Re: [mill_drill] Re: new article available: A Few Basic Tests to Perform on your Mill
- Brian,I assume you are looking at version 1 of the article. I do a better job of explaining why I drew it this way plus the CNC standard in the latest version:
On Jul 5, 2011, at 9:45 PM, Brian Bayorgeon <rakort@...> wrote:not to be picky, but the way you define the positive direction of your coordinates is a little off "norm" (in the picture that shows the positive direction of each axis) The way you have your Y-axis pointing forward, the z-axis should be positive in the downward direction based on conventions of the Cartesian coordinate system. In the later picture with the block in the vise you show Y positive towards the column which is what I would expect. That way positive z would be upward.
this link explains the right hand rule.
Forgive? I’m just thrilled that you are back among us! I’m sure it was a harrowing experience. Two years ago I had abdominal surgery and was out of commission for 6 weeks. Not fun.
As to your table not being flat, I agree that milling and/or scarping or lapping will bring it into true. I lapped mine and it was a less than enjoyable 6 hours of heavy labor.
Until then, you may want to use soft pads to support your work. They will give you an extremely true surface since they are cut in place and not disturbed.
First forgive me for taking so long in replying to this. I had a side trip to the operating room for a double coronary bypass and am just now starting to get back to a little bit like normal.
I did read your article and agree completely with what you say. I guess we were saying the same thing with different words. Your sketch shows my point very well.
I have a situation on my mill where the table is not flat. Tramming shows irregular errors when the column/head is optimized. Perhaps +/-0.004" or so. Unacceptable in my opinion. When I get it set up again, probably two or three months off now, I hope to improve this figure with a combination of milling it flatter and perhaps some scraping or lapping with a small surface plate and sandpaper. Then I plan to do a really good tram.