That Last Cut

[John T]

Hi Art
When I am cutting a gear, it takes multiple passes. A very common standard for me is 1/4" Baltic Birch, and I use a very small spindle and I usually take 0.060 increments. That means I need five passes in order to complete the gear. The first four are the full 0.060 depth cuts while the last one is only 0.010 in thickness.

The problem I'm faced with is the gear will "break" free and move while the spindle is still making the last incremental path or cut.

Is it possible to make the last cut a full cut and put the fractional cut in the middle or second from the last?

My current work around is to watch the cut and as soon as I detect motion of the gear being cut I hit the emergency stop and remove the item.

John

[ArtF]

Hi John:

  Have you set a tab number? Setting "Teb" to 4 for example will put 4 holding tabs on the final pass, you may want to set a slightly thinker final pass so it holds, but setting 4 tabs with a tab width of 1mm or so will hold the gear in place so you can cut the tabs to complete it..

Art

[marklazarz]

Another technique is to drill the arbor hole first and insert a screw through it into the spoil board.  If you have tab capability and the gear has spokes, tabs can be inserted in the spoke area with the waste held down with screws so you won't have to sand tabs from the gear tips.

[John T]

Thanks guys. I have done those things and they work. Just looking for a lazier solution.

John