Considering a 3 phase CNC small lathe - - - have 240V single phase

[MrMetric]

OK, I admit that it has been a long time since I purchased my unit. In fact, I suspect that they don't even make it now. I got a DPC10 when they first came out. I actually swapped it with a rainproof model later on, and they had me 'drop ship' the old unit (basically a return), quite literally. I took it over to another guy's house (or he came to mine... I really don't recall anymore) that lived near me. Everyone was happy.

I *love* the Phase Perfect. I'm not a fan of the price though.... I wish someone would do an open source design, which is probably the only way it could be legally done (no money involved). But... not a lawyer so I can't say for sure. Anyhow, the concept is easy enough, although the devil is always in the details. But it would be *really* nice if you could take components from an established design and then add on some auxiliary open source boards to make the equivalent function. I've got too many other projects and too little time (plus... probably not enough knowledge to do it alone). It would be a neat project though.

 

[Cogsy]

I *love* the Phase Perfect. I'm not a fan of the price though.... I wish someone would do an open source design, which is probably the only way it could be legally done (no money involved). But... not a lawyer so I can't say for sure.

Even if someone was not charging for a copy of the design (doesn't actually make it 'open source'), the original design is still protected. Same as sharing MP3's or photocopies of plans, it's not about the charging of money but the sharing of the material. Until their patent runs out the only way around it would be a different design, whether that is open source or not.

 

[dazz]

Again.... Nicely done.... Out of curiosity, what is the gauge/thickness of the metal you used for the box, and what did it end up weighing.

I used 2mm steel but I don't have weight constraints. I purchased 1.6mm welding rods specifically to weld the enclosure. That was before I had a MIG welder.
I think down to 1.2mm would work OK if you can weld something that thin.

There was grill on the bottom side and on the door to provide cooling air circulation. The grill on the door was formed to be flush with the door.

I'm also curious if you used a break at all or are your sides all welded together? It looks like you bent the front but I can't really tell about the rest (I'm assuming that if you had the ability to bend anything, you'd like do as much as you could.

The front edges were bent over and the corner seams fully welded. The rear was tack welded. No need for a full seam weld.

The rear panel was bent to fit around the lathe. It was fully pre-drilled and tapped for everything that was to be attached. Where necessary, reinforcing tabs were welded on before drilling and tapping.

 

[dazz]

Hi
I had a look at the Phase Perfect website. It looks like a good whole-of-workshop solution and would be cheaper than retrofitting VFDs to multiple machines.
I suspect the main problem would be having access to a sufficiently high current single phase supply to drive the Phase Perfect.

There would also be the risk of sending spikes and dips down the supply, causing problems for the neighbours.
It does look like an option worth investigating.

Dazz

 

[L98fiero]

Again.... Nicely done.... Out of curiosity, what is the gauge/thickness of the metal you used for the box, and what did it end up weighing.

Nothing wrong with the gauge of metal Dazz used but most commercial enclosures you'd encounter are made from 16 gauge(1.5 - 1.6 mm) steel.

 

[mu38&Bg#]

I have to ask if you've investigated rotary and digital converters, why wasn't this noted in the original post? These are essentially the only two solutions.

Do some research online to see if anyone has done anything out of the ordinary to power your specific machine.

My setup is like MrMetric. Phase Perfect, 230->400V trafo, two small machines and 3HP compressor. Was PP expensive, yes. It's been great. I knew I had to make three phase, and that it wouldn't be cheap. Pay to play kind of deal.

 

[MrMetric]

Dazz... Beautiful work...

Cogsy.. I wasn't actually talking about copying the design. I was talking about designing a similar function independently. If anything at all, this would be a patent issue, not a copyright one. My recollection is that you can design something with a similar function and publish that all you want. If you *make* it and offer that for sale, however, then it is a patent infringement issue. Many of the engines that are built by hobbyists, or which that little widget tool you saw and though "I can make this myself" (and did), would likely infringe on patents using the interpretation you seem to be implying. However, I don't believe that is the case. I may be wrong, although I hasten to add then that I doubt any of us haven't got *something* in our toolboxes that probably fits that category. The OpenSource comment was relating to the publishing of a circuit that was independently designed but performs a similar function. Granted, that one may be more restricted, I don't know. I'm not a lawyer and not even an armchair lawyer. I also have to say that I have almost no interest in pursuing the research to develop an open source PP-type design, so it is all rather academic.

