G61 vs G64 as default

[Gaeldk]

Hello,

I have noticed that using the blendercam generated paths on LinuxCNC did create small errors here and there (mostly sharp corners that are rounded by the machine). Strangely the GCODE is perfectly fine but the machine did not follow it exactly.

This is because LinuxCNC is by default in G64 mode (max velocity).

Currently looking at the exported GCode neither G64 nor G61 (exact stop mode) are explicitly in there but my LinuxCNC did default to G64.

I have fixed this by adding G61 as the default in my LinuxCNC.

Ideally, I think that the G61 option should be added by blenderCAM (or the post processor?) in each generated file since I believe blendercam assumes G61 when calculating paths...

I believe the issue could be the same with Mach 3 if it also defaults to G64 as LinuxCNC does...

Thanks

[blenderCAM developer]

Hello, thanks for pointing to this. 

Sincirelly I am not an expert on gcodes, but I think this should be set by user in the controller. 

E.g. for me I set my Mach3 always to constant velocity - so that I dont lose speed. When I had my machine set up to exact stop, the movement was very jerky, the machine was shaking, and it was slow... There is a very small tolerance to the result. 

But if you need exact results, I understand you need this mode.

so... what to do? I think in future I might implement some UI for these commands, so the user can set them from blenderCAM, but now I guess I will leave things as they are because I have now several development targets which seem more important to me...

I can however add this to the todo page, so that your suggestions dont get lost.

[Gaeldk]

I think you are right, this is down to the controller and there are other priorities. I found a way to have this setup by default in LinuxCNC

I ended up not to use G61 but G64 with the P option. Right now a precision of 0.001 which runs ok.

By the way what acceleration do you have for your machine in Mach 3 ?

For me I have velocity of 33mm / s which is roughly 2m / min

and the acceleration is currently set to 300 mm /s2 ...

For the acceleration I would be curious to know what you have for the KK1000s

[blenderCAM developer]

Hello, I will look when I am in my studio(hopefully this week have some time ;))

and I would be VERY curious about your LinuxCNC setup, because I never had the patience and time to spend time setting it up properly. 

For me a safe speed where I never lose steps in MACH3 is 1800mm/min. I used to use also 2m/min, but with that I got sometimes into trouble.

Will let you know about the acc. values, but I guess it will be very similar.

Cheers

Vilem

[bgio...@gmail.com]

Il giorno domenica 29 settembre 2013 22:08:05 UTC+2, Gaeldk ha scritto:

..." I found a way to have this setup by default in LinuxCNC"...

Please, how did you that?

[Gaeldk]

Put it in the INI file :

http://www.linuxcnc.org/docs/devel/html/config/ini_config.html#_rs274ngc_section_a_id_sub_rs274ngc_section_a

[bgio...@gmail.com]

Thank you!