Granite base CMM to Router Conversion
Well,
Its been about 3 years since I started this project with no documentation and some parts are getting long in the tooth, so I think its time to document some upgrades to the first CNC machine I own.
Let me introduce you to Little-Mill. This was a ROI OMIS II CMM with a travel of 24" X 18". I think the base is cast granite. It measures roughly 43"X40"X5" and weighs about 500 lbs! (If it didn't come with a cart to put it on I wouldn't have bought it!) The coolest thing about the base besides it's shear mass, are the vibration dampeners that isolate the slab from the cart.
The stationary gantry is made from a combination of cast aluminum sides and a ceramic span. The linear rails on the X axis are bolted right to the ceramic span with epoxied mounts. The aluminum cast sides are bolted through the granite base with 4 1/2" bolts! The gantry itself weighs about 80 lbs.
On to the Z axis... When I bought this contraption it has no Z just a mounting plate on the X axis. The guy who sold it to me said that he would give me a z axis that I would have to do some work to bolt on. I looked at the actuator he was talking about and saw that it linear rails and a ballscrew! He even threw in 3 stepper motors! SOLD!
The next step was loading it into my Dakota and hoping the cops didn't stop me on the 1 hour trip home! When I got home I had to get the sucker inside the basement. Thats a story for a another time.
Over the next 2 weeks I had to mount the motors, z axis and come up with a motor driver, power supply, and limit switches. Hooking it all up was a snap. The worst part was waiting for the driver to come in the mail! I currently use a Xylotex but I'm thinking of a Gecko 540 and a new power supply.
When I first taught myself the process of CNC, I used a Techno DaVinci mill. The Techno had no CV mode and took forever to do curves. I was pleasantly surprised to see my machine with mach 3 turning smooth curves. The speed and smoothness was amazing! Then I started to tune the machine. WOW! The screws on the X and Y were lead screws with 2 starts and I think a 10mm pitch. The nuts are different from ones I see on the zone, they have two parts connected with metal posts and a spring.
I have to watch LOST now, I'll post more later.
http://www.glenspeymillworks.com Techno LC4896 - 2.2Kw Water Cooled Spindle | Moving Table Mill from Omis 3 CMM, 500Lb granite base | Epilog Legend 32 Laser Engraver