Level Y Axis

Gents,

Now that me machine is running, not 100% but running I thought I would check how level it is. It was suggested that I purchase a DTI clock which I did and began to check the Y Axis. The following was noted and I would be greatful of feedback comment.

I have installed 4x80x40 alu sections to help stiffen/support my sacrificial bed. The supports are at 170mm ctrs so I check at these settings.

0, 170, 340 and 510mm ctrs

0=0 in the DTI clock.
170mm on the Y = 1.36mm
340mm on the Y = 1.48mm
510mm on the Y = 0.75mm

If I were to level 0 and 510mm this would still leave 170 and 340 out. I am assuming that the supporting Y rails are deflecting causing the readings above.

Im a total novice to CNC but work within Architecture therefore undertand some things.

Any guidance would be apprecaited. Who ever said that having a hobby CNC would be easy.

Don't bother about it, it's less than 100mm :whistling:

No seriously you will always have some errors on a build like a gantry, the answer is to machine your sacrificial board in situ to flatten it.

Someone put a program on here I think to do just this [ or may have been on the Vectric forum ] you just plug in max travels and depth of cut and it goes all over the bed and takes a shaving cut.

[Edit]
Or use the surfacing wizard in Mach.

John,

Surely machining the SF bed will only provide me with a dished SF bed? If 1-2mm seems ok then I will do me best to limit this as much as I can. I am only cutting throught MDF, plastic and die bond so I guess deeper cuts are what is required. If 3d controuring then I will have to try my best to take this into account.

Yes the bed will be dished but not dished in relation to the Y.
It will be dished in relation to the base but parallel to the Y.