inappropriate cutting speed on ramps.

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freman
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Re: inappropriate cutting speed on ramps.

Postby freman » Mon Jan 13, 2020 8:28 am

Helical paths are the obvious exception to existing tools not doing simultaneous x,y,z movement, are there others I'm missing.

I think chip load is the key consideration here since feeds and speeds are the fundamental in the user specifying horizontal feed rates. Something which radically changes that without notice is not good.
cahlfors
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Re: inappropriate cutting speed on ramps.

Postby cahlfors » Thu Jan 16, 2020 8:40 pm

freman wrote:
Mon Jan 13, 2020 8:28 am
Helical paths are the obvious exception to existing tools not doing simultaneous x,y,z movement, are there others I'm missing.
I can think of holding tags, slots, pockets, profiles etc with ramp or zigzag entry and anything 3D.

I think there was a discussion on this topic as well and think the conclusion was that any tool has a maximum angle for ramped entry into the material. For a face mill that only cuts around its perimeter, this is quite shallow but not zero. For an end mill with "plunging" capability this is 90deg/vertical (at least in theory). For every turn of the tool, it can only cut so much vertically. In reality, plunging with an end mill is a very unfavorable operation leading to heat and vibration. The various entries vastly improves this and a practical angle (much smaller than 90deg) for these entries and a given tool can be set also here.

In other words, it starts with an angle property for each tool, which can be used to calculate the vertical feed depending on horizontal feed (simple trigonometry), in turn calculated by the usual rpm, chipload etc.

Not sure if this is the only, divine truth, but that is how I interpreted the discussion.
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freman
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Re: inappropriate cutting speed on ramps.

Postby freman » Wed Feb 05, 2020 9:51 am

Wsk8 wrote:
Sun Jan 12, 2020 4:31 pm
Hello,
i modified current version from github with your 2. option and added "Ramp feed rate". Does this satisfy your needs?

mfg
As I pointed out in my reply, I was not actually using rampDressup, however this discussion links to another issue.
https://forum.freecadweb.org/viewtopic. ... 10#p366575

in the file you uploaded, line 575:

Code: Select all

              commands.extend(PathGeom.cmdsForEdge(edge))

        lastCmd = Path.Command('G0', {'X': 0.0, 'Y': 0.0, 'Z': 0.0})

        outCommands = []
It seems that if you supply vspeed and hspeed to cmdsForEdge it will deal with ramp speed in a reasonable way without the need for further coding.