Newbie help with 4th axis gear cutting

[JustinO]

What air are you cutting? Is it as though the gear were much thicker than it is?

It seems to be cutting too deep and too wide, could this be a problem of unit conversion somewhere in user interface entry field?

--Justin

[esawyja]

Hi Justin,
It cuts the 1st tooth, then shaves the tooth, then move to the Y- way past the blank and then starts cutting air, once that is done, it move back on Y+ to the blank, cuts the 2th tooth, shaves and then moves back in Y- and starts cutting air again. I'll try and compress a video I made and upload it

[JustinO]

Is the tool comp/tool radius in inches or mm?
.5 inches + 7mm + .5 inches = 32.4mm. Is that about how far it is moving?
It should  be moving:
.5mm + 7mm + .5mm = 8mm.

Justin

[esawyja]

Hi,
I've uploaded the video to http://youtu.be/QaW5jkDZGoY , maybe that would help to illustrate the air cutting  ???
As far as I know, everything was set to mm, in the screenshot of the output manager the diameter of the tool was set to 1mm
Thanks for the help so far!!

[JustinO]

It looks like it is trying to cut with the side of a tool that is an inch wide, not a mm wide.

In the Output Manager, in the NC Parameters box, in the Tool Diameter field, try dividing that number by 25.4 (mm/in).

There is another, proper place where this should be corrected, but it slips my mind (I'm only out of bed for a "business trip").

[esawyja]

Thanks Justin,
Will try the settings!

[esawyja]

Hi,
Strange but my settings are set to metric, but I will try the INCH to MM over the weekend for the tool diameter

[JustinO]

I take back everything I've been saying.
Your posted g-code and the video do not appear to be doing the same thing. I don't think this is a Gearotic issue.

When the root of the gear gap is cut, the X and A axes seem zeroed, but when the tapers are cut, the X and A axes seem to not be zeroed. The "left taper" and the "right taper" are both off to one side, for both the X and A axes. What are you using? Mach3? LinuxCNC? Is the G-Code interpreter reading a different ASCII character definition? Does the code your NC program shows on the screen match the code Gearotic puts out **EXACTLY**?

Very weird.

--Justin.

[JustinO]

Once again, I take back everything I've said.......I do that a lot.

I think you zeroed the machine while the program was stopped in the shaving mode.

{I said some stuff in here that was stupid, so I cut it out}

You need to zero everything at the start of the program where the program thinks all the axes are zero.

This explains cutting air, and it also explains cutting too deep.

--Justin.

[esawyja]

Hi Justin,
Yep I did ZERO the machine just before starting the cut, X-Y-Z and A, I did not stop the machine during the shaving. I'm using the HEIZ High-Z S-1000 machine, http://www.cncsolutions.co.za/products. ... %20S%20400 and the CNC controller is their program called WINPC-NC.
I wonder, Gearotic outputs for MACH3 (I think)?, do I maybe need to specify a different Post-Processor? Do you think that might be the problem? I'm out of ideas...
Regards

[ArtF]

Hi:
  Sorry Im late replying, I didnt get notifications again on this thread..


The video shows whatever this is its bad, while its common to miss onme or two shaving steps,
this one is missing too many and is way off.

Final Depth means nothing in 4th axis, its only for 2.5D cuts, in 4th axis you'l cut to root depth
always. Your teeth look too deep, the shaving is way off so Im surprised oyu get teeth at all really. :)

OK..

  hmm, you know , that gearis just too large to show effect properly.. Can you try a 10 tooth
module 5 or so, any gear with 10 teeth thats about 100mm in diamter would be good.
Show me just the first tooth cutting on it and I cxan usually tell whats wrong..

Tx
Art

[JustinO]

I am quite certain that the you are really close to getting a perfect gear.

G-code programs with only G00 and G01 are pretty global. There are differences around the globe besides metric/inch that might need to be addressed in a preamble line. Some controllers default slightly differently, who knows?

For some reason there is an offset in the A and X axes. The Y and Z axes seem to be okay.

The offset is about what you would expect if the machine were zeroed where the faces are cut with 11 Y passes, instead of where the roots are cut with 4 Y passes.

I think the G-code is fine. Perhaps there is a persistent offset variable being saved between runs. You should have a preamble line to make sure that your controller is starting fresh. G20 G54 G40 G49 G90 G80 G94 is a preamble that I just sucked off the web. It is for a machine being run in inches (G20). You would want to find out what other people with your controller use when they run a typical North American program.

Double check your zeroing procedures, and check and confirm the results as you zero.

Are you working with cncsolutions? They might be more familiar with international issues than we North Americans. They would  also be a good source for a generic preamble line.

You really are very, very close to having your gear. It's probably something silly and simple.

[esawyja]

Thanks for the replies guys, I will have to put this on the back burner for now, off to Bangladesh for a 4 week project, I will definitely try all the recommendations as soon as I'm back home again, I did speak to the guys at cncsolutions and this is what they recommend I change the code to

From This:
G90.1 T1
G21 G0 Z5.0000
F 1000.00 M3 S3000

To This:
G64 G17 G90
N1 T1 M6
S40000 M3
M8
G0 X0 Y0
Make sure the feed speed is included in the code.

[esawyja]

Hi all,
I had some time before flying to Bangladesh, I tried cutting a 18 tooth gear 100mm, at least the results made me laugh!! I tried changing the pre-processing code as per the previous post. Hope you can discover what I'm doing wrong?
Video is here
http://www.youtube.com/watch?v=HcbOVptC ... e=youtu.be

[ArtF]

Hi:

It looks very much like your not centered at the top of the disk?? You must be at the absolute top, and the rigth distance from the center of the disk. Is that the way its setup or am I seeing a perspective issue in the video?

Art