V bit true angles

I watched this video on Youtube about how to find the real angle of V bits, and thought that I would try the process.

I haven’t tried my 90° bits yet, but I tested a 1/2" 60° from Lee Valley and a 15mm 60° from Sienci. Both came out to be 59°. I don’t know how much difference this will make to my future projects, but Peter (cncnutz) believes that even one degree can make a noticeable difference. Since all it took was a bit of time to do the toolpaths and a scrap of MDF, I figure it was time and material well spent.

Peter provides the VCarvePro .crv files and .dxf files. His toolpaths will not work in UGS. If anyone is interested, I have the .crv files and the toolpaths


Grant, good reminder to check the cutter against its specs. I had a problem making pockets to the exact size I wanted that I tracked down to the real vs spec’d diameter of a mill. I went back and checked other ones I used regularly and found about 1/3 were off - usually smaller than spec’d. Now I guess I have to check the Vs!.



@BillKorn It’s not something that occurred to me, Bill. It should have, as I have some very good drill bits and measuring two of them that are supposed to be .25 " showed me that neither was, and they were different. And, we won’t even get into .24" dowels or .75" MDF.

If you have watched the video, Peter correctly points out that, in the normal use of these bits, a degree plus or minus would not make any difference to the end result. It’s our use of the bits that calls this into question.
On the Vectric site, they did a similar test. I think that’s where Peter got the idea, actually. One comment was that another test, and one that I’m going to try, would be to run a v groove of a set depth in a straight line along a board. Then, measure the distance between the two long edges of the groove. With this dimension and the known depth, using any software, you could see what the actual angle was.
Just for giggles, I’m going to try this and use Sketchup to measure the angle. It will be interesting to see if I get the same answer as I got from Peter’s process.

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Try comparing your measuring tapes around the shop for another surprise.

I had to dispose of one that was out more than 1/8" from my others.


@jwoody18 Jeff: I know exactly what you mean. I was taught to pick one tape when you start a project and stick with it throughout. You may be out some, but as long as all the pieces are out by the same amount, pieces will still fit. I did have one tape, though, that was fine for the first 13". Then it lost something over 1/16". I don’t know if it stretched or what went wrong.

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I hadn’t even thought of being careful about the tape until I had a friend working along side me. I was using my track saw to break down some sheet goods and he was measuring one end and I was measuring the other to position the track, trying to speed things up. But the track wasn’t square and after a few attempts of double checking each other’s measurements it dawned on me that it could be the tape - that’s how we found the really bad one. After that I confirmed the others laying around the shop are all very close so I can switch between them. At least below 4’ anyway, haven’t looked out further… I guess I should. :slight_smile:

Some really good info here guys, thanks. Now I have to go out to the shop and check all me tape measures :slight_smile: