Resetting the tool height after a bit change

[mark]

When I first start my job I set the bit at my home position (usually in the centre of my job) and issue a G92 X0 Y0 Z0 and have a macro setup in the universal g code sender to do this.
My problem is that when I change the bit I have to reset the height and only the height, Currently I re-issue the G92 command again after resetting the height with the router at the original x0 and Y0.
What I would like to do is set the height (Z) only and retain the original x and y zero positions whatever the current x,y location is now. Is there a way of doing this?

I am having great fun with the Carve King - It cuts very well and accurately. I have made a few mistakes (thankfully with damage only to my workpiece) - The issues I have had so far are

• a loose Z backlash fitting (not tightened properly on assembly) My multi cut passes were not lining up and I couldn't understand why
• Pressing return to zero when I have set the zero on the machine bed and the workpiece is still there. Big shock as the router was still spinning and made a very deep hole in my work
• Plunging too fast with a vee bit at the start of a cut (The router starts to chatter as each pass gets deeper)

I have one request (for safety) can the software be changed so that the return to zero does the Z move last? That way when the router traverses back to zero the bit will not hit anything in the way (like the edge of my work because it is 1mm too high).

I am looking for ideas to cut down the mess - is there an easy way of adding a chip extractor without interfering with the cut?

[aforww]

G92 Z0 will zero just the Z axis. If you're using UGS Platform, there are buttons to zero each axis individually as well.

In regards to your movements when you return to zero, I have a couple questions to narrow down an answer as it's supposed to raise Z then traverse or traverse then drop Z before depending on where it ended when the operation was completed.
1. In your CAM are you setting the origin to the bottom or top of your work piece?
2. Are you typing in your Gcode to return or hitting "return to zero" ? If typing, what are you putting in?
3. Are you using the latest version of UGS? And which one? The regular version or platform?

As far as Dust/chip evacuation is concerned, there's a whole bunch of options there. Plenty of folks here have made DIY options. Search "dust collection or dust collector" and you'll find a few.

[mark]

Thanks
I am using the UGS I will try what you suggest
In answer to your questions. I am using the return to zero button. The origin was at the top of the workpiece in the centre and The router was n the home position (I have homing switches fitted). i pressed return to zero an the machine zerod the Z first then traversed to the centre of my work (or tried to) but the workpiece was not quite flat so the bit hit the edge of the work.

I am using a version of UGS downloaded from your site about a month ago.
So to clarify tge issue it is return to zero button that shoud do Z last not return to home, that is ok.

[mark]

Note that if I have set the zero position on the bed the return to zero has the same problem but in my case the result was even worse because the router tried to traverse through the workpiece with the bit still spinning.

[aforww]

Shouldn't have zero set at the bed with material on it, ever lol. No benefit and risk destroying things. Follow the link and get the most updated version of UGS. I suggest using UGS Platform.
winder.github.io/ugs_website/download/
There was a version of UGS that didn't raise the Z prior to rapid movements but don't recall which version it was.

[aforww]

You could also type G91 G28 X0 Y0 Z4.0 instead of the "return to zero" button. This will raise the cutter up 4mm from it's current position then traverse.

[mark]

Thanks for all the help.
There are some cases where I need to set zero on the Bed - My thicknesser machine broke and I needed to machine my blank to 15mm thick and the only way to do this is set the zero on the machine bed.
Cheers
Mark