I think I screwed up a Hardinge TM mill purchase.

I am very new to machining as a hobby. Found a decent looking Hardinge TM mill locally to buy that the seller was asking plenty for. Not having to drive the old gas hog pickup for 5 hours each way to a better area for buying machine tools was very appealing. I was assured it ran fine. Seller was on his lunch hour, in a hurry to get back to work, and the lathe in his shop was hard wired to a roto phase. He did not have the mill hooked up as he did not want to unhook his lathe. The mill was wired with a 3 phase 220 plug, and the transformer in the electrical box on the side of the mill for the 110 volt controls was wired for 220. I made shure to check. Should be 220 - right? Well today I hooked it up to my VFD that I use to run a couple other machines in the shop. Got some humming, power light is on, But no go. Have 110 volt on the control circuits. Looked inside and the motor plate is 440 volt. Not dual voltage, si I cannot just change wires? And maybe the little belt drive motor in there that I think does the 2 speed might not play well with a VFD? Am I screwed? Can I put a 220 volt 3 phase motor in and will it have 2 speeds? Help please.

Buy a transformer

D6Joe said:

I am very new to machining as a hobby. Found a decent looking Hardinge TM mill locally to buy that the seller was asking plenty for. Not having to drive the old gas hog pickup for 5 hours each way to a better area for buying machine tools was very appealing. I was assured it ran fine. Seller was on his lunch hour, in a hurry to get back to work, and the lathe in his shop was hard wired to a roto phase. He did not have the mill hooked up as he did not want to unhook his lathe. The mill was wired with a 3 phase 220 plug, and the transformer in the electrical box on the side of the mill for the 110 volt controls was wired for 220. I made shure to check. Should be 220 - right? Well today I hooked it up to my VFD that I use to run a couple other machines in the shop. Got some humming, power light is on, But no go. Have 110 volt on the control circuits. Looked inside and the motor plate is 440 volt. Not dual voltage, si I cannot just change wires? And maybe the little belt drive motor in there that I think does the 2 speed might not play well with a VFD? Am I screwed? Can I put a 220 volt 3 phase motor in and will it have 2 speeds? Help please.

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Not a major disaster. That mill uses very small motors. It won't cost a great deal if you have to replace them outright. And you probably will NOT have to.

Ex: If a specific 440 V motor cannot be "re-connected" for 240 V, it can assuredly be "re-wound" for 240 V, and perhaps it already HAS been. The PO may have simply used a transformer instead.


First.. the quality of the information so far furnished needs improvement.

Job One is a phone call to ask the PO what he WAS running it on. Be polite. "Puzzled" is a good opener. "Angry", not so much. Sellers get defensive and you'll not get the info you need.

Job two is to get ALL the nameplate data off the motors. Decent photos you can post here highly recommended.

Set the VFD aside for now. You are not ready for it yet. Most especially "not ready" to damage it!

Are you supposed to / can you run a transformer from 220 to 440 from a VFD?

D6Joe said:

Are you supposed to run a transformer from a VFD?

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I'm "supposed to do" a lot of things.



Irrelevant question until we know what you have and have need of.

But "in general".. Where needed, either a single-phase transformer on the utility mains side of a VFD ELSE a 3-Phase transformer on the load motor side of the VFD can work. VFD has to be rated for one, the other, or BOTH of the voltages involved.

EX: I just threw away a 10 HP Altivar 71 VFD. It was 380-440 Volt input, same-same output, and functional. However ... the silly transformer was taking up too much space, the load was re-connectible to 240 V, and did not need the variable speed feature of a VFD (has a Reeves VariDrive clone). RPC or Phase-Perfect made better overall sense and last longer than VFD's do anyway.

Pics of motor plates, Only have 220 v single phase in shop. Using a VFD to make 220 v 3 phase, rated for up to 7.5 hp. Do not think it’s transformer rated. Is putting out About 190 volts on each leg so my meter says. I run a 3 hp grinder and a 2 hp mill just fine with it.
The little “switch motor” has 110 v on tag. Main motor is 440 volt 3 phase. Pics on I pad were very good, did not translate well to lower resilution. Sorry. I can type in plate data if helpful.

The original motors used in the mills are 3/8 HP at 975 RPM and 3/4 HP at 1750 RPM. I recall that they have 3/4" shafts, which is not a modern standard, so the frame size is also not a modern standard.

