# Some Voltage and Frequency Lathe Questions



## Matabele (Nov 21, 2013)

Hi guys,

I was wondering if anyone with some electrical knowledge could give me some advice. Im looking to buy a Grizzly G0509G lathe. So the Grizzly is a 3 phase, 120 Volt machine that is designed to operate on a 60Hz Frequency power supply. I would like to import this lathe into South Africa which uses a 220-240 Volt system but runs on a 50Hz frequency. Is it possible to somehow convert or transform the power supply to get this lathe to operate ok in South Africa?

Any advice appreciated thanks!


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## SEK_22Hornet (Nov 21, 2013)

Actually, that lathe is listed at being 220 Volt , 3 phase, 60Hz.  Contact Grizzly to find out for sure, but if you have 220 3 phase power, it should run OK on 50Hz, just a little lower RPM.  If you only have single phase available, then a Variable Frequency Drive could be used to generate both the 60 Hz and the 3 phase from the single phase power.

Dan


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## Matabele (Nov 21, 2013)

Thanks for the reply Dan, yep sorry I got the voltage wrong on the Grizzly. Good news I can just get a VFD to fix the problem. Is it possible to link several machines up to a single VFD, assuming the power requirements are the same or do you have to have a dedicated VFD for each machine?


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## Hawkeye (Nov 22, 2013)

I run a mill and a lathe off the same VFD (not at the same time). They both have 1 1/2 HP motors, but one is 1725 RPM and the other 3450. I vary the frequency from 10Hz to 90Hz and have never had any problems.


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## Matabele (Nov 22, 2013)

Thanks for the replies guys, seems like a VFD is the way to go!


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## GLCarlson (Nov 23, 2013)

Matabele said:


> Hi guys,
> 
> I was wondering if anyone with some electrical knowledge could give me some advice. Im looking to buy a Grizzly G0509G lathe. So the Grizzly is a 3 phase, 120 Volt machine that is designed to operate on a 60Hz Frequency power supply. I would like to import this lathe into South Africa which uses a 220-240 Volt system but runs on a 50Hz frequency. Is it possible to somehow convert or transform the power supply to get this lathe to operate ok in South Africa?
> 
> Any advice appreciated thanks!



A VFD will work. However: don't just drop a motor designed for 60 cycle current onto a 50 cycle main and expect happy results. There is a very sound basis for the difference in construction (mostly, 50 cycle needs more iron) and you WILL need to derate a 60 cycle motor, transformer, etc if you run it on 50. Same reasoning applies to using a VFD. Your torque and motor performance WILL degrade above and below design frequency. For a home shop, typically light and intermittent loads, likely no problem- but don't expect to run heavy production all day long.

All that understood, why not ask Grizzly to mount the RIGHT motor for your mains? I'm sure it's an option- ask. The GO509G is a 16 speed, gear-head, gunsmithing lathe.  I didn't check, but if it's designed right, the 16 speeds (between 45 and 1800 rpm) will be spaced properly (that is, geometrically), and there is no reason to go through all these efforts when a simple motor swap at purchase would solve the entire problem.  Yes, I understand the theoretical basis for infinitely variable speed; in practice, machinists have found that correctly spaced speeds -especially in a gear-head drive- give enough range without additional complexity.

Just get the right motor to start with. Especially on a new purchase, doing more is way too complicated.


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## Matabele (Nov 24, 2013)

Thanks for your reply GL, appreciate it. I did ask Grizzly about the possibility of swapping motors but they don't offer anything other than what comes as standard (well in terms of motors anyway), so that's not an option for me. Saying that, how much would a properly rated motor cost, any idea? Maybe I could just buy one 3rd party and have it swapped out. It would void the warranty that's for sure, but i guess in this situation there has to be a compromise somewhere.


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## GLCarlson (Nov 25, 2013)

Matabele said:


> Thanks for your reply GL, appreciate it. I did ask Grizzly about the possibility of swapping motors but they don't offer anything other than what comes as standard (well in terms of motors anyway), so that's not an option for me. Saying that, how much would a properly rated motor cost, any idea? Maybe I could just buy one 3rd party and have it swapped out. It would void the warranty that's for sure, but i guess in this situation there has to be a compromise somewhere.



