Wednesday, January 7, 2009

Mounting the Z Stage

I got the metal for mounting my Z stage at a surplus/recycle metals place not too far away.

Wandering around the yard I found a piece of aluminum that was 1/3 inch thick, eight inches wide and about 15ft long which had one end a lot splattered welds and had been drilled for mounting in it’s previous life.

Got them to cut me a few pieces in various lengths of which I used the longer length as a base and split one of the pieces vertically with my small band saw to hold the Z stage vertically.

Needless to say the small band saw wasn’t really up to the task even with a new cutting band on it. The cut wandered all over the place so it you look closely at ExMrClean you will see that the back side edges are uneven for the Z axis mount.

From ExMrClean

The metal was also fairly groady from being out in the elements and sort of had this northwest Seattle climate slime on it. Hmmm, how to clean it up? A couple of passes through the dishwasher on heavy pot scrub cycle did the trick!

In the first mounting it was substantially out of true, it was almost ¼ inch out of true between the top and bottom of it’s travel. Since this spread out over almost 14 inches of travel in the vertical axis I initially left it at that.

With having to rewire I figured time to take it apart again and see if I could get it more accurate. About the only tool that I had that I could use to do this is my bench belt sander and needless to say it was a real adventure to try and sand the Z axis supports true by hand.

After chasing it for quite awhile I finally used a level to make sure the sander surface was level and then clamped the level to the top of the Z stage and watched it while I sanded the supports on the bottom. Still not perfect but a heck of lot closer!

As I mentioned in another post this design that I came up with is not really ridged enough as nophead suggested if you are going to be doing milling you shouldn’t be able to move things by grapping on to them. ExMrClear fails that stiffness test in its current form.

In hindsight the base should have been thicker and like the McWire design the Z movement should have been over the center of the moving table. I have this long arm to reach the center of the XY table from the Z axis so any pivoting permitted by the stage is magnified at the end of the arm.

Given that I can barely pick ExMrClear up now to move him; I will hold off beefing him up more!
Of course part of it might be that the center arm is made of wood. I haven’t been back to the metal place as our area has been fairly much snowed in with a once a decade (or more) snow storm and every time I have been by they have been closed.

No comments:

Post a Comment