If you have an original motor with 220 V three phase input, you can get a 1 HP VFD with 110 V single phase input and connect the output to the high speed windings of the motor and run the mill from an ordinary 110 V outlet. They are very simple to operate that way, but you have to get rid of the 220/110 transformer and run a separate 110 V line to the machine light. You also should rewire the old drum switches to operate the low voltage control inputs on the VFD. Never put a switch between the motor and the VFD. There is no advantage to using the drum switch for low speed; just set the VFD to 30 Hz to get low, or dial in any frequency between 30 and 90 Hz.. The cleanest solution is to not use the drum switches at all and only use the controls on the VFD for on/off, direction and speed.

The 440 V motor is not worth the very high cost of rewinding. I do not like the 220/440 transformer and 440 V VFD idea, which is also expensive.

I suggest this: It is often possible to find a 1 HP 1150 or 1750 RPM 220 V three phase motor in new or at least OK condition for well under $100, so I suggest you look at what is on eBay. Do not get a 3450 RPM motor. Once you hook up to a VFD, there is no advantage to using a two-speed motor. The VFD does the speed controlling. You may have to drill new holes in the mill's motor mount plate and adapt the motor pulley to a 7/8" motor shaft, but that is not difficult.

Larry

Thanks. I am kicking myself for not having run it before handing over the cash. Every other machine I bought I at least seen it run. Ggggrrrr.

D6Joe said:

Thanks. I am kicking myself for not having run it before handing over the cash. Every other machine I bought I at least seen it run. Ggggrrrr.

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There doesn't appear to be a damned thing wrong with it. So far.

MUCH nicer than most others I've seen on PM.

It is your power environment that has the shortcomings.

D6Joe said:

Pics of motor plates, Only have 220 v single phase in shop. Using a VFD to make 220 v 3 phase, rated for up to 7.5 hp. Do not think it’s transformer rated. Is putting out About 190 volts on each leg so my meter says. I run a 3 hp grinder and a 2 hp mill just fine with it.
The little “switch motor” has 110 v on tag. Main motor is 440 volt 3 phase. Pics on I pad were very good, did not translate well to lower resilution. Sorry. I can type in plate data if helpful.

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If you are CERTAIN it sez 3-P and 440 VAC (which I cannot read, even zoomed), then good enough. Confirm with the PO as to what HE was using to power it.

My guess is it was an RPC + transformer, and that he is STILL using the RPC to power other equipment, but maybe NOT the transformer.

BTW - What you have already been doing is not a great way to use a VFD. They like to be "married" to a single load if they are to live very long.

Your newly acquired mill has a 3/4 HP (max) two-speed primary drive motor.

If you can budget a new VFD of - I suggest 2 HP - dedicate it to the mill. It needs to be rated for 220/240 VAC single-phase IN, and will provide 220/240 VAC 3-Phase OUT.

You'll then need to follow that output with a 3-Phase 220/240 <=> 440/480 VAC transformer as well. Voltage is not overly critical. Just remember it needs to be THREE PHASE. Used is OK for that. A 1.5 KVA size is slight overkill, but probably cheaper than anything smaller because it is so common.

If you use an RPC + transformer instead, you could also power some or all of the other machines mentioned with it.

Personally, I'd change-out the motor to DC, but thats easy for me to say. I keep a stash of DC motors and DC Drives!



Others might go to a single-phase motor. This size mill has, and will, make chips just fine on single phase.

Monarchist said:

...Others might go to a single-phase motor. This size mill has, and will, make chips just fine on single phase.

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Except you will only have four spindle speeds instead of eight (or infinite, with the VFD).

Larry

I have the VFD wired in the shop on the cheap. I put a 3 phase plug in on the output side so only one machine can be used/plugged in at a time. Did not want to get too permanent as a machine tool room addition may be in the works. I am really enjoying the bit of amateur machining I am doing.

D6Joe said:

I have the VFD wired in the shop on the cheap. I put a 3 phase plug in on the output side so only one machine can be used/plugged in at a time. Did not want to get too permanent as a machine tool room addition may be in the works. I am really enjoying the bit of amateur machining I am doing.

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No fear. VFD are consumables anyway.

New caps at 7 to 9 years in cost more than a new VFD, so a new one makes more sense, usually.

That's part of why I prefer Dee Cee. No caps.

