Toolpaths, Adaptive, Trochoidal, and others

[WillAdams (William Adams (Carbide 3D))]

Working through this aspect of my project now and thought it merited its own topic.

First up, managed to get my own version of a trochoidal toolpath in TPL:

function trochoidalx(px, py, pbottom, endmillshape, pdiameter, plength, pwidth, pdepth) {

rapid({z: safeheight}); // Move back to safe position

rapid({x: px+pdiameter, y: py+pdiameter, z: 0});  // Go to start position

arc(pdiameter/2, 0, -pdepth, -2*Math.PI, XY)//helical plunge
arc(pdiameter/2, 0, 0, -2.5*Math.PI, XY)//flatten bottom

icut({x: pdiameter/2});  // advance

var i;
for (i = 0; i < pwidth*pdiameter*0.75+1; i++) { 

arc(0, pdiameter/2, 0, -1*Math.PI, XY)//trochoidal cut

arc(0, -pdiameter/4, 0, -0.5*Math.PI, XY)//begin return
arc(pdiameter*0.75, 0, 0, -0.5*Math.PI, XY)//finish return

} 
}

Calling it with:

trochoidalx(-tr, -tooldiameter*2, 0, 0, tooldiameter, Width, tooldiameter*2, Thickness) 

which yielded the toolpath:

[WillAdams (William Adams (Carbide 3D))]

The next consideration is what is involved in transferring the settings from one project:

Box - fitted - round - 2in. diameter

to another:

Expressed as numbers, the values used for the “Box - fitted - round - 2in. diameter” are (roughly, some numbers are rounded off for convenience of calculation):

//bamboo settings
dpp=1.5;
stepover=2.75;
feedrate = 1652;
plungerate = 317.5;
rpm=16000;
roughingclearance=0.5;

[WillAdams (William Adams (Carbide 3D))]

First though, we apply those settings in Carbide Create as a check/reference:

Import a file, select the geometry which you wish to cut, then inset it by the value of roughing clearance:

[WillAdams (William Adams (Carbide 3D))]

and apply toolpaths:

[WillAdams (William Adams (Carbide 3D))]

For the finishing pass, select the original path and assign a full depth pass interior cut:

[WillAdams (William Adams (Carbide 3D))]

For the outer profile, offset the outermost path as necessary to allow the selected endmill to cut as a pocket, and the path which defines the profile by the roughing clearance:

[WillAdams (William Adams (Carbide 3D))]

For the final pass use the original profile and add tabs:

[WillAdams (William Adams (Carbide 3D))]

One concern about the above is that it assumes stock of the proper thickness — in this case, the stock thickness ~14mm and it would be necessary to face off sufficient material to reduce the thickness to 6.35mm, so starting depth needs to be added to the above as a variable entry.

[WillAdams (William Adams (Carbide 3D))]

Okay, working up a pocket cut which is:

• climb cutting (see: Climb vs conventional, definitive guidelines anyone? )
• ramps in (ditto)

We have the code:

rapid({x: px+plength/2-stepoffset/2, y: py+plength/2-stepoffset/2, z: 0});  // Go to start position
cut({x: px+pwidth-plength/2-stepoffset/2, y: py+plength/2-stepoffset/2, z: -dpp});  // Go to start position
arc(0, stepoffset, 0, -Math.PI, XY)//make turn

which gives us:

[WillAdams (William Adams (Carbide 3D))]

Updated code:

rapid({x: px+plength/2-stepoffset/2, y: py+plength/2-stepoffset/2, z: 0});  // Go to start position
cut({x: px+pwidth-plength/2-stepoffset/2, y: py+plength/2-stepoffset/2, z: -dpp});  // cut to other side
arc(0, stepoffset/2, 0, -Math.PI, XY)//make turn
cut({x: px+plength/2-stepoffset/2, y: py+plength/2+stepoffset/2, z: -dpp});  // return
arc(0, -stepoffset/2, 0, -Math.PI, XY)//make turn
cut({x: px+pwidth-plength/2-stepoffset/2, y: py+plength/2-stepoffset/2, z: -dpp});  // clear ramped cut to bottom

which cuts as:

[alanbc (Alan Rothenbush)]

I’m an occasional Camotics user and a new reader of this site.

Your recent post seems to show the code to generate cutting info. I thought Camotics was only used to display existing cutting info (GCode) generated by some CAM program, not create its own code.

Am I missing something?

(I’m interested because you’re talking about trochoidal milling, which my CAM does not generate …)

Alan

[WillAdams (William Adams (Carbide 3D))]

CAMotics also supports

https://tplang.org/

which allows one to use JavaScript to describe toolpaths as in the code above.

[alanbc (Alan Rothenbush)]

Cool! And thanks for the reply.

Sadly, it seems that just as I was getting competent with GCode, I get to learn something new.

Ah well, that’s what retirement is for!

Alan

[WillAdams (William Adams (Carbide 3D))]

I believe I’ve gotten this puzzled out:

just have to add the finishing pass to final size.

Then I’ll have to work up the logic to cut the various pockets and then the rabbet and we’ll be ready for a test cut.

[luc.onthego (Luc)]

Great, the step after that is to integrate into CC Pro! Too bad CC does not support apps.