CNC electric supply

[Jon Snider]

I realize this is probably a pretty open ended question, but I’m building a shop and have decided to add as many electrical circuits (or conduit etc for future circuits) as I can for equipment I don’t have now but hope to have some day.

Can anyone one tell me what is the usual requirement for a CNC? Maybe a 4x8’ Shop Bot or equivalent.

More than one motor to wire? Plus I think an air line is required?

thanks

jon

[Jim Becker]

Honestly, there is no "usual" without knowing the requirements for the spindle for sure. For example, a 3kw spindle which wouldn't be unusual for a 4x8 or 5x8 machine like you describe would "likely" require a 40 amp four wire 120/240v combo circuit for the machine (240v for the spindle and 120v for the on-board circuitry), but that's not assured. (That's the requirement for my Camaster if it had the 3kw spindle) My suggestion is to put in a generous conduit run for your prep for the CNC so you can easily bring in the required electrical for the machine you ultimately choose after you actually order it. Camaster provides a "prep" document when one orders a machine and I would be surprised if a similar document isn't available from other typical manufacturers like ShopBot and ShopSabre.

You will need an air drop for components like a g a Z-axis assist and other potential functions near the machine location. The air requirements are likely very reasonable since things like the Z-assist only requires pressure and doesn't actually "use air". You may also need a separate 120v circuit for a computer, depending on what manufacturer/machine you select. Don't forget that you'll want dust collection, too, and that's typically supplied overhead in some manner.

[Martin Wasner]

Honestly, there is no "usual"

This

Mine is on a 50 amp 480v circuit. That's the controller, spindle, and three 4hp pumps.

and please feed it clean, dry, cool air. I pulled an air fitting off of mine when I picked it up and it was full of rust. The catch cup had a bunch of water too. Your spindle will thank you.

[Jon Snider]

Thanks guys. Are these ever three phase? I can easily run conduit, but need to know which panel (if not conduit from both).

[Jim Becker]

Thanks guys. Are these ever three phase? I can easily run conduit, but need to know which panel (if not conduit from both).

The spindles are three phase even on these smaller machines, but the VFD on/in the machine deals with that. Big machines are typically three phase and the big vacuum pumps like Martin mentions are absolutely three phase. For many 4x8 or 5x8 machine like you seem to be considering, unless you go top end, you will not likely need three phase for the CNC...just 240v 1~ at whatever amperage the manufacturer tells you the machine requires. If you go upscale, then three phase may be a factor. It really does come down to the actual machine you buy. If you are interested in vacuum, you can get single phase solutions; they just don't have the duty cycle/life that the bigger, three phase units have, because they are essentially based on beefy "vacuum cleaner" type motors/fans rather than designed for purpose.

If you want to pre-install conduit but don't know "which panel" to go to, either just don't finish the panel end until you make a decision or run dual conduits so you have access to both three phase and single phase in the CNC location.

[Jon Snider]

Thanks Jim. Got some work to do here. Clearly my education is incomplete.

[Jim Becker]

Yea, the fact that there are so many variations with the machines makes it hard to pre-plan unless you make the machine decision. If you are at least down to a "short list" get the specifications and/or prep guide from those manufacturers for the machines you are considering and see if you can work out a prep plan that will work for whichever choice you make. Bare conduit remains the safest, however, IMHO.

[Martin Wasner]

or run dual conduits so you have access to both three phase and single phase in the CNC location.

Oh it hurts.

Put a big junction box in and mix voltages in the same pipe. Mucho easier and you don't have to worry as much about pipes crashing into one another as much. Also, if you do need to change something, you can yank the wire out of the pipe and pull what you need

[Darcy Warner]

Oh it hurts.

Put a big junction box in and mix voltages in the same pipe. Mucho easier and you don't have to worry as much about pipes crashing into one another as much. Also, if you do need to change something, you can yank the wire out of the pipe and pull what you need

This is a pet peeve of mine. I hate when there are different voltages run in the same pipe. Nothing like some 480, 240 and let's throw some 120 in there too.

Pulled too much stuff apart that had a mixed bag of voltages in it.

If its marked well ok, orange, brown, yellow for 480, but nothing like a pipe full of 15 blue wires and mixed voltages.

[sean meltvedt]

Jon for my 4x8 cnc I only have single phase. I have 2ea 30amp 240, and 1ea 20amp 120 circuits for it. 1 30 is for the vacuum, 1 30 for the spindle, and the 20 for the drives and pc.
Cheers
Sean

[Martin Wasner]

This is a pet peeve of mine. I hate when there are different voltages run in the same pipe. Nothing like some 480, 240 and let's throw some 120 in there too.

Pulled too much stuff apart that had a mixed bag of voltages in it.

If its marked well ok, orange, brown, yellow for 480, but nothing like a pipe full of 15 blue wires and mixed voltages.

Everything has it's colors in my building.

[Jon Snider]

Jon for my 4x8 cnc I only have single phase. I have 2ea 30amp 240, and 1ea 20amp 120 circuits for it. 1 30 is for the vacuum, 1 30 for the spindle, and the 20 for the drives and pc.
Cheers
Sean

Thank you Sean.

[Bill Dufour]

Do you see a lot of lightening? If so you may want to have a line reactor upstream of any computer to protect the electronics.
Bil lD

[Jon Snider]

Do you see a lot of lightening? If so you may want to have a line reactor upstream of any computer to protect the electronics.
Bil lD

Yes, nearly every summer afternoon. Thx for advice.

[Lyndon Klassen]

In my part of the world it is a huge code violation to run mixed voltages in the same pipe. Special considerations aside.