I started carving lines in my CNC router’s spoilboard to identify vacuum holddown zones. Soon I realized this grid was handy for other things. I could use them to a place a piece of material at a known point on the table. As soon as I had my own machine (without a vacuum table) I decided to get creative and carve all sorts of layout grids.
I’ve been using a pretty simple version for quite a while now. Lines along the x and y axis every 1′, as well as a few more lines along x near the center of the table. I use a Shopbot Buddy. The table moves on top of an aluminum beam centered along the x axis. This is the most supported and used area of my table. I do a lot of my work centered above this beam.
X=Left to Right Y=Bottom to Top
I carve it with a 60 degree v-bit at a depth of .003 inches (.08mm).
That has served me well for a while now. It takes 2 minutes to draw and it works great.
I’ve recently decided to try something new I’d been thinking about for awhile now and I think it will replace my carved grid. It’s an idea that I think I got from a wicked welding table I saw at Toolmonger.
I drilled a grid of 1/4″ holes, 6 inches on center, starting at the machine’s absolute 0,0 position. I use these holes to hold 1/4″ dowels. They offer me precise positions to butt my workpiece against acting as a fence. Choose any line of circles as your x and/or y axis. Place a couple of dowels along a line, slide your workpiece against them, set your zero location to the center of the dowel (plus the radius of the dowel, .125″), and Bob’s your uncle.
I can also use this grid to line up 2 sided machining operations like this.
If I want to lay a long piece diagonally, I start by importing this grid of holes into my drawing software. I use a few of the circles to align a rectangle representing my material. I then align my drawing to my material. Toolpath your file and go to you machine.
Here’s how it works after I have finished my drawing.
- Zero the table in the x and y using your machine’s proximity switches or other system by which you find a consistent 0,0 location.
- Re-zero your machine after moving it to .125,.125. This compensates for the radius of the dowel we are using.
- Place the dowels in the holes matching the circles you are aligning to in your drawing.
- Place your part and use appropriate holddowns.
- Cut.
I’m starting to really enjoy this setup. Create your own grid. It’s easy. Just make sure it’s something that makes sense to you and your work.