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Discussion Starter · #1 ·
I had the wrong bit but I tried anyway. I figure I can either hit it with a heat gun to smooth it out, OR maybe spray it with a light mist of Acetone, or MEK ??? Or I could put some Acetone on a cloth and rub the surface to smooth out the foam. This one was just a TEST carve. I will figure out the best bit and cut speed, etc. and then make the real tombstones, that will be sprayed with the stone surface paint to add some realism.

Joe

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I prototype almost everything that I do in foam first. You can get much smoother results than that right off the CNC. What bit did you use and what were your feeds and speeds? As an example, here is a pic of the results that you can easily attain.

This is with no sanding or post carve processing.
 

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Discussion Starter · #3 · (Edited)
I prototype almost everything that I do in foam first. You can get much smoother results than that right off the CNC. What bit did you use and what were your feeds and speeds? As an example, here is a pic of the results that you can easily attain.

This is with no sanding or post carve processing.
What bit did YOU use?

The carvings for the tombstones are

White Z = 0
Black Z = 1

Cut speed: a RIDICULOUS 800 inches per minute o_O

For this test, I bought round router bits and did an initial test by scaling the Z to 10%. It carved the face nice and smooth, but there was almost no definition. So JUST to see if this would work, I switched to a rotary RASP :oops: and let it carve the full 1" depth in a single pass. Obviously it chewed up the foam but it cut much faster, and gave me these results.

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The V shape of the rasp created more problems as the bit plunged to the correct depth, but also carved away at the sides of material that was NOT supposed to be removed.

I would love to find something like this, with a rasp cutting surface, a longer shank, and two full inches of cutting depth along the shank, and a round cutting bottom for plunges!

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I am using my Samson 510 table and DesignEdge software. It is intended for single plane CNC plasma cutting, so I cannot set up the router to do deep cuts in several passes, and I cannot find a round tip two-flute bit that will cut 1" deep SIDEWAYS. Someone needs to design and sell bits specifically made for FOAM, since a 1" plunge into the material and carving in a single pass will NOT overload the router with X and Y movements!

The round ball bits WILL cut that deep, but of course the material ABOVE the ball's cut path must be removed first for the deeper cuts.

So I may switch back to the round ball and then cut the face at 10%, and a second pass at 25% scaling of Z in the pattern, and then maybe 50%, and so forth, to see if I can eventually get down to the depth I seek.

Also, DesignEdge sets the depth of their "3D" cuts by gradients in the image, so as the colors of the tombstone get lighter and darker, the software reads this as +/- Z settings. So the MAIN PROBLEM with this is that I do not have a good cut file is based on actual contours rather than gradient values.

I will try again today, with a different bit and a different technique.

I have V-Carve PRO, but I am not familiar with how to import a photo such as the one above and have the software SLICE that into passes, using a 1/4" two flute bit to hog out the meat, before coming back with a final pass with the correct bit and a much narrower step-over setting.

Joe
 

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Discussion Starter · #4 ·
Today I am going to experiment with a heat gun, and with acetone and MEK, to see if I can get that rough texture to lay down. It is a tombstone, after all, so it doesn't need to look "polished." But the texture in the photo above is obviously TOO ROUGH!

Joe
 

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Acetone on foam always makes it dissolve. It will be uneven. Sanding might be Ok if the foam particles are tiny. But I know that theaters carve foam with a hot wire. Low voltage across a fairly fine piano wire bent into the shape you want.
 

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Discussion Starter · #8 ·
Yes, I am familiar with the HOT WIRE cutting process. This surface is rough. I believe I can put some acetone onto a cloth such as a cut up bath towel or an old washcloth, and rub it over the surface. The acetone SHOULD momentarily melt the rough foam and the towel would then smooth it out. I could be entirely wrong about this. It is all experimentation, after all.

Now that I have this nifty new laser, I am going to experiment with using it to carve the foam. I will pass over the surface at 5%, 10%, 15% etc. and see how deeply the laser cuts into the foam. At least with the X-Tool proprietary software, it is not possible to vary the laser power as it crosses over the material. I THINK LightBurn allows this though. If I can carve the tombstones with the laser, I will be in 7th Heaven!

Joe

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Discussion Starter · #9 ·
Acetone on foam always makes it dissolve. It will be uneven. Sanding might be Ok if the foam particles are tiny. But I know that theaters carve foam with a hot wire. Low voltage across a fairly fine piano wire bent into the shape you want.
I also want to hit this surface with a heat gun, to see if I can lay down the rough texture that way.

Joe


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Joe - pay attention to the fumes that the laser may produce when cutting the foam - it may release some unwanted stuff into your work area. (thus comes into play the filter you are looking for).
 

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Discussion Starter · #11 ·
Joe - pay attention to the fumes that the laser may produce when cutting the foam - it may release some unwanted stuff into your work area. (thus comes into play the filter you are looking for).
Yeah ... I am moving the lasers out to the shops. I tried to run them here in the house. I am a bachelor and I live alone, so there is no one to complain!

i have one of those 48" shop fans that will be running to blow everything outside, or I may just roll the lasers outside and cut there, under a shade canopy.

Joe


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Sorry for the delay in replying. I used a 1/8" ball nose. I didn't need to cut as deep as you do, though. I use VCarvePro for my projects, I know nothing about the software you are using and I don't understand what black and white Z refer to, so I really can't be of any help.
 

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800 inches per minute!
You could probably set it to 1000 ipm and it would cut the same because it never reaches 800 ipm or likely even 200 ipm given the 3D nature of the carving. But it is fun to set it as high as possible! ;)
 

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Discussion Starter · #14 ·
Sorry for the delay in replying. I used a 1/8" ball nose. I didn't need to cut as deep as you do, though. I use VCarvePro for my projects, I know nothing about the software you are using and I don't understand what black and white Z refer to, so I really can't be of any help.
My software is really for a plasma table, but PlasmaCam also dabbles in 3D carving. so they import a gradient image. The height of the Z is set at two values; Absolute TP and absolute BOTTOM of the carving. In the gradient image, if WHITE = 0 and BLACK = 1, then when the software "sees" a WHITE pixel, the cutter will raise to the top surface of the material. If it sees a BLACK pixel it will dive to a depth of one inch. So a GRAY pixel might cut at 1/2" depth, or 1/4" depth, depending on the percentage of gray that it represents BETWEEN absolute WHITE and BLACK.

The paths are drawn by the value of any particular pixel that is not black or white. It actually works quite well, if the image is designed correctly, perhaps in Photoshop, for example.

Joe
 

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Discussion Starter · #15 ·
Sorry for the delay in replying. I used a 1/8" ball nose. I didn't need to cut as deep as you do, though. I use VCarvePro for my projects, I know nothing about the software you are using and I don't understand what black and white Z refer to, so I really can't be of any help.
I believe I could use a long thin STRAIGHT RASP bit to hog out the meat, and then come back with the 1/4" ball bit and a much smaller stepover, to clean it up. Once the meat was carved out, it would not matter if the ball moves X or Y deep into the design, because any material above the ball tip that the shank would have hit has already been removed.

Still testing ...

Joe
 
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