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Old 12-15-2018, 12:27 PM
ArlingtonM2 ArlingtonM2 is offline
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Default Fitting Inlays and Mosaics

I've got two projects in mind. They're sort of related, but not really.

ParillaWorks made a cutting board with inlaid dots. (Check out his YouTube video.) I've tried inlaying pieces before, and I recall that if I cut the hole and the inlay material using the same pattern, the inlay doesn't fit. That is to say, if I were to cut a 2" diameter pocket with an end mill bit, and a 2" diameter "positive" inlay with square edges, I don't recall that they fit. I don't understand why. I remember having to use a small offset. Can someone help explain to me how VCarve manages these cuts and rules I should follow?

The other idea I have is to make a cutting board as mosaic of pentagons. Again, before I cut the pieces, I want to make sure that I've got my geometry right. Can I cut a bunch of these pentagons and piece together? Any reason why they won't intersect crisply at each corner?
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File Type: jpg Dot Cutting Board.jpg (91.0 KB, 76 views)
File Type: jpg IMG_3F8994B1AA46.jpg (96.5 KB, 77 views)
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Last edited by ArlingtonM2; 12-15-2018 at 01:09 PM.
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Old 12-15-2018, 01:50 PM
Jim Becker Jim Becker is offline
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Playing with the offset is certainly important to get a good fit, but you also must measure the cutter to get the EXACT diameter it is for your design software to create toolpaths that are accurate. Gary stresses that in his intro courses...tooling can be variable. And also don't forget the allowances that might be needed for sharp corners since every cutter has a defined radius. You may need to adapt to that in the toolpath or do some minor hand work after cutting to get the precise fit you want.
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Old 12-15-2018, 02:12 PM
Charlie_L Charlie_L is offline
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Ken,
Doing inlay with the vcarve toolpaths works very well. Basically, it offsets the depth of the male inlay so it has a little gap below it, and stands proud of the surface. Then you just remove the male portion that is above the surface.
I sent you a pm that has more details.
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Old 12-15-2018, 06:37 PM
rcrawford rcrawford is offline
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Wood fibres will 'bounce back' a little after being cut. The tooling shears off the fibres, but the fibres are getting compressed a little as they are cut, so they will bounce back a little and you end up with a hole that is slightly smaller than was cut, and a male inlay piece that is slightly larger than was cut.

Then you have to account for deflection of the bit, any small amount of backlash, spindle slightly out of tram, etc. These small errors all compound to affect the fit. You would get a better fit machining a metal with a solid, 10,000lb milling machine. But there are just limitations to working wood with a light machine. A great woodworker learns to compensate for these limitations, and can still get a seamless fit.
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Old 12-15-2018, 07:51 PM
ArlingtonM2 ArlingtonM2 is offline
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Thanks gents. I went back and watched the Vectric tutorial again, and I see what you mean about tooling, wood expansion, etc. Will run some test pieces.

For the mosaic pieces, should I also expect to have to use an offset, or will the pieces all fit together crisply? Since they aren't inlays, will an offset be needed?
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Old 12-15-2018, 11:10 PM
rcrawford rcrawford is offline
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You probably won't need an offset for the mosaic pieces. The problem will be holding them securely while you cut the whole profile.

If you plan on making a cutting board, I don't think your glue joints will hold up for long if you make it like that picture shows. I would suggest using end grain pieces and gluing them up. That way you have a better cutting board surface, and all the pieces will be end grain. The best way to do this is to shape a long board with the profile you want (using a jointer, planer, and table saw), then cutting off pieces with a mitre saw and glueing them up. Much more efficient than using a cnc.
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Old 12-15-2018, 11:36 PM
ArlingtonM2 ArlingtonM2 is offline
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Quote:
Originally Posted by rcrawford View Post
I don't think your glue joints will hold up for long if you make it like that picture shows.
I've thought about that a lot, and still not 100% sure about my design. I've made "mosaic" cutting boards like you describe. No matter how careful I was on the saw, I was off by 1/32" and the pieces didn't line up very well. Too many voids.

For this design, I agree with your point about the glue joints maybe not being strong enough. I think this will be more decorative for cheese and crackers than a big carving board, so it won't get a whole lot of use.

I did some test cuts tonight, and the pieces fit together nicely. No offset

And on the other one with the inlaid circles, I figured out that a -0.02" offset works great.
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Old 12-16-2018, 07:59 AM
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james mcgrew james mcgrew is offline
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I always cut the male first and I use the inlay toolpath feature in vectric, then I can cut female a little shallow and test depth and fit, once i get it right I am off to completion !
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Old 12-16-2018, 11:30 AM
ArlingtonM2 ArlingtonM2 is offline
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Here are test pieces for the mosaic. They’re about 3” in length
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File Type: jpg 0A1509F8-C2A7-4C3E-A992-F7C6D8109566.jpg (87.2 KB, 50 views)
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Old 12-22-2018, 09:29 AM
ArlingtonM2 ArlingtonM2 is offline
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As an update, here are the final products.
The pentagon cutting board pieces were certainly more precise than if I cut on a table saw. The most difficult part was getting everything to fit together tightly. I had to fill the gaps with epoxy
Attached Images
File Type: jpg F5A87F5C-D85A-4CA6-9CC5-BD79F9651811.jpg (70.1 KB, 40 views)
File Type: jpg 76EDA8DD-233C-47C8-9EE1-1D49DC1332CD.jpg (97.0 KB, 41 views)
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