Help me translate caliper to mill measurements

If in doubt you can clamp either jaw of the caliper in a vice and push the free section with the axis of your choice to confirm the movement per division ;-)
 
Did more reading, there IS a z-axis lock, and I should use it. :)
Z-Axis Lock Lever - The Z-axis lock lever is on the right side of the head assembly behind the Z-axis coarse feed hub. Use this lever to lock the Z-axis so it does not move inadvertently.
Click to expand...

Will report back when I have more shop time.
 
On my LMS, I use the Z-lock all the time for accuracy. Just by locking the lever down a little bit, it can change the depth of cut a couple of thousandth. You need to install DRO's. Then you can "see" exactly how much it changes the cutting depth. Once you install DROs and learn the "personalities" of your mini mill, you'll be able to make cuts accurate enough to make a diamond. It's actually a very fine machine. I've had mine for over four years (I think) and it's never had ANY problems, period. Most people on this site know that I use mine all of the time for precision work.
 
chris.trotter said:
- I measure 3.225 on the caliper.
- I need to take material off to hit 3.125.
- This is a difference of 0.100.

I get my z-axis 0, then turn the knob 4 increments (4 times 0.025 = 0.100).
When I re-measure the part, it measures 3.200. (i.e. it seems to take off 10% of what I expected it to)
Click to expand...

Did I answer this above and not realize it?
.1cm=40 increments of Z not 4.
Or is the 3.225 a mix of 3cm and then .225 is mm?
Difference between .225mm and .225cm is 2.025mm or .07972 in english speak.
 
Dangit. Was hoping to avoid DROs, at least for now. Don't really have the budget at the moment. But good to know about the potential!

@rgray I'm confused, too. Don't feel bad. The 40 vs 4 increments thing is probably also part of it. I will report back with some actual data and not vague memories. :)
 
@rgray I've seen the cheaper DROs like that before - is what I'd choose, however, $400CAD is still outside my budget. :) Will start saving...until then, lots to learn about how this machine works - and let's be honest I have practically zero machining experience. Practice makes perfect...
 
https://www.harborfreight.com/6-in-digital-caliper-61585.html

These might help.
I must have 6 or 8 around the shop. Keep a 50 pack of batteries on the shelf also. Batteries are cheap on ebay.
I haven't gotten a battery eater for years (one that drains it's battery quickly) but have had one in the past. With those I either pitch them in the
trash or pull the battery every time I'm done with it.
 
I have a digital set, but batteries dead. Will check out ebay for the batteries, did not think of that.

I'm preeeetty sure I am reading the calipers correctly. Mill is just not cutting what I'm expecting it to.
 
If you are dialing down in -Z-, don't expect it to follow the readings. It was mentioned to dial past your set point and back up to it, I believe. And if you overshoot it, back away enough to overcome your backlash and try again. In my mind, I'm comparing this to lowering the table on a BP and expecting it to move with the dial, when in reality I think most people only move to their set point when the axis is "loaded", which on the BP knee would mean moving up.
When you are power feeding down, unless there is enough friction to "load" the quill, it may not, and probably will not be true to the dial. You could stick an indicator on it and run it both directions and see how it behaves. Plus I would imagine that between the handwheel and the feed gearing there would be considerable lash. In fact, it could be quite the opposite of keeping the dial in sync with the movement, there the lash may be your issue.
 
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