Horizontal 3D incomplete

[billo]

I'm using Horizontal Roughing to pocket an area in a 3D slab. I'm showing a simple part here to demonstrate the problem (my parts are more complex than this).

Horizontal (and Vertical) do not pocket the entire area. (Although Waterline Rough works well for this part, it does not work well for my more complex parts.)

I've used a large bit and Horizontal Finish to better visualize the problem, Rough does exactly the same thing.

The toolpath is leaving 45mm of material, 40mm of which should have been cut (if my calculations are correct).

Is there some setting I'm missing?

Thanks,
Bill

The .cb is attached

[dh42]

Hello

Yes, 2 other toolpaths should fit in Y on each side (step over) ... looks like a bug ...

Along X it is the resolution that is too low (0.2 * 50 = 10mm) so you can't follow the model closely.

++
David

edit: and it seems it is the same bug as here, because the toolpaths are Ok if I try your project on 0.98L

https://cambamcnc.com/forum/index.php?topic=10517.0

[dh42]

re

I tried the trick: Resolution = Step Over, as explained on the bug 76 post ... and there is still a problem, another toolpath should fit into the cavity (green tool position) ...

++
David

[pixelmaker]

Hello David
A toolpath lies exactly on the edge, it does not count.

If I use a stepover of 0.1 and a resolution of 0.1 I get 5 straight toolpaths and the sixth follows the contour. 5 toolpaths = 25mm and the resolution of 5mm allows differences. This is correct for me.

The higher the value of the resolution, the less accurate the toolpaths become. With a value of 0.2, the toolpaths are only scanned every 10mm. There are differences with edges. Also the edges on the X-axis are milled round and have a higher distance. And they do not run vertically

I would mill this part with a resolution of 0.05 and a stepover of 0.2, so a toolpath every 10 mm.
A vertical toolpath on the edges on the X-axis only exists at a resolution of 0.1 anyway.
I have no faulty toolpaths with this resolution even with a stepover of 0.6.
I have the impression that the error occurs mainly with round surfaces. But this would have to be tested further.


ralf

[dave benson]

I was curious, so I generated the code and simulated it and re-imported it into CB and
superimposed the original and actual cut surface for comparison.

You have to keep in mind that I used a cut surface from camotics and it was medium
res so the measurements will have some error.
I then did an edge detect and measured the extra material on each end that was uncut. 24.34mm, 48.68mm total.
The stepover would have been 10mm.
It seems to me that you could sneak in an extra tool path at each end and still not exceed the
stepover or cut into the model. If my measuring is up to scratch.

I do recall from other threads a long time ago now that the solution to some toolpathing problem was to change the tool diameter from 5 mm to 4.98.
I did try with a 49 mm tool but no dice, I didn't do a thorough job though and there might be some profit in testing a range of other diameters.

I don't know the answer to bill's problem, other than to say that if the pocket dimensions
are important and I was in a rush, then I would change the 3d model to compensate for the error
ie. I would add an extra amount of mm's 48.68mm to the model's pocket.
This by no means a satisfactory answer but only thing I could think off, if I had to get
the job done yesterday.

Dave

[pixelmaker]

Hello
I have 1. redone the 3 D object and replaced it in the file.

• Then I used the value 0.01 for stepover and resolution respectively.
The first toolpath that go down is about 24.8mm from the edge at each edge of the pocket. There is even a little too much milling away.
II copy the mop to test different values.
• 0.1 -> The of the last straight toolpath is 24.8mm. It must not go down, because the radius is 25.
In X direction, the toolpath goes down at 25.17. This is correct, but I can already see that the toolpath on the X-sides does not go vertically downwards.
• 0.2 -> The distance of the last straight toolpath is at 24.8. It is also correct that this toolpath does not go downwards.

The toolpaths always run exactly on the edge of the pocket. I can't find a way to move them in the Y direction.

For comparison, I have created a z-constant toolpath.
The toolpaths are all in a logical same range.
Only the fact that a 3D toolpath is only vertical at the lowest resolution bothers me.

[dh42]

Hello

Hello David
A toolpath lies exactly on the edge, it does not count.

Yes, but look on the picture, another toolpath could fit into the cavity (red arrow)

++
David

[pixelmaker]

How large is stepover and resolution for the toolpaths in the image?
What you can see in the file of mine is that the scanline toolpaths do not deviate from the z-constants.

[dh42]

resolution = 0.2 ; step over = 0.2 ; tool = Ø50 (one TP every 10 mm)

++
David

[pixelmaker]

Hello David
I wrote a longer post and after submitting it is gone, just gone. There goes of course the fun in this forum to write something. Now I write it outside and then copy it in, I hope that works.

I made a file (is attached) with several values. I copied a z-constant toolpath into each part for reference.
The only reasonably fitting toolpath is the one with 0.01. At resolution 0.05 and above, the toolpath no longer goes vertically down.
I don't see any errors even with a resolution of 0.01 and a stepover of 0.2, not even with stepover of 0.4.

So if you want to create vertical toolpaths after an edge you have to use a very low resolution. From a resolution of 0.05 the toolpath becomes oblique.
With respect to the stepover, CamBam creates the first toolpath that has a complete distance. If the distance has to be 25mm and stepover is 10mm then 30mm distance is included and the next toolpath goes down. You can try this with different values.

If you use higher values for stepover, a border to the edge is created. It can also be that CB calculates this edge in x and y direction.

If you want to mill vertical sidewalls you have to work with very small resolution (0.01) or use a second z-constant mop for the vertical ones. The most accurate way is to mill straight walls with z-constant and use the scanline toolpaths for clearing.

I have attached the file
The first screenshot is with 0.01, the second is with 0.2.
In the second one you can see that the tool moves beyond the edge.
This distance is the same in X and Y direction and the toolpaths are not vertical down.

ralf