CNC Projects
#7
I was asked to make a simple bench with large finger joints.  Normally I cut finger joints on my table saw, but the seat of the bench was too long and heavy to stand up on the saw, so I had to do it a different way.  Cutting them completely by hand or even just the ones needed for the seat had no appeal.  I decided to make some router templates using the  CNC.  That turned out to be a learning experience in itself to get the mating halves to nest properly, but I had had some experience with the finger jointed drawers already so I got it in only two attempts.  

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I clamped the templates to the parts and used a bearing guided mortising bit to cut out the slots, working progressively deeper.  With two length bits I got more than half way down through the 1-3/4" thick stock.  Then I rough cut out the rest with a hand saw, flipped the piece over, and then trimmed the remaining little bit with a bottom bearing mounted router bit.  That still left me with squaring the corners by hand with a chisel.  After that was done I test fit the mating parts and they fit really, really snugly but it was amazing how just a little bit of paring loosened them up.  Still, I spent at least a couple of hours fitting the joints until I was satisfied they would clamp up tight.  Of course, you can never have enough clamps.  

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I used to sign and date my projects somewhere out of sight, but decided as long as now have a CNC why not make a signature inlay and inlay it into the project.  So I made this mahogany inlay (not happy with the spacing of some of the letters, but that's for another day) and matching router guide and glued it into the bottom of the bench. 

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After I flushed the finger joints and sanded it the bench looks like this.

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Oh yeah, it's made from cherry with a Sapele strip.  It's 48 x 19-1/4" W x 15" H x 1-3/4".  

I've done some simple inlay work, but nothing like a Celtic knot.  There are lots of Celtic knot designs.  I thought this one looked interesting and would be a good challenge with the CNC.  

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It's actually a pretty straight forward process once you understand how it works.  You make a male and a female with tapered sidewalls that join before the male bottoms out.  That assures a tight fit and seamless joint.  Getting the depths of everything right would be quite a learning experience on your own.  Fortunately, I watched a very informative YouTube video and the guy gave the settings that would work. I had to make a slight change to them to accommodate my design but it came out correct on the first shot so I was pretty pleased.  

So here's the two parts, maple and cherry, cut with a 45 deg V bit, and the flat sections with a 1/4" endmill.   It's 5-1/2" tall/wide and the parts each took about 25 minutes on the mill.  This is pretty much how they came off the mill, with only a little brushing with a brass brush to remove a little fuzz in a few places. 

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I held my breath as I test fit the parts.  Looked good. 

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The little gap between them is just what you want.  I filled the female piece recesses with TB II, nested the male into it, and clamped it all together.  This morning I band sawed off the male part and sanded it flush.  

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Not perfect in a couple of spots, but pretty close.  This took about an hour of design work, mostly because I was learning how to do it, and maybe an hour of my time to put the wood onto the CNC, glue the parts together, and cutoff and sand the excess flat.  Imagine how long it would have taken by hand and I'm pretty sure I wouldn't be capable anyway.  

Woodworking is all new again.  

John
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#8
Very nice, John.

How big is that name plate you made?  Judging by the grain it's set into, it seems pretty small.  If so, the detail seems very nice.
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#9
(03-12-2022, 03:39 PM)atgcpaul Wrote: Very nice, John.

How big is that name plate you made?  Judging by the grain it's set into, it seems pretty small.  If so, the detail seems very nice.

The name plate is 3" x 1.75".  It's really pretty amazing how crisp V bits cut.  I did no clean up of the letters; it's straight off the CNC.  

John
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#10
Thumbs Up 
Nice work John - good to see you are enjoying this new machine!

Doug
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#11
John. I also recently tried that v-carve inlay technique and was absolutely thrilled with the results.  The detail one can get is amazing.  Here is my first attempt at a Broncos logo coaster.  I did it in two steps and inlaid walnut and cherry to represent the navy and orange from the real logo.  You likely can't see it in this picture but there is actually a cherry dot for the eye ball.

   
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#12
(03-14-2022, 10:37 AM)BrentDH Wrote: John. I also recently tried that v-carve inlay technique and was absolutely thrilled with the results.  The detail one can get is amazing.  Here is my first attempt at a Broncos logo coaster.  I did it in two steps and inlaid walnut and cherry to represent the navy and orange from the real logo.  You likely can't see it in this picture but there is actually a cherry dot for the eye ball.

That's very impressive Brent, especially considering how small it is. too.  

John
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