V Carve Star Help

Good Morning Everyone,

I just purchased a new XL machine and just worked my way through cutting a bunch of clamps etc to finally get ready to run the machine for projects.

I decided to run a Start test today as I make flags (like 90% of wood guys out there! LOL)

Well Ran my First Test on a scrap piece of Ply I had in the garage. The bit being used is a brand new RC-1148

Material is 3/4 thk and board overall was 7.5X14

The Stars are coming out crappy. Tips are rounded and there is really no definition on the arms.

I have attached pics below as well as the Gcode I used.

Any help you guys can throw my way would be appreciated!!

Star Test.nc (85.3 KB)

that kind of looks like you have a wrong angle configured.
previous versions of CC would need to specify “half angle”, latest changed that to full angle.

can you

  1. check that the preview looks right (to rule out anything on the digital side)
  2. try to create the toolpath using bit #302 (which is the preconfigured 60 degree V bit)

The #327 is preconfigured in CC for the Bit I used. The preview looked good on screen.

I can try rerunning with the 302 selected to see of it makes a difference.

the other thing to look at is how you zero.
V carves are very sensitive to a correct zero

(for new machines normally another trap is slipping bits/Z axis, but all your stars seem to be the same so less likely. but could you check that your retract height is set to les than 0.25" just in case)

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I don’t have a touch probe yet so I use the paper method to 0 the bit and I believe my retract height is .39. Seems to be the factory default.

.39 is not horrible (but for vcarving you want to eventually go much lower… a decently tuned machine with flat wood can go to 0.05" easily… and this distance is going to dominate your cut time)

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another thing that is a tweak and likely not going to solve your issue, but I’ve learned to zero the “Z” in the middle of the wood, even if I do X and Y in the corner; wood is not always flat and especially the corners can be off by quite a bit.

ok you showed a small part, but can you see if all stars that you cut have the same quality, or do the issues change depending on where / order of cut?

All the stars are the same. So they are consistently wrong across the entire piece.
I zero the z in the middle of part so we can rule that out.

One thing I noticed is in CC there is vcarve and advanced vcarve. In advanced it looks like I can set the top and bottom heights of the cut.

if they’re all the same, that rules out many of the potential issues… no slipping etc.
(those are often the hardest so I’d say good news)

this may sound weird, but one thing to try is to run the same toolpath twice without moving the zero or the wood…

if there’s some kind of force/slop issue, the 2nd time you run it these forces will be much less. if the 2nd cut cleans up the cut, then this is where to look next

Bits are notorious for not being what they are sold for. Vbits seem to show it the worst. You really need to measure you bits with a micrometer and try various cuts with the vbits to make sure you get the proper shape on your angles cuts like the star shape.

You didnt say what the angle of the vbit was but lets say it is 60 degree for demonstration. Make 10 stars at 1 degree increments from 55-65 degrees. Assign a toolpath to each star in 1 degree increments and see if you get better quality.

Some people try to measure they angle on a vbit. Pretty difficult in my book.

If you dont find the bit angle is in error with the above test, you have something mechanically wrong or running the machine too fast or depth of cut too deep for your bit and machine.

Also there are bits that are not vbits but like like vbits with a flat section on the tip. You will have to get a magnifying glass or loupe to see if the bit has a true point. This will make alot of difference in the sharp corrners.

I’m using a Amada RC 1148 60 deg v bit. I’m sure that’s not issue.

I’ll try some of these other suggestions. But I’m leaning towards a program issue at this point

It’s not likely a program issue. Millions of stars are carved on machines all around the world. It may be a user drawing issue in the CAD program or a mechanical issue. I dont use the Carbide CAD or CAM software but hopefully someone will do a test cut of your file to determine that.

And dont think the Amana bits are perfect. There have been slight deviations in all the vbits I have every used including the expensive ones. Normally they dont make any difference or no visible difference. But in points of entrance and exit of some models they seem to get exaggerated.

one thing if you have high forces (e.g. deflection etc) is to reduce the depth of cut.
for my own stuff I never do a max depth of cut > 0.1" for V carves…

another thing to learn/try… if you are not sure about your digital design side… grab the “camotics” application. It’s open source (so free) and can simulate gcode as if it was the shapeoko and show what the cut will be like.
It’s slightly clunky in how you need to define your tools again in it, but once you have the tools set up… it’s a great tool to double check gcode.

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Looks like I figured it out. Had to use the Advanced Vcarve path tool and just mess with depth to get it where I wanted it.


that star looks nice and crisp for sure

Also, did you purchase your file - or did you make/design you star? The is a small help file somewhere in the Forum to build an exact shaped star and that may help, but it will be flat unless you do other work on it. That could also let you know whether or not your milling them to the correct depth as well.
A friend of mine purchases files and do you know the old caveat - "Buyer Beware"? Some of his purchases have cost him lots of lost time with bad milling done with those files. 
CHECK EVERY line, check for duplicates overlaid precisely on top of each other, etc. I know that takes time but that is time well spent also.  GOOD LUCK!

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