Awkward workholding when machining 4 sides

I’m working on a piece in 6062, on my Nomad3, which requires machining on 4 (or at least 3) of the sides. I’ve solved a lot of the problems, like cut settings, table squaring, registration, stock facing, etc. The last one is fixturing.

I can get my part machined on 2 sides pretty easily. But when I move to the third, there has been so much material removed that the remaining piece flexes, and I start to get chatter. I’ve lost a few cutters this way, and my only minor success still gave a part that had a lot of chatter marks on it.

Anyone have experience with fixturing wax? I’m thinking of millling two sides, then “casting” the stock in a temporary (masking tape) mold that I fill with fixturing wax - back to the dimensions of the original bar stock. I’d let the wax solidify around the voids, so that the part is held better while machining the third face.

A photo would probably help here, but just imagine I’m trying to machine a chess knight, out of a piece of stock that’s 0.5" x 1" x 6". I have plenty of clamping force with my toe clamps across either end (I’m clamping the last 2" of either end). But since I’m removing stock from the middle of that bar, my last operation is getting kinda wiggly :wink:

Ideas?

Machine a fixture which is a negative and secure things in it with fixturing wax?

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Hot glue with a loose negative could also work.

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I just ordered some water soluble wax from machinablewax.com. I was thinking maybe a 3D printed “moat” that I can bolt to the table around the part, and then fill with the wax to surround the remaining stock. Thanks for the idea.

I noticed you used to carry some fixturing wax on the site - any chance it’s the same stuff?

I was thinking hot glue to the bed maybe. I have some fixturing pins that I can insert in the threaded XY plate. I could place a few, then hot glue around the part and capture the pins. Thanks for the idea.

Does the hot glue shrink though?

I doubt it’s the same — ours is not described as water soluble — check in w/ sales@carbide3d.com to see what they say.

Not sure if it shrinks but I would just use as much as I could without getting in the way of your toolpaths