View Full Version : Auto adjusting Z Axis?

Peter Meacham
10-09-2013, 9:18 AM
Another thread on this forum piqued my curiosity about the possibility of engraving an arched surface, in this case a wine barrel stave, by an auto focusing Z axis or another method.

A typical wine barrel stave arches about 1" to 1.5" in the middle as you go from one end to the other, on a 28" long stave for example.

Anyone have thoughts on how to have an engraver adjust it's Z axis automatically as it travels along the stave to compensate for the arch in the middle?

Right now I do the engraving using a CNC router with 3-D (Aspire) software which can adjust for the arch.

Just looking for a way to do it with a laser engraver.

Doug Griffith
10-09-2013, 10:24 AM
Engraving might be a bit tough because of the speed of the flying laser head. The z axis would have to move very quickly. Cutting would quite a bit easier if built into the machine but then you'd have an angled cut unless the laser head moved on a 4th axis at which point you'd need a few more mirrors at the head.

A long focus lens might do what you need to do depending on the detail and power of your machine. Just a thought.

Dan Hintz
10-09-2013, 10:32 AM
The machines out there won't do this natively, though you can get away with a partial hack by layering the graphic. Each color in the graphic covers a Z-height range of roughly 0.25", and with the job control set up to set the height correctly for each color, you can essentially push play and walk away.

If you were a more enterprising individual and took control of the Z level yourself, you could put the stave lined up top to bottom of the machine where speed of the flying head wouldn't be a concern. As the Y-axis slowly creeps down, the Z-axis is lowered until you hit the centerpoint of the stave, at which point the Z-axis is raised. I actually just thought of an interesting way to do that if you're following a 1-dimensional curve (such as a stave)... a 2-dimensional curve would require significantly more work.

Mike Null
10-09-2013, 12:06 PM
In my opinion the easy answer is no. My first choice would be to try flatten the stave by clamping it to a rigid base. That would not be a lot of stress given the 28" length of the stave. On the other hand, if it is a 3/4" or 1" thick stave that would likely not work. I assume it is white oak.

Joe Hillmann
10-09-2013, 12:34 PM
Lets say you want to engrave the word WELCOME across the length of the stave. You could program the laser to engrave the W and the last E at one Z heigth, the first E and M at another Z heigth, the L and O at another height and the C at the last height. Doing it this way will take about 3 or 4 times longer to engrave than a similar sign would take on a flat board.

You could flip the graphic 90 degrees and engrave going up the y axis with each letter at its own Z height which would also be time consuming.

It also may be possible to rig up something like this http://www.youtube.com/watch?v=SDqTp33xjME.

You could put a weight on the left hand side of the stave, engrave the WEL. Take the weight off, engrave CO. Put the weight on the right hand side and engrave the ME.

You could get a longer focal length lens so you have a larger area that is close enough to in focus. If you were doing lots of them I would combine Mikes idea of trying to clamp out as much of the curve as you can and a longer length lens. That would be probably be the quickest way to engrave them.

Peter Meacham
10-10-2013, 8:18 AM
Greats inputs everyone, thanks.

I will try some of them and report back.

Thanks again.