The DC MOTOR's brushes wear. But @ 2,000 POH hours or so life expectancy, a set is "the rest of my life" at my age.

L Vanice said:

Except you will only have four spindle speeds instead of eight (or infinite, with the VFD).

Larry

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They weren't born with VFD's. Pulleys are still cheaper. 2-speed motor still works off an RPC, no control or wiring changes needed.

A VFD's variable range has practical limits as far as useful torque and HP anyway.
So, too, DC. Just handier ones for Old Iron RPM's and HSS tooling.

I could not read a voltage rating from the picture you posted. If it is straight 440V I am running the same motor in my UM. I made a rotary phase converter from a 1 1/2 or 2 HP (forgot the exact size) 3Ph 220/440V 1725 RPM motor. Requires a 220v to 440v transformer and a few oil filled capacitors for some balance. I was given a Hoffman box so all the components fit and the box mounts behind the mill. Its been running for 15 years...no problems. If you want to go this route and need some assistance let me know. This was the cheapest method for me at the time.

Interesting. I put it back up on Craigslist for now. If it doesn’t sell, I will look hard at getting it to work in my shop. I wanted it for the horizontal part, I have a virticle mill, so I am going to catch my breath and see what happens.

Don't give up yet.

The advantage to an RPC is that it'll run all your machines without replugging into the VFD and changing the VFD settings settings. And it's cheaper and allows more opportunity for expansion. The kicker is that you'll have to learn a bit about RPC's. It's not hard, you don't have to learn much theory, just connections and minor concepts.

Your 220V 3 phase equipment could be easily run by a 3 phase, 9 lead motor (25$? $50?) and a pull-to-start rope from an old lawnmower. After that, you can expand into self starting, with power factor correction, load centers for more sophisticated current protection, more safety equipment, yadda, yadda, all good reasons, btw. But a motor and a pull rope just flat out works.

Add the aforementioned 220/440V 3 phase transformer for the mill, and you're good to go.

D6Joe said:

Interesting. I put it back up on Craigslist for now. If it doesn’t sell, I will look hard at getting it to work in my shop. I wanted it for the horizontal part, I have a virticle mill, so I am going to catch my breath and see what happens.

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Well. a Hardinge TM or TU is about as cute a small horizontal since the Cataracts. But neither of those have much balls. Even the crude, rude, and socially unacceptable Burke # 4 typically has 2 or 3 times the guts. That due to having the far higher-torque capable #9 B&S taper in its cheap-arsed WWII Jeep wheel bearinged spindle.

Unless you are making nought but mortise locks or Cuckoo clock sized goods, as you are to start-over on seeking a horizontal, the not so easy to find but still out there 9 B&S should be your absolute minimum, a 40-taper spindle far, far better yet.

A Nichols "the mill that uses its head" can be found in either B&S or NMTB now and then.
Sheldon (Vernon) made a very compact mill, space-wise. US Burke/Houdaille/Powermatic had another very solid and space-efficient model.

D6Joe said:

Interesting. I put it back up on Craigslist for now. If it doesn’t sell, I will look hard at getting it to work in my shop. I wanted it for the horizontal part, I have a virticle mill, so I am going to catch my breath and see what happens.

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Before you give up on the mill, I would take the junction box on the side of the motor apart.

If there are only 6 wires going to the motor and only 6 wire splices having only 2 wires each, it is single voltage. If that junction box is very full with way more than 6 wires from the motor, (it should be 18). This is a dual voltage motor. I have the correct connection plans to connect to either voltage.

Just don't pull the connections apart before verifing what voltage connection you have first.

Bill

hitandmiss said:

Before you give up on the mill, I would take the junction box on the side of the motor apart.

If there are only 6 wires going to the motor and only 6 wire splices having only 2 wires each, it is single voltage. If that junction box is very full with way more than 6 wires from the motor, (it should be 18). This is a dual voltage motor. I have the correct connection plans to connect to either voltage.

Just don't pull the connections apart before verifing what voltage connection you have first.

Bill

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One of the photos showed a substantial sized add-on panel, door-open, to reveal contactors, etc. Roomy and looked to have been professionally executed, so it probably was.

I'm betting it would be easier than average to trace out, clean up, test that it was good to go, and fire up off an RPC + transformer.

Then again - colour me cynical - maybe the whole exercise here is all about getting support for a quicker flip on the resale?