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Consistent Z axis cut

Posted by Anonymous User 
Anonymous User
Consistent Z axis cut
May 29, 2015 03:24PM
I just got this to work on my CNC router. Everything looks great, except for one thing (not PCBgcode's fault). My z-axis cuts deeper one time, then not so deep another.

My technique for zero-ing out the Z-axis is to position X and Y to my desired location, loosen Z-axis milling bit, let it drop to hit copper, tighten it, set Z-axis to zero......and it's inconsistent. The collet might slip upwards/downwards during tightening??? Not sure what's happening. The machine has a very tight tolerance. Drill holes are dead nuts centered. So, I don't think it's my router.

Would a probe be more effective? I'm also considering using my 200x PC microscope ($50 - hey it works great) and calibrating visually every Z-axis attempt.

You may have found a better way and I am open to ideas.

Great software program.

Mike
Re: Consistent Z axis cut
January 31, 2016 06:49PM
Re: Consistent Z axis cut
February 16, 2016 10:11AM
What software do you use to control your router?

I use MACH3 and one of the input pins to automatically set the Z zero

In short you connect one side of the connection to the spindle and thus the cutter, the other you connect to the PCB (I use an old pair of battery clips from a battery charger)

With a very small piece of code in Mach3(easy to implement) it will lower the Z axis very slowly looking for the contact point, when it achieves contact it zeros the Z and backs it away from the surface - Bingo perfect Z setting every time.

Ric
Re: Consistent Z axis cut
March 10, 2016 12:20AM
Hi, I use mach3 and had the same Z problem I setup auto leveling by loading a different screen set (2014 I think) and earthing the spindle and having a posative plate on the end of a 5volt lead that I rest on the surface of the work,of course neadless to say mine is an MDF table a metal table would be somethig different. Try googleing the arcsoft website to see clips of the system.
Re: Consistent Z axis cut
May 23, 2016 05:16PM
I use auto leveling and it works well.
Re: Consistent Z axis cut
June 01, 2016 12:32AM
Hi,
achieving consistant cutting depth is one of the challenges of circuit board milling. I use a jig
to hold the board so I can skim the depth of the jig. Even then the warp of the board can change
the depth enuf to wreck the result. Double sided tape will pull some warp out but vacumn holding
seems to be the best.
Have a look at Autoleveller software from the UK, there is a freeware version. I have yet to try it
but reports by those who do look very encouraging.

Craig
Re: Consistent Z axis cut
August 12, 2016 12:39AM
Hi 3DCutter,
I have now tried Autoleveller software. The freeware version works great but
the subscriber version (20UK) is more flexible and worth every pence.

Over the weekend I etched a board 45x80 with 35micron copper at a Z depth of
only 50micron (0.05mm) and achieved perfect isolation over the entire board.
Easily the best result I've ever had.

Amongst the software milestones that have allowed hobbyists usable CNC and
PCB isolation in particular are Linux CNC, Mach3 and similar controller software,
PCB-GCode, the subject of this forum, and I believe Autoleveller represents the
next milestone.

These advances mean at least to me that more, if not all, projects will be SMD
henceforward. The board I've just made has a TSSOP outline (0.65mm pitch,
0.3mm isolation between pads), I ordered the chips by mistake, I really wanted
the SOIC (1.27mm pitch, 0.62mm isolation) version of the same IC. The great
detail available with PCB-GCode and Autoleveller has made these tiny chips
usable afterall.

Craig
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