Cross in cross experiment

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BillK
Vectric Craftsman
Posts: 289
Joined: Wed Mar 27, 2013 4:16 pm
Model of CNC Machine: CNC Shark Pro Plus
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Cross in cross experiment

Post by BillK »

I wanted to try carving a small celtic cross that I designed into a traditional cross that I hand made with a lap joint to hold the pieces together. The total size of the outer cross is 4”x7” and the carved is 2”x3.5”. The wood is 1 1/4” wide, spalted sugar maple.

Wanted to try some of the feed and speed changes that are being discussed as well. In this case I used a well used 1/16” TBN and a new 1mm TBN.

I used the 1/16” with a 65 in/min feed and 20 in/min plunge with a large 20% stepover. The rough cut took 15 minutes. You can see the peaks of the steps with a calculated height of 0.00063 in the carve. I brushed on a light coat of Danish Oil, and used the 1 mm with a 100 in/min feed, 40 in/min plunge and a 12% stepover. The depth was set .012” below the first cut. This took 40 minutes to complete.

This piece was good for a test as it had sections cutting with the grain and against the grain, solid wood and slightly punky.

The cut came out completely clean cutting across the grain (bottom and top) and only a slight bit of fuzz on the left side which came of easily on the with the grain cross piece.

Years ago I made these stepover charts for 1/16”, 1/8”, and 1/4” TBN cutters and now added one for the 1 mm size. You can see where the points of diminishing returns happen and also the gain/loss in cutting times are. At one time I based all my cutting on the .0003” peak height which was 10% step for 1/8”, 14% for 1/16”, and 7% for 1/4”. These worked well for film finishes like lacquer or polyurethane and you couldn’t tell by looking. For thinner oil type finishes, it looks to me that about 1/2 of that, in this case .00014 step height gives good results.

Attaching some pics of this project and snips of these charts I have.

Thanks for looking!
Hand made with lap joint
Hand made with lap joint
1/16” tbn rough cut
1/16” tbn rough cut
Finish cut
Finish cut
1/16” tbn
1/16” tbn
1 mm tbn
1 mm tbn
Height to stepover
Height to stepover
BillK
https://www.facebook.com/CarvingsByKurtz

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