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V bit text coming out wavy?

Posted: Sun Jul 26, 2020 6:37 pm
by boardbutproductive
We have had our Shark HD4 for about 6 months now. Recently, we made a few simple text signs in melamine-coated particle board using our 90 degree and 30 degree V bits.

We keep getting these wavy edges and a warped look on the corners, as you can see in the pics below. (I included a screengrab of the original vector file too, so you can see what the letters were meant to look like.) The effect is much more pronounced on the smaller letters carved with the 30 degree bit, which even have some extra bumps along the bottoms which also shouldn't be there. I've inspected the vector file itself, and there aren't any tiny bumps or anything there.

Anyone have an idea what's going on?
Screen Shot 2020-07-26 at 7.32.38 PM.png

Re: V bit text coming out wavy?

Posted: Mon Jul 27, 2020 3:48 pm
by Kayvon
It looks like the "waves" only occur on the corners, right? Those are the spots where VCarve tries to climb the corners at the angle indicated to give you a nice clean, crisp corner. Only for you it's making the corner larger than it should be, suggesting that the V bit you're using is bigger than VCarve thinks it or. (Or, conversely, that you Z ratio is wrong, but let's try the simple solution first.)

Go back into VCarve and make sure that the V bit angle in your toolpath matches the angle of the bit itself.

Re: V bit text coming out wavy?

Posted: Tue Jul 28, 2020 12:24 pm
by boardbutproductive
You're right - it's mostly in the corners, and most exaggerated there too. Though there are also some areas in the bottom-center of some letters where it looks like it pushed too far outside the vector path as well. (See the bottoms of the P, t, a, y, R etc.).

Here's a screengrab from VCarve where you can see both the tool settings, and the individual toolpath settings. We used the 45771-K 30 degree Engraving bit from Amana Tools. It looked to me like in the Vectric tool settings, the angle they are asking for is the half-angle, which I *think* would be 15 degrees in this case. Is that not correct?
Screenshot (3).png
Alternately, I noticed that for other bits we have saved as "V Bits" rather than "Engraving" bits, Vectric asks for the full angle rather than half. Should this bit actually be saved as a Vbit rather than Engraving? I'm pretty new to this, so I don't understand the nuances of why Vectric would ask for the half angle on one type vs the full angle on another.

Re: V bit text coming out wavy?

Posted: Tue Jul 28, 2020 5:49 pm
by Kayvon
I've never tried entering (or using) an engraving bit for a v-carve path. I tried it just now and simulated it. VCarve producees slightly different toolpaths for an engraving bit vs. a V-bit.

But just because VCarve can accept an engraving bit for a V-carve path doesn't mean we should use it. It'll also accept a ball nose bit, but produces suboptimal results.

I would try it again with a true V-bit rather than an engraving bit. I don't know why engraving bits only request a half-angle. The extra Flat Diameter field makes sense, of course. I've only ever used engraving bits for PCB production and cheap V-bits v carving paths.

Re: V bit text coming out wavy?

Posted: Wed Jul 29, 2020 2:55 pm
by boardbutproductive
Unfortunately we need to use the 30degree Engraving bit for the smaller text... our smallest actual Vbit is 60degrees, which was too wide and therefore too shallow for the small names at the top. We assumed the 30degree engraving bit would be ok to use, since VCarve Pro calls that type of toolpath operation "V Carving / Engraving Toolpath" if you hover your mouse over the toolpath type icon, haha. Not a very scientific reason, I know. :)

Also though, the larger "Memorial Garden" words have the same issue, though far less pronounced. And those were carved with our 90d Vbit in a simple V grooving toolpath.

The simulation preview VCarve runs looks fine on both paths, even the one with the Engraving tool selected. We are stumped.

In your first reply, you mentioned it could be an issue with the Z Ratio as well. Can you explain what you meant by that?

Re: V bit text coming out wavy?

Posted: Fri Jul 31, 2020 5:07 pm
by Kayvon
Sorry, what I meant is that I would try running a test carve after entering your bit as a V-bit in the system, rather than an engraving bit. Same bit, just don't tell VCarve (shhhh!).

The Z ratio I mentioned means the Z axis (up and down) doesn't move the correct distance. When the system instructs the gantry to move upwards by an inch, maybe it's actually moving 1.01". It's not a very likely problem with a leadscrew system like we have.