How to prevent "dwell"?

[Zamm]

Hi guys, I'm making guitar bodies and have had amazing luck using the spiral ramp to get the best finish on the side of the bodies. They only problem is the dwell spot where the bit stops. I have tried lead in/lead out but it is not available with the spiral ramp. It doesn't give me as good of a clean cut as the spiral. Any suggestions to fix this?

[srwtlc]

Try using your spiral ramp with an allowance as your first pass (down to an onion skin if needed) and then do a full depth profile pass without an allowance and no ramp, but with a lead in/out. Run this light cut profile at a slower feedrate and a higer RPM and you should get a clean cut. Use a good sharp tool also for clean cuts. If you have waste material in the way of the lead in/out, you can do a zig zag to start the lead in or cut a relief area at the start point first.

[Zamm]

Thanks! I will try that. I used to use a rough and finishing path but I got a lot of chatter at a specific part of the end grain. I left 0.05" for the finishing path and went at the same speed and feed. I'm going to try to leave less material for the finishing path and try the lead in/lead out technique with the slower feed and higher RPM.

[srwtlc]

I usually leave 0.02" and that seem to clean up any 'water line' marks on oak, maple, and walnut. Add a bit more if you see them. One thing that makes a big difference on the finish pass is to use a 0.375" bit instead of 0.25", if you can. I prefer compression ones.

[Zamm]

I'll try 0.02", I have been told 0.03" by one builder. I have been using a 0.5" Chip breaker finisher. I will look into compression bits. I'm cutting Poplar with a Hardboard top.

[Zamm]

Thanks! I finally got a chance to test out your suggestion and it worked out great!!