Taking the CNC Plunge

mksj said:
I would recommend a 5K speed pot, the spec. for the WJ200 is 1K, so anything in the 1-5K should be OK. The P1 and P2 are thermostats (P-Stats), alternatively I often connect them either to the E-Stop circuit or there is the inputs/settings to connect them to the WJ200 as noted above, which will shut down and give you an error code. The connections will differ if you use source vs. sink logic. Consideration should be given to if you want the P-Stat to shut down the motor AND also send a stop single to your CNC program, similar to a limit switch. Shutting down the motor in the middle of a cutting sequence could be problematic. It is also possible to use a simple 2 pole 24VAC relay powered through the motor P stat which also provides power to the main power contactor and connect one pole to the the VFD P-Stat contacts and the other to CNC program stop function. Breaking power to the E-Stop, Power or the P-Stat opens turns off which opens the relay and stops the motor, powers down the VFD (this takes about 30 seconds) and sends a stop signal to the CNC program.

I had previously posted a 3 wire connection diagram that can be used with momentary buttons as opposed to 2 wire sustained on to input 1 and 2. It also utilizes the current machine E-Stop system to power down the VFD. A few people have used this on their PM mills. I am a bit unclear if this machine is going to be used for CNC, then the computer/program would control both the direction and speed of the motor directly unless you are manually going to be doing this.
Click to expand...

I found your schematic last night, couldn't remember where I first saw it, and studied it thoroughly. Bear with me as electricity is not my strong point. If I understand your logic the factory supplied for/rev switch is still used to control spindle direction. I understand the function of the two momentary switches; one for On and one for Off. Is this correct? Is the symbol in the wire between forward and reverse a diode?

For info my mill is CNC but will manually be changing speed and spindle direction until I move onto phase 2. Phase 2 will be a ESS and spindle control board upgrade.

Til the next onslaught of questions, thanks for your help.

Tom S.
 
tmarks11 said:
P1 and P2 are a thermoswitch inside your motor; you are supposed to hook them up so it kills power to the motor if it overheats. The Hitachi WJ200 has connections that are designated for that purpose.
1. Set code C005 to "19" (Page 4-6 "PTC) - (activates thermal protection)
2. P1 and P2 should be hooked between terminal "5" and "L" (page 4-30).

5K or 10K pot will get the job done. You don't want to go much higher than that, since EMI will induce sufficient current to cause unstable response.
1. Set Code A001=00 (Page 3-12) -activates external pot.
2. Connect it between "L" and "O" (page 4-5).

Yes, you want to hook your FWD/REV switch into the VFD. You probably also want to buy an E-Stop button and hook that into the VFD too.
1. Set Code A002 =01 (Page 3-13) - activates terminals for control
2. Lead from the FWD switch terminal to "1" (Page 4-16).
3. Lead from the REV switch terminal to "2"
4. Switch power to "P24"

Not sure what on your switch equates to which position. Basically, when the switch is in FWD, it should allow current to flow from "P24" to "1". When in REV, "P24" to "2".

A couple other points:
1. You will want to set up regenerative braking to slow down faster
2. Make sure that your VFD controller box has good ventilation. That thing can be putting out 100W of heat. You notice in the manual they specify installing it in a box that is at least 4" clearance above,4" below, and an 2" on each side. That might be more than needed, but in the little box you have you might end up having to install a fan to keep ventilation flow (page 2-8).

EDIT: Hitachi, not Fujitsu....
Click to expand...

Tim - your input is appreciated. I've got four wires coming from my for/rev switch. Are you saying two go to P24, one goes to terminal 1 and the remaining one goes to terminal 2? Sorry for any stupid questions but I want to make sure I don't fry the VFD because I mis-wired something.

Yes, my plan is to add a fan to the enclosure. Got it on the P1/P2 leads. Seems simple enough.

Tom S.
 
Not sure if the picture of the VFD in the box is the way you intend to mount it but you will want the control panel facing you for programming etc.
 
jbolt said:
Not sure if the picture of the VFD in the box is the way you intend to mount it but you will want the control panel facing you for programming etc.
Click to expand...

Unfortunately that's the only way it will mount. It's a 12" x 12" x 6" enclosure. I opted to go with this enclosure because it was in stock locally. My mill has been down for a month and I want to get it running. Worst case is I leave the wiring a bit long and do the programming with the VFD out of the enclosure. The screen is visible and I can get to the buttons the way it is. Thankfully I only have to program it once.

Tom S.
 
Thanks to mksj and others I've got my VFD wired. Next step is to wire the motor but I can't do that until I get the spindle grease so I can assemble the spindle. I'd like to do the VFD programming while waiting for the grease but I think I heard that you can't run the VFD unless it's connected to the motor. Is this true?

Tom S.
 
Success, at last. Got my spindle together and installed and ran it with the belt. No abnormal issues except a rattle coming from the spindle. It's the spindle spline rattling in the drive sleeve. I know it's the spline and drive sleeve because when I tighten the spindle lock the rattle becomes louder. I ran for 15 minutes at 900 rpm, then another 15 minutes at 1800 rpm, then ramped up to 3600 rpm and finally a run of 6400 rpm for another 15 minutes. Highest measurable temp was 103 deg. F at the drive sleeve bearings. It also whines a bit but my understanding is this is normal. I seem remember there is a parameter setting that helps to reduce the whine.

I got a over-voltage error when I quickly turned the pot down from 90 hz to 0 hz. It's got something to do with dynamic braking I'm sure. I'll look through the parameters and figure out which one to change. I'll try it with no braking and see how long it takes to coast down.

All in all a great learning project. Thanks to MKSJ (Mark) and several others for chiming in with answers and suggestions. I would not have taken on this project without their help and guidance. I've attached the files MKSJ sent me so that others can see what I did. Hopefully it will help someone else. I tried uploading a short video of the mill running at 6400 rpm but the file is huge. I'll see what I can do about reducing the file size.

Tom S.

KM2 and KM3 are no longer there nor is the DC Z axis lift motor.
VFD Wiring Diagram.jpg
 

Attachments

If you install an external braking resistor ($20-30 on eBay), it will help the rapid deceleration. You would be able to stop the spindle in less than a second.
 
I had the spline rattle and fixed by greasing it.

I don't use electronic breaking with spindle controlled from Mach3. There is enough drag with the belt drive to slow it down quickly enough. I do like it on the lathe though.
 
You must log in or register to reply here.
Back
Top