OpenBuilds CONTROL Software

to cut 1um off a bit of titanium probably does not take a lot of power, can maybe scrape that off with a fingernail?.
to spin a leadscrew that moves a gantry that holds a motorized tool that does the cutting, that takes quite a lot more power, and to hold high accelerations so you can maintain cut speed (important in Ti) takes even more power.

 

I guess I have an idea in my mind about the sort of machine that would be rigid enough to meaningfully machine difficult materials like titanium: it would be very substantial, probably made of cast iron (or granite) and running on dovetail or hydrostatic slideways with large diameter, preloaded ballscrews. The machine would be unavoidably heavy and the ballscrews would have a lot of inertia and some friction. I would expect to need more powerful motors than are available in NEMA 17 form factor, but I guess they could be geared down.

Good luck with your project, whatever.

 

It's pretty standard engineering...

Not sure about that - just old. (Having spent my working life in various forms of manufacturing, some things rub off.)

 

Use a CAM, instead of manually writing Gcode?

grbl (and grblHAL) supports a subset of the LinuxCNC standard so LinuxCNC "G-Code" Quick Reference is a good lookup for specific commands

 

This isn't bad:

G02 / G03: Ciruclar interpolation (Theory & Examples)

It's a lot easier to use a CAM program though.

 

here is a good primer on arc coding, more than you need to know, CAM is much easier, much quicker and much more robust (ie once the CAM is debugged it always does the correct thing, whereas hand coding will let you make mistakes every time ). if you don't like Fusion360, there is always Sketchup Make 2017 with the SketchUcam plugin



a thing to note on arc coding, some controllers can do full circles, some can only do half circles and others can only do 90 degrees or less, per arc command.
SketchUcam outputs 90 degree arcs, the OB postprocessor for Fusion360 outputs arcs up to 180 degrees, full circles may work for GRBL, I cannot recall exactly now, but smaller segments = works in more places ,more often.

GRBL can do helical arcs, ie an IJ arc with a Z component that changes, like for threading or boring. some controllers cannot do this and then the CAM must linearize the arc into little line segments.

 

Like the others have said, I usually design what I want in CAD first, and it's then a logical step to use CAM to generate the gcode (it means I don't need to get my head around IJK coordinates for one thing!). You get a lot of nice options like being able to leave a little stock and take a finishing cut, or to take several cuts to get the depth you want without having to do too much thinking. And if you change your design, you just have to click a few buttons to generate the corresponding gcode.

If you're already using CAD/CAM, then it's a no-brainer, however it would be an extremely steep learning curve if not - certainly not quick!

If you will only ever do a few simple jobs that don't really change, then it might make some sense to stick with hand coding gcode. For anything else, you are going to meet CAM sometime, so you may as well start...

FWIW I use Fusion360 for CAD and CAM with their default GRBL post processor. It works for me.

 

Now you're getting into the detail - there's a fuller explanation here:

G Codes

 

do not use R format arcs, anywhere, anytime, just don't <-: so prone to massive errors, just not worth it
X32 shoudl do a circle ok with IJK format.

 

if you have fusion360 on an actual licence then you can partly ignore this....
if you have it 'free for personal use' then you should be using the Openbuilds postprocessor fot GRBL, it has advantages, like putting back the rapids the personal license takes away

 

some things are easier than others. Fusion360 is very powerful but is also more complicated.
how about just flat 2D drawings? easy, right? Sketchup is a possible answer (as is OB Cam)


but wait you say, my object is not just flat.... (but is not curved either)

 

I'm on the personal use licence. I did try the OB post, but switched back to the Autodesk one in an attempt to resolve some issue or other (maybe not post related) and have stuck with it since. The OB one didn't seem do to much to the rapid feeds. Like I said, it works for me, and "If it ain't broke; don't fix it!"

 

It should do.

For reference, this is what F360 outputs if you ask it to contour around the inside of a 10mm diameter hole 2mm deep with a 5mm dia cutter and no bells or whistles. Hole centre is at the top of the stock at X0, Y0:

Code:

(10mm hole 2mm deep with 5mm cutter)
(No lead-in or lead out)
G90 G94
G17
G21
(2D Contour1)
S10000 M3
G54
G0 X2.5 Y0
Z15
G1 Z1 F1000
Z-2 F200
G3 X-2.5 Y0 I-2.5 J0 F1000
X2.5 Y0 I2.5 J0
G1 Z15
M5
M30

That's about as complicated as I would like to get by hand. Attached is a file that bores the same hole with multiple passes of a 3mm dia cutter with a finishing pass and lead-in / lead out paths to avoid leaving dwell marks on the work. No way would I go near that by hand!