Start Point of a Profile

Discussions around the CAM Add-On of QCAD version 3

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Start Point of a Profile

Postby jthornton » Sat Oct 26, 2013 3:46 pm

There needs to be some way to select the start point and the order of cut for a profile. For example you have a profile with lead in and lead out arcs you need to pick the lead in arc then the profile then the lead out arc.

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JT
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Re: Start Point of a Profile

Postby andrew » Sat Oct 26, 2013 5:05 pm

Yes, I have plans for future versions to 'tag' entities as start, end, with / without tool correction, etc. Machine configurations can then choose to interpret those tags accordingly.
The basic system for that is already in place (in the property editor you can add custom properties with the + button at the bottom), but there should be a more standardized way to define properties that are typical for CAM usage.

I'm certainly open for suggestions and ideas.
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Re: Start Point of a Profile

Postby srl » Sun Oct 27, 2013 6:54 am

HI Andrew
As far I need is only a "Start" "0" or "1" , 0 or 1 for setting the path direction. Of course open contours will only need start at one end for you to set the direction. The rest we can put in the config file.


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Stephen.
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Re: Start Point of a Profile

Postby jthornton » Sun Oct 27, 2013 1:22 pm

In commercial CAM software when you are picking a path to cut you click on the start point then a prompt pops up and you pick the direction and side then pick on the end point. I'm guessing that because the CAM is an add on you can't interact with the drawing as you configure your profile? Gotta think about this some...

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Re: Start Point of a Profile

Postby andrew » Sun Oct 27, 2013 1:32 pm

jthornton wrote:I'm guessing that because the CAM is an add on you can't interact with the drawing as you configure your profile?


Interaction is certainly possible for CAM tools in the same way as other QCAD tools interact with a drawing. I can for example imagine a tool 'CAM' - 'Define Path':
- Click first entity of path
- Click start point (start, end or middle of the first entity)
- Choose ramp on / ramp off options in options tool bar (circular or straight or none for both)
- Click side of contour for radius compensation or on start point for no compensation (with circle as tool preview)
- Click first entity of next path...

The entities of that contour would then get tagged accordingly for the machine configuration file to interpret these tags by for example adding a ramp on / a ramp off, G41,G42,G40, etc.

How does that sound?
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Re: Start Point of a Profile

Postby jthornton » Sun Oct 27, 2013 1:34 pm

That sounds wonderful!

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Re: Start Point of a Profile

Postby jthornton » Sun Oct 27, 2013 1:36 pm

When ramping in and out of a part using compensation you also need some overlap so if you could specify the overlap that would be great.

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Re: Start Point of a Profile

Postby andrew » Sun Oct 27, 2013 1:44 pm

Thanks, yes I forgot about that. I think that option would probably only be available if the start point is chosen in the middle of an entity though. Overlap at a corner usually does not make sense, what do you think?
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Re: Start Point of a Profile

Postby jthornton » Sun Oct 27, 2013 1:58 pm

That seems reasonable to only have overlap if you pick the center of an entity until you are cutting a profile made up of thousands of tiny lines like some software will spit out. But when using G41/42 or G41.1/G42.1 and overlap is needed to prevent the hump from the entry move.

Entry moves not using cutter compensation can usually specify the type of entry "line", "arc-line", or "arc" as well as angle and length of the "line" component and radius of the "arc" if used.

When using cutter compensation an arc move is the preferred entry move and it has to be larger than the tool diameter to avoid getting the gouging error from LinuxCNC.

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