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Thread: V Carving Cedar Help

  1. #1
    Join Date
    Oct 2017
    Location
    Oregon
    Posts
    6

    Default V Carving Cedar Help

    Hi,

    I'm just getting started using my new (to me) ShopBot. I've made a nice vacuum jig to hold down boards while I machine them and that works well. I have a Porter Cable router which I bought new - I think it's the 3-1/4 or 3-1/3 hp one. Has a switch along the top to let you select 10k, 13k, 16k, 19k or 21k RPM. I'm able to make sign designs with vCarve Pro 7.5 and export them to the ShopBot. All is well up to this point.

    And mostly it carves well, but it tends to tear out the wood. I'm using a new carbide, 90° bit, 1-1/2" wide bit. Seems nice and sharp. I've tried different speeds on the router but it doesn't make much difference. I know cedar is pretty soft. And I don't remember where the settings for that bit came from. Attached are photos of some carving I've done and the settings for that bit.

    Ultimately I want to make signs where I paint the top after carving and sand the surface leaving just the carving black - nothing earth shattering. Now I end up with poor edges and ragged places where the woods been torn out and the paint tends to wick along the grain. Not very satisfying.

    I've tried figuring out the correct settings but I'm not very confident. I could use some advice about how to improve things.

    Thanks!
    v-bit.jpg
    20180707_190719172_iOS.jpg
    20180707_190719172_iOS.jpg
    Attached Images Attached Images

  2. #2
    Join Date
    Oct 2009
    Location
    Elgin Illinois
    Posts
    656

    Default

    Hello Steven. Welcome to the forum. I can't really read your speed setting,,,,, I kind of think it looks like 200 inches per minute...… I always do my V-carving at 1 to 1.5 inches per second (60 to 90 IPM). The bad news is that your cutting looks terrible! The good news is that your cutting looks terrible, so bad, that I think it will be easy for people to tell you what is wrong.

    When I first started cutting, I had never seen V-carving before, and I thought what I had was not very good, because it wasn't perfect. And the little bit of imperfections I wanted to get rid of was hard to figure out, and I mostly just learned to ignore the little bit of chatter that I had.

    I think people are going to want to know your settings right off the bat, so if you could repost your setting so they are big enough to read, it will help. And people will also want to know what brand of bit you have. Your wood looks more torn then cut, so the bit may well also be adding to your disappointing results.

    Good luck, Chuck
    Chuck Keysor (circa 1956)
    PRT Alpha 60" x 144" (circa 2004)
    Columbo 5HP spindle
    Aspire 9.0, Rhino 5

  3. #3
    Join Date
    Jan 2004
    Location
    Jasper, TX
    Posts
    496

    Default

    Sealing the wood before carving will help some with tear out and a lot with the paint bleeding issue. The corners of the letters are not crisp indicating that the bit is not true 90 deg. Try telling the software that the bit is 89 or 91 deg. I can't read your speed settings either but try Chucks recommendation. I would try a different font to eliminate that ridge in the middle, but that's just me. A lot of folks here like the CMT laser point bits for vcarve.

  4. #4
    Join Date
    Oct 2017
    Location
    Oregon
    Posts
    6

    Default

    Thanks for the help!
    I can't seem to post a picture that's any larger than what's in the OP. I'll just list the settings then.

    Diameter: 1.25 in
    Included Angle: 90.0 deg
    Pass Depth: 0.5 in
    Final Pass Stepover: 0.0163 in / 1.3 %
    Clearance Pass Stepover: 0.25 in / 20.0 %
    Spindle Speed: 12000 RPM
    Feed Rate: 100.0 ipm
    Plunge Rate: 30.0 ipm

    I'll try figuring out the exact angle of the bit - here's the link. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    It seems pretty nice - sharp!
    What do you use to seal the wood? That seems like a good idea.

    And what about router speeds? I've tried different speeds and none seem to make it better - I think something else is the big contributor.


