Reverse-Side Router Indexing

How to index your workpiece and your router for working the back side of a panel. November 8, 2008

Question
Does anyone have experience routing on the reverse side? How about registering the routed image on the front side and back side? Material is MDF and AL.

Forum Responses
(Architectural Woodworking Forum)
From contributor B:
I've done a number of projects with reverse side indexing. It's actually pretty simple.
On the first side design some strategically placed holes that are symmetrically located. For example, if you are cutting a 24" circle pattern, go outside the circle on the left and right with one hole on each side. If you are cutting the 24" circle pattern out of a 30" square sheet they would be typically 2" from the left and right edges, 15" from top and bottom corners. This is assuming you have centered the 24" circle on the 30" square material. If the holes are placed correctly they will locate your piece properly when flipped. Drill these two holes all the way through your material and into the spoil board. After cutting the first side, remove the material and drive two dowels into the holes in the spoil board. Slip the flipped over material onto the dowels to locate the piece for the second side routing.

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From contributor T:
I've seen some people just use pop-up pins as their locators, but the above approach is the most common and the most accurate.

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From contributor J:
Of course if you have a newer nesting machine and software, you just flip the work piece and push it up to the pins, which unless you have a fixed spoil board is actually the most accurate method.

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From contributor L:
Just use the pop-up-pins. Hard to see how you could get much more accurate. The software will make the location positions automatically.