# Thread: Chamfer Feed & Speed - G-Wizard?

1. Hi guys,

I need to do a 45deg chamfer on some Walnut with a 2-flute TCT bit. The total depth of the cut will be 9mm and I can do it in multiple passes (I was going to use 1mm passes).

Can anyone advise how to calculate the optimum feed and speed? I suppose the answer is, there isn't one since the tip will have a far lower surface speed than the wider section. Or perhaps I need to reduce the RPM as a take each deeper pass?

I do have G-Wizard and I can select a 45deg V-bit but I'm not sure if I should tell it the depth per pass or total depth or what.

2. Clearly it depends on the strength of the machine, but on mine I would probably do that in 1 or 2 passes, not 9. So long as the centre of the tool is offset from the edge of the material, and you are only cutting on one side, the force on the tool will not be too great. As a starting point I would set the spindle speed assuming that the tool is the maximum diameter it cuts at, as that will be a minimum speed so should guarantee nothing is broken or burnt. You can then work up from there if the material removal rate does not initially meet your requirements.

3. I just gave it a try and found it works best a fair bit higher RPM than one might expect. I'm going for 2500mm/min and 12,000RPM. Not surprisingly it cuts well at the wider part of the cutter at lower RPM, but I get a bit of tear-out near the point so it seems to work with higher RPM.

I'm cutting on both sides of the bit. Anyway I found what works well :)

I realise G-Wizard has a V-Bit option but it is really for engraving so expects the whole depth of cut in one pass.

4. If cutting on both sides of the bit, i.e. V-carving, then it makes sense that the rpm should be quite high, otherwise the centre of the bit isn't moving fast enough to cut efficiently.

5. Yeah actually I just tried it in the Walnut instead of MDF and it needs even higher RPM - about 18,000RPM.

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