Gallery, Projects and General > How do I??

DRO calibration

<< < (3/4) > >>

vtsteam:
Also, the zero adjustment in a DRO is naturally setable (absolute, incremental etc.). So what I'm doing is equivalent to your span calibration. The biggest span I can measure in a trustworthy manner is about 6" with the equipment I have.

vtsteam:
It seems to work. I got a calibration of 2562 on X and 2563 on Y, and with those numbers I hit the same measurement as the micrometer in thousandths on a 6.000" span.

The 123 blocks were great because I could arrange them to check measurements of 5.000,  4.000 and 3.000 inches as well as 6.000, showing me that linearity was good as well. And repeatability was also perfect with lots of measurements and traverses always returning to an agreed zero with the DTI, as well as repeated setups again to earlier measurements.

You can actually calibrate lines per inch to two decimal places using this DRO software -- I just stuck with whole numbers. I feel like I'm in my "close-enough" comfort zone now, and I'd need a bigger micrometer, more blocks, etc. to go finer

The general 2500+ lines per inch of these scales mean a resolution of a little under 4 tenths, so the nearest thou is really a matter of practicality, and I've limited the display to 3 decimal places. That's also adjustable.

If anyone is interested in this kind of interface, there is a prebuilt version of the interface board (the software is free) -- it's called TouchDRO .

Well, back to the Bluetooth DRO thread, and on with the mounting of the Z axis scale......

Thank you Andrew, again... :beer:

awemawson:
Steve,

I well remember the frustration of using my first 'machine tool', a Taiwanese Mill/Drill that I bought brand new, where the calibration of the down feed although marked as 'thou' was completely arbitrary, and being a 'round column' machine any head movement  lost any datum points anyway.

I got quite good with gauge blocks, engineers buttons, and other mechanical devices to find out where I was!

Glad to be able to pass on something useful for once.

vtsteam:
Andrew the Z axis scale is going to be a bear. The support for a moving quill scale will have to be cantilevered. And there's no really convenient place to put it. Most people who have done a DRO addition, choose to have a moving read head, and replace the Z axis quill stop in front. But no room there for a moving scale. About the only place that I can find room is behind the drill handle on the right side.

That stop is a mess -- I found 20 thou of vertical backlash, and the pinned side groove in the quill which is supposed to keep it from rotating has major slop. Thus the quill rotates a fair amount. I will probably have to replace the pin with something I make up. That's before even figuring out where to mount the scale. And as you say, all DRO axes are lost when you crank up the head.

I'll probably make one of those side rail attachments some day to keep X and Y aligned when cranking. There seems like a good version shown on, pardon the name, Winky's Workshop on the Tube. includes a motorized lift as well.

vtsteam:
Oops, hit the edit button on your post instead of mine -and messed it up  -- restored now, but now has edited by sig, sorry!  :loco:

Navigation

[0] Message Index

[#] Next page

[*] Previous page