Exclusion zones possible while pocketing ?

[dudz]

So I have a piece of 20mm thick 6068 aluminium (400x300) .

I know I can create holding tabs in cambam when profiling.
Instead of cutting around a piece via profile, I am pocketing around the outside of the piece to be less harsh on the 6mm single flute endmill (although it will have a lot more material to mill) and also I will get much less vibration . I’d like to know if there is a way in cambam to avoid areas while pocketing to avoid clamping areas ? Then I can move the clamps once done to finish.

[lloydsp]

I did just such a job DBY.  My solution was to explode the profile line, and extend two approximately-half portions of it past the work sufficient to clear the tool diameter, then mill those two lines as separate MOps, moving the clamps from one side to the other between MOps.  Actually, I didn't move the clamps, I installed a new set before removing the prior set, so as not to disturb the work's position.

One of the profiles was a simple 'outside L-shape' so I did that one as a simple line.  The other line was more complex, so I converted to one edge of a pocket slightly larger than the tool width, so it could mill the entire profile in 'depth-first' mode without ever lifting the tool.

I arranged the two portions so they passed the edges of the work at corners, so as not to create any visible joints in the milling paths.

Lloyd

[EddyCurrent]

Sometimes lateral thinking is the most viable solution.

[Dragonfly]

Not directly related to the thread but I came across an interesting clamping solution.
If yo have Facebook (not sure it will open alone in a browser) you can see the video here
https://www.facebook.com/reel/3056592867816088

[EddyCurrent]

I don't use Facebook but it does open in a browser okay.

That clamping system is excellent, looks like it's pneumatic.


Edit:

Looking at holding tabs, in the Collection there is a parameter called, "Parametric Point", it appears to be the location of a tab as a fraction of the length around it's parent ID perimeter from the start point.
I'll bet this could be used by a plugin to generate some lift and drop points for the holding system in that video.
Although I can't think how that could be output to each valve.

[Dragonfly]

Although I can't think how that could be output to each valve.

One possible way is to insert a Mach3 macro call in the G-code. The macro could communicate with something like Arduino which will control the valves according to the number it gets from Mach3.

[Garyhlucas]

Could you create a Region with islands where your clamps are?

[lloydsp]

Yep.  You'd still have to run it in two MOps with two sets of islands to represent where you re-clamped it after the first pass.

Lloyd

[Dragonfly]

One more video with automatic clamps and this is a commercial no less than 4 axis machine.
https://www.facebook.com/reel/3513801628871478

[lloydsp]

I am 'entertained' by the question of whether or not this was a "modification of the control software".  Um, "No... the machine just 'knows' when to lift a clamp!"  <Heh!>

Lloyd

[dave benson]

I had a look at both the videos, and they are doing light finishing operations.
The first video shows what looks like a test run of a prototype, and the second is of a
machine cutting the flashing of a motorcycle casting.
In both cases I don't think the fixture would change all that often, so in Mach3 you
could use a “Mach3 Brain” and write some Geo-fencing code.
This would be a bit of work.
For the hobbyist that may want to change the fixture like their underwear then doing this might
be impracticable.

If I had a need to do this, that is a outside finishing pass with no interior mops then I would make the clamp a single unit and use a micro controller
to measure the distance to the spindle and open the clamp, and with  two sensors measuring the spindles distance on the approach and departure from
the clamp, you could precisely set the opening and closing area around your clamp.
This would make the clamp operation independent of the machine controller or the generated Gcode.
A pro for sure, a con would be discriminating the difference between a cut on the periphery and a cut near to the periphery and close to the clamp if you
had some interior mops.

I think I would also include a sensor to indicate that the clamp is actually open and if not, then pull Mach3's reset button low.

Dave