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Mounting brackets
21:30 27/11/2004 |
| The really cool thing about CNCing a mill is that you actually use it in manual mode to make it automatic! I'd seen several people online using
structural steel tube for this purpose, so finding a supplier near me I had some cut.
It was very cheap - but it
certainly wasn't "engineering grade". Lovingly pre-rusted in a natural outdoor environment, and bowed into an ellipse it actually rocks when you put it on a table! Not good
for mounting precision servo-motors to! Fortunately, there was a college workshop with a surface grinder
to the rescue, and after that I had rather nicely polished (and very parallel) faces. I don't know what I would have done otherwise
- as the metal is VERY VERY hard, especially the outer cake of oxidization. Even the carbide end-mills I used to work on it ended
up slightly chipped and had to be thrown away afterwards.
I then carefully machined cutouts into the square tube for the motor shaft and pulley to pass through and drilled some holes to allow the motor to be mounted from the inside. Replacing the bolts that usually hold the bearing block to the mill with longer ones
I bolted the brackets onto the mill.
A bit of blue paint to hide that horrible rust (where the surface grinder didn't get around the sides), and the result was quite
pleasing. Since the faces were parallel from the surface grinder, the servo motors and pulleys were nicely lined up. I slightly oversized the mounting holes, and put a bit of downward pressure on the bracket as I tightened up the bolts to tension the timing
belt. |
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Z-axis
21:45 29/11/2004 |
The Z-axis was about the easiest axis to convert to CNC - you just need to bore out the pulley to the correct size and make a
very simple flat mounting plate. I used some 1/8" aluminium for this. The mill has a graduated adjustable stop on the Z, so as you
won't be using this anymore, you just take it off and replace it with a pulley. Not much more to it than that - the last picture
perfectly explains it.
You can see that the same technique (minus the complexity of the bracket) is used for the Y-axis
in the 2nd picture above. We're just taking off the graduated handwheel/stops and replacing them with pulleys. |
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