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Author Topic: Right way to pocket with islands  (Read 635 times)
Mark81
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« on: April 15, 2019, 05:58:17 am »

Hi, see the CB file attached.
I want to pocket the area of item #26 that contains some islands (#9, 10 and 23).
If I select the correct primitive ID the toolpaths don't go "beyond" the islands because (I guess) it assume there is no space for the tool. But actually there is nothing to prevent the tool to go around the islands (i.e. the stock boundary is far away).

To overcome this issue I had to create a dummy item offsetting the item #26 to item #27. Now, selecting this one in the pocket MOP gives the desired results. But this method has at least one big drawback: every time I have to modify the initial item (#26 in the example) I must recreate the offset and update the ID in the MOP. For such a simple drawing it's not a problem, but with more complex object it's more difficult and all those dummy items will create a mess!

So I guess I'm not using this feature correctly.
Right now CB calculate the toolpaths to pocket "no more" the defined area. Instead, it would be useful if I can tell CB to pocket "at least" the area. In this way it knows there's nothing wrong to go a bit outside if needed.

Is there such an options hidden in the parameters?



* Heatsink.cb (8.61 KB - downloaded 35 times.)
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Bubba
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« Reply #1 on: April 15, 2019, 12:26:42 pm »

I think you want to convert the pocket with islands to Region.. Use  'Edit" "Convert to" "Region"
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Mark81
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« Reply #2 on: April 15, 2019, 12:29:15 pm »

I've just tried but the behavior is the same: CB doesn't mill anything outside the given boundary.
It's understandable, but in such a situation there should be an override.

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Dragonfly
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« Reply #3 on: April 15, 2019, 15:10:29 pm »

I downloaded and opened your file. Generated the pocket tool paths.
Is this what you want to do?


* Heatsink.png (20.9 KB, 616x575 - viewed 41 times.)
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Mark81
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« Reply #4 on: April 15, 2019, 15:14:59 pm »

Yes, but this is my workaround using the dummy item as explained in the first question.
The right item to use should be #26.
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EddyCurrent
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« Reply #5 on: April 15, 2019, 15:27:16 pm »

The pocket MOP does not use stock boundary in it's calculations, if you specify #26 then it will keep inside that line.
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Mark81
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« Reply #6 on: April 15, 2019, 15:46:11 pm »

The pocket MOP does not use stock boundary in it's calculations, if you specify #26 then it will keep inside that line.

So the short answer is "no, you can't and we don't plan to add this feature".
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Bob La Londe
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« Reply #7 on: April 15, 2019, 18:34:51 pm »

The short answer is that it doesn't make sense to set a boundary and then ignore it.  

Just create another pocket geometry for that operation and be done with it.  Or profile those elements with to close clearance after pocketing.  Either way works just fine, and its a feature already built into the software.  

MOPs are free.  Geometry is almost free (3D can push memory limits).  Use all the MOPs and all the geometry you need to cut your part.  
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dwc
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« Reply #8 on: April 15, 2019, 18:50:11 pm »

Hi Mark,
Please think about what a pocket does.
A pocket clears an area _inside_ a shape.
If there are islands that area is not cut, but the pocket does not cut outside the shape, that is how it is defined.
There is one little possibility, but I don't know if it will help in your case.
That is the roughing clearance which can be negative causing the shape to be cut larger.
I would suggest, however, that using an offset from the shape is the best way to work.

Adding many special cases to commands to do things that can be done simply with a little planning with existing
commands is not the best way to keep a program simple, clean and error free.
I hope that CB will become your work horse as it is mine, it just works.
Don

 
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Mark81
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« Reply #9 on: April 15, 2019, 19:02:15 pm »

The short answer is that it doesn't make sense to set a boundary and then ignore it.  

Not ignore, but use with a different meaning ("at least", instead of "no more").


Quote
MOPs are free.  Geometry is almost free (3D can push memory limits).  Use all the MOPs and all the geometry you need to cut your part.  

