[burnley1]

Hello.

I built a CNC machine by myself im almost done with mechanical work and I just need some regulations of three axis.
Which machine or tool should I use to measure and accurate the perfect 90°angle between two axis and check if the rails are parallel and so on.

Which tool do you use for that? A regular spirit level tool with air bubble in water is not accurate enough right?

Please answer me.

I found some digital angle meter: http://www.chronos.ltd.uk/acatalog/LEVEL5.jpg
Is that tool good for what i need to do or do i need some other device?
Thank you so much.

[awerby]

For the XY plane, try cutting a square. Measure corner to corner diagonally. Compare the measurements. If they are the same, you're square. If not, you need to adjust your machine until they are.

To make sure the spindle is orthogonal to the table is a little harder. This is called "tramming". You can put a dial indicator on an extension bar, or use a flycutter or something similar in the spindle with something flat on the table, and revolve the tool by hand (don't turn on the spindle). Note where the point of the tool touches the flat plate,. If it touches evenly (or if the measurements from the dial indicator are all the same) then it's in tram. If not, decide whether it's out front-to-back or side-to-side (or both). It's usually easiest to adjust side-to-side by loosening bolts, moving the spindle mount, and retightening. If it's out front-to-back, you will probably need to put shims in on top or bottom of the mount until it's pointed straight up and down. An old feeler gauge set comes in handy for this.

If the rails aren't parallel, you'll notice that the gantry gets stuck. You can confirm this by measuring between them. Adjust them until it slides freely.

[RCaffin]

Hi Andrew

For the XY plane, try cutting a square. Measure corner to corner diagonally. Compare the measurements.

That usually assumes zero backlash.
You can cheat and mill parallel lines (on X & Y axes) always from the same direction if you have backlash.

Cheers
Roger

[awerby]

It shows if you can cut a square that's actually square, which is important for many projects. If backlash throws off the squareness, yes, it will show you that. If you use backlash compensation in software, it can show you if that really worked, or if you need to change the compensation values. If all you care about is whether the axes are orthogonal to one another, sure, you can produce a square your way, but that doesn't mean you can cut an accurate square (or anything else).

[RCaffin]

Hi Andrew

Yep, I agree 100% with all the points you made.
Personally, I don't think backlash compensation really works all that well. It can't. Best to remove any backlash.

Cheers
Roger

[shujaa]

Hi Rcaffin,

for the purpose of tramming can you please give comments on my post.
http://www.cnczone.com/forums/diy-cn...30004-cnc.html

[RCaffin]

Hi shujaa
See that tramming thread. Not a viable idea I am afraid - for all the reasons Jerry wrote.
Cheers
Roger

[shujaa]

Thanks RCaffin