Big shout out to MartinW.Mcclary(Profile - MartinW.Mcclary - Inventables Community Forum)
I have recently begun doing 2 sided carves using two hold down bolts tightened into 1/4" Tnuts in my spoil board. You bolt the blank onto the board, run the carve, then flip the blank over bolt it down into the same two Tnuts and carve the second side,
Has been working very well for me accuracy usually within 0.5mm
So while waiting for repair parts for my machine yesterday I built these two small fixtures so that I could use the t track in my spoilboard, the first pic is of the blank bolted to the spoilboard fixtures.
The second image is of the underside. My finger points to the tbolts that hold everything onto the spoilboard, the short pieces of track slide in the gap in the spoilboard and keep everything in line on the Y axis. Gives much more flexibility than using the fixed t nuts under the spoil board and if doing a batch, once you have set center, you only have to probe for height, and do long runs one at a time.
underside
Took me just a couple of hours to make, have not tested it yet but I see no reason for it to give problems.
This is a variation of a youtube vid by DP woodworks that was posted years ago using aluminum extrusions for the fixtures.
If these pics work (a first for me) will post pics of the machine using them, once i am up and running again.