- Joined
- Sep 23, 2014
- Messages
- 54
My adventure started with a burst of optimism guided by a lack of experience. After quite a bit of shopping I decided on a PM1340GT as best fitting my size requirement after a few years of using an inherited Atlas 10F. After the Atlas experience I was convinced that an old style gearbox and variable speed would be a great leap forward, so I ordered the three phase model and the Hitachi NT925AX supplied by PM. I assumed the conversion would be a piece of cake when in fact it is quite difficult if you are not experienced in electronics. I made it more difficult by deciding to do the installation in the original Electrical Control Box (ECB) on the rear of the headstock.
After installing the lathe I set out to do the “piece of cake” conversion. Boy, was I surprised. I began to do some research and got a lot of help from MKSJ on the Hobby Machinist Site including a complete parts list and sources. My original idea of reusing some of the relays was bogus and in fact you need to toss everything except the control transformer and the connector strip. Along the way the control transformer shorted out so I replaced itwith a higher quality model.
The following photos show what I did, but take note:
• I did not put the VFD in a NEMA enclosure, but I did protect it from bumps and splashes.
• My shop is private and I have no children or pets in the shop so I have some hot connections in reach of prying fingers
• I have a lot of experience with line voltage wiring.
• I am cheap and prefer to reuse items that I have “in stock”.
1.1 Wood shelf attached to top of ECB and overlaps the PM1340GT splash guard to protect VFD from splashes. Note the space above VFD for ventilation.
1.2 ECB door.
1.3 Alum angle screwed to ECB door.
1.4 Alum angle frame around VFD for physical protection.
1.5 VFD controls are fully accessible.
1.6 220VAC 1 phase in from switched outlet on the wall at tailstock end of lathe. Goes to line voltage connector strip.
1.7 220VAC 1 phase out to VFD.
1.8 12VAC line to work light. I changed bulb to 12V. 24V hard to find.
1.9 220V 3 phase from VFD to motor.
1.10 Lathe control wiring from ECB to VFD.
1.11 Work light bracket.
2.1 Corners of frame are cut so that the faces of the angles are flush. It would have been nice to weld connections but I don’t have the equipment.
3.1 220VAC to 6VDC wall wart to power MachTach.
3.2 220VAC from line voltage connector strip.
3.3 220VAC fuses from line voltage connector strip to Control Transformer. Both legs are fused.
3.4 MachTach sensor wiring to MachTach.
3.5 Line voltage connector strip.
3.6 12VAC Control relay.
3.7 New Control Transformer.
3.8 12VAC fuse from control transformer to work light and control relay.
3.9 Low voltage connector strip.
3.10 MachTach sensor wiring out to sensor on spindle. See photo 7.
4.1 New 12V LED pilot light.
4.2 Wood knob on new potentiometer. This replaces PUMP switch which I did not order.
4.3 Direction switch for Jog button. This is really handy.
5.1 Modified barrel bolt to latch ECB door closed. Door is held open with a bungee cord.
Note how the shelf is attached to the top of the ECB.
6.1 MachTach mounted on a wood block angled up toward the operator.
It does get splattered by oil from chuck.
7.1 Bushing over existing stud for gear cover. You may have to remove stud and add some threads.
7.2 Existing threaded stud for gear cover.
7.3 Nut and washers to clamp bracket.
7.4 MachTach sensor on aluminum bracket.
So far everything works well. The variable speed is terrific and worth the effort.
After installing the lathe I set out to do the “piece of cake” conversion. Boy, was I surprised. I began to do some research and got a lot of help from MKSJ on the Hobby Machinist Site including a complete parts list and sources. My original idea of reusing some of the relays was bogus and in fact you need to toss everything except the control transformer and the connector strip. Along the way the control transformer shorted out so I replaced itwith a higher quality model.
The following photos show what I did, but take note:
• I did not put the VFD in a NEMA enclosure, but I did protect it from bumps and splashes.
• My shop is private and I have no children or pets in the shop so I have some hot connections in reach of prying fingers
• I have a lot of experience with line voltage wiring.
• I am cheap and prefer to reuse items that I have “in stock”.
1.1 Wood shelf attached to top of ECB and overlaps the PM1340GT splash guard to protect VFD from splashes. Note the space above VFD for ventilation.
1.2 ECB door.
1.3 Alum angle screwed to ECB door.
1.4 Alum angle frame around VFD for physical protection.
1.5 VFD controls are fully accessible.
1.6 220VAC 1 phase in from switched outlet on the wall at tailstock end of lathe. Goes to line voltage connector strip.
1.7 220VAC 1 phase out to VFD.
1.8 12VAC line to work light. I changed bulb to 12V. 24V hard to find.
1.9 220V 3 phase from VFD to motor.
1.10 Lathe control wiring from ECB to VFD.
1.11 Work light bracket.
3.1 220VAC to 6VDC wall wart to power MachTach.
3.2 220VAC from line voltage connector strip.
3.3 220VAC fuses from line voltage connector strip to Control Transformer. Both legs are fused.
3.4 MachTach sensor wiring to MachTach.
3.5 Line voltage connector strip.
3.6 12VAC Control relay.
3.7 New Control Transformer.
3.8 12VAC fuse from control transformer to work light and control relay.
3.9 Low voltage connector strip.
3.10 MachTach sensor wiring out to sensor on spindle. See photo 7.
4.1 New 12V LED pilot light.
4.2 Wood knob on new potentiometer. This replaces PUMP switch which I did not order.
4.3 Direction switch for Jog button. This is really handy.
5.1 Modified barrel bolt to latch ECB door closed. Door is held open with a bungee cord.
Note how the shelf is attached to the top of the ECB.
6.1 MachTach mounted on a wood block angled up toward the operator.
It does get splattered by oil from chuck.
7.1 Bushing over existing stud for gear cover. You may have to remove stud and add some threads.
7.2 Existing threaded stud for gear cover.
7.3 Nut and washers to clamp bracket.
7.4 MachTach sensor on aluminum bracket.
So far everything works well. The variable speed is terrific and worth the effort.
