AC with VFD or 180V DC for lathe?

[Ross77]

Im looking for the best option to power a small lathe. (ML10)

The standard motor is a 1/2hp 180v Dc motor but Ive killed the controller and a replacement is about £115. It looks like I could have issues with the 0-10v speed control and need an isolated supply etc.

I would like to do threading so wonder if I should swap it out for an 1.5hp AC motor and VFD to give plenty of power and easier connection to the BOB.

Any pro's for sticking with the original DC or swap it out? thanks in advance

[magicniner]

You'll get higher low speed torque from a DC motor of a given power but for a given spend on motor and controller you can get a much wider speed range from a 3 phase motor & VFD.

I run a 1hp 3ph 2 pole motor at 7000rpm all day on my benchtop CNC Mill, the VFD is Siemens, the motor is a Compact Frame Electro Adda. My Myford S7 has a 1hp 3ph 4 pole TEE motor and a Siemens VFD, the motor and lathe are comfortable at 3000rpm.

For a given total spend you will probably be able to get a better spread of power, torque and speed using a 3 phase motor with the right power and gear/pulley drive ratio but that will probably cost more than just replacing your DC drive.

- Nick

[Clive S]

My Myford S7 has a 1hp 3ph 4 pole TEE motor and a Siemens VFD, the motor and lathe are comfortable at 3000rpm.
May I ask the model of the VFD and have you changed any of the drive line or kept the original belts etc.

[magicniner]

Micromaster Vector, one of the old ones with LED display rather than LCD, belts are just what my local industrial supplier can provide in the correct length.
The head is on taper rollers with 30.5mm through capacity though, the standard pulleys transmit power well enough for this -

https://youtu.be/pUI2GIGTz_c

30mm 304, 2.5mm depth of cut, the video was actually shot to show the capability of the Dickson clone QCTP

[Ross77]

For a given total spend you will probably be able to get a better spread of power, torque and speed using a 3 phase motor with the right power and gear/pulley drive ratio but that will probably cost more than just replacing your DC drive.

Thanks Nick, I already have an inverter but would have been a pain swapping the motor as i needed a 100x 125 mount spacing witha 14mm shaft which meant a new pulley or fudge the mounts.

Ive picked up a cheap sprint 400i DC controller which has isolated inputs so I will stick with the DC to get it up and running and learn with, then upgrade later.

Thanks

[Clive S]

Micromaster Vector, one of the old ones with LED display rather than LCD, belts are just what my local industrial supplier can provide in the correct length.
The head is on taper rollers with 30.5mm through capacity though, the standard pulleys transmit power well enough for this -

https://youtu.be/pUI2GIGTz_c

30mm 304, 2.5mm depth of cut, the video was actually shot to show the capability of the Dickson clone QCTP

Thanks for the info Nick My Myford S7 is only 3/4" bore:upset: but it is CNC'd and can cut threads nicely.

[Toolman321]

I recently had a simalar decision to make for a denford mill spindle drive, in the end I decided to buy one of these controllers from eBay https://m.ebay.co.uk/itm/PWM-DC-Motor-Speed-Controller-AC180V-260V-Input-DC180V-Output-8A-Digital-Display-/282377725571?epid=591627938&hash=item41bf062683%3Ag%3A6SoAAOSwhQhYykMs&_trkparms=pageci%253Aa043d7a2-9a19-11e7-b98a-74dbd1a03495%257Cparentrq%253A85b90e3d15e0a9c4f03b 6d2fffedf74a%257Ciid%253A2 they are available as 8 amp or 4 amp versions and seem reasonably well built

[keith77777]

Hi Ross
i use ex washing machine motors on both my machines. 6 inch chuck lathe and Gingery clone horizontal mill. They have well enough torque and are variable speed. I make the controllers at calenterprises.

Best Regards Keith2510325104

[magicniner]

. I make the controllers at calenterprises.

Any chance of digital or analogue speed control?

[keith77777]

Hi magicniiner
Yes I have make a model which can use PWM to control the speed. I test it with Zeus but Mach 3/4 is supposed to give out similar pulses. You have to modify the tacho generator on the WM motor because the desgn is made for some of the older motors. I have that instruction in my on line leaflet. On a lathe its best to use the WM pulley for reduction. I had a chap use it on a pillar drill he complained the controller was getting hot but then it transpired he was trying it without reduction gear so the whole thing was under stress. I am an engineer electronics mechanical anything which is needed..

Cheers Keith