My first 4th Axis gear out of GT (1 of 4 posts)

[SkyMoBot]

This is literally the first thing I have cut using my "Chinese 4th Axis" that I bought on Ebay.  Turned out pretty good all things considered.  Here is my step by step illustrated how I did it following Art's you tube video and hints I have read here.  Please comment especially if I am not doing something like I should. 

Of course start with a nice simple gear in GT.  16 big easy to cut teeth.

Then use a drawing program like DraftSight to draw your blank to the right size and cut one,  GT displays the radius and it's also in the output file. (Maybe GT could output code for the blank as well?)  There is also the Material size in the GCode processing screen but I am not sure what that refers to as the dimensions are not the same as 2x the radius.  GT also likes to round up my tool size.  It's .125,  shows as .13 on the screen and .1250 in the Gcode output.

I use nylon bolts to hold my clamps in case I mess up something, saves an expensive bit when I hit one of them.  Also use a lot of medium density particleboard as it's very cheap and seems to work well for prototyping.

[SkyMoBot]

I made sure you align my 4th axis and find the center of it.  I am using a touch probe and one of the automatic probing routines in MachStdMill.  Makes stuff like this easy.  I think of of the things that made this all work the first time was double checking all my setups.

[SkyMoBot]

Here is the gear after the roughing pass.  The top looks uneven, but that's due to the background I think.  The teeth at the bottom of the photo are more in focus.

[SkyMoBot]

And here is the finished gear.

I had to do this in four posts so I could put in all my pictures.

[ArtF]

Hi:

  Excellent post, and thank you for doing that. You did perfect work near as I can tell, and I agree
with all your comments. I do see one thing that will be changing real soon, and that is the radializing of the
root clearance. Its my intention to change rooting so that the tooth can be rotated during clearance of the root
as it woudl take away those aliasing artifacts in your roots. They are cleaned as well as can be done without
rotation, and I didnt put it in originally as it doesnt make sense to do that for pulleys and such, but for evolutes,
having a radialized clearance would make them cleaner when under 24 teeth. At about 24 teeth on an evolute
the trochoidal undercut goes away so its only an issue on fewer than 24 teeth....but Ill make it an option shortly.

  Very good display of how its done though, we at Gearotic  salute you..

Art

[SkyMoBot]

It was a lot of fun and I learned a lot having never done 4th axis before.  The new drive arrived in less than a week from China, but then I needed to revamp my controller box since I didn't plan on expanding it beyond 3 axis when I built it.  Even though I made the mounts out of hardwood, it still took a bit to map them out so I had room on my table to do both the creation of blanks and the gears.  Learned about setting work coordinates so I could keep both options of blanks and gears open at the same time.

Then making sure everything was aligned (pretty easy thanks to the probing routines).

And making the mandrels to mount the blanks.

Bottom line, same rules apply.  Take your time in the setup and walking through the GCode before you cut.  Then the actual machining is a breeze.    If I had one small request, it would be to take the tool change out of the default.  It's easier for me if there is nothing there but the code so I can add all my custom stuff in the prefix section.

[ArtF]

Thx, I will do that and allow a user to instead set the tool change in the
prolog.. until such time as I put out multitool code anyway.

Thx
Art