Certainly. I thought you might have asked Grizzly, but never assume! In the US, a 3 hp, 1800rpm, 206-230v 60 Hz 3ph motor (Marathon, a good brand) is around $250 from Dealer's Electric (also a good source of VFDs). A 50 cycle unit should be available in your location for a similar price, perhaps a few bucks more. I rarely buy new equipment (and warranties are short, anyway) so this hasn't been a problem; I routinely swap out motors on older equipment. One point: check the balance. An occasional motor will have a poorly balanced rotor, and can cause finish problems (hard to find, too). Don't forget to match rpm, or change the motor pulley so you actually get the indicated speeds. Fenner (adjustable link) belts can help, too. Swapping out a motor is as simple as making sure the mounting matches (and the other physical dimension are OK. Get a TEFC unit to avoid problems with swarf, if the motor is exposed at all. The control electrics should work (although, if there's a magnetic starter, the contactors will also be a little light on the core iron). Short summary: this should be a trivial fix. If you're uncomfortable with  the electrical side, a local contractor should be available to help (and might have an easy source of motors, too. Also- check local rebuild shops; often deals there, especially small 3 phase units).

I'd push a little on Grizzly, too. Or maybe consider getting a Jet/Wilton. Perhaps Grizzly will consider selling a lathe without the motor (doubt it, but can't hurt to ask). This is light industrial/small shop equipment. It's not reasonable that there are no motor options. (Well, it is- because that's the manufacturer's choice- but the lack of options reinforces my general feeling that Grizzly is simply one of the better places to buy Chinese iron...and no more than that). In the same vein, if swapping a motor voids the warranty on the rest of the machine (presuming you don't uprate hp) previous comments also apply.


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## rdhem2 (Nov 25, 2013)

Mr. GL Carlson;

Nicely stated, well phrased reply.  Right on point, to the point.  Good work.


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## SEK_22Hornet (Nov 25, 2013)

Matabele said:


> Thanks for the reply Dan, yep sorry I got the voltage wrong on the Grizzly. Good news I can just get a VFD to fix the problem. Is it possible to link several machines up to a single VFD, assuming the power requirements are the same or do you have to have a dedicated VFD for each machine?



There have been several good comments on the use of a VFD, so maybe I should expand a little on what I was suggesting - My thoughts were to simply use the VFD as "quick and dirty" way to generate the required 3 phase, 60 cycle voltage from the 50 Hz source - not to actually use the VFD to control the speed of the lathe by varying the frequency.  I am essentially using a VFD as a phase converter in my shop, since I do not have 3 phase available (I run a power hacksaw and a lathe off of mine). At this time, it is set to provide a fixed 60 hz output.  I may, at some point in the future re-program mine and add a pot to use it to provide a speed control for the lathe, but I have not yet had a situation where it was worth doing. It may or may not be cheaper than replacing the motor, but it does offer another option.

Dan


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## Matabele (Nov 25, 2013)

Many thanks for the input gents, it has certainly given me something to think about, and a few things to research in the interim! GLCarlson would you have any suggestions for lathes that offer similar features and in a similar price bracket to the Grizzly that are not "Chinese" made. Are the Precision Mathews lathes any good, the PM1340GT model looks interesting?


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## Ray C (Nov 25, 2013)

Hi...  The 1340GT is Taiwanese and is a very good lathe.  I have the PM 1236 and like it very much (it sees a lot of use, just lookup all my threads) but often wish I went with the 1340.   The PM equipment is similar to all the other brands but, the dealer goes a long way to make sure they're constructed with better-than-typical components and, he does a QC check on all machines before sending them to the customer.  No other dealer goes to that much trouble.


Ray




Matabele said:


> Many thanks for the input gents, it has certainly given me something to think about, and a few things to research in the interim! GLCarlson would you have any suggestions for lathes that offer similar features and in a similar price bracket to the Grizzly that are not "Chinese" made. Are the Precision Mathews lathes any good, the PM1340GT model looks interesting?


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## GLCarlson (Nov 26, 2013)

Matabele said:


> Many thanks for the input gents, it has certainly given me something to think about, and a few things to research in the interim! GLCarlson would you have any suggestions for lathes that offer similar features and in a similar price bracket to the Grizzly that are not "Chinese" made. Are the Precision Mathews lathes any good, the PM1340GT model looks interesting?



