Damaged milling table surface

[nojay]

We have a Novamill that's been donated to the local Hacklab here in Edinburgh. It's functioning OK but at some time in its past someone left a cut running unsupervised and the final depth of cut was below the table surface, resulting a rectangular-with-rounded-corners area of the table being roughed out to a depth of a couple of millimetres (I can only imagine what the cutter looked like afterwards).

I suspect that a new replacement table would be impossible to source and even a second-hand one from a junked Novamill would cost a pretty penny. We've considered a few options but I'd like to find out if anyone else has dealt with a damaged table, what they tried to rectify the situation and what the result was.

1. Take the bed off and have it skimmed at a local engineering shop on a surface grinder. We might need to re-harden the top afterwards. The cut doesn't go down as far at the top of the T-slots but there would be not as much thickness left afterwards to prevent T-nuts pulling up through the metal under load. The squareness of the table to the spindle is another worry after refinishing the top to that extent.

2. Fill the hole with weld and get the top reground as in 1. I don't like this idea as the heat is likely to warp the table and possibly cause problems with jamming the X-travel ways.

3. Fill the hole with metal-loaded epoxy and permanently bolt a new T-slot plate on top using the undamaged T-slot channels at either end of the existing table. This will eat into the already limited Z-axis spindle travel and we'd need to level the new table with some care but that's achievable. The epoxy would be there to fill the void under the new T-slot plate, not specifically as a retainer or glue for the plate.

4. The same as 3 but with a home-made "pin" table as shown in another posting on this board. This would be cheaper but it would preclude using regular T-slot hold-downs for vices, tooling etc.

Does anyone have any other ideas or suggestions?

[Steve]

could you post a picture of the damage?

You could possibly machine a deeper pocket in the area where the damage is, then fit a steel plate into it. Pin that then skim it level with the table top?

[moray]

Does the damage affect what you want to do with the mill?

Personally, unless the damage was causing issues with clamping things down, I wouldn't worry about it.