I had a friend ask if I could make a “tray” for someone with my Xcarve. The tray was a strange shape, with a ledge and pocket, and the same mirror image on the second side. It would be very difficult for normal woodworking tools to create but the Xcarve should be able to do without trouble.
Being a novice I said sure. So I started to draw it up on Easel and finally had a fair representation. With some help from the forum I figured out the toolpaths and tried the cut. Turned out my drawing wasn’t that good and I wasn’t able to get it much better using Easel or Inkscape. Turned out my dimensions came out a bit long in the “X” direction. Being 2-sided I did a fair job on the mirroring of the tray (with help of alignment/locator dowel pins), but all in all it was a unsuccessful project. It was a good learning experience. It lead me to recheck my machine for alignment and calibration, all OK, Next was reading on a number of CNC topics to determine where to go next. I found I had used nominal bit OD rather than actual which accounted for a longer than expected part.
Having a new copy of ArtCam express I decided to try it and found the drawing process was actually pretty straight forward and after some practice I can draw a project such as this fairly quickly. The toolpath process in ArtCam is more complex than Easel and required a number of Project files (side 1 and side 2) and required a number of toolpaths: locator pin pocket cut, ledge clearance cut (side 1 and side 2), pocket clearance cut (side 1 and side 2), outline relief cut with careful use of the single bridge in ArtCam.
I ran the 1st tray using a 1/8" 2 flute 22mm DOC bit and the total time was in excess of 6 hours (my Xcarve has the standard spindle). My side 1 looked good, but when flipped the outline was not correct, my mirroring was off. Back to the reading, more tutorials. Turns out I had not been centering my drawings within the workspace correctly as needed in ArtCam. I have this correct in my process now.
To address the job duration I revisited the bits I chose and tried using a 1/4" upcut 2 flute 3/4" DOC. Problems again, chatter, rough top edge. I was unable to find a shorter 1/4 bit than 2" which lead to deflection. Some of the chatter was cleared up with adjustment of spindle speed and depth of cut.
My last problem is that of start point. I have the end stops installed, but when I home my machine it races to the “X” “Y” spots stopping with a thump, enough to suggest this is not a good thing. The way I have been getting repetitive start point (home) is by using a small laser pointer with a smaller beam than as supplied and cross hairs marked on my waste board. This works pretty well and is fairly repeatable but not always, but then sometimes I miss something in Chilipeppr too which ruins my toolpaths.
So, at the end of my tale of “discovery” I decided I could not do the project as well as I felt it could be done. My question to you the reader is what can I do to improve my results, and would a edgefinder/touch plate benefit me by providing reproducible start points.
Photo of original part
Photo of reproduction
Photo using 1/4" bit