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Would you use a 10HP CNC with an RPC?

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Nikoli

Plastic
Joined
Feb 25, 2011
Location
vancouver, washington
10 hp cnc with a rpc. Digital needed?

Sorry for the title mishap.

So I have been researching my options to power my 10 hp cnc mill. I see that a rpc is the preferred method. At least in the posts I have read. What I havent come across is if the digitally controlled assemblies are a must, recommended, or if a homemade setup will work if the "wild" leg is balanced. I am planning on using a 20hp motor for the idler. Thanks for any help.

- Nick
 
Last edited by a moderator:
Yep, you betta fix that title, or just start another thread titled ......

Uh, what are you asking?

Oh, okay, how about "is a ten HP rotary converter (for CNC machine) an entry-level project?"

That's what you are asking, right?
 
Nikoli said:
how do I kill this thread and try it again?
Click to expand...

Ignoring it is one tactic.

You might be able to "Go Advanced" when editing the first post, see if it allows you to revise the title. At the least, you can make the first line of the first post into the title, so a person "mousing over" the thread's link would see the topic being discussed.
 
I have an Anderson Converter rotary than runs a Haas VM-3 just fine. It's a 40hp. It was about $2200 new. I also have a Phase-A-Matic 30hp with the voltage stabilizer that cost twice as much and it runs a Mazak 200B and a VTC-41 at the same time. No problems with either setup. There isn't anything digital on either one.
 
Title was fixed.....

Thanks for the "fessing up", Nikoli. Looks like I get to "go advanced" longer than you do.
 
Good news, Nikoli- You wouldn't be the first guy to botch a thread title... OR to ask the RPC-> CNC question.

There are guys that RPC their CNC, and like anything else in life, it's not WHAT you do, but HOW you do it. If you understand what the RPC is doing, and WHY it works, you'll likely have no difficulty getting the CNC kit to be happy running on it. Just realize that the finicky stuff will be most unhappy if they're powered via the 'generated' leg... because the generated leg's output will vary based on load. The other two legs (the utility mains) will be much more stable.

The other way to do it, is to go through the machine, and look for everything that NEEDS three-phase power, and everything that DOES NOT, set up to run on single-phase, and then run the three-phase components off of a dedicated RPC, or VFDs. I'm amidst this process with my Maho... and aside from a 90v servo power supply, the only other things that 'need' 3-phase, is the drive motor and the coolant pump. The latter will be resolved with a single-phase pump, the former, a VFD...
 
Good to hear. Thanks for the input guys. Dave I have a question about what you stated. I was told that the generated leg needs to be run like you said on the 3 phase only side of things. I was attempting to go thru the schematic but I had a few areas where it looks like different legs power different areas. What I mean is that say R+T power the N/C and R+S power some other box. How can you determine which is the better choice for the generated leg?
 
Well, what they're referring to is identifying the three phase leads as R-S-T.

R=A, S=B, T=C.

In a rotary converter, we always refer to the two leads fed by utility mains to be A and C.

The generated leg is B.

So what you DON"T want to do, is power the Numeric Control system (the computer) off of B. Power the NC kit off A and C... it will be a stable 240v... B will vary based on load, hence, your numeric control system will be getting goofy power... it'll upchuck and spit nuts in the middle of a job.

In essence, what you WANT to do, is make sure that the ONLY thing using the generated leg, is a MOTOR.

Not always an easy thing with some of these CNC monsters... my MAHO has the phase legs mix-matched at every change-of-page... it's like trying to sort out genetics at a hillbilly swinger's ball. It takes patience and GOOD DIAGRAMS... and plenty of ibuprofen and adult beverages. Make photocopies of your diagrams FIRST, then take colored pencils to your diagrams. I use RED and BLACK for the 240v mains, and BLUE for the generated leg, and follow it through the main distribution. Once you get to reversing contactors, everything AFTER that is a crap-shoot. To make matters WORSE, you may find that your CNC machine has a PHASE SEQUENCE PROTECTION system- it detects the phase ORDER operating backwards, a phase-reversal contactor (EARLY in the wiring) swaps it back, so that it automatically CORRECTS it. If you miss this one, it could swap your generated leg someplace you didn't WANT it... just beware.
 
That's a fairly good word... but I'd look for something somewhat... hmmm... stronger...

Keep in mind that there's no such thing as a complex device... there's only large assemblies of small simple devices working together. Divide, and conquer, one segment at a time.
 
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