FlatCAM prevents you from start machining at Z0

[bluecnc]

FlatCAM prevents you from start machining at Z0,
This is very odd and some machines start the machining at Z0 and go below it in negative number.

For example if you want 10mm of clearance from the surface of the material, and 0.1 depth of cut you set your “Z clearance height” to 0

And the depth of cut to -10.1

If i set the Z to 0 I’m getting an error - see attached picture

Blue CNC

[Marius Stanciu]

@bluecnc, make me understand. This is very odd for me.

In FlatCAM, Travel Z (or Clearance Height as you want it named) is just a height (a distance on Z axis) measured from the top of the material (where the Z0 is meant to be). At this distance from the top of material (Travel Z value) we consider safe for the milling bit to move in between cuts into material.
Cut Z parameter value will control the cut depth or how much to descent into material to make a cut.

If we make the Z0 on top of the material and if the Travel Z (Clearance Height) is set to 0 (zero) then when the milling bit will try to move, it will scratch the top of the material all the way from start to stop, possibly breaking the milling bit.
Why would you want to do that?

[bluecnc]

The surface of the material is not necessarily Z0 is can be any value that you like. and in most cases in machining the bottom face is your reference face,

In my case I like the top face to be Z-10 (negative 10)
and my starting point (clearance height) need to be set to Z0.

This way my G-code only go negative, for simple setups it is not critical, but if you start adding fixtures, and more complex stuff, it is much easier to just touch-off your fixture, and go up fixed value, after that you set the offset to Z0, instead doing it from the surface of a material that can be uneven or not even loaded yet to the fixture.

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On other cases the surface of the material is not relevant, and the thickness of the final part is important value, in a case like that the starting point will be set to the bottom face of the part, and the the clearance height can be any positive number as long that it more then the thickness of the part.

this way you will be able to know how deep your Z axis go, and be able to know what is the thickness of the material without taking it out the fixture and measure it.

Blue CNC.

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[Marius Stanciu]

Ok, I understand your point of view. It’s a machinist point of view while my point of view was the PCB manufacturing.

I may add in the near future a setting or a FlatCAM tool named perhaps “Machinist Tool”. Activating it will allow the user to set values like you mentioned and other things too like: creating pockets, contours with different touches (spiral, zig-zag and others), vector (paths) closing if within a certain distance (tolerance) etc.
But otherwise (without that setting) the Travel Z and Cut Z parameters will stay as they are right now because they make sense for PCB manufacturing.

[bluecnc]

I’m using flatcam for PCB prototyping.

The fact that I’m a machinist doesn't make the point of origin something spacial for PCB manufacturing, it is just a user / machine preferences.

Also some small marking machine use spring loaded Z axis, so the Z is only 0 or -1

You don’t need to make it so complex, also for 2.5d machining (pockets) you also need 3d simulation to be a practical solution in 2019, otherwise it is a very big risk to run the code on the machine.

I think all you need is just to replacing the error “Travel Z parameter is None or zero” with a check box “Allow Z zero or negative value”

Or even better, just remove this restriction from the software. and this way every one will be able to decide what point of origin they want to use.

Blue CNC.

[Marius Stanciu]

I understand you view but I think that having the Z reference point the top of material is the most intuitive and I also think it is safer to not allow by default negative Z travel (Clearance Height). Not everyone can understand things like fixtures or using different reference points.

Yet, since there are peoples that may be used to think like you do and since my philosophy in FlatCAM is to let everyone have it as they want and not imposing my view wherever is possible, I will introduce a setting that will allow you to turn off this limitation. After all I’ve added so many settings in Edit → Preferences that I’m sure that just looking at them may deflate some of the users One more will not change things.

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[bluecnc]

Those are really GREAT news!
I agree with you, to add it to Edit → Preferences is very good idea!

Blue CNC.

[Marius Stanciu]

Implemented.

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[bluecnc]

You made my day!!

This is look amazing!

I can't wait to try it myself.

Blue CNC.

[bluecnc]

Not sure why but I can’t see the FlatCAM 8.99 on the download section.
I really want to try the new feature.

Blue CNC.

[Marius Stanciu]

I'm sorry but I can't publish a build every day. Right now I am very busy at my work and not much time for FlatCAM. Once I finish the features I am working on, I will publish the new build, 8.99. Probably in about 2 weeks.

[bluecnc]

I really appreciate the time and the effort that you put in to FlatCAM,
Thank you for implementing the feature, looking forward to try it on my machine.

Blue CNC.

[Marius Stanciu]

Fix will be available in beta version 8.99.