Author Topic: vintage lathe restoration - 3 phase supply.  (Read 25079 times)

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Offline eKretz

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Re: vintage lathe restoration - 3 phase supply.
« Reply #100 on: September 04, 2016, 05:32:07 am »
Spray mist coolant would be a very good move. Machining without some form of coolant is a pretty big handicap - both to working speed and to tooling life. The largest cut I ever took on a lathe with carbide was about ¾" per side at .077" feed rate. That was a 52" swing lathe, an old German made machine called Schiess. I served my apprenticeship in a very large shop that did a lot of repair and new work for the big steel mills - US Steel, Inland, I/N Tek, Arcelor Mittal, etc. The largest lathe was a Niles with 72" swing, it had something like a 200 HP DC drive. That was a cool place to work.

Water soluble coolants won't cause rusting of the lathe unless they're mixed too thinly. Mixed in the correct ratio, they leave behind an oily residue - at least the good quality ones do.
« Last Edit: September 04, 2016, 05:36:55 am by eKretz »
 

Offline capnahab

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Re: vintage lathe restoration - 3 phase supply.
« Reply #101 on: September 04, 2016, 09:10:27 pm »
The largest cut I ever took on a lathe with carbide was about ¾" per side at .077" feed rate.
- blimey. making my lathe look small.

tautech, - yes me too, will try and get hold of a current clamp. When I turn fast motor on and go up to 720 rpm the motor on the converter speeds up a bit  but it docent struggle to keep the lathe going. As you say I will be interested in how much current it draws.

Meanwhile I have nearly got a replacement for the switch contact cover.
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Offline tautech

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Re: vintage lathe restoration - 3 phase supply.
« Reply #102 on: September 04, 2016, 09:40:40 pm »
Spray mist coolant would be a very good move.
How is that normally done?
Is a higher pressure pump required?
Are "off the shelf" submersible spray mist pumps available?
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Offline Cyberdragon

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Re: vintage lathe restoration - 3 phase supply.
« Reply #103 on: September 04, 2016, 10:38:08 pm »
You can get kits to add spray lubricators to metal working machines that don't have them.
Take your pick
http://koolmist.com
http://www.sterlinggundrills.com/spraymist-kits.php
http://littlemachineshop.com/products/product_focus.php?Focus=Coolant
Exc.
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Offline eKretz

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Re: vintage lathe restoration - 3 phase supply.
« Reply #104 on: September 05, 2016, 07:34:59 am »
Normally the spray mist coolant is distributed with compressed air. The liquid coolant is pulled into a mid pressure air stream via siphon - the air is passed over the top of a liquid pick-up tube. So no liquid pump is necessary, only compressed air. The better systems are actually quite impressive, almost able to cool as well as flood coolant. They can be adjusted to provide from hardly any liquid to quite a lot. For most modern carbide machining (high speed, high feed, low D.O.C. - mostly CNC machines with recirculating ball guide ways) they are more than adequate. Flood coolant still rules the roost for heavier duty box way machine tools and drilling though.

BTW, just found a couple old photos you might find interesting. One is of the old 52" Schiess lathe on which I was O.D. grinding a tapered journal, the other is an ~24" swing American engine lathe on which I made a replacement crankshaft for a large air compressor.





Capn, the switch cover looks good, nice job.
« Last Edit: September 05, 2016, 08:00:33 am by eKretz »
 
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Offline Len

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Re: vintage lathe restoration - 3 phase supply.
« Reply #105 on: September 05, 2016, 03:47:15 pm »
You can get kits to add spray lubricators to metal working machines that don't have them.
Take your pick
http://koolmist.com
http://www.sterlinggundrills.com/spraymist-kits.php
http://littlemachineshop.com/products/product_focus.php?Focus=Coolant
Exc.

Or you can make your own using a soda bottle:
[Edit: Skip to 9:30. Stupid forum software screwed up the youtube link.]

https://youtu.be/G3wUoPdK_ms
 

Offline capnahab

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Re: vintage lathe restoration - 3 phase supply.
« Reply #106 on: September 05, 2016, 04:17:32 pm »
Lovely to see the old lathes and methods at work. The crankshaft must have needed a lot of careful setup, - makes neurosurgery seem a bit crude, tho at times it can be very elegant.
 

Offline eKretz

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Re: vintage lathe restoration - 3 phase supply.
« Reply #107 on: September 05, 2016, 06:18:14 pm »
Yes large crankshafts do need a lot of careful setup. Order of operations is also critical - if things are done in the wrong order it can result in scrap due to distortion/movement of the steel. Drilling the oil holes from one journal to the other on large crankshafts (sometimes the holes can be 2 or 3 feet deep!) can also be an interesting proposition.
 

Offline _Wim_

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Re: vintage lathe restoration - 3 phase supply.
« Reply #108 on: September 06, 2016, 08:02:42 pm »
Thanks eKretz,
The most powerful VFD available in the UK is about 2.5-3 Kilowatt. Not sure exactly why.

Most VFDs that have a single phase input I have come across are indeed low power. Higher power VFDs typically have a 3-phase power input (not a problem in industry). If you only have single phase power available in your home, a VFD is therefore not an option for a high power machine...

