So I'm trying to mill cavities in a guitar body to lower the weight. I have a simple fusion 360 design and output the tool paths to the grbl plugin. Other than having to remove T1 M6 from the gcode this generally works fine. I've since switched to the black box (neat) and openbuilds control. The issue I'm seeing is that the first cavity in the guitar body is milled exactly as expected. Once it is done it trucks off in the wrong direction to go to the second cavity. Here is the first part of the toolpath. It does that cavity and then the final red line is the trip to the second. Instead of raising the tool it is plunged deeper and heads in the opposite direction. This hasn't been great for that body. Any ideas where I'm going wrong? Fusion 360, this weird gcode preview thing I found on the web and openbuilds control all show the same, correct, toolpath. Thoughts?
Just checking: you are using the correct Grbl Post: (not the default one) Fusion 360: grbl post processor install (the easy way) Lots of fixes, like removed M6/Tx commands, fixed decimal places, and many more
so i loaded the chambering7.nc file in control. just as it finished rendering it said it wanted to update.180 to .185, I clicked yes, it did this and then updated ok
That bug during updates was fixed in 1.0.184 (but only released as 185, 184 was internal only) - so Wont happen again See: v1.0.185 · OpenBuilds/OpenBuilds-CONTROL@9359a07
Giving that a go. I had to install it differently as I didn't get the cloud option. Thanks for your help.
So, after some fun that behaved somewhat differently but still kept the bit down at the first cavity. The gcode simulation shows the bit coming up and then moving to the second cavity. Not sure what it was showing at the time of the failure as it induces a heart attack every time. I wonder if it is the final finishing pass that is giving me grief. Cavity is 1 inch deep. Tool's cutting length is 1 1/8 inch so that shouldn't be it. Even so it would do 1 or 2 passes (2, I think) and then lift and go to the second cavity.
are you ticking 'smoothing' in Fusion? This greatly reduces the number of points in the Gcode which reduces file size and runtime. yesterday I ran your chambering7 file through OpenbuildsCONTROL to a bare Uno+GRBL and it ran without apparent fault for over 2.5 hours before I stopped it (needed the pc for something else). now it was not moving any gantry etc so that means that the gcode is ok and points to a mechanical or EMI issue on your machine. my current feeling is that your Z acceleration is too high and it is missing steps on the retract movement, causing it to stay down. to prove this you need to change the Z acceleration to half of what is is now and run the job again. I suggest cutting a piece of insulation foam instead of an actual guitar body (-:
@DarkPenguin oh! looking at chambering10 I see it is doing a full depth finishing pass. that may be too much for your machine to handle. Code: ( Tool 1: Flat End Mill 2 Flutes, Diam = 6.35mm, Len = 25.40mm) the tool length is defined as 1" long which may cause issues with a cut of 1" depth. change the tool to the real stickout?
I'll give that a try. I can't imagine an EMI issue hosing me in the same way every time. Is that a thing? I'll double check the bit. I'll do a few things tonite when I give this another go. 1. removing full depth finishing pass. The bit is actually slightly longer than 1" but I don't need this to be neat. 2. I'll reduce z acceleration. 3. Temporarily switching back to bCNC. If that doesn't do anything for me I'll fire up estlcam. I'll do those one at a time. I'll also tic smoothing in fusion cause faster is better. The guitar body is largely to me so I'll keep butchering it until I get a good run. Then I'll, hopefully, not butcher the body blank I have waiting in the wings. Thanks for your help!
I changed 3 things. I killed the full depth passes. I turned on smoothing which shrank the overall program by like 1000 steps. And, interestingly, I turned off the keep the bit down option. Maybe that's why the bit stayed down? Still that didn't show up in any of the simulations and, according to my reading, should have only kept the bit down in each cavity. It didn't all go well as after days of screwing with this one of my clamps loosened and the CNC chucked the body across the table. Neat trick that. I didn't think the Makita had the HP to do that. Thanks for everyone's help!
