How to Easily and Accurately CNC Engrave on Both Sides

Have you ever wanted to engrave your project on both sides making sure that both sides line up accurately?

Well, now you can and I'll show you how!

One way would be to use a purpose made jig to hold your stock and help you locate it after its flipped to the other side. While in some instances this method can be useful, it's not always possible to use it (ie. when you need to cut out your design after it's engraved).

So here is a way that I've come up with while making double sided key fobs. I'm not aware of other CNC makers knowing or using this method but if you didn't know about it and find it useful, why not leave a vote for this Instructable? :-)

OK, here it comes!

Step 1: Add Locating Holes to Your Design

In this case I'm using Vectric Vcarve but this method will work with any other vector design program.

As in the pictures, add holes to your design to help you locate the start position after the piece is flipped over. These holes will also help you align your project with the X axis of your router, in case you're cutting it out of a scrap piece of wood with uneven edges.

Place the first hole in position X0, Y0 and the other hole at the other side of your project. In this case, my project was 100mm wide so I placed the other hole at X0, Y100.

Thing to note - the farther apart the holes are, the more accurately you'll be able to align the stock with the X axis.

Generate the toolpaths for the holes and the rest of the design. In this case I used 1/8 endmill for drilling and cutting and a 60deg V bit for engraving.

Step 2: Drill Out the Holes and Engrave One Side of Your Project

Now is the time for action!

Go to your CNC router, place the stock you want to engrave and secure it to the cutting bed.

Drill the locating holes and engrave your design on one side. I used an 1/8 end mill for drilling - it's easier to find the centre of a smaller hole.

Step 3: Flip Over the Stock and Align the Holes With X Axis

Jog the V cutter to get it exactly above the centre of the left hole.

Move the cutter along the X axis ONLY to reach the hole on the right. Move the stock to align the hole with the V cutter making sure that the first hole stays in the same place.

Move the V cutter along the X axis back over the first hole and make sure it reaches the centre of the hole. If it does, reset X and Y axes to zero.