V Carving Cedar Help

[stevenblake]

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!
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[Chuck Keysor]

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

[dmidkiff]

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.

[stevenblake]

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

[stevenblake]

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.

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[Burkhardt]

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.

[dmidkiff]

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.

[Burkhardt]

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:
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