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.
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.
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.