Carved seat and Aspire issue

Hello all,

I finally started carving my seats…The blank is 516 x 503 x 40 mm. I am only carving the seat and the nose on the CNC, the contour is done with regular woodworking tools.

So I started the rough cut with a 0.25 straight upcut bit. So far so good. Then I changed to a 0.25 ball nose bit ( … UTF8&psc=1) but the bit is too short. I thought it would be fine since I rough carved it, but the smoothing carve starts at a place when there’s full height (see picture). It is trying to go full depth and the collet hits the top of the material.

Any idea how I could fix this?

Thank you.

Run an additional pocket path using your rough cut bit to create the necessary clearance for the collet. Or acquire a longer ball nose bit.

The amazon link you posted is not working, so I cannot see the bit you are using. This is what I use for larger work: 1/4in (0.2498 in, 6.345 mm) dia. 4-flute 0° Tapered Ball-nose Carving bit, 1.00 in. max DOC, 1/4 in. shank, 2.5 in. OAL

If you go with a longer bit, keep in mind that you need to make more conservative cuts to avoid chatter, depending on the material used. I highly recommend giving this article a read if you haven’t practiced dialing in perfect feeds and speeds: Finding the Sweet Spot When Machining. There is a lot of very good information hidden behind the tabs in that article.

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@EdgarHaase sounds good. Too bad I have to order the longer bit. That will take 2 weeks to get there. But the clearance + longer bit combo look adequate, unless I add some zero plane to the design. I’m just no good enough at Aspire yet.

@PhilJohnson preview looks good in Aspire. Looks like it doesn’t take in account the bit length.