Build Thread- King Rich KRV-2000 Knee Mill CNC Conversion

[BMSTECH]

Around 2 years ago I first discovered CNC Zone and was inspired by Chich2’s thread Hafco HM52 conversion to CNC. http://www.cnczone.com/forums/showthread.php?t=25895
I was considering purchasing a King Rich Knee Mill at that time until the AU$ exchange rate went through the floor. In Feb this year and the AU$ in much better shape, I decided to revisit the idea and have gone ahead and bought a KRV-2000 with a few factory fitted extras which will help with my CNC conversion. I’m in Adelaide and my new machine was shipped to my computer business in the city and transferred to my ute for the short trip home. At around 1300kg the logistics exercise in moving and positioning a machine of this size shouldn’t be under estimated. A chain block and rollers did the final job after a fair amount of sweat and cursing. I have interests in motorsport also I have begun a Honda S600 restoration. Conversion of a Mill is another project to keep me busy in semi retirement and is mainly for hobby use in future. My workshop includes a Hafco AL-340D 415V Lathe and 1200 x1.6mm folder.

[BMSTECH]

I mentioned a few factory fitted extras. My mill has been prepared by the factory for fitting a Proto Trak CNC system. The motors and controller are normally fitted by the Australian Distributor in Melbourne and adds nearly AU$20k to the price of the package including software. The factory fits ball screws and X and Y axis Cast servo motor mounts. Other additions include a larger transformer 1600VA for 110Vac servo supply, Universal Monitoring Safety Relay for E-Stop and Limit Switches, a heavy cast pendant arm for mounting the controller display. Another handy addition for continuous use is an automatic lubrication system. First thing to do is run some 3 Phase power and isolator switch. New column from floor to ceiling to bring conduit down and mount switch. Reworked the E-Stop circuit for manual operation just to get the machine to start.

[RayGardiner]

Hi John,

Congratulations on buying such a nice machine, should make for a good conversion, have you given any thought as to what servos and control software you will use?


Regards
Ray

PS. Is the Z axis drive on the knee or the quill?

[BMSTECH]

Ray, I am watching what you are doing with a lot of interest. I have not committed to any solution at this stage. I think my machine is a little bit bigger and heavier than the HM52 but that would only matter if the weight of the table and saddle is significantly higher. The SWI Proto Trak system uses 160V DC Brushless servos with the Amps integrated in the motor housing. 1:3 reduction on X and Y axis. I am focusing on the X and Y at this stage and will do the Z axis when I am satisfied that all is good. Your AC servo solution looks good and I am keen to understand the Pros and Cons? I have no specs or circuit diagrams to the SWI system to do comparisons? I took the following pics in the Standaco showroom in Melbourne. I have no experience with CNC software and will follow recommendations?

[RayGardiner]

Hi John,

Yes, I think that your machine looks better than the HM52, having the ballscrews already fitted is a nice plus.

AC servo's versus brushed DC, it's a long and involved topic, but to cut to the chase.. AC servo's are generally smaller, more efficient more reliable (no brushes) but tend to be more costly, and require a bit more sophistication from the amplifier design. Brushless DC on the other hand, are very much in the same ballpark as AC servo's. There are some very knowledgeable people on this forum who could probably add considerably to the discussion. The main advantage of brushed DC is the cost and availability, not to mention a reasonably wide choice of amplifiers.

I chose AC servo's because I spotted them on ebay at a reasonable price. They run on 240v AC single phase, which simplifies the power supply design..

Whichever way you go, there are plenty of people around here who are only to happy to help you through the rough spots.

Regards
Ray

[BMSTECH]

I have taken the plunge and ordered some Servo motors from Korea on Ebay. Is anyone familiar with these units and can steer me in the right direction to get these up and running? I'm following Ray Gardiner's lead but have choosen a different AC servo pack. Please Jump in with any suggestions.

ROCKWELL SAMSUNG 750W AC SERVO DRIVERS AND MOTORS FOR 3 AXES

DRIVER
THREE SAMSUNG CSDJ-10BX21 1Kw
INPUT VOLT. : 220-230 Vac 1PHASE 50/60Hz
OUTPUT POWER : 0-230Vac 3PH
CONTROL : POSITION, TORQUE, SPEED ETC...
SUPPORT CW/CCW, PULSE(CLK)/DIRE INPUTS
MADE IN KOREA, ROCKWELL SAMSUNG AUTOMATION.

AC SERVO MOTORS
THREE CSMZ-08BA1ANM3 750W-1HP, ONE WITH BREAK-24V DC)
RATED REV. 3000 RPM
MADE IN KOREA, ROCKWELL SAMSUNG AUTOMATION.

ACCESSARIES
THREE 3M-10350 CONNECTORS FOR WIRING SIGNALS
THREE 3M-10320 CONNECTORS FOR ENCODER CABLE-BOTH SIDE (NEED TO REWIRE)
THREE POWER CONNECTORS(MOTOR<=>SERVO DRIVE)
SIX PHOTO LIMIT SWITHCHES
ONE NOISE FILTER
ONE PC-BREAKOUT BOARD INTERFACE CABLE
SERVO SETTING SOFTWARE AND ENGLISH PDF MANUALS ON CD-ROM

[BMSTECH]

The servo kit arrived Friday from Korea and all looks good. I've ordered some timing pulleys and belts from Naismith in Melbourne that should arrive tomorrow. The encoder cables need to be made up using the connectors supplied with the kit. I have decided to order new AMP Mate-N-Lok caps and socket contacts to match the encoder and power plugs on the motors rather than trying to remove used pins from the connector caps supplied. For around $20 form RS Components it will be a lot easier to use new contacts. Still looking for some suitable cable to use for them. A 30m reel of good cable costs over $400 from RS. I need about 5m. Another idea was to run 3 high quality SVGA cables from the servo drives enclosure out to the 3 servo motor mounts and make adaptors to HDDB15 connectors for the encoders. Good quality SVGA cables are flexible, have 5 twisted pairs and excellent shielding. The 3 coaxial connections would be unused. I've got a 200 page manual on the drives to read and understand!

[BMSTECH]

Had some fun today making the timing pulleys fit. 48T516 and 16T516 pulleys and 400mm belt for the X axis and 450mm belt for the Y. The 19mm motor shaft was a problem for the small 16 tooth pulley.

[BMSTECH]

More pics of X and Y motor configuration.

[Jackal66]

BMS,

That sure is looking good. Keep showing the pics and any info or trouble you run into. Any advice or comments are welcomed.

Good luck,
JAckal

[BMSTECH]

I am very new to all this. This is the first time I have ever used a milling machine. This is the first job my new machine has done. With some advice, experimentation and a little common sense, I am happy with the results. The X-axis motor is mounted and the cast table top fitted to cover and protect it. That is the mechanical side of a 2 axis system done, now wiring the servo drives is the next daunting task.
Jackal, I welcome your comments and advice.
Cheers,
John

[skullworks]

You need to mount and test your axis limit switches and E-stop circuits.

In the event of a run away for any reason you need to be able to stop that thing before it self destructs.