraemeVW
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This is what I thought I'd read before.
Am I right in thinking you can wire the motor for one speed and then use one?
GraemeVW
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I just Took this pic
I have a few questions you might be able to answer actually, mind if I send you a PM?
Lewis_RX8
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Yea most on eBay and import sites are 220v 3 phase outputs but they just advertise as 3 phases have to check the details for the output voltage, you need a boost VFD that outputs 3 phase 440v as that's what mine runs on two speed happily
Lewis_RX8
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Looks like the same winding as me ,Sure send a PM or ask here I don't mind.
Ubique
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The motor is rated at half the speed as @Lewis_RX8 's motor.
GraemeVW
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Indeed. And yet the lathe is 34 to 1500 rpm.
Can I not just bang a single phase motor in it?
If not, I'm assuming a 1400rpm 3 phase and drop revs with a vfd may be easier than if 1400rpm was the low speed?
I don't know, clueless.
GraemeVW
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Ah, I see where your coming from now.
GraemeVW
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They did do this lathe in single phase.
I assume though that using a single phase motor I'll have no way of getting the low speeds, where if I used a 3 phase motor, I can at least vary with a vfd.
If I could use the original speed change switch to switch between 2 settings on a vfd, that would be ace!
I assume though that using a single phase motor I'll have no way of getting the low speeds, where if I used a 3 phase motor, I can at least vary with a vfd.
If I could use the original speed change switch to switch between 2 settings on a vfd, that would be ace!
Ubique
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Electric motors are designed to have peak torque at their rated frequency, significantly higher or lower will reduce the available torque and increase the temperature of the motor with a constant load. Not really a consideration with something like a pillar drill that has lots of on/off cycles but a lathe can be run for some time. Personally, I'd look to use the gearing more and use a VFD to fine tune the speed.
You can but a 3phase with a VFD is far better.
GraemeVW
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Could easily be done. It's undoubtedly a rotary changeover switch. Depending on the switch you could probably have more speeds as well. eg 1/2 speed, full speed, 1-1/3 speed and maybe even have a v/r controlled speed.
Certainly it's better to try and use the gears *first* then vary the motor.
With a newer VFD rated motor you can go down to 5Hz and up to 75Hz (some will do higher) but with an old motor I'd be wary of going too far either way, although with a 2 speed you do at least know it's ok to run at half speed. I'd probably keep it 25Hz-60Hz.
Lewis_RX8
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It is indeed a rotary changeover switch.
See behind the speed select switch , I use that first for most turning jobs high or low speed select on the original switch gear but can also vary frequency if I want but don't really need to that often there is enough speeds with gears and the switch in my opinion.
Undoubtedly the different motor speeds. Doesn't that little bit on the far left say "1962 & 981 RPM"? That's almost certainly the input speed.
Although the actual gearing is different you'll probably find it's similar to Harrisons which also had 8 speeds with the option of a two-speed motor.
31 to 720 rpm - 1.5 hp 1500 rpm motor (750RPM input).
42 to 960 rpm - 2 hp 1500 rpm motor (1000RPM input).
62 to 1440 rpm - alternative range with the 2 hp 1500 rpm motor (1500RPM input).
31 to 1400 rpm - 16 speeds: two-speed 1.5/3 hp 1500/3000 rpm motor (750/1500RPM input).
There may have been different versions of the single speed version of yours that did 34-750RPM or 68-1500RPM and maybe even an intermediate one. You have any option you want if you change the drive pulley.
FWIW as I replaced the motor on my Harrison L5 I went with the 31-720RPM range to start with, this gave me with the VFD 3RPM to 1296RPM with under and overspeeding.
Reality was however with carbide rather than HSS I barely used the bottom end of the speed range and as I was using it mostly at night I'd back it down to 33Hz for noise reasons. So I bumped the pulley up to give the 62 to 1440 rpm range on the gears instead. That still has a bottom speed of 6RPM but now a scary (from a 1940's lathe) 2880RPM top speed.
Ubique
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Can't help you there - i'm sure someone will know better, my first thought would be to pick the lower range and overdrive to get the higher range - the benefit of a faster speed is increased cooling so if the motor is working harder, at least it'd be getting a corresponding better airflow. doing it the other way round, you'd be driving it slower but losing some of the airflow cooling. Maybe a VFD rated motor (and VFD) is the way to go?
GraemeVW
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Maybe. That's still within what I was sort of expecting to pay.
It's just the 1k rotary that was a surprise!
As I wrote above I'd *personally* go the other way round if you're going to use carbide rather than HSS.
If you use a 4 pole 1440 rpm motor (this being closest to the original) with approximately a 3:4 ratio (I make it to be 0.733945:1 to match the ratio to give 1962RPM input to the head while the original would have been 0.713558:1 as it was a 1400rpm not 1440rpm motor) it would then give the original range at 50Hz.
As an example (and it is only an example) https://inverterdrive.com/group/Motors-AC/Universal-UMHA-100L-4-B34/ being rated between 5Hz and 70Hz would then give an range of 6.8RPM to 2100RPM.
Or if you use a cheaper 2 pole 2860 rpm motor (for example https://inverterdrive.com/group/Motors-AC/Universal-UMHA-90L-2-B3/ ) with a different ratio (approx. 1.43:1) it would again give the same original range at 50Hz but overall have a slightly wider range of 6.8RPM to 2250RPM (as it's rated to 75Hz rather than 70Hz).
All that said, I don't know how advisable it is to overspeed the students. I'm reasonably happy to do so with the Harrison L5as they produced a higher speed (2000RPM) version with no fundamental changes except to the clutch but a quick browse of the page for the Student seems to suggest 1500RPM was the fastest option.
really? you had a static go bang, just from switching?
