finishing pass on pocket 3D

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freman
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finishing pass on pocket 3D

Postby freman » Wed Aug 14, 2019 7:34 pm

Hi,

I have just cut a 28mm diam. hole 30mm deep with pocket 3D. I now need to enlarge by a few thou to give clearance for another part.
This is, in fact, a classic finishing pass.

How can I do this without running the same job and watching it cut air to the next 20min ?

I see "pass extension" though what this actually does is not clear and searching seems to throw up a similarly named property which is largely unrelated.

Is there currently an implementation of anything which allows a single pass on a surface without assuming that the volume needs clearing as well?

TIA.

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OS: Linux (LXDE/LXDE)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.16988 (Git)
Build type: Unknown
Branch: master
Hash: ff7975291d33a88e6a8282b88a62dbcbcc01ba2b
Python version: 2.7.15
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedKingdom (en_GB)
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freman
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Re: finishing pass on pocket 3D

Postby freman » Thu Aug 15, 2019 2:37 am

I realise that the 3D pocket tool is still under development ( though it does seem pretty usable ) .

Is there one of the other more stable path tools that I could use to do the finishing cut?
chrisb
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Re: finishing pass on pocket 3D

Postby chrisb » Thu Aug 15, 2019 5:18 am

There are only two operations which can handle a 3D surface: 3D pocket and 3D surface. There is no such thing as 3D profile.
You may either - if supported - have to skip at the machine the useless commands or remove the unneeded manually before feeding the machine.
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freman
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Re: finishing pass on pocket 3D

Postby freman » Fri Aug 16, 2019 5:12 pm

Thanks Chris.

In this case ( a cylindrical hole ) I was able to finish with a helical path.
There is no such thing as 3D profile.
Is the logical conclusion then, that there eventually needs to be a 3D profile tool? Presumably this is just subset of the cuts needed to clear a volume and probably looks like the first cut of a "spiral" clear out. Presumably all the calculations to do this are essentially there already.

If such a path existed one could clear out with a 3D pocket path with extension of 0.1mm and then finish with a profile.
chrisb
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Re: finishing pass on pocket 3D

Postby chrisb » Sun Aug 18, 2019 10:27 am

I'm not sure about this, but the pockets may need some kind of a "FinishOnly" property, which skips all intermediate steps. I have no idea how the outer walls in such a case are usually handled.
dubstar-04
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Re: finishing pass on pocket 3D

Postby dubstar-04 » Sun Aug 18, 2019 5:42 pm

freman wrote:
Fri Aug 16, 2019 5:12 pm
Thanks Chris.

In this case ( a cylindrical hole ) I was able to finish with a helical path.
There is no such thing as 3D profile.
Is the logical conclusion then, that there eventually needs to be a 3D profile tool? Presumably this is just subset of the cuts needed to clear a volume and probably looks like the first cut of a "spiral" clear out. Presumably all the calculations to do this are essentially there already.

If such a path existed one could clear out with a 3D pocket path with extension of 0.1mm and then finish with a profile.

Could you share a file? I'm interested to see what your machining.

Thanks,

Dan
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freman
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Re: finishing pass on pocket 3D

Postby freman » Sun Aug 18, 2019 7:05 pm

Sure, it's nothing very interesting, more an exercise in using FreeCAD and testing the hardware. I could have saved myself several ops it I'd had you tip earlier.
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RatonLaveur
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Re: finishing pass on pocket 3D

Postby RatonLaveur » Sun Aug 18, 2019 7:12 pm

Really cool result. You even chamfered your holes. Seems like you ran at least two jobs (two positions of the workpiece). Would be awesome to associate it to the actual FC file so we could retrace your steps, how you reppsitioned your part etc... and who knows, maybe help you troubleshoot and guide the streamlining of the workflow.

As for your original question, it seemed to me like I'd have done the exact same workflow:

First 3D pocket for materal removal (or adaptive clearing) Second profile or spiral with adequate tool compensation.

Some industrial guys i know actually run a program with increased tool compensation to have lateral allowance followed by a correctly compensated finish (not using FC mind you).
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freman
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Re: finishing pass on pocket 3D

Postby freman » Sun Aug 18, 2019 7:46 pm

Salut monsieur le Raton. Tu es un laveur de raton ou un raton qui lave ;)

To be honest, since it's only ali I did the chamfers with twist of the wrist, it wasn't a programmed op.

The workflow was mess, several files and moving the work to different positions. It was all rather piecemeal. Much of that was because the blank was not much larger than the finished object so I couldn't profile the whole thing. The sloping edge was also just a tidy up of the raw material, rather than a designed feature. The finish is a little mediocre since I do not have enough rigidity in y axis. It's good enough for this job but needs to be better. This piece is one of several I am changing to improve that.

What is the tool compensation you mention? Is that "pass extension" ? This is another unhelpful hover hint. "The distance the facing operation will extend beyond the boundary shape."

extend beyond does not describe well what happens on a hole .
chrisb
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Re: finishing pass on pocket 3D

Postby chrisb » Sun Aug 18, 2019 9:41 pm

freman wrote:
Sun Aug 18, 2019 7:46 pm
What is the tool compensation you mention?
Tool compensation is to move the tool at the distance of the half tool diameter besides the target line.