Excello 605 CNC VMC Controller Retrofit

Rebuild the controller for an older Excello 605 CNC Vertical Machining Centre using modern components driven by EMC2.

As it happens, I was in the processing of humming and hawing over a couple of different entry-level VMC machines including Tormach and Mikini milling centers. Each of the Tormach and Mikini systems when fully loaded with the largest work envelope, most powerful spindle, table with coolant system and enclosure, and an assortment of tools sufficient to begin machining right away, will run in the neighborhood of $12,000. Shipping is easily another $800 ~ 1000 depending on your area and shop accessibility.

Around the same time, a machine came up on Kijiji from a fellow in Peterborough who had salvaged it for parts and was dumping the remaining iron back onto the market. The machine came from a manufacturer who purported it had been struck by lightning - not directly of course, but the resulting spike was sufficient to cause the controller's demise. What remained after the salvage - after much of the external electrics, electronics, and hydraulics were removed - was the bare machine with its servo motors, encoders, and limit switches intact, and as it happened, a large complement of Kwik-Switch 300 series tool holders. In fact, opportunities like this seemed to crop up for months, as if the gods wanted me to rebuild this machine (but not without throwing in a few tests here and there to keep it real.)

After a long discussion over the state of the machine, exchange of photographs, remote video demonstrations of functionality (e.g. 12V car battery on the servos to show the axes still functioned), the commitment to buy was realized and I soon found myself on a roadtrip to Peterborough. Very nice fellow, Dan, who runs two businesses; one a regular sign-making business that seasonally goes on the road with a clever mobile sign making shop producing made-to-order signs as easy as fresh-cut french fries, and the other is fabricating polyester-fiberglass motorcycle body parts. If you need a sign made to order, or a motorcycle body part, or even a motorcycle body part with integrated made-to-order sign, Dan is your man. At any rate, we chatted for some two hours before realizing we'd talk shop forever if we didn't get back on the road to Toronto with my new toy.

Getting the machine onto Dan's 20-ft twin-axle trailer was easy enough - he just lifted with his gantry and cranked it down with strapping. Getting it off the trailer and into my garage proved a little more challenging. I called around to several towing companies until I found one with a boom long enough to lift the machine off the trailer and with a price reasonable enough to justify. We removed the motor and hoisted the machine off the truck where it swung like a wrecking ball until the driver realized he had his parking brake engaged. A little more careful this time, we backed it up more carefully to the garage and slipped under the door with exactly 1/2" of clearance. A few weeks later with the help of my wife, a few iron pipes and a large lever, we rolled the 3500lb machine to the center of the garage, spun it around, and backed it up into its final resting place.

And now for the engineering feat:

The tight budget for this retrofit required considerable planning and design to match the machine's specs and motor/tach/encoder interfaces, and whatever resources that were available on the cheap had to match the machine's original performance specifications as close as possible. The completed system incorporated not less than twenty different manufacturer's components, the partial list of which is shown below:

  • The Ex-Cell-O 605 CNC Machining Centre (with original factory drawings) (Kijiji)
  • Troyke NC10-360BLH 4th axis rotary table created for Excello (with original factory drawings) (Troyke)
  • EMC2 Linux-based Machine Controller (linuxcnc.org)
  • Mesa Electronics: 1x 5i20 FPGA controller, 2x 7i33 Encoders, 1x 7i43 GPIO card. (Mesa Electronics)
  • 7.5HP Allen-Bradley PowerFlex 70 VFD for the Excello's spindle (eBay)
  • 7.5KVA 1Ø 240 -> 600V step-down transformer - wired in reverse (Kijiji)
  • 1500VA 120/240AC to 70V DC transformer (Keling Automation Technologic, Inc.)
  • Four AMC 30A8 Analog Brushed Motor Servo Amplfiers (AMC used from eBay)
  • Four SCR relay board 1x 40A, 3x20A for AC such as pumps and lights (cnc4pc.com)
  • Four mechanical relays for DC switching (cnc4pc.com)
  • MPG4 6 axis pendant and LPT port converter (cnc4pc.com)
  • 30x20x10" enclosure (eBay)
  • A 3.2GHz Pentium system put through the bandsaw to fit inside the enclosure (courtesy: my own PC scrap-pile)
  • Kool-Mist cooling system with custom 5-gal reservoir (eBay and KBC Tools)
  • One-shot aftermarket oil system (KBC Tools)
  • Fuse Panel, terminal block fuses, wiring terminals, and other miscellany (local surplus stores)

The project took six months to research, design, scrimp, shop, save, and finally piece together components to bring this Frankenstein's monster to life. I was able to realize 90% of the motor's original performance capacity, but give it substantially more functionality due to the modern capabilities of EMC2 (Now Linux CNC). Overall, this project was tremendously successful.

The machine boasts a 3 1/2 HP spindle and a variable transmission with high and low gears. It'll run from about 20 RPM to 4000 RPM across two gears, and can displace 3.0in^3 of mild steel per minute, or 9.0in^3 of aluminum. Suffice it to say, it beats the pants off both Tormach and Mikini machines for a fraction of the cost, and paid for itself within the first year of operation.

Ex-Cell-O 605 CNC Machining Centre
Manufacture Date: 1984
Spindle: 3.5HP Spindle, Infinitely variable transmission, Hi-low gearing, 80 - 4000 RPM
Collect System: Kwik-Switch 300 Series
Table Workspace: 47.25" x 11" table, 750lbs max load
Work Envelope: 30" (x) x 15" (y) x 6" (z quill) + 13.5" (z knee)
Axes: 1.1HP Electrocraft Brushed DC Servos, 500LPR encoders + tachometers, 5:1 ballscrews, 2:1 pulley ratios
Machining Capacity (in mild steel): 3 cubic in/min, 1" drilling, 4" boring, 3/4-10 UNC tapping
Control Resolution: 0.0001"
Min Movement: 0.0001"
Position Accuracy: 0.0005" (all axes)
Repeatability: 0.0005" (all axes)
Rapids: 180 IPM (estimated)
Floor Space: 105" wide x 70" deep
Height: 88"
Weight: 3500lbs
Est retail value: $9500 excluding tooling
Estimated value to me: priceless

News: I have recently added an original Ex-Cell-O CNC 10" 4th axis rotary from Troyke, and will be diverting my previous 4th axis conversion to that of a 5th axis with direct table encoder feedback for a slow, but very stiff, high-precision 5-axis setup.

TODO - Near Future
Wire up 4th axis (DONE)
Trim, route, and tie down wiring after 4th axis added (DONE)
Add Monitor/Keyboard mounting arm (whenever...)
Add spindle index (or encoder) for rigid tapping (IN PROGRESS)
Add 5th axis directly to 4th axis table and wire it in (IN PROGRESS - EST SUMMER 2013)

Click images to enlarge:

Missing a ton of photos - I was so involved in building it out, I lost sight of keeping up with the whole photo blog thing