It is maybe also possible to find high power VFDs with a DC bus input (typically 600Vdc), but then you need to find/built a very capable DC power supply  8)
 

Offline capnahab

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Re: vintage lathe restoration - 3 phase supply.
« Reply #109 on: September 06, 2016, 09:08:57 pm »
Yes this is exactly why VFD won't work for this sort of motor. I can get a 6kW VFD in the UK but it is only 230 volts.
 

Online NiHaoMike

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Re: vintage lathe restoration - 3 phase supply.
« Reply #110 on: September 07, 2016, 01:10:05 am »
Thanks eKretz,
The most powerful VFD available in the UK is about 2.5-3 Kilowatt. Not sure exactly why.

Most VFDs that have a single phase input I have come across are indeed low power. Higher power VFDs typically have a 3-phase power input (not a problem in industry). If you only have single phase power available in your home, a VFD is therefore not an option for a high power machine...

It is maybe also possible to find high power VFDs with a DC bus input (typically 600Vdc), but then you need to find/built a very capable DC power supply  8)
All you need is a rectifier made from a large cap or two and some large diodes.
« Last Edit: September 07, 2016, 01:12:15 am by NiHaoMike »
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Offline Jeroen3

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Re: vintage lathe restoration - 3 phase supply.
« Reply #111 on: September 07, 2016, 05:29:52 am »
Yes this is exactly why VFD won't work for this sort of motor. I can get a 6kW VFD in the UK but it is only 230 volts.
Get a three phase one, and connect three times one phase. Just like your stove. Which is often >3kW as well. There you just use more wires and a higher amp MCB.
*Not all VFD support this.
 

Offline woodchips

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Re: vintage lathe restoration - 3 phase supply.
« Reply #112 on: September 07, 2016, 04:37:12 pm »
Some comments.

Be cautious using coolant with carbide tooling, if the tool isn't completely flloded all of the time then the thermal shock can break them.

Don't just wire the inputs on a three phase inverter together across a single phase supply. The inverter is assuming the much smoother rectified DC from the three phase. At the very least you will need to up the current rating of the rectifiers and increase the smoothing capacitance.

If running from a DC source then the easiest is to use something like the Farnell/Advance etc DC PSUs stacked in series. These are rated to be connected in series to 250V, so connect to make +200V and -200V having first checked there are no earth connection problems.
 

Offline _Wim_

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Re: vintage lathe restoration - 3 phase supply.
« Reply #113 on: September 07, 2016, 06:28:09 pm »
Thanks eKretz,
The most powerful VFD available in the UK is about 2.5-3 Kilowatt. Not sure exactly why.

Most VFDs that have a single phase input I have come across are indeed low power. Higher power VFDs typically have a 3-phase power input (not a problem in industry). If you only have single phase power available in your home, a VFD is therefore not an option for a high power machine...

It is maybe also possible to find high power VFDs with a DC bus input (typically 600Vdc), but then you need to find/built a very capable DC power supply  8)
All you need is a rectifier made from a large cap or two and some large diodes.


Good tip! I did not think about doing it that way. That is indeed an easy and affordable solution...
 

Offline _Wim_

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Re: vintage lathe restoration - 3 phase supply.
« Reply #114 on: September 07, 2016, 06:32:22 pm »
*Not all VFD support this.

Thats the problem, how to know if your VFD supports this? You wont find such a thing in the manual, as nobody in industry would typically do this. For consumer equipment this is indeed sometimes done (for example my induction cooking plate), but it is also documented in the manual.
 

Offline _Wim_

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Re: vintage lathe restoration - 3 phase supply.
« Reply #115 on: September 07, 2016, 06:34:55 pm »
If running from a DC source then the easiest is to use something like the Farnell/Advance etc DC PSUs stacked in series. These are rated to be connected in series to 250V, so connect to make +200V and -200V having first checked there are no earth connection problems.

I am unsure of what kind of PSUs you are talking about. I would suspect this to be quite an expensive solution for higher powers unless I am missing something
 

Offline PaulAm

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Re: vintage lathe restoration - 3 phase supply.
« Reply #116 on: September 09, 2016, 12:50:35 pm »
You can run most 3 ph VFDs from a single phase supply, you just have to derate them.   I' d had no problems running a 3hp motor on a 5hp VFD fed with single phase, for example.  That's a fixed frequency situation; I'm not sure how well it would work if you're going to use the VFD for speed control.

Of course there's http://www.phaseperfect.com/p/t/overview if you have the money.
 

Offline woodchips

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Re: vintage lathe restoration - 3 phase supply.
« Reply #117 on: September 09, 2016, 08:47:58 pm »
The Farnell etc PSUs are just a standard single voltage brick, many people make them. Something like 24V 10A are common, used in industrial electronics and so few other places they are thrown away, I have just done that so nothing to photograph. Floating switch mode supplies to 250V does not seem a rare atribute.

Make sure you have reverse polarity diodes across the outputs though!
 

Offline cncjerry

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Re: vintage lathe restoration - 3 phase supply.
« Reply #118 on: September 09, 2016, 10:28:59 pm »
without reading back thru this thread, there was a problem between the high and lo speed of the motor.  Was this with/without a chuck?  Meaning did the problem go away without the chuck mounted?
 

Offline tautech

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Re: vintage lathe restoration - 3 phase supply.
« Reply #119 on: September 10, 2016, 07:43:57 pm »
For those following this thread, the OP has started another:
https://www.eevblog.com/forum/repair/restore-lathe-electrial-panel-lights-mainly/
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