Tree Lathe Retrofit
16 Feb 2015 06:20 #55995
by vertcnc
Tree Lathe Retrofit was created by vertcnc
I am looking at retrofitting a Tree Lathe. Most likely updating servo motors and drives. Turret is hydraulic with switches to sense position. The biggest question is what to do about the Siemens DC spindle 5HP motor and drive. I don' have much data on it except for it appears the drive has 200V AC 3 phase input. Motor has tach. to drive. Separate encoder on spindle shaft.
I am guessing the cheapest would be to try and use current drive. Really would like lathe to be single phase.
Should I ditch the DC motor and drive and use VFD and new AC motor?
Any options for maybe a different drive?
Any Ideas would be appreciated.
I am guessing the cheapest would be to try and use current drive. Really would like lathe to be single phase.
Should I ditch the DC motor and drive and use VFD and new AC motor?
Any options for maybe a different drive?
Any Ideas would be appreciated.
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16 Feb 2015 22:40 #56012
by andypugh
Replied by andypugh on topic Tree Lathe Retrofit
it is possible that the drive can work on single-phase.
The input stage of any drives is a 3-phase rectifier, so many will work perfectly happily on single phase of the correct voltage.
Alternatively many drives allow power-sharing via shared DC-bus connections, so you could arrange your own rectifier and filter capacitor setup and connect to those terminals.
The first place to look is probably the drive manual if you can find it. Experimenting with single-phase input to each terminal combination is unlikely to damage anything. (a drive ought to be resilient to failure of an input fuse on a single phase).
You ought to be able to replace the drive and keep the motor, which is likely to be cheaper than swapping both, but keeping both is likely to be better still.
The input stage of any drives is a 3-phase rectifier, so many will work perfectly happily on single phase of the correct voltage.
Alternatively many drives allow power-sharing via shared DC-bus connections, so you could arrange your own rectifier and filter capacitor setup and connect to those terminals.
The first place to look is probably the drive manual if you can find it. Experimenting with single-phase input to each terminal combination is unlikely to damage anything. (a drive ought to be resilient to failure of an input fuse on a single phase).
You ought to be able to replace the drive and keep the motor, which is likely to be cheaper than swapping both, but keeping both is likely to be better still.
The following user(s) said Thank You: vertcnc
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17 Feb 2015 01:41 #56018
by vertcnc
Replied by vertcnc on topic Tree Lathe Retrofit
Not sure I can find manual for Siemens drive, Just a rack with bunch of boards. I am leaning toward new spindle motor and VFD. Question is what size motor? The current motor has about and 18" pulley on the motor side and about a 6" on the spindle side. I am pretty sure with standard AC motor I could downsize the motor pulley and probably get away with a 3-5 HP motor. So with this combination.and retaining the encoder on the spindle, what king of capability will I have. Threading?
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17 Feb 2015 02:01 - 17 Feb 2015 02:02 #56023
by andypugh
If you swap the DC motor for an AC asynchronous motor you will lose a lot of low-speed torque. This probably means that you will lose the ability to index the spindle.
Unless you use live-tooling this probably doesn't matter. But it does seem a shame.
Threading synchronises the carriage to the spindle encoder, it doesn't matter what is driving the spindle. It still works when you drive the spindle by hand.
Replied by andypugh on topic Tree Lathe Retrofit
So with this combination.and retaining the encoder on the spindle, what king of capability will I have. Threading?
If you swap the DC motor for an AC asynchronous motor you will lose a lot of low-speed torque. This probably means that you will lose the ability to index the spindle.
Unless you use live-tooling this probably doesn't matter. But it does seem a shame.
Threading synchronises the carriage to the spindle encoder, it doesn't matter what is driving the spindle. It still works when you drive the spindle by hand.
Last edit: 17 Feb 2015 02:02 by andypugh.
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17 Feb 2015 08:25 #56043
by vertcnc
Replied by vertcnc on topic Tree Lathe Retrofit
I don't have live tooling, so that probably won't be an issue. If I use a Sensorless Vector VFD maybe torque won't be a big issue. I think the problem using the old Siemens drive is trying to come up with the three legs of 200V from the 220v line voltage and no support for 25 year old equipment.
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17 Feb 2015 08:29 #56044
by andypugh
If you are prepared to swap it out then there isn't a lot to be lost by seeing if it will run on single phase.
Replied by andypugh on topic Tree Lathe Retrofit
I think the problem using the old Siemens drive is trying to come up with the three legs of 200V from the 220v line voltage and no support for 25 year old equipment.
If you are prepared to swap it out then there isn't a lot to be lost by seeing if it will run on single phase.
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18 Feb 2015 06:00 #56061
by vertcnc
Replied by vertcnc on topic Tree Lathe Retrofit
True, Maybe I will give it a try.
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