Just wondering why - for those with too much time

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Just wondering why - for those with too much time

Postby Karl60 » Fri Nov 02, 2018 11:46 am

VCarve 9.510

Why in the attached crv does the top part cut out but not the bottom part?

Clearly there's room for the tool bit - the top cuts out.

Practically, problem simply solved by increasing the vertical space between the parts or turning off separate last past; but that's not the coffee-time query.

Thoughts?

Karl
(gone for a coffee)
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profile test.crv
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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Fri Nov 02, 2018 12:27 pm

Karl,


This has obviously to do with the allowance. In some parts of the curves, the distance between internal curves is about 6.845 < 6.35 (bit Ø) + 0.5 (allowance).

If you calculate separately the toolpath for each vector, it is OK. If you select both, the calculation probably detects there is not enough room for the tool to cut one part without cutting the other one.

But the result is not totally logical as you get a full depth final pass for one of the parts without the first passes.

Better send the file to Vectric.
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Didier

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Re: Just wondering why - for those with too much time

Postby scottp55 » Fri Nov 02, 2018 12:32 pm

Changed to a Spiral Ramp changing nothing else, and it cut. Hmm...?
scott
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CHANGED TO SPIRAL RAMP.jpg
profile test SPIRAL RAMP.crv
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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Fri Nov 02, 2018 1:12 pm

I don' think so, Scott. If I'm not mistaken you only have 1 pass between the parts.

Time for another espresso? :D
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Re: Just wondering why - for those with too much time

Postby scottp55 » Fri Nov 02, 2018 1:24 pm

Right as usual Didier :oops:
Didn't quite slow the cut down enough in preview, OR check toolpath:(
ODD behavior!
(MAYBE another cup:)
I'm claiming distraction on this one...playing with the pedestal, and almost ready to cut Quilted Big Leaf Maple.
scott
Attachments
1 pass center...maybe one more cup.jpg
2018-11-02 08_18_32-VCarve Pro - ShopBot Edition 9.510 {Aloka LLC} - 10.30.18 HEART PEDESTAL 2.jpg
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Re: Just wondering why - for those with too much time

Postby joeporter » Fri Nov 02, 2018 4:46 pm

I think you need a separate toolpath for each part...joe
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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Fri Nov 02, 2018 5:07 pm

joeporter wrote:I think you need a separate toolpath for each part...joe


No, if the space between parts is sufficient, the toolpath will be calculated without problem.

If you run 2 toolpath with the original spacing each toolpath will cut a little the other part because of the last pass allowance.
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Re: Just wondering why - for those with too much time

Postby sharkcutup » Sat Nov 03, 2018 2:56 pm

Change both start points on each section to the top center of each section and re-calculate toolpath.

It cuts the parts out thoroughly but I noticed that the second part the is not necessarily started at the start point. The toolpath reverses direction cuts top section after completing the bottom section.

Here is the file


profile test.crv
(63.5 KiB) Downloaded 7 times




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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Sat Nov 03, 2018 5:25 pm

Sharkcutup,

In your file, the separate last pass is reset to 0, so the problem disappears. If you set it back to 0.5 mm as in the original file, it won't cut properly.

Whatever you do, if tool Ø + last pass allowance > distance between parts, it won't cut properly which makes sense.

Karl, still not back from coffee? Better take an espresso than a long one. :D
Best regards

Didier

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Re: Just wondering why - for those with too much time

Postby sharkcutup » Sat Nov 03, 2018 5:42 pm

Sharkcutup,

In your file, the separate last pass is reset to 0, so the problem disappears. If you set it back to 0.5 mm as in the original file, it won't cut properly.

Whatever you do, if tool Ø + last pass allowance > distance between parts, it won't cut properly which makes sense.

Karl, still not back from coffee? Better take an espresso than a long one. :D



And so it did change the setting on its own, good catch LittleGreymen for I did not see it change, Thank You. So the problem remains unchanged!

I will take the Espresso, Thank You!!!

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Re: Just wondering why - for those with too much time

Postby Karl60 » Mon Nov 05, 2018 2:35 pm

Back from coffee ....

As far as I can see; the query remains a mystery. It's not a practical problem per se - just a curiosity. Just seemed logical to use a 7mm gap (nice round number) to run a 6.35mm bit up and down. We'll upgrade to 8mm gaps; bigger is surely better.

Onwards.

Thanks.

Karl
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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Mon Nov 05, 2018 6:02 pm

Karl60 wrote:Just seemed logical to use a 7mm gap (nice round number) to run a 6.35mm bit up and down.


Yes, but you have a last pass allowance and the gap is less than 7mm in the curved part.

profile test.jpg


6.35 + 0.5 (allowance)= 6.85 > 6.839

There is not enough space for the bit before the last pass.

But the toolpath is not correct and you'd better send the file to Vectric.

(and take another coffee as I already mentioned that in my first reply :D )
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Didier

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Re: Just wondering why - for those with too much time

Postby gregk » Tue Nov 06, 2018 10:18 am

In addition to what LGM explained, it is worth noting that the allowance is applied to both vectors. So, the correct gap between the vectors have to be at least 6.35 mm + 0.5 mm + 0.5 mm = 7.35 mm

I will see whether we can display a useful error message in such case and fail to calculate the toolpath, rather than end up with a wrong toolpath.

Greg K
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Re: Just wondering why - for those with too much time

Postby LittleGreyMan » Tue Nov 06, 2018 2:23 pm

Thanks for the feedback, Greg.

I gave a try with a much larger gap, so I didn't notice the double allowance thing.

Karl, back from coffee? :D
Best regards

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