Lookahead for TNG

I am in the process of replacing my MK2 controller with and MK3/4 and TNG. Have not fired it up yet.

But trying to translate the old settings to the new ones I noticed pretty much all the old lookahead settings are gone and instead there is the "join/break angle" on the "blend" tab. For a regular mid-size 3/4-axis router should I just leave the 0 degree/135 degree values alone? And is the 1.5mm XYZ and ABC blend tolerance O.K.? I used to have a lookahead angle of 172 degrees and lookahead radius of 1mm with 200 mm/s^2 radial acceleration to avoid lost steps. Not sure if that was the optimal settings but it worked.

Thanks, JB

I just went through the same process of going to the new controller and software. After chasing a number of issues for a while I went back to the old software and everything works great. The new software supposedly has a much better look ahead algorithm, but i didnt get far enough to test this. The best upgrade I ever did was to get closed loop steppers, all of your missing steps will disappear forever and you can run them much closer to what they can do because you dont need a huge safety net.

Issues I ran into with TNG that made me go back:
-initial rapid move to program start being ignored
-gcode not loading
-tool offsets acting very wacky
-mpg jog being very ****ty
-tool change now requires me to write code to get the old functionality?

Switched back to usbcnc and ALL of these issues are gone.

I was sad because I was looking forward to testing the new motion algorithm. The lookahead feature on the old software was missing some intelligence IMO, though it would work pretty well in most situations for a hobby mill. I could generate a tool path on my cam program of straight lines that would make it try to accelerate faster than was possible. Once i got used to tuning the parameters for what I was cutting, I did get some pretty fantastic results.

Thanks,
in the meantime I did fire it up and went back to old software as well, mainly because I know what to do. I will try the TNG version maybe with the next update. Another thing that I am missing is the transformation matrix. I need that because my gantry is a tiny bit off perpendicular and that corrects for this error. I am pretty sure the TNG can handle that somehow but I have no idea how. Oh, and I am missing the simple pocket wizards. I know I can do that on CAM and transfer but for a quick surface planing at the machine that was very convenient.

This is very common situation. Almost everything that old software has is implemented in TNG. But it is done differently and some users are lost.
A lot of features in old software needed some checkbox checked somewhere. This enabled particular feature which was doing what I programmed it to do. There is no checkbox in TNG so this feature is missing. Wrong!

Here is typical example:
CNCUSB software has command in menu "Machine/Go To/Use Homing Sequence". Its MDI shortcut is /430. If enabled, it modifies "Machine /Go To/Zero" command because usually we want to move Z axis first.
TNG does not have this. When we use menu "Machine/Move/Zero" all axes move at same time and this is undesirable. Lots of users conclude that TNG is not ready and revert back to CNCUSB.

Now try this. Press and hold Ctrl+Alt, then click menu "Machine/Move/Zero". Your text editor should open file named "_Move.To Zero.gcode". This is script that is executed when you click this command. You can easily change it to move Z axis first. But because it is a script now it is much more powerful than CNCUSB preprogrammed implementation. You can stop spindle, change and/or measure tool, ... you can do anything you want.

Most commands in "Machine" menu can be changed this way, most M codes can have script that implement their behavior. M6 - toolchange is now done in script for example.
It is even possible to make gantry squaring script

But to answer your questions:
1. Transformations are implemented in TNG and are much more powerful. Major advantage is that they can be controlled from g-code directly.
2. Instead of preprogrammed wizards TNG offers "user defined" scripts. Scripts that are already included by default are pockets that you know from old software.

New TNG will have those last missing things implemented (Import Image for example), it will have powerful API for different usage scenarios, ready made routines for lasers, lathes, 3d printers and other "not CNC" machines, lots of other fixes, improvements,... It will be best CNC software ever.

Quote:

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Originally Posted by PlanetCNC

.... But it is done differently and some users are lost.....

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Well, that is exactly the problem. I am lost. Part of the problem is maybe my limited understanding of G-code.

1. As for transformations, I suspect that would use the G10 L3 code? Where do I find information how to use/implement that? And how do I make sure the transformation is always active when I turn on the machine? I don't want to modify my CAM postprocessor to include that in every gcode file.
What I need is that the x-axis is shifted +2.45 mm for every +1000mm of y-axis movement (my gantry is 0.14 degrees off perpendicular and I can not fix that mechanically).

2. I have noticed the included user scripts for some pockets. Do I have to edit the script every time I want to tweak a parameter?

1. Transformation is normally used through menu Program same as before.
2. When you run user defined procedure sw will as you for parameter values.

Thanks, I am getting the idea. Maybe I am a slow learner...

I found how to set the transformation in the menu. But that was deactivated and cleared after I closed the program and started again. Is that because I have not activated the license yet for TNG (still using simulation mode)? I really don't want to enter the value again manually every time I start the program.

I am also beginning to understand the scripting thing. What I noticed however, when starting a script and modifying the default values in the dialog, the machine will execute with the modified numbers but the toolpath trace display will stay with the default values. Is that normal?

Otherwise, I am a bit more optimistic about using the TNG version. I only have to swap the +/- jog button wiring in my mpg. The settings do not seem to have a swap check box like in the old program but that is easy enough.

GB