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Vcarve and under cuts?

Posted by Mark Evans 
Vcarve and under cuts?
March 31, 2017 05:44PM
I find myself needing to make undercuts more and more often. So far I've just made these by hand but if someone knows how to make Vcarve behave to do my bidding on this it would be great.

I use this for things like t-tracks cut into wood, slots/keyholes for hanging and other things that need an overhang.

The bits are called keyhole bits but Vcarve as smart as it is is not smart enough to know what not to do with them.


Re: Vcarve and under cuts?
March 31, 2017 08:46PM
I tried creating a form tool that would show a keyhole cut...but it doesn't seem to render the actual tool profile in preview. There is a keyhole toolpathing gadget (under the gadgets menu) that will plunge--follow a vector--retrace the vector back to the start--and pull out...this will keep the bit from retracting at the end of your keyhole. That seems to be the best way to handle it. Unfortunately gadget generated toolpaths can be a pain to edit because you have to re-do them each time, rather than just opening the toolpath on your side bar and adjusting settings.
Re: Vcarve and under cuts?
March 31, 2017 11:50PM
I'm not sure if there is that much difference between Vcarve and Aspire or you are misremembering?

The widget in Vcarve lets you plunge and then go a set distance N,S,E, or W and return.

I think I have it worked out, though. Sometimes just asking encourages me to look deeper. Looks like the Flute tool path will do the trick with the right settings. It will never give a proper preview but if I can get the right cut without hand jamming code I'm happy.

If it works I'll write it up.
Re: Vcarve and under cuts?
April 01, 2017 01:33PM
As always, all good thought Bill, I had thought of those I just was having a moment figuring out how to get a single plunge and retract. According to the toolpath simulations in Vcarve, the right settings in flute will do it.
Re: Vcarve and under cuts?
April 01, 2017 10:26PM
I cut keyholes with my router's keyhole bit with the handibot but without gadgets. I also first pocket them out with a regular endmill the same size or smaller than the shank of the keyhole bit. VCarve doesn't support keyhole bits, so I just create an endmill with the exact same size as the shank and use that.

As for entering and exiting in the same point, I just use a profile with a rectangle vector with a length of whatever you want, and a width of something like 0.005". If you specify "Use vector start points" under "Machine Vectors", then the tool will use the vector start point of the rectangle for entering and exiting. Just set your pass depth >= cut depth and it works. It will plunge down, go forward, back, and exit out of the same start point of the vector. Make sure to preview and probably even run an air pass to double-check everything is going to work as expected.
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