Indexing thick stock for flipping question

[baaja (F B)]

I’m working on a guitar neck and I’ve run into an issue. I previously worked with 1.25" stock, which seemed to be within the shapeoko capability of milling a 3/8 hole all the way through into the spoil board. This allowed me to flip the stock over and mill the other side without issue.

I’m working with a piece of 2.2" thick stock, and it seems there is just too much wobble in the long reach bit, no matter how slow my speeds and feeds are. There is significant runout at the end of the bit with 2.5" of bit hanging out. This makes it so I can’t really rely on the holes and pins to index on when I flip

I’m interested in how others would rack indexing thick stock like this for two sided machining.

[partferret (T Chen)]

If you’re using vcarve, place your two dowel holes arbitrarily on face A. Select and copy to face B. Then use a short bit to do both. A on the stock surface. B on the spoilboard. It’s not a through dowel, so I’d probably use something you don’t mind leaving in there.

If you want it reversible, then with the stock flipped into B position, do the B side dowel holes on the new top surface of B. And then A dowels on the spoilboard.

[gdon_2003 (Guy Donham)]

You could drill some holes in the spoilboard and use dowels to register the side of the stock and not in the stock.

[baaja (F B)]

This sounds like a good solution. Would you recommend just creating another job and copying the drill points to drill the spoil board?

[baaja (F B)]

That’s a good idea, but unfortunately I’m not using stock that is dimensioned well enough to index off of.

[partferret (T Chen)]

Export dowel hole toolpaths by themselves. You’re switching back and forth to the long bit anyways when you have these done.

[partferret (T Chen)]

Ah, I figured I’ll post the video where I got this from.

Jumps to hole toolpath on the side B (note the yellow ruler). He’s already copied from A at the beginning.

Two Sided Machining 1 - Part 30 - Vectric for the Absolute Beginner

Later on, he does the selective exporting with selected toolpaths.

[Tod1d (Tod (with 1 'd'))]

@baaja

That’s a good idea, but unfortunately I’m not using stock that is dimensioned well enough to index off of.

Machine 2 holes in the spoilboard for dowels, then machine the back edge straight to a known dimension. Now when you flip it that machined edge lines up with the dowels.
I would also machine the left end flat to use as my X zero. You could add a dowel hole on that end too so no measuring would be required after the flip.