Renovating a Hardinge HLV-H

[BillTodd]

Hi Rodger,

Thanks for the kind words . :)

The paint I used was a standard automotive enamel. If I were to paint it again I would choose a different paint (perhaps a Sherwin Williams machine paint) The paint I have has held up well (resistant to coolant or oil) but it a little brittle and prone to chipping. The colour is a light/mid grey (perhaps edging toward blue-ish) that was a reasonably close match to the original base colour.

A rotary phase convert will work OK (please don't let a static converter fry that irreplaceable motor) and is probably a good choice if you have a few machines to power. However, the VFD does give some extra options*, and I would not hesitate to do the same conversion again.

I did look into an electronic lead screw. I like Paul Babin's version a lot; It keeps the lathe functioning as it should and doesn't try to do too much. However, last I heard from Paul is that he has no plans to make it available outside the US (I guess it makes it too difficult/expensive to support).

There is John Dammyer's excellent Electronic Lead Screw** DIY project in kit form. It was aimed at mini lathes but could be adapted for use on the HLV-H (might require a servo motor instead of the stepper currently used) . The Yahoo group is very active and John really gives excellent support.

I keep thinking about trying to make an ELS of my own (I've just bought a little Haighton Cadet, and am looking to make it cut metric screw threads) but, in the end, I just made myself a metric banjo and bought a set of Myford gears (Hardinge gears being almost unobtainable & expensive).

Let me know if you need any help, and start a blog so wee can see you progress :)

Regards,

Bill




*here's one I've just been showing to a guy on the Yahoo Hardinge group
Hardinge HLV-H threading-lever speed control.mpg - YouTube

**John's Yahoo group:
E-LeadScrew : Lathe Electronic Lead Screw R&D

[pauly45]

Hello Bill,

I can only echo what other people have said about your rebuild. It has been a great read prior to the, hopefully soon, delivery of a KL-1 I'm negotiating to buy.

In the mean time I have been reading about your VFD conversion, including the information and drawings from the Yahoo Hardinge Group.
If I may, I had a couple of questions about the VFD that have been confusing me.

Yourself and some other people use a 240v to 480v transformer to power the VFD.
From the information I can find about the Siemens MM150 you use, it appears to be a 240VAC Single Phase input device, and looking through general component suppliers (RS), the only 480VAC input VFD's are 3 phase inputs, and the single phase input VFD's are 240VAC.

I wondered what the reason for the transformer is, since I assume that you are still only getting a single phase output from the transformer, just at 480v ?

I wouldn't have thought you could feed a 480VAC single phase into a FVD designed for a 480VAC 3 phase input, can you ?

Yours Confused !
Paul.

[BillTodd]

Hi Paul,

the Siemens MM150 you use, it appears to be a 240VAC Single Phase input device,

No. The Siemens MM150 VFD I am using is the 1.5kW 500v three phase input version. It is fed from the single phase 415vac output of a step up transformer.

All VFDs run on DC internally, so they do not really require more than one phase to work. High power ones have 3ph input because they need more current and it is easier (i.e. smaller, cheaper capacitors) to smooth the DC from a poly-phase input (like a single cylinder engine needs a bigger flywheel than a multi- cylinder engine) .

There is sufficient capacity in most VFDs to operate on a single phase input without causing any real problems (especially on a lathe with a low duty cycle operation).

Some VFDs have phase loss detection, which would prevent single phase operation, but most newer ones just sense DC bus ripple voltage so will operate fine on single phase input (they will still fault if excessively loaded).

Bill

[pauly45]

Hi Bill,

Thanks for such a prompt reply.

That makes a lot more sense now.
I'm assuming that the risk is that since only one phase is being used to supply all the output power, that it is the rectifier diodes on the one input that risk being over-loaded - all the output power being derived from one phase set of rectifier diodes rather than three ?

Do you just leave two of the input phases disconnected ?

Using a 3 phase 415 input VFD makes the selection choice much larger and cheaper !

Many Thanks - I'll look into 415v 3ph VFD's now !

Regards
Paul.

[BillTodd]

I'm assuming that the risk is that since only one phase is being used to supply all the output power, that it is the rectifier diodes on the one input that risk being over-loaded - all the output power being derived from one phase set of rectifier diodes rather than three ?

True, but since the rectifier diodes are usually integrated with the rest of the power devices, there's virtually no cost to the manufacturer to make the devices very robust (i.e. to use the same spec devices for the smallest and largest power VFD in a range).

The only real issue is ripple current heating in the capacitors.

Bill