Transitions between regions

Here's the place for discussion related to CAM/CNC and the development of the Path module.

How should freecad perform region transisitons?

At clearance height.
2
33%
At safe height.
4
67%
At the height of a new property, which defaults to clarence height.
0
No votes
At the height of a new property, which defaults to safe height.
0
No votes
 
Total votes: 6
GeneFC
Posts: 1025
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Transitions between regions

Postby GeneFC » Sat Aug 03, 2019 11:16 pm

IMback! wrote:
Sat Aug 03, 2019 9:33 pm
yes it does, for g1 moves not g0 moves. spindel-at-speed dose not pause g0 moves in linuxcnc. the use of g0 to go to stock-top is a freecad issue
I do not believe anyone has ever suggested that there should be a G0 down to the top of the workpiece. That would be relatively insane. However, there is nothing wrong with a G0 down to clearance height, safe height, or retract height, as long as those parameters are set properly.

My CNC mill is nothing special, but it does what it is told. If directed to G0 down to a preselected height "above" the workpiece it does exactly that. It never overshoots. I also measure the top of the workpiece to the full required accuracy for making the part. If someone does not care to set the workpiece touch-off carefully or does not care to make sure the safe height and/or retract height are correctly set they should not complain about the CAD-CAM software.

Gene
IMback!
Posts: 68
Joined: Sat Jul 13, 2019 9:40 pm

Re: Transitions between regions

Postby IMback! » Sun Aug 04, 2019 7:59 am

GeneFC wrote:
Sat Aug 03, 2019 11:16 pm
I do not believe anyone has ever suggested that there should be a G0 down to the top of the workpiece. That would be relatively insane.
Yes, I agree. This is however, what freecad currently does at the start of each job.


sliptonic wrote:
Sat Aug 03, 2019 10:38 pm
safe height was never intended to be used as an engagement height. You're reading that into it. Never happened. It was intended more as you are using the term 'operation clearance' It was intended to be the height at which movement within an operation was safe, like moving from one recess to another while avoiding an island.
I am not trying to read anything into it, i am merely describing how i currently is used in freecad. It currently is the de facto engage height and is not used for its documented, de jure, purpose anywhere in the code.


sliptonic wrote:
Sat Aug 03, 2019 10:38 pm
...
I agree with everything else you say here. I therefore would like to submit this proposal, a small alteration to my previous one to your and others review:

Proposal:
  1. Rename current property "Safe Height" to "Engage Height" in the code/ui
  2. Rename current property "Clearance Height" to "Safe Height" in the code/ui
  3. Add new property "Clearance Height" at job level
  4. Add travel at new property "Clearance Height" to the first region at the start of every operation
Benefits:
  • We gain an "Engage Height" that works correctly everywhere for basically zero work
  • "Safe Height" now works like the documentation and sliptonic suggests
  • Documentation stays correct
  • Implementation effort of 1 and 2 is trivial as the code already works this way
  • Implementation effort of 3 and 4 is not trivial but is not very large
  • Consistency between ui, code and documentation is achieved everywhere


sliptonic wrote:
Sat Aug 03, 2019 10:38 pm
Sorry. We didn't have the benefit of your clear-eyed vision and ability to rally consensus at the time. We did the best we could integrating legacy code from HeeksCNC and libarea and adapting things to the FreeCAD model as we went.
I am going to ignore this personal semi-attack and say that i am grateful for your and everyone elses work on freecad path. It is IMHO the best currently avilable FLOSS gcode generator by a huge margin.
chrisb
Posts: 17494
Joined: Tue Mar 17, 2015 9:14 am

Re: Transitions between regions

Postby chrisb » Sun Aug 04, 2019 8:12 am

Should "EngageHeight" be rather "EngageDistance"? It could be equally used for horizontal moves as well.
IMback!
Posts: 68
Joined: Sat Jul 13, 2019 9:40 pm