DieselPilot... Prior to the phase perfect, I had a home-built rotary that fed the entire shop. Frankly, it was pretty inexpensive to make and I was generally pretty happy with it. I can't say it was all that efficient, though. Of course, the offset to that comment is that $3500 (which appears to be the roughly current price of a PP) is an awful lot of inefficiency dollars to pay off.

 

[mu38&Bg#]

The first patents used by Phase Technologies have expired. There is new patent, which probably applies to the newest models. It will be interesting to see if anyone tries to use the old design/patent to create competition.

Used RPC can be had at reasonable prices. When talking new 40+ HP idler based RPC, it's a large fraction of PP.

 

[MrMetric]

Hmmm, that is interesting indeed. I have so little interest in the matter that I didn't even bother checking that out, although I guess I shouldn't be surprised. PT has been in business for a long time, so it stands to reason that the patents have probably expired... unless they've made technical improvements that allow them to extend them.

For the record, I'm generally pretty good about promoting intellectual property rights *for myself*. I caveat that because I also feel that it is very much a personal decision and that I should not impress my opinions on others. I felt I should say that because HMEM has a reputation for sometimes going far on the latter. I also believe, however, in the concept of both open source and competition. Although I don't agree with modern patent law (software and process patents, for instance), they are precedent now. It was a horrible movement in the law, IMHO, but it is, nonetheless, the law. But I digress.... If the PT patents have truly expired, then there is no ethical/legal boundary that would be broken by designing *and selling* a competing product that uses the concepts covered in the original patents (subject, of course, to legal interpretation of the ability to do so). I can also attest to the fact that the original DPC10 is a wonderful product. If it can be made in a patent-free mode, I'd highly recommend it to anyone wanting an excellent shop phase converter. It beats the snot out of the old rotary guy I used to have.

Diesel... I suspect that a 40HP need is probably *far* beyond the scope of the average person on HMEM. At best, people are likely in the 10HP max range. If they are talking about a VMC, that would put that able to use a Haas Super Mini Mill as well as a decent sized lathe. Although, this is an interesting topic, indeed. It would be fun to have a separate thread (if one doesn't exist) on what people are using in their shops. I'm guessing 30% Sherline sized, 40% Myford/Emco 11/Hardinge size, and 30% larger. But... that is a different topic. We'd be straying too far away from the original posters question about phase converters.

 

[mu38&Bg#]

That's the thing. Any RPC vendor will suggest a 30-40HP based RPC to power the OP's lathe. Would it actually run on somethign smaller? I don't know. Compare new price to a 20HP Phase Perfect which will do the job without breaking a sweat.

In any case, powering an industrial machine in a residential setting isn't trivial and power should be first consideration. For a hobby, large machines get expensive quickly. If these machines earn their room and board, the math is a little different.

Most home shops never need anything more than 20A, 240V outlets, welders excepted.

 

[MrMetric]

Which gets back to the other half of why there is a bit of suspicion about sales. You are right. Size for what you need now, with a bit of realistic future growth, and get that. I've left "get" as ambiguous because it really isn't that hard to make a darned good balanced rotary converter from parts retrieved from a junk yard. The biggest expense is likely going to be the oil filled capacitors and the enclosure.

And, yes, most shops don't need much more than 20A. I think I have 40A in mine, but I've got a couple of big machines (much to my wife's chagrin, but that is a different matter! )... But I know I don't use that for anything more than in-rush when starting a motor...

 

[Gordon]

I believe that a rotary converter is drawing very low amperage when it is just idling with no additional load. When a load is applied the amperage draw is not a whole lot more than the three phase motor would draw if it were hooked up to straight three phase line. I may be wrong, I am not an electrical engineer but I have done amperage readings on the rotary converter that I used in the past. As others have stated a problem with the rotary converters is the noise of the idler motor running. I solved that problem by putting the motor in a different room. I have since converted my home machines to a variable frequency unit because it gives me variable speed and none of my machines are over 2 HP. For the average hobby shop the cost of running an idler motor on a rotary converter is negligible. When you start talking about a larger shop and 20 HP machines you are in a different situation.

 

[MrMetric]

Gordon, I agree.... PT has a relative cost of usage on their site, but it really is geared towards the entity that has large motors. Frankly, I'm kind of surprised that there are very many people that would have such a need, but they apparently have found a niche business.