Perhaps your jobs are different than mine, but often my customers ask me a prototype, then want a small change, another prototype and so on, several times. And no, usually it doesn't follow a production. Few pieces and the job is done.

Now, I understand what you all are saying. But re-creating all the dummy geometry to "fit" the features of the MOPs is tedious for complex shapes. It takes a lot of time even if the changes are fast on the original item. And you easily forget something after the third of fourth iteration...

IMHO, the geometry should be as close as possible to the original drawings without dummy items. In this way you can update one primitive and all the MOPs will be automagically updated (I mean about IDs, of course you must check collisions, etc...).

But I understand I'm the only one who likes this approach Grin and CB is almost immutable.

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dwc
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« Reply #10 on: April 15, 2019, 19:30:47 pm »

IMHO, the geometry should be as close as possible to the original drawings without dummy items. In this way you can update one primitive and all the MOPs will be automagically updated
You can always write a plugin or script to do what you would like. One of the big advantages of CB.

D
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lloydsp
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« Reply #11 on: April 15, 2019, 20:05:04 pm »

Mark,
You seem to be expressing awfully negative opinions about a tried-and-true product that might not have some features you'd enjoy, but has 'workarounds' for most of those things, and which cost you nothing (not even excessive time) once you learn to use them.

You'll note that folks AGREE with you on some things (like the MOp tree issue).  Those who disagree are trying to help you understand how you can make CB work to meet your needs with the features it has.

And no... CamBam is not "immutable".  Andy has made tons of improvements to the package over the years, and most were based upon user commentary and wishes.

Don't get discouraged, please!  CamBam will do your jobs.  Several folks here use it in fairly heavy-duty commercial endeavors.

Lloyd
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Bob La Londe
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« Reply #12 on: April 15, 2019, 21:27:48 pm »

The short answer is that it doesn't make sense to set a boundary and then ignore it.  

Not ignore, but use with a different meaning ("at least", instead of "no more").


Quote
MOPs are free.  Geometry is almost free (3D can push memory limits).  Use all the MOPs and all the geometry you need to cut your part.  

Perhaps your jobs are different than mine, but often my customers ask me a prototype, then want a small change, another prototype and so on, several times. And no, usually it doesn't follow a production. Few pieces and the job is done.

Oh, yes.  I am sure my jobs are different than yours.  I do 99% 3D organic custom jobs.  I create supplemental geometry as a matter of course to expand and to limit operations. 
Quote

Now, I understand what you all are saying. But re-creating all the dummy geometry to "fit" the features of the MOPs is tedious for complex shapes.

Perhaps, but copy and paste is fast and easy.  I usually copy and paste whole layers so I can make modifications for one operation and keep the original geometry for another.  Some are quite complex 2D organic shapes drawn from 3D organic shapes by various methods.
Quote

It takes a lot of time even if the changes are fast on the original item. And you easily forget something after the third of fourth iteration...


Might be wiser to keep the original geometry and have a version2 version3 version4.  Then if a customer changes their mind about a change you still have he original geometry. 
Quote

IMHO, the geometry should be as close as possible to the original drawings without dummy items. In this way you can update one primitive and all the MOPs will be automagically updated (I mean about IDs, of course you must check collisions, etc...).

But I understand I'm the only one who likes this approach Grin and CB is almost immutable.


I do this for a living.  I work with complex organic shapes every day. 
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Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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http://www.CNCMOLDS.com
EddyCurrent
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« Reply #13 on: April 15, 2019, 21:53:22 pm »

Going back to the first post, if the stock boundary is your main concern then just draw a line around it and use that for your operations.
Personally I don't care what or how I have to do things to get my end result. Nothing for me is a "work around" as you frequently call it, it's just what has to be done to get the result.
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Garyhlucas
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« Reply #14 on: April 16, 2019, 00:24:01 am »

Are you trying to cut the outside corners left by the round tool? You might try Corner Over Cut that is typically used to clean out corners so a square can be inserted without round off the corners.
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