Adding a DRO to an X2 Mini-mill

[krazy]

hehe yes the sherline and HF "micro-mill" and the like are reeeeaaaallly small
kudos to you for being able to finish an 80 on one, i'd have thought they wouldn't quite be up to it...

its actually thanks to guys like you that i was able to accomplish it though! DIYs and How-tos from the forum gurus. I love this place!

[Spaceghost]

Sweet set up Goober! Really impressive, what do you plan on making with it? Besides your time machine of course.

[goober]

Sweet set up Goober! Really impressive, what do you plan on making with it? Besides your time machine of course.

why thanks Spaceghost! (BTW how's Zorak?)
i've already done numerous 80% AR lowers, including an AR45 and an AR10 (in progress, got sidetracked with the DRO thing ), as well as various small parts for my own use and for others, including these.
I have some 1911's in the queue... More ARs... maybe something from scratch...
eventually i'll be getting a bigger mill, maybe go CNC on it or this one...

oh and um.....
ixnay onway ethay imetay achinemay, okayway?....
shhhhhhh!

[goober]

Followup- Checking XY Accuracy

Just thought I'd post a little followup. Before relying on my new DRO setup it seemed like a good idea to make sure they produce accurate measurements.
I did a quick & dirty test of the XY accuracy using something I had laying around that had some holes in it that are in known locations: namely, an AR15 drilling jig

First I clamped one half of the jig in the vise on some parallels. Then I chucked up a 1/4" drill bit and moved the table into position so that the bit was positioned over the pivot pin hole in the jig, and tested that it could be moved up and down freely through the hole w/o contacting the jig.
I then zeroed the X & Y axis readouts on the display.

Sorry for the hard to read display. Oh yeah, I also put together a mount for the display using a magnetic indicator base arm-thingy.

Many drawings/plans for AR15 lowers (such as the Ray-Vin guide) use the pivot pin location as a zero datum in X, Y, & Z. The locations of most other holes are then given from this point, like so:


So, I cranked the table over to X = -3.604", Y = -0.375", put a 5/32" bit in the chuck (this is the size for the hammer & trigger pin holes), crossed my fingers, and lowered the spindle...

BADA-BING! The bit passes right through the hammer pin hole like butter, no contact at all
I then tried with the trigger pin hole as well, and also returning to 0,0 to try again with the 1/4" bit in the pivot pin hole. All good. looks like the accuracy and precision of the DRO will serve my needs.