- Feb 10, 2018
- Reaction score
- Central Florida
Your comment about attempting to use a 3D printer slicer to generate your tool paths leads me to beleive you are not satisfied with your CAD program. I think you should look around and find a CAD program that you can bend to your will.
I think that's essence of this whole thread. To be a pain in the *** about it, it's the CAM program that's the issue. I'm fine with my CAD program.
It is good to edit your own Gcode as you become familiar with the post processor and the codes used, but doesn't your CAD program allow you to create a profile, or contour operation where you specify the stepdown and it generates the whole toolpath without the need for copy and paste Gcode? When ever you have to get in there and hand edit a tool path there is an opportunity to make mistakes.
Nope. It has two options that are similar, waterline and contour. Waterline allows me to set a step vertically and (I thought) a keep out horizontally. It turns out it uses the keep out distance vertically as well as horizontally. With this conn rod lying down like it is, I set the top of the part to Z=0 and cut everything going in more negative numbers. That part is configurable, I could have made the bottom Z=0, but I guess I'm used to this. What that keep out does is create a file where the machine spends time cutting in air above the part.
Contour only makes one pass around the part, with no settings to change that. That file was what I edited in the text editor to create seven identical paths at multiples of 0.031 deep.
I'm spending most of my time sitting here, not in the shop, trying to convince the CAM program (DeskProto) to do what I want it to do. I find I had to play with all sorts of things to get it to do what I wanted for the two files I ran on the rough cuts pictured in the last post. Same for the two files I just ran today.
Secondly, I have found it best to avoid plunging the cutter into the part. You are only stepping down .031" I think you said, so this would not be an issue. but you do have the opportunity to enter the cut from either the right or the left.
Somewhere in my reading, I had come across the idea that as long as we cut a slot with a depth less than the cutter width, it was more than likely to be OK. But snipping a bit...
... As the tool is cutting the slot it is making a conventional cut on one side of the slot and a climb mill on the other. The tool will be pulled to the side of the slot that the flute is advancing into (conventional milling) and pushed away from the other side (climb milling). The tool will have a tendency to bounce back and forth, the amount depending upon your system's rigidity.....
I think I observed a problem that this explains. On the second to last pass of the rough contour pass (supposed to leave 0.031 extra all around the part) I started to notice a strange sound like some sort of resonance and I could see and feel the mill shaking. About halfway into the pass, the motor on the spindle shut down. As in completely off, with the LED RPM indicators off. I shut down Mach3 and the controller and made sure nothing bad had happened, then went to look at the motor controller. A fuse holder had been vibrated loose enough for the circuit to open. The fuse was fine and screwing it back into the holder got the system working again.
With that said, the experiment here was "potting" the part in epoxy to get the second side done.
I used cutting oil instead of my Fogbuster for this contour path. A single cut around the part at 10 IPM, which took one minute. Next is to try to get the epoxy to break down in my toaster oven.
EDIT 7:33 PM (my time - Eastern US): I thought the epoxy worked but it's barely visible in this view that the epoxy pushed out of the top right corner. I haven't run the oven to break off the epoxy. That's something to do on the back porch tomorrow, rather than indoors in the shop which shares air with the house.
I used all the epoxy I had on hand for this - Gorilla Glue brand, 5-minute epoxy. I think this means I need to do the real part differently.