In general, the VFD or rotary converter is a perfectly fine way to go, and a lot less expensive than a Phase Perfect. The *only* reason I got the PP was, as I previously indicated, a 380V European machine (so, step up transformer for those of us in the States) for which I could not isolate the power being used by the electronic components. That machine did *not* like my well balanced rotary. If it had, I wouldn't have gotten the PP.... That said, it is a really really really nice solution. If you can justify it, the PP is very nice.

This might be a good place to discuss one of the big concerns I have about the PP thought too.... Because it is a specialty item, you can't find used components for it. As such, if the PP ever goes south, I'm pretty much up the proverbial creek. Make no mistake about it... My shop is a hobby and competes with surplus family funds all the time. This is why I will not buy a subscription software product (big thread on that about Fusion360 now... but not for this thread). The point is that if the PP dies, I'm not going to be a happy camper. I'm sure if I used it day in and day out, I'd have gotten my money's worth out of it. But as a hobby user, I haven't even come close. Sure, I'd try to repair it, but it is all conformal coated and such. It would not be an easy/fun thing to repair. Plus, being high voltage, generally these things don't fail in a nice way. Unless something inane like a cap blows or a MOSFET goes (which hopefully doesn't take anything else), the system could be unrepairable. PT has clearly moved beyond their original designs...

[added several hours later...]
I must admit that this has been a day of awakening... Although I love my PP, I don't think I'd buy another one and here is why... My model was discontinued and support is no longer available. They will not repair the boards or sell replacement boards. Frankly, this is the liability of buying from a small company. Service is critical, and if a company isn't willing to provide it, then I cannot feel comfortable recommending them for purchase by another hobbyist. It might work great for a commercial entity that amortizes the cost of ownership over only a few years, but a hobby person generally doesn't have a lot of funds. Further, it seems like the older designs were really not built with serviceability and circuit protection in mind, which is not good. When mine dies, therefore, I'll be up that creek. Ironically, it will be cheaper for me to find another lathe and retrofit it than it would be to spend almost 5K (I was way off on prices) to replace the unit.So, from a happy Phase Perfect owner, my recommendation is that you stick with a rotary phase converter in another room (or outside) if you want shop production, or an integrated VFD for per machine conversion.

 

[kf2qd]

This is a rather inefficient and expensive way of getting three phase power. Ask yourself why electronic VFD's have become so popular!

If he only has to power a1 motor, no problem, but isf he has to power the whole machine off 3 phase a VFD WILL NOT WORK.

 

[dazz]

Hi
I really like VFDs. Both of my lathes are fitted with them. They are especially good for powering up to about 4kW machines off single phase domestic supplies (unless you live in the USA with 115VAC). I have the advantage of being an electronics engineer so I understand what is involved and how to do it. My Nardini started as a 6kW 400VAC 3 phase lathe. It is now a 4kW 1 phase VFD (fitted with a 3 phase 240VAC motor). With modern tooling, it has more power than I can use.

Fitting a VFD properly requires the complete strip out and replacement of the machine's entire electrical system, regardless of machine size. That is not something many people can or want to do. On my Nardini, the only original electrical item remaining is the forward/stop/reverse switch at the tailstock end. On my Denford, only the mains switch remains.

If you do go down the VFD path then make sure you invest in a decent quality industrial unit. The added cost will pay off in the end.

I look down with arrogant condescension at VFDs hanging off the wall by the machines they are powering. If you do install a VFD, please understand they are not a straight swap for mains power. Motor drive and machine controls need to be separated. Expect to replace most, if not all, electrical parts including the motor. Fitting a VFD should be a major project beyond figuring out where to drill the holes in the wall. If you can, VFDs are the way to go.

 

[Lloyd-ss]

This sounds like it could be a real can of worms. Remember that the input power (50Hz, 60Hz, 480-3Ph, etc, etc) is an option that is chosen by the original purchaser, and that probably nothing inside the CNC machine runs directly on that original power, 3Ph in your case. The power into the machine goes thru power distribution, a main transformer, and various power supplies to convert the 3Ph into the various AC and DC voltages needed within the CNC. Will all of those various power supplies and systems within the CNC machine work on the "fabricated 3Ph"? Maybe, but maybe not, and you might not know until it's too late. This isn't just about driving a motor, it is about powering electronics.
The only way to be sure is to talk to someone who has done the conversion on the machine you are looking at. Maybe there is a CNC refurb shop in your area that could offer some advice. Be cautious.