Re: Transitions between regions

Postby IMback! » Sun Aug 04, 2019 8:48 am

chrisb wrote:
Sun Aug 04, 2019 8:12 am
Should "EngageHeight" be rather "EngageDistance"? It could be equally used for horizontal moves as well.
Yes that would be better. Then we would also need to make it an offset of stock top in current operations (all of which engage from Z). This is essentially what sliptonic also suggested in his post.
GeneFC
Posts: 1025
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Transitions between regions

Postby GeneFC » Wed Aug 07, 2019 12:44 pm

It is common on the forum that someone comes on board and wants to change various items to match their personal preferences. This renaming effort seems to be exactly that

"Engage height" means nothing to me. It would need to be defined and learned just like every other term, such as safe height or clearance height. Don't forget there are translations to a number of other languages. What seems to make sense in English may not make sense in some languages.

Changing names will not make a bit of difference in the utility of FreeCAD, but it will create a lot of forum traffic. :roll:

Gene
RatonLaveur
Posts: 303
Joined: Wed Mar 27, 2019 10:45 am

Re: Transitions between regions

Postby RatonLaveur » Tue Aug 13, 2019 9:42 am

I tend to agree with GeneFC, engage distance or engage height really wouldn't mean much more than the current nomenclature.

Now intuitively I'm thinking of Safe height as the height at which there is nothing that can happen if I translate with rapids, hence comparable to a full retract, and Clearance height seems to me like "just enough clearance to move on to next area", which would suggest an inversion from the current FreeCAD nomenclature. the Autodesk definition on a immediate google search is attached.

I will shamelessly add a link to another discussion on which a few key PathWB contributors have already chimed in: https://forum.freecadweb.org/viewtopic.php?f=15&t=37026
Where we were discussing the possibility of improved visualization of these different heights, much like the diagram above clarifies.


In my opinion: it is not critical to change the nomenclature, so long as it is immediately evident in FreeCAD which is which. Through a combination of diagrams/tooltips/coloredplanes....etc.

EDIT: removed mention and screencap of commercial software. As per mlampert recommendation. Sorry for that infringement.
Note: while I mention Autodesk related software in this post, please understand that I in no way suggest we copy any of it. I'm just using them as illustrations of "one way to do things".
Attachments
2019-08-13_11h32_48.png
2019-08-13_11h32_48.png (10.25 KiB) Viewed 215 times
Last edited by RatonLaveur on Tue Aug 13, 2019 5:05 pm, edited 1 time in total.
IMback!
Posts: 68
Joined: Sat Jul 13, 2019 9:40 pm

Re: Transitions between regions

Postby IMback! » Tue Aug 13, 2019 10:03 am

you and gene are misunderstanding. Im not proposing we rename any of the current nomenclature or change its definition. Rename in the previous post refers to how how the changes would be made in the code as the safe height currently is not used for travel height inside of one single operation, which is inconstant with the documentation, instead clarence height is always used for every travel. safe hieght is however used in the code to signify from where the operation will feed from with g1 speed, this meaning is not documented currently. This meaning would be split of into a new property called retract distance.

The first point is a bug fix, as the operations output and the documentation currently disagrees. While changing the documentation to reflect the current gcode output would also be possible, it is not sensible as this would leave the Safe Height with no documented purpose at all.

The second point is an enhancement giving the user control from where to feed at g1 without affecting the height at which travel is performed
mlampert
Posts: 1274
Joined: Fri Sep 16, 2016 9:28 pm

Re: Transitions between regions

Postby mlampert » Tue Aug 13, 2019 3:58 pm

Please do not post screenshots of other CAD/CAM software in this forum!
RatonLaveur
Posts: 303
Joined: Wed Mar 27, 2019 10:45 am

Re: Transitions between regions

Postby RatonLaveur » Tue Aug 13, 2019 5:06 pm

Removed. Sorry. I should have been aware this is an infringement.