Unfortunately, pretty much everything in the new, under $10K range manual is Chinese iron (and a lot above that-not much iron being poured in North America these days). The quality is whatever is inspected in. Grizzly does a reasonable job at a specific price/performance/value point; Jet is perhaps a cut above that, and Wilton even better (in my opinion), but the designs are essentially identical. There is a difference between Taiwan and mainland (Taiwan is usually better). If you follow the hobby magazines (Home Shop Machinist, etc) or forums, you'll find a regular stream of "how to improve a Chinese machine" articles. I believe that's both diagnostic and prognostic. After owning one of them (a Rong Fu round column mill) I decided never to buy straight Chinese brands again. I will buy Chinese manufacture with first-world quality control (example: Tormach, which is superb and has legendary, best-in-class product support).

So. Two options to recommend. By all means look at the Precision Matthews (the company has a fine reputation). And look at the new South Bend offerings (maybe the heavy 10), which has been revived by the owner of Grizzly but is aiming at a more discerning market. And, as above, Jet or Wilton- again Chinese, but marketed to a more industrial target with higher expectations (and, probably, more powertrain choices).

The other option is to seek out lightly used earlier production. Monarch 10EEs are popular (e-bay had a glorious rebuild for just on $10K not long ago), older/bigger S. Bend, etc. I have a 1978 Standard Modern that I bought 20 years ago that had perhaps 500 hours on it when purchased. That's a fine option for big, heavy industrial base countries, but hard outside N. America and parts of Europe and Asia, so it may not be much help.

A few final thoughts, after a few decades of shop-building. First, pick a work envelope and stick to it. Always buy quality machines. Never buy a machine that needs work as received. Every time I've broken one of those rules, I've paid for it- both time and money- and (so far, always) regretted it. A marginal machine is worse than none at all. 

One final thought- your implied work envelope/shop philosophy is, I think, a good one for a generalist/hobby shop. Smaller (Sherline, Taig, etc) are fine for modellers, but just too small for most of us. And multipurpose machines (Smithy, etc, that try to be Emco-Maiers on the cheap) are tainted with the stench of compromise, promising to be all things to all people while delivering modest performance and low rigidity. Avoid the "everything" machines- or, at least, understand what you are getting.

Good luck. And do tell us what you ultimately do.


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## SEK_22Hornet (Nov 26, 2013)

If you look at the other suppliers, be sure to ask if they can provide the machine with a motor suitable for your power requirements as an option. You might also look as suppliers who deal with the UK and other European countries, since they use 50Hz mains. There is a Harrison lathe group on Yahoo that I belong to, since I have a Harrison L6 lathe.  I'll post a question there about UK suppliers - The group has a lot of members in the UK.


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## stupoty (Nov 26, 2013)

SEK_22Hornet said:


> There have been several good comments on the use of a VFD, so maybe I should expand a little on what I was suggesting - My thoughts were to simply use the VFD as "quick and dirty" way to generate the required 3 phase, 60 cycle voltage from the 50 Hz source - not to actually use the VFD to control the speed of the lathe by varying the frequency.  I am essentially using a VFD as a phase converter in my shop, since I do not have 3 phase available (I run a power hacksaw and a lathe off of mine). At this time, it is set to provide a fixed 60 hz output.  I may, at some point in the future re-program mine and add a pot to use it to provide a speed control for the lathe, but I have not yet had a situation where it was worth doing. It may or may not be cheaper than replacing the motor, but it does offer another option.
> 
> Dan



Hello, the solf start/stop feture of vfd is nice it spins up from 0hz to selected speed. Slows the spindle quicker than coasting to a stop.

arnt most motors rated simply at different rpm if their 50 or 60hz i know all the motors i have are plated like that.  

I do find my mill motor gets a little hot if i run it under 40- 45hz for any period of time



Stuart


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## Matabele (Nov 26, 2013)

Many thanks again for all the input and advice, its appreciated. I'm going to get in touch with some of the suppliers you have all mentioned and see what they say with regards to supplying a lathe with a motor better suited to my power requirements. I will keep you posted on that development!


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