 

[xpylonracer]

Dazz

I think the last para in your reply is OTT for what is required when fitting a VFD, many but not all 220/380/415v 3 phase motors can be configured to run at 220/230v 3 phase AC which is attained via the 230v AC supply to a VFD.
The motor plate will have the operating voltages listed with the Amps, speed and Frequency.
OK so they may not perform as well as a new motor designed to run with a VFD but the difference will be small.
If the lathe currently has apron switches via control levers it's likely these can be retained and connected into the VFD control circuit.
If for any reason the VFD has to be fitted away from the machine you would use a machine mounted within reach of the operator enclosure remote stop/start fwd/rev+speed control pendant that is simple to wire and connect.
Safety interlocks and stops should be connected into the VFD Stop circuit and not an additional device as the VFD may be damaged if the motor is disconnected before the power has been removed.
Some may prefer a contactor in the power supply to the VFD to act in the event of an emergency stop, this method may or may not cause damage to the VFD but is no more than a power supply failure.
Follow the VFD makers advice regarding bonding to earth(ground) the motor power supply cable screen as this is sometimes at the supply end and others state both ends.

xpylonracer

 

[dazz]

Dazz

I think the last para in your reply is OTT for what is required when fitting a VFD, many but not all 220/380/415v 3 phase motors can be configured to run at 220/230v 3 phase AC which is attained via the 230v AC supply to a VFD.

Selectable voltage motors are common, but perhaps not much so with the older lathes often seen in home workshops. If you end up with a selectable voltage motor, then that is just one component that doesn't need to be replaced.

The motor plate will have the operating voltages listed with the Amps, speed and Frequency.
OK so they may not perform as well as a new motor designed to run with a VFD but the difference will be small.

Agreed. Neither of my lathes is fitted with a "VFD rated" motor.

If the lathe currently has apron switches via control levers it's likely these can be retained and connected into the VFD control circuit.

Yes, I did that. The rest of the control/protection/cabling got dumped.

If for any reason the VFD has to be fitted away from the machine you would use a machine mounted within reach of the operator enclosure remote stop/start fwd/rev+speed control pendant that is simple to wire and connect.

That would be entirely reasonable, and it is not uncommon to see "professional" machines with floor standing controls enclosures. My comments are limited to the ones hanging off the wall.

Safety interlocks and stops should be connected into the VFD Stop circuit and not an additional device as the VFD may be damaged if the motor is disconnected before the power has been removed.
Some may prefer a contactor in the power supply to the VFD to act in the event of an emergency stop, this method may or may not cause damage to the VFD but is no more than a power supply failure.

Cutting the power to the VFD as an e-stop action is a really terrible, dangerous and overly common practice. Something like a lathe can have a lot of energy stored in spinning mass. If you have to hit the e-stop because your arm is caught, then all that spinning energy will be transferred to your body, or whats left of it. My Nardini VFD is configured to apply max power to drive the motor to zero rpm. The aim being to bring the lathe to a zero energy state as quickly as possible.

Follow the VFD makers advice regarding bonding to earth(ground) the motor power supply cable screen as this is sometimes at the supply end and others state both ends.

VFD Motor Cable Shielding best practice

 

[xpylonracer]

Dazz

As we seem to be in agreement on most points why state:
"Expect to replace most, if not all, electrical parts including the motor."

xpylonracer

 

[Richard Carlstedt]

This thread started with the poster asking about 3 Phase supply for a CNC machine in a home shop.
It has gravitated to other machines ( not CNC ) and I think may create confusion for some .

Returning to CNC only applications, you cannot use a VFD to power a CNC because VFD's need to be directly wired to the motor load.
Phase Perfect and Rotary (RPC's) can and do work well for such applications and make the install very clean and simple , but the difference here is that the RPC will draw more current in the overall application and that needs to be evaluated based on the power available to the user in his location/shop.

If you do not want the above, there is another possibility - and it is to rewire the CNC control cabinet for a VFD driving the motor only. Single phase is brought into the machine to run the control circuits ( which are single phase) and the CNC relay contacts are used to turn a VFD powering the motor on/off. If a 3 phase pump motor is involved, a seperate VFD must be added for it or a single phase pump installed. If the Servos use a single phase supply ( DC i.e.) then they are still functional with a single phase input. If not, then a review of the entire CNC schematic must be made.

Rich