Go to B&Q and buy a roll of 2 inch wide blue masking tape and a squeezy bottle of their superglue.

Cover the surface of the table with blue tape, also the underside of the wood.

Squeeze & spread superglue thinly on the table; attach the disc and clamp down firmly for a few minutes.

When you have finished, be fairly brutal about pulling the wood off. The blue tape stops the glue actually sticking to the wood or the table.

This method will hold down plate for CNC milling so should be plenty strong enough for your purpose.

Cut shallow recesses in the underside of the disc and glue-in some small magnets

MichaelG.

make some simple blocks with pegs on them to locate into the holes around the edge of your table and screw upwards through them into the wood.

You do not say how often you need to attach and remove the disk nor how concentric or repeatable the process needs to be.

The magnets is a good idea, but may have too many degrees of freedom. If you bore a shallow recess, the diameter of the table, in the underside of the disk, you assure concentricity (but not repeatable clocking).

The blue tape and supeglue is good for a one off where concentricity is not important.

The blocks and screws is reasonable for both so long as you number the blocks and use the same screw holes.

Sand three rectangular blocks to fit the T-slots (width and height). Put a couple of sheets of paper under them so they stick slightly above the T-slot. Glue the disk to them with a heavy weight on it until the glue sets. It is a one-off challenge to make the disk concentric but after that, so long as you mark one block and one T-slot, it will always go back concentric and in the same clock position.

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Quite so … and to constrain (unidirectional) rotation only needs one additional peg to locate in a tee-sot

[ none of which was part of the actual question ]

MichaelG.

Edited By Michael Gilligan on 10/09/2021 08:14:41

Glue four tenons under the disc to match the tee slot positions and place on the RT, number them and the slots so you can place it back in the same place each use. It won’t move under the pressure of a pen. No need to glue to the RT if the tenons are a good fit.