    Oh, and the corners aren't supposed to all be sharp - attached is a shot of the toolpath.
    tool path.jpg

  5. #5
    Join Date
    Oct 2017
    Location
    Oregon
    Posts
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    Default

    Slowing it down to 60 ipm helped quite a bit. I'll try slowing it down further. Most of those ridges along the center of the letters are intact, but some still rip out a bit.

    20180708_195613772_iOS.jpg

  6. #6
    Join Date
    Jun 2013
    Location
    Pasadena, CA
    Posts
    947

    Default

    Just to make sure the machine and parameters are not to blame, do an experiment with some more forgiving hardwood like maple or cherry. I have had mixed success with softwoods and even with the same species some pieces are more or less likely to tear out.
    Box Joint, Dovetail, Guilloche and MazeMaker Software Here

  7. #7
    Join Date
    Jun 2004
    Location
    Springfield Mo
    Posts
    801

    Default pass depth

    So the pass depth is .5 inches ? / you are doing all this in one pass ? Perhaps a bit deep and loading up the bit too much ?

    sign master / Oklahoma Joe uses a layer of rubber cement on his surfaces before v carving I believe.

    It seals well for the painting stage and is removed as the last step.
    The decimal point seems to be the most important on the z axis... x & y not so much....
    ShopBot... Where even the scraps and things you mess up and throw away are cool....

  8. #8
    Join Date
    Jan 2011
    Location
    gleason, wi 54435
    Posts
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    Steve I think you need to get your carving under control before you worry about paint bleed. You have a vertical grain cedar board that is going to chip out very easily. Look how wide the growth rings are on your board. try to find boards with a narrower pattern which will come from a slower growing tree or an older tree. next you have to run cedar painfully slow (40-60) ipm. I would turn that pass depth down to .2 or maybe .25" and a last pass at .010. Another option is to use a different species of wood. Some of my favorites are walnut, cherry, white oak, Spanish cedar, African mahogany. There are some finishes that work well but no clear coat that I am familiar with will last even a moderate length of time including spar varnish. Once you are happy with your carving we can help you with stopping the bleed.

  9. #9
    Join Date
    Jan 2004
    Location
    Jasper, TX
    Posts
    496

    Default

    Quote Originally Posted by stevenblake View Post
    Thanks for the help!
    I can't seem to post a picture that's any larger than what's in the OP. I'll just list the settings then.

    Diameter: 1.25 in
    Included Angle: 90.0 deg
    Pass Depth: 0.5 in
    Final Pass Stepover: 0.0163 in / 1.3 %
    Clearance Pass Stepover: 0.25 in / 20.0 %
    Spindle Speed: 12000 RPM
    Feed Rate: 100.0 ipm
    Plunge Rate: 30.0 ipm

    I'll try figuring out the exact angle of the bit - here's the link. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    It seems pretty nice - sharp!
    What do you use to seal the wood? That seems like a good idea.

    And what about router speeds? I've tried different speeds and none seem to make it better - I think something else is the big contributor.


    Oh, and the corners aren't supposed to all be sharp - attached is a shot of the toolpath.
    Sanding sealer, shellac, then carve and seal again before paint. The sealer will help some with tear out, but the other recommendations will also help. Those tails at the corners are where the bit is supposed to emulate a hand chisel going in from the corner. Should not be round. Not trying to be critical just wanting to help.

  10. #10
    Join Date
    Jun 2013
    Location
    Pasadena, CA
    Posts
    947

    Default

    One more thing you could try for such soft/brittle wood is a burr bit. That will not tear into the wood with 2 or 3 flute edges but rather grind it to a fine powder. I have used that on cheap and brittle redwood with good success. You may need an air jet to remove the dust and avoid burning the bit and go slow. It won't work well if the wood is resinous and clog the bit grooves.
    Something like that:
    s-l640.jpg
    Box Joint, Dovetail, Guilloche and MazeMaker Software Here

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