Context:
Been reintroduced to facegrain advanced vcarves after having spent a long while doing endgrain ones in an effort to try to save myself from having to always make endgrain boards.
My inlays are 4mm deep (4.5mm for male for the gap) and I’ve been using the following parameters for the v-bit (kyocera 2-flute, 1/4", 30deg):
20000rpm
2.25mm DoC
800mm/min
From online sources, they indicate with facegrain you should use the v-bit BEFORE the pocketing endmill to reduce/eliminate chipout.
I did a test the other day with sapele (female) and oak (male) and it turned out great. I decided to scale up in size to test over larger project of Waltnut (female) and maple (male).
The female turned out fine.
The male had a bit of chipout.
For the male, I did find on my final toolpath (where i cut out the perimeter for my final shape after the inlays completed) that my stock started shifting out the clamps so i emergency stopped. However, this might have happened during the vcarve on a smaller, less noticable level which may have been entirely to blame for the chipout I experienced on the male (i had other symptoms on it that indicated shifting too).
Question:
is the logic correct that using the v-bit first before the pocketing bit reduces chipout or does it make zero difference?
anyone here any extensive experience with facegrain inlays can weigh in on how you had most success?
I generally find I get a better cut when doing the V-bit first. However, on male plugs there are usually a lot of thin features, so it may not make much of a difference.
Maple is so tight grained / dense that when it chips it’s usually a good sized chip rather than a small tearout.
The best luck I’ve had is sealing the surface before cutting. A good thinned out lacquer sealer and 3-4 coats so it really soaks in good helps hold that top grain together. If you still get chips, then a smaller depth per cut will also help, but add a lot of time.
I think the most important aspect is a very sharp cutter, and a less aggressive cut. Narrow V-bits have a very low cutting surface speed, so lighter slower cuts are warranted.
Snapped the end of my 30deg vbit when I tried running the vbit first on the second 2.25mm pass. This doesn’t always happen but running the vbit first typically leads to me losing steps or breaking the tip of it just as often as it is successful from my sporadic experience over the years. So, though it was facegrain, I decided to just do the pocketing first instead. Since my male only uses a 1/16", I expected no chipout issues from the pocketing bit running first.
After pocketing, I ran a new 30deg vbit and it came out perfect with no chipout with 2.25mm DoC.
My primary difference was clamping the absolute sh!t out of my stock so there was zero chance of any movement.
I got it gluing up and will find out tonight how the glueup turned out. Thanks everyone
Question:
I may consider trying 3.5mm DoC vbit first pass, then 1mm second pass, in future instead of an even 2.25mm and 2.25mm - do ya’ll think there’s any advantage in doing that for reducing chances for chipout in theory since the cutting forces increase semi-exponentially at greater amounts with depth? Perhaps goes a way to equalise the forces on both passes a bit?