On Wednesday, February 25, 2015 at 12:30:48 PM UTC-8, robobass wrote:
On Wednesday, February 25, 2015 at 6:25:20 PM UTC+1, jon_banquer wrote:
On Tuesday, February 24, 2015 at 11:29:02 PM UTC-8, robobass wrote:
Doesnt it feel good to do it the right way?

(VBG)

OH Yeah Baby!

When you have rigidity most of your problem go away or are much easier to diagnose.

Well, you only get so much rigidity with a machine like this. You have to learn to work around it. Now I've discovered that the MDF table is not exactly on the X-Y plane of the spindle. Surprise!. I didn't discover this until I ran an array of 24 parts. It wasn't off enough do destroy the job, but I can easily correct it by facing the mounting plate before I make the next run. Yes, it's not a knee mill, but with care and tweaking I can cut brass. I paid 3.5K for a fully set up CNC with about 25" x 30" x 5" XYZ travel, and I don't need riggers to move it. Works for me. I don't need to cut steel though.

I think you mean your spindle axis(Z)is not perpendicular to the XY plane (your table), right?

A knee mill, such as a Bridgeport Series I, isn't very rigid as the table hangs over the saddle and is unsupported. The advantage of a Bridgeport type knee mill is that it's very versatile at the expense of rigidity. Bridgeport series I knee mills also suffer from a knuckle that isn't very rigid at the expense of versatility (The head can be tilted left or right as well as front to back).

Do you have a link to the CNC machine you own?