How do I overcut the last corner?

[Dougal]

I have a problem on parts that are continuous curves where the cutter stops where the maths should all line up. But due to machine flex/backlash and tool flex it often doesn't quite make it. I end up with a very small ridge which on some parts isn't soo small.

What's the easiest way to overcut these? Ideally I'd like to carry on and go around the next already cut curve and then tangent out. Can the "leadout" moves handle this or do I need something more elaborate?

[10bulls]

Hi Dougal,

Have you tried the latest CamBam 0.9.8 release? (Release 'i' is the latest).
CamBam CNC Software - Downloads

This has a new feature where you can set the LeadIn move to spiral then set the spiral angle to 0 degrees. CamBam will then use the depth increment value to control the pitch of the lead in so that it does 1 spiral per depth increment.

This produces a very nice, efficient toolpath that gently spirals all the way to the target depth then does another cleanup pass at full depth.
I use this method all the time now...it works well.

The downside is that you will do at least 2 circuits around your parts rather than 1 (which it sounds like you are doing).

This might actually be a good thing. If your machine is not that rigid this will reduce the cutting forces so you might find the gap between start and end is reduced. The spiral lead in will also overcut the start point which should cut away the residual ridge.

I hope this helps and good luck!

Originally Posted by Dougal I have a problem on parts that are continuous curves where the cutter stops where the maths should all line up. But due to machine flex/backlash and tool flex it often doesn't quite make it. I end up with a very small ridge which on some parts isn't soo small. What's the easiest way to overcut these? Ideally I'd like to carry on and go around the next already cut curve and then tangent out. Can the "leadout" moves handle this or do I need something more elaborate?

[Dougal]

I'm on release h. I'll give that a shot.
I am pushing to reduce cycle time on these parts, that's why I'd prefer not to do a full cut, but I should be able to run faster as well. On the last part I did a manual edit to put an overcut in. It worked well but was a lot of work to set it up.

I'm very impressed with the improvements in release h. It's cut my setup time hugely for each part and I've also finally nailed the import of 3D curves as DXF from solidworks through Rhino.
Essentially the combination of solidworks I already had, Rhino which I needed to buy for another job and CAMBAM has meant I can now cut everything I need without a mega $$ CAM package.