Carve King - issue with z axis (aluminum)

[mrspicman]

Greetings community,

First off, just want to say I am in no way a pro at this yet, still learning the ropes (there are tons of ropes   ).

I am a bit confused because this is my second go at milling aluminum and the first round I had no issues what so ever.

This second time round I seem to be having an issue with my Z axis losing some steps (and repositioning itself in height).  I created a Youtube video to show what's going on:



I just want to point out that this is the third time trying.  It seems to have gotten down to about 4mm (this is at about the 20sec point in the video) and then it just stops stepping down.  At the second and third time understand there is no longer any material that would be causing the z axis to jam in any way.  Also, after it finishes the first cut it moves to the second cut and the original z position is now lost (higher z).

I stopped and checked my voltages on each stepper driver to make sure I wasn't losing steps because of voltage.  All are hovering at around .649v to .651v so everything on that side of the world seems to be in check.  Checked the threads and motor coupler to make sure nothing was loose there as well.

I didn't want to change material yet (or another project) until I figured this out (and also could complete this job).

If anyone has any info, tips, or what I might be doing wrong here, would be greatly appreciated.

One last thing (although it doesn't matter since I explained in the last 2 tries I am not even cutting material and the spindle is still losing steps) but here are my settings for my aluminum:

- Amana Tools 3mm O spiral flute aluminum cutting bit.

- 0.4mm pass depth
- 1.2mm stepover
- 800mm/min feed rate
- 600mm/min plunge rate

Dewalt 611 router set at 1.5-2 speed setting (so a bit over 16k rpm)

Thanks for reading!

[deepdivetc]

Not sure if it is the same issue, but the first time I ran mine it did something very similar. I had the tension on the z axis just a tad too tight. Adjusted and it has been smooth every since.

[aforww]

I would think loosen up z a bit but don't know as I don't own the CK

[Derek the Admin]

Here's what I just wrote on your YouTube video:
It's a short end mill and you are right at the bed. The issue is probably that your Z wheels are hitting the Z bottom plate and it physically can't go any further. Check your anti-backlash nut tension too, but I bet it's Z bottoming. Jog it somewhere where there is no stock, then start jogging down. See where it bottoms out... I bet it bottoms out in a position corresponding to how deep you are getting in the material. The Z is running to the bottom and losing steps because it's being pulsed downward but mechanically stopped from doing so.

Either shim the work piece up more with one more waste board or lower the router in the mount. I like to set my router in the mount so that with a 1/4" regular length end mill that I use I'm just above the bed surface.

[mrspicman]

This is one of those duh!!! moments!!! 

I did as you suggested and brought down the z axis, sure enough, I am hitting bottom before the end of the material.

I feel foolish but meh...baby steps and we become pros!

Thanks Derek!

[Derek the Admin]

No problem. Don't feel foolish. It's all part of learning.

Do me a favor though: Delete or make private the video. People often use youtube to post vids seeking support help, which I completely understand. I just don't want one day a couple years from now all the results that get returned to be "problem", "issue", "fail" without the person seeing the solution that came about. LOL

[mrspicman]

I wanted to close this post to show what I was trying to accomplish initially when I had issues.

I know this is not completely original (you'll see) but since I have some aluminum lying around needed to see if I could successfully do this.  My John Deere tractor key was lonely and in need of a key chain so I figured I would try it out with some aluminum.  After working out the (silly) issues from my previous post I was able to successfully complete my project.

Here is my mini knuckles bottle opener key chain:




Loving the machine and the community!

Cheers!

[aforww]

Sweet. Glad you got a successful run!

[Derek the Admin]

Nice jo

[Jerry]

Don't feel foolish on running out of z and getting confused. I have seen it happen in professional machine shops too. :-)


Jerry