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IndustryArena Forum > CAM Software > BobCad-Cam > Controlling the Pocket Start Position
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  1. #1
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    Jul 2006
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    Controlling the Pocket Start Position

    Hi!

    Issue 1: I can't figure out a way to control the starting position of a pocket feature.

    I defined a point on the edge of the stock geometry where I would like the ramp (or even a plunge) to start so that it enters the usable part of the material at the right height, but it ignores me and starts on the right side instead of the left

    Issue 2: The software is not holding the tool dimensions which means not only the parameters get passed incorrectly to Predator (that is why the tools are skinny in the video), but also it misses tool changes because it can't figure out that tools are different (that is why it is drilling twice the same hole in the video instead of doing a tool change and chamfering it).

    What am I doing wrong?

    Video: http://www.screencast.com/users/Extr...a-32566aae005f

    Thanks!
    Attached Thumbnails Attached Thumbnails probe.gif  
    Attached Files Attached Files

  2. #2
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    Well I played a bit more with the location of the point and the size of the pocket envelope and I got something closer to what I wanted

    http://www.screencast.com/users/Extr...d-2f8421ac6338

    Not sure how it works... it seems that the starting point needs to be inside the "hole" meaning you have to offset it to the inside by the tool radius.

    On the last line of each pass the tool comes back by retracing where it just milled. I could not figure out how to avoid that... I suppose we could reduce the step... but it would be better if the tool started on the left instead of starting on the right, because that edge is more critical.

    Ideas?


    BTW, the tricks Allen showed us with HSP work here too, but I wanted to also learn to better use the standard pocket feature because it is so much simpler for some geometries
    Attached Thumbnails Attached Thumbnails probe-2.gif  

  3. #3
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    Well I did it by hand, but I really wanted to learn to do it with BobCad

    http://www.screencast.com/users/Extr...e-6f0679ab7561

    BTW, these will be further trimmed about 1/8" once they get attached to the metal blocks where they belong.

  4. #4
    Join Date
    Apr 2007
    Posts
    243
    If you edit your post it will pass the right information.


    110. Tool list format.
    "(MTOOL","T",list_tool_number,mtool_type,"D",tool_ diameter,"H",tool_length,mtool_angle,mtool_corner_ rad,"DIAM_OFFSET ",list_tool_number,"= ",tool_radius,")"

    Replace line 110 in your post with the above code. This will fix the problem


    It looks like you are doing a good job programming by hand. You might want to use BobCAD for the more complicated profiles you might work on.

    Other wise keep the good work up!

  5. #5
    Join Date
    Apr 2007
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    243
    In some of the older builds of BobCAD you could use a start point out side the pocket boundary so that the tool would start off the work, but then they made some changes for gauge protection , now you can't do that.

    So if you are going to use a start point keep it on the side of the boundary. ( I know kinda defeats the purpose but, that's how it works. )

  6. #6
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    Thanks. That is the same line I have currently. I believe the issue might be with the tool database. I'm hoping they have a utility to fix it. Bobcad itself forgets the tool properties that we select in the features and perhaps because of that skips some tool changes. For example it is drilling the same hole twice instead of drilling, changing tools and chamfering.

    Waiting on support to call me back. It seems they are busy. Have to be a bit patient. I just do not have to enter all my tools again with all the details *sigh*

    We will see.

    From your response above I take that you also do some retouching by hand as well... I'm okay with that, I just do not be touching up things by hand if BobCad can do them automatically for me

  7. #7
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    Apr 2007
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    That's strange that the line doesn't do what you need. Also I wouldn't setup the tool database in bobCAD. It's just as easy for what you are doing to use system tools and edit the info.

    1) yes it's nice for the speeds and feeds to come over !

    2) it doesn't seem like BobCAD has totally figured out what they want to do for a tool database yet. What they have is some make shift kinda thing

    Also I was able to program your part with BobCAD to do the same thing ( close ) to what you did by hand. You really need to work with the HSP a bit more you'll find the ramp pocket feature to do what you are doing by hand.

    I am trying to do a jig video but the images keep coming up black. But here's the file I created. See if you can't simulate it correctly.

    Also another little tip. What ever feature name is in the cam tree is posted in the G-code. So if you want to list the tool name and type. Keo # 3 1/4 bla bla bla. Write that stuff as part of the feature name, then you will see it posted in the code.

    I'm not sure but I don't think the tool names you created in the tool database are being posted in you g-code. So this is an easy work around so you know what tools are being used. Seeing you have to load everything by hand, it's nice to have the name of the tool right in the code so you know what you are doing.
    Attached Files Attached Files

  8. #8
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  9. #9
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    I see what you did with the HSP and the 1% approach... very cool!

    Often the HSP starts doing those crazy curves and I'm not quite sure how to get it to stop.

    Anyway, I was milling this piece and there are lots to learn. I'll need to rethink how I'm doing this part. I used a thinner stock than i had programmed for so some areas are very thin, but it also good because it amplifies the problems.

    I'll post the video now and tomorrow I'll comment on it and the different things that went wrong... getting a bit late already

    [ame="http://www.youtube.com/watch?v=pncq0NCcSm4"]YouTube - Help me fix my Mill - Part 13 - How not to mill Acrylic[/ame]

  10. #10
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    I just finished adding comments

  11. #11
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    Forgot to mention...

    The tooling problem is solved with build 1478.

    Since it is still being tested it has not been released to the larger community, but I gave it a try and it did solve the issue.

    If you have an earlier built you can get around it by using system tools. It seems that the issue is limited to tools you pick yourself.

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