Need to put in new ones. Best way for extraction??
If you have the installation tools you can remove the grub screw and machine the plastic box away, layer by layer.
If you only have hand tools then you can use a holesaw in a drill (1-1/8 inch dia, I think) and remove the center drill bit. With a pre-drilled (holesaw) piece of masonite tightly taped over the round end of the box, you can drill out the connection of the end of the box to the board using this jig as your guide. This cut should be no more than 1/8 inch deep!
For the straight part use a hacksaw blade wrapped with a rag (cuts on the pull). Again, only 1/8 inch deep, start it by scoring.
The hard part is to use a jigsaw to cut around the box slot and screw hole. Use a 1/4 inch drill to make a starter hole for the blade. This hole should only be 3/4 inch deep. Maximum blade stroke should only be 3/4 inch, tape blocks to the shoe of the saw to get this. Cut all the way around the slot and screw hole staying 1/8 inch outside of these areas.
The outer flange will fall away and the inner part can be shocked loose by putting a fin in and extracting the box.
This method is a lot cleaner than just ripping the finbox out…
Hope this helps.
I assume by “machine”, I can use a plunge router, shaving off mm’s on each pass? After top perimeter rim shaving, I won’t be able to put a fin in there to tear off the bottom trough because the tabs are missing inside the box - probably can router that out too? Thanks
That’s right. The system uses a stepped hole. Best to use a capture jig, as freehand would be too risky.
Plunge router makes it MUCH easier. Straight flute bit with 1/2 inch dia. You could plunge the center part first, starting at the screw hole, moving about 1/4 inch and plunging again. This “hopping” method generates less heat. Then, “flycut” the outer part, maybe 1/32 inch at a time so the heat won’t bother you.
Good Luck.