Chinese mill to CNC Conversion – Completed

I want to up front state this was a group project. My friend Eddy did the electrical for this project. I did the mechanical design and the more critical machining. The bulk of the machining was done by our friend John. At the start of the project, he didn’t know how to use machines very well and he hadn’t get been named John. By the end of the project, he was very capable and could do many jobs without assistance and without mistakes. The project took us about 4 months to complete.

We took a lot of pictures during the build and there were a few parts that were tricky. I’ll start you off with the good stuff, the before and after reveal. If you want to see construction pics and hear about some of the challenges, keep reading along.

Disassembly

Disassembly was pretty straight forward. When I started taking the mill apart I didn’t know what parts would be useful. The column seems rigid, but since it was round, didn’t lend itself well to a CNC machine. The base casting seemed fairly rigid, but the stand was beat. After disassembly, the only parts I decided to use were the base and the milling table.

The milling table was a good casting, just a bit rough around the edges. I had it re-ground and John milled the T-slots and side pockets. After cleanup, it looked like a new table. We also milled grooves for the x-axis rails and drilled/tapped holes for mounting. The table later had the side machined to allow mounting of the x-axis motor.

The base warped once it was unbolted from the stand. It was challenging to machine. I ended up clamping it as lightly as possible and milling down the 4 legs in one setup. I then bolted it down to rigid plates and did the rest of the machining. This one probably the hardest part to machine. It was awkward and took a few tries to get it right. By the end though, it was flat and relatively rigid.

The Z column was attached with a ground steel plate.¬† I tried using the tapping machine to tap the y-axis servo mounting holes but broke the tap… twice! Two trips to the EDM shop to have them burnt out. It’s not expensive but it wastes a couple of hours.

There were a fair  number of parts to make but most were basically flat plates with holes. The mounting plates for the servos all recesses for the servo motor flanges and I did those on the lathe with the 4 jaw chuck.

The assembly was pretty straight forward. We aligned the rails, bolted things together in sequence and then wired it up. We actually didn’t have too many issues during final assembly. We have a pretty good 3D model of the mill so we were able to avoid a lot of potential problems that way.

By | 2018-05-31T04:42:45+00:00 May 21st, 2018|Featured, Madeit|0 Comments

About the Author:

Brian is an intrepid maker living near Shenzhen China.

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