I've been contemplating on buying a small cheap lathe to both learn how to operate one and to do some barrel work just as a small hobby. Anyways, I've noticed some of the cheap new lathes from like grizzly use single phase motors and don't really go lower then like 150 rpm so I was wondering would it be possible to use a single phase to single phase VFD to control the speed of the motor to get it below 150 for like chambering barrels? Or are they more suited for single phase to 3 phase applications?
Gunsmithing VFD on a lathe?
- Thread starter acebanana
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Re: VFD on a lathe?
I have a VFD on my Logan lathe wired thru a drum switch and I can dial it down to 1 RPM if desired. The VFD lets you set ramp up and braking time and some other neat stuff to play with.
My lathe has back gears so I do not change the speed much. I was ID threading to a shoulder and I did slow it down for that. My motor was 3-phase and I went VFD to avoid a static phase converter or a rotary type converter.
I have a VFD on my Logan lathe wired thru a drum switch and I can dial it down to 1 RPM if desired. The VFD lets you set ramp up and braking time and some other neat stuff to play with.
My lathe has back gears so I do not change the speed much. I was ID threading to a shoulder and I did slow it down for that. My motor was 3-phase and I went VFD to avoid a static phase converter or a rotary type converter.
Re: VFD on a lathe?
Here is one option for a single-phase-output VFD up to 1.5HP:
http://anaconsystems.com/text/opti_e2.html
Refer to the data sheet for information on compatible motors (not all single-phase induction motors will work with a VFD). You're looking at approximately $500 for such a device, which may not be an intelligent investment for a $1000 lathe.
A better approach might be to find an appropriately-sized three-phase motor for one of these lathes, which would allow the use of the far more common (and far less expensive) VFDs for three-phase motors. You would also get far better performance at low motor speeds. I am not a huge fan of single-phase induction motors, and certainly not in an application where they would be asked to provide high torque at low speeds.
Here is one option for a single-phase-output VFD up to 1.5HP:
http://anaconsystems.com/text/opti_e2.html
Refer to the data sheet for information on compatible motors (not all single-phase induction motors will work with a VFD). You're looking at approximately $500 for such a device, which may not be an intelligent investment for a $1000 lathe.
A better approach might be to find an appropriately-sized three-phase motor for one of these lathes, which would allow the use of the far more common (and far less expensive) VFDs for three-phase motors. You would also get far better performance at low motor speeds. I am not a huge fan of single-phase induction motors, and certainly not in an application where they would be asked to provide high torque at low speeds.
Re: VFD on a lathe?
Its been a good miute since I did any kinda electrical work. The VFDs I am use to working with were all for 3ph stuff and were in the $8k and up price range. There was a hospital that had a single phase speed controller on an exhaust fan. I learned on that job that if you are going to use something like that, then you must put a motor on there that was designed to have its speed controlled. I have no clue what type of motors are on lathes, but you might want to look into it. The single phase ones, I recall, were only rated for fractional HP and Amps, depending on voltage.
Its been a good miute since I did any kinda electrical work. The VFDs I am use to working with were all for 3ph stuff and were in the $8k and up price range. There was a hospital that had a single phase speed controller on an exhaust fan. I learned on that job that if you are going to use something like that, then you must put a motor on there that was designed to have its speed controlled. I have no clue what type of motors are on lathes, but you might want to look into it. The single phase ones, I recall, were only rated for fractional HP and Amps, depending on voltage.
Re: VFD on a lathe?
If the motor is really old ( windings with poor insulation )a VFD can hammer it more than a regular 3 phase input. The VFD does not output a sine wave curve of power, its more like a switching vertical line straight up and down,repeat. This voltage hammering ( I was told by one of our EE types) can have a negative effect IF the motor insulation is "iffy".
3-phase and DC servo motors works well for speed control. I never played with AC motors but the availability is fewer and more expensive.
If the motor is really old ( windings with poor insulation )a VFD can hammer it more than a regular 3 phase input. The VFD does not output a sine wave curve of power, its more like a switching vertical line straight up and down,repeat. This voltage hammering ( I was told by one of our EE types) can have a negative effect IF the motor insulation is "iffy".
3-phase and DC servo motors works well for speed control. I never played with AC motors but the availability is fewer and more expensive.
Re: VFD on a lathe?
Why would you want to chamber barrels at less than 150RPM? High speed steel reamers are called that for a reason. Chamber around 270RPM for better finish.
Why would you want to chamber barrels at less than 150RPM? High speed steel reamers are called that for a reason. Chamber around 270RPM for better finish.
Re: VFD on a lathe?
Thanks guys, I'll definitely look into the prices for buying one of the cheaper lathes and switching out the motor for a 3 phase vs a better lathe. Had no idea VFD's were that expensive for single phase.
As for wanting lower rpm, I had assumed after reading a couple discussions on the interwebz it was better to use a much lower speed (one guy said he prefered ~67rpm) for chambering without a system to keep oil flowing and reduce chatter. I figured a infinitely adjustable speed would be better than being limited to changing gears for a set selection of speeds any ways.
Thanks guys, I'll definitely look into the prices for buying one of the cheaper lathes and switching out the motor for a 3 phase vs a better lathe. Had no idea VFD's were that expensive for single phase.
As for wanting lower rpm, I had assumed after reading a couple discussions on the interwebz it was better to use a much lower speed (one guy said he prefered ~67rpm) for chambering without a system to keep oil flowing and reduce chatter. I figured a infinitely adjustable speed would be better than being limited to changing gears for a set selection of speeds any ways.
Re: VFD on a lathe?
I dont know anything about lathes, but I am an Electrician by trade. You will need to use motors that are inverter duty rated to avoid overheating. Motors that are not rated and used with a VFD will have a short life.
I dont know anything about lathes, but I am an Electrician by trade. You will need to use motors that are inverter duty rated to avoid overheating. Motors that are not rated and used with a VFD will have a short life.
Re: VFD on a lathe?
All the VFD's I have seen are three phase out. I am in the process of rebuilding a South Bend Heavy 10 I got for cheap. I picked up a Hitachi WJ200 for my mill rated for 2HP and it was around $200. Probably get the same for my lathe since I like those a little more. You can get Teco FM-50's for a better price. Many guys have done it with the results you are looking for at around $125-150. Lots of good info on the Teco drives.
Here's a good place to start for VFD's:
http://dealerselectric.com/mfg-subcat-item.asp?cID=0&scID=164&mID=-1&Format=
All the VFD's I have seen are three phase out. I am in the process of rebuilding a South Bend Heavy 10 I got for cheap. I picked up a Hitachi WJ200 for my mill rated for 2HP and it was around $200. Probably get the same for my lathe since I like those a little more. You can get Teco FM-50's for a better price. Many guys have done it with the results you are looking for at around $125-150. Lots of good info on the Teco drives.
Here's a good place to start for VFD's:
http://dealerselectric.com/mfg-subcat-item.asp?cID=0&scID=164&mID=-1&Format=
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