KMB1 Conversion

[Bob La Londe]

I've got a KMB1 I am converting to Mach 3 control. I looked at EMC and its fine, but I already run Mach 3 on two other machines and I am very familiar with it. Anyway, I am pretty much scrapping all of the old servo controllers, processer, memory boards etc.

Its got Randtronics Servomates.

I am saving a couple transformers, and power supply hardware, the VFD, position sensors, the servos, all the mechanical hardware, and spindle motor. (I may change the spindle motor later to a smaller one. This one is 5HP, and the manual says its a 4.) Two of the encoders crumbled when I touched them, but the one on the Z axis is till intact if somebody wants it.

If anybody needs any parts tell me what you want and make me a reasonable offer. I already looked to see what the salvage guys are asking en Ebay. No I am not trying to get nearly new prices like some of those guys, but I'm going to laugh at you if you offer nothing for everything too. LOL.

I've about got the VFD setup figured out. The motor was a trick since its actually two motors in one. If anybody has a cooling fan for it I would sure appreciate it. Two of the blades broke off the cooling motor in mine. The motor is a Leland with a 6273 that has a second motor inside to just run the cooling fan when the main motor is running to slow to cool itself.

The machine is getting new step direction input servo controllers and new 1000 line encoders. I looked at Gecko for a long time, but as near as I can tell these servo are powered with 90VDC and Marcus' responses didn't give me the warm fuzzies when I asked him about it. He said there is a safety margin in his controllers, but another conversation let me know if there was a problem I would be out the cash if they fried. I am currently vacilating between Dugong controllers and Viper controllers. We will see when I have the cash for them how I feel about them.

Its been sitting in the shop for a while with half the stuff pulled and half not. I got on a kick over the last weekend to get on it some more, and started pulling everything I didn't think I would need. One thing I pulled not really realizing what they were was the braking resisters. Holy crap, those things are huge. Of course then the first thing I started to reconnect and configure was the VFD... LOL. "Braking resister? I didn't see no braking resistor.... Oh CRAP! Yes I did." LOL.

Anyway, I'm not sure how this will progress, but I'll try to keep a build log on this thread as I go.

I already overcame my first hurdle. I couldn't figure out why there six primary wires coming out of the spindle motor... As I mentioned before. Its because its actually 2 motors. I ordered another smaller inverter to just run the fan motor for now. I'll set it up so the fan motor is on any time the main power is on so I just won't have to worry about it.

[Dave Rothermel]

You might want to read about Jack & I retrofitting a KM3. Might give you some in site. We used Gecko with good success. Took some turns off the transformer to lower the voltage a little. http://www.cnczone.com/forums/knee_v...urco_km3p.html
Good luck Dave

[Bob La Londe]

Originally Posted by Dave Rothermel You might want to read about Jack & I retrofitting a KM3. Might give you some in site. We used Gecko with good success. Took some turns off the transformer to lower the voltage a little. http://www.cnczone.com/forums/knee_v...urco_km3p.html Good luck Dave

Dave, Thank you. I really appreciate that. I've been exchanging messages with Danno for a while too. He did a KMB1 conversion. I think he has a basic video posted on You Tube of his machine running. I was wondering about the voltage. Seems like the motors were originally rated at 45VDC, and Hurco figured out that because of the way they are voltage controlled they could peak at upto 90 so they ran them that way. I have been considering dropping the voltage to somewhere in between.

I assume you are just running basic rectifier/cap unregulated power for the servo power circuits? I'll go read your thread.

[Dave Rothermel]

I took turns off the transformer so I had about 78 volts DC with the rectifier and capacitor hooked up. Here is a link to that. http://www.cnczone.com/forums/genera..._windings.html
I used the PMDX 126 BOB because it has a built in power supply that can be powered with 110 or 220 volts ac. After using the PMDX 126 I found many more great things about the board. I will help any way I can.

[Bob La Londe]

Originally Posted by Dave Rothermel I took turns off the transformer so I had about 78 volts DC with the rectifier and capacitor hooked up. Here is a link to that. http://www.cnczone.com/forums/genera..._windings.html I used the PMDX 126 BOB because it has a built in power supply that can be powered with 110 or 220 volts ac. After using the PMDX 126 I found many more great things about the board. I will help any way I can.

I decided to use a Smoothstepper and a C23. Not the cheapest solution, but I run some pretty long jobs on my smaller machines, and I would like to take as much load as possible off the CPU. My smaller machines both run PCI LPT ports to G540s. This is my first servo based machine.

I picked the C23 because it provides a charge pump, selectable input (pull up or pull down) operation, 0-10VDC analog spindle control, and a few other features along with giving me screw terminals for everything. The C23 gets its power off the Smoothstepper.

The Smoothstepper can either be USB or externally powered. I'll probably go with external power. I just don't trust the USB power on most machines. Heck I have one on my desk with 6 ports. 4 will power devices and 2 won't, but otherwise they work fine for things like camera links.

[Bob La Londe]

I was just doing some searching on power supply design and found this awesome on-line tool.

Martin E. Meserve - K7MEM - Un-Regulated Power Supply Design

According to their calculations the 60V secondary transformer provided with the machine should give about 84VDC when rectified. Still above the rating of the Geckodrives, but much closer.

