How to setup for a production run - Carbide 3D Community Site

I have a new project for my shapeoko and need to be able to have repeatable results as I have to make a couple hundred of these as accurately and as fast as possible.

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I need to be able to make a pocket cut, well more like a trench centered each time in a piece of wood. The wood is 1/2" thick, approximately 8" x 6" size. the trench needs to be 3/4" wide , 1/8" deep running in a square shape that is 4" x 3.75".

The issue is the 8"x6" boards may have some variation in them:

Up to 1/2" in width possibly but most should not exceed 1/4" variance.

There should be no variation in length but it is possible by about 1/8" maximum if the board length is miscut slightly.

My question: how do I make this trench centered every single time even if there is variation in the width and possibly length of the board ?

Not sure I picked the right discussion channel for this, if its wrong please let me know and move to appropriate channel

If the pieces are pre-cut to the final outer dimensions, and those dimensions vary, then it is rough to get things centered every time without a lot of effort in either programming or in resetting the varying dimension’s zero on every piece.

On a programming aspect: Make yourself a X and Y fence for repeatability there. Measure out the final dimensions of the material and sort them into groups. Your tolerances will be the guide as to how many groups you have. Then make a program for each variance of outer dimensions. Then run a batch of sizes, switch programs, run the next, etc.

If you can, start with oversized material and do the exterior contour in the machine as well. And as pointed out, if you have the capability grid a lot of pieces and just let the machine run them.

You will get efficient and thoughtful service from NEXTAS.

I also think that, depending on your tolerances, the tightness of the individual cams will cause the piece to shift in one direction or another - possibly both x and y - a little bit…maybe negligible, but it depends on your specs.

I think you’d want something that has a parallelogram set up with the center point fixed. Kind of like this (Warning: Horrible artwork alert):

If you fix the center point to the zero, you should be able to shift the piece on your board until the pieces all fit properly. I would think. I’ve used the parallelogram to locate center of a piece, but haven’t thought about fixing the center and using the jig to position the wood. I don’t know why it wouldn’t work.

EDIT: Better drawing of the jig:

That center point would need to be fixed to your spoilboard at origin 0. You place the workpiece into the jig between the arms, manipulate the arms of the parallelogram until they’re snug - and the piece SHOULD be zeroed.

As long as the routed trench looks centered to the naked eye thats good enough. So I would say within ±. to maybe ±. tolerance would be fine. ±.125 would probably start being noticeable?

It’s a decorative function, nothing mechanical in nature. the trench just needs to look centered to the naked eye. It can’t look off center.

Im not quite understanding how the cam clamps would center it as wouldn’t they need to be rotated simultaneously through some sort of cable or linkage system?

I also looked at Garys method and I’m not quite understanding how to build something like that. I tried looking up YouTube videos, or google searches for such a design or even parallelogram jig and came up empty handed

For more information, please visit Self Centering Vise(ja,es,ar).