I bet you are thinking… Why doesn’t Ed just lay the Z zero plate on the bed before he puts the material to be cut on it? It’s quite simple you know!
When I change cutters in the middle of a job, I want to re-zero to the bed. I cannot do that with the bed covered with the job. So, here is how I solved that.
What you are looking at is a 1.5” diameter aluminum rod about 9” long. It is mounted to the end of my table and has a wire connected to the bottom and runs to the input #1 in the control box.
I copied the ShopBot supplied Z zero file to a Custom Cut file and changed the variable for the Z zero plate to a fixed number 0.00 since the top of the rod is the same height as the table of the machine. I also entered the fixed location of the X and Y that I needed the spindle to go to in order for it to be centered over the rod. Now all I have to do is run the Custom Cut file and the machine will move over the rod, run the Z zero routine and pull up to the safe z height. Nothing could be easier!
But wait! How do I get the surface of the rod exactly the same as the top of the table you ask? Well, here is how I took care of that. I created another Custom Cut file that will call the Custom Cut to zero the cutter to the aluminum rod. Then it will move away from the rod and prompt me to push the START button. Then it will surface 0.005” off the top of the rod. Next it changes the spindle speed by using the neat utility Ryan Patterson wrote. Be sure to look at the ShopBot Labs page to find the one for your spindle. http://www.shopbottools.com/mSupport/shopbotlabs.htm. Then I surface my table with the same 0.005” depth as I surfaced the rod. Now both the table and the rod are at the same height. When I lay 4′ X 8” material on my machine and cover the entire table, I can still zero the Z by using the “ZZR” (Z Zero Rod). Below are a few more pictures of the rod and how it is mounted. If you can make use of something like this, please improve on the idea and let us all know.
It’s now time to get back to making those Christmas yard cut outs before it is too late!
Z you later,
Ed