[Dave Rothermel]

I hooked up the charge pump on the PMDX 126 right away. I manually moved the servo motors with a 12 volt car battery. I could set up the limits moving everything slow. If I hit the stops, (end of travel) it didn't have the power to break anything. I used the original proximity switches with good luck. I messed up one of the encoders. Replaced it from Digikey for $ 24.00. PMDX 126 has provisions for smooth stepper, and a second parallel port. You can double up (Matrix) the parallel ports pins to get more inputs / outputs with one parallel port. I set my computer with Mach. 3 right next to the the cabinet with the BOB & Gecko's while I made adjustments.
The computer will be mounted in the control council when finished. I have remote led lights at the control panel to keep watch on everything. Hope this helps.

[Bob La Londe]

Well, after reading up on power supplies yesterday, I took the last of them and all the transformers out of the machine today. One board really had me confused for a while. It had 4 different rectifiers on it and 4 caps. I finally sat down and looked at the caps to determine that none of them were rated high enough for the servo power supply so out they came. LOL. I kept expecting to see a seperate power supply for the servo motors. Then I got to studying the Servomate controllers. The only cap in the machine big enough to be the filter cap for the servo power supply is the one on the Servomate assembly. What got me was I could not find an individual recitifier that fed to it. There is one on each servo amp card. Weird. I'm not sure how that works, but because I am not going to damage the cards somebody else might need I'll leave them alone and just buy a big rectifer. They are cheap enough after all. (Rectifiers that is)

Whoever said to move the servos with a car battery. Thank you. That was the ticket. It moves plenty fast enough for testing. I had tried to move them previously with an alarm battery, but I guess its too much load for that little 12/7 gell cell.

I had hoped the inverter for my motor cooling motor would show up today. (That wasn't a typo) No luck. Then I would have setup to do a test run on the spindle motor VFD with switches and a pot. I guess I'll have to wait until next week for that.

Tomorrow I think I'll install the replacement for the servo motor that was damaged during transport. Then I can play with all 3 axis and see how the limit switches work.

If that goes ok, I may spend the afternoon removing the one side cabinet and setting it on top of the other. I know it sounds goofy, but with the location I have for the mill it will make service much easier in the future. Both doors will open from front to back giving me better access to them. It will also give me more room on the other side to get around to the back of the machine to fill the oiler check filters, etc.

With VFDs providing AC motor power and already having 230 I see no reason for that giant 460V transformer on the back so that back cabinet will come off too. My only concern will be if the 230/60V transformer may be a little noisy and interfer with the VFD in some way. or vice/versa I figured I'ld put that transformer and my two VFDs in one cabinet and everything else in the other. Well, once I get things figured out I'll probably need a couple other low voltage power supplies, but I don't see any reason they can't be in the bottom of the top cabinet with the controls.

... And I guess I better put the spindle braking resistors back on. LOL.

I'm not sure how I feel about putting the computer in the cabinet like in that other thread. Seems like a lot of noise will be bouncing around inside that cabinet, not to mention the heat. I did consider putting the computer inside the console, and just making a custom face plate so I could access critical things like a USB port to load g-code and install programs. (My CNC computers do NOT go on the network.)

[Bob La Londe]

By the way. Good read on the transformer unwind. If I go with the Vipers or the DuGongs I won't need to do that, but if I go back to the Geckos its good to know. By the way. I liked the nice simple way you had your power supply layed out.

[Dave Rothermel]

When I did mine the Vipers or the DuGongs drivers was a problem getting. Might do a search on this site. I didn't have the Geckos, just the BOB. That is why I did the limit switches first. PMDX sold me the Gecko's at a discount price. you buy there board and they knock off ten dollars each for the gecko's. The bridge rectifier and cap is on the servo-mate. Like I said the power supply is on the BOB. It has 5,12, and 24 volts. That is the only power supply, other then the servo 80 volts that I have.
Dave Rothermel

[Bob La Londe]

Tachometers.

Since I won't be using the tachometers on the servo motors what do you think about taking the brushes out of them and putting them in a spare parts bag in one of the cabinets? I have not looked yet, but are the tach brushes by any chance the same as the motor brushes? Speaking of brushes. What are the life of these brushes? The Y axis motor looks like it will be a real pain to get to if they need replacing.


Cabinets.

Since many of the items in the cabinets will have various indicating LEDs, (fortunately nothing so old it has lamps) I was considering cutting out the middle of the doors and replacing with a piece of lexan and maybe a wire screen (for RF noise) behind it so I could see all those lamps. Wadda ya think? When I get the shop rearranged this machine will be positioned so that when I come in the back door I will be facing the cabinets.

[Dave Rothermel]

I don't think the tack. brushes are the same. I took mine out. Jack put his computer in the cabinet with the BOB. He has to open the cabinet to turn it on, but i think he leaves it on all the time. Mine is in the control conses, where I can plug in a zip drive easily The screen and lexan glass would be good in the cabinet. Make it how you want it, because you are the one that you got to please. The hardest thing is to do is figure what to rip out and what to save. I used all the contractors, but the do different things. i have two transformers All are 220 volts in. One transformer has 12 volts & 110 volts out. I power my BOB and my computer from this. The 12 volts I rectified to dc and drive fans to move air. After that transformer is on, I take off the 220 volt input through an other contractor to turn on the servo amps. If the first transformer is not on the second transformer won't come on. Hope that makes sense. Now when it quits, I can fix it without spending lots of money for secret repair. My Y motor is on the outside of the frame KM3. The KM3P has the servo motor inside the base frame. You got to take it out to do anything. Dave I live in Indiana