Problem with involute gear generation

[Scott Pancheau]

Hello,
I am having trouble with involute gear - code generation in fourth axis method. I have tried to machine three different gears and have same problem each time. The code roughs out the first two half teeth fine. Then the a axis rotates and the z axis moves down even further than it was at the bottom the first cut and plows back through the blank in x, then z heads down again even deeper. I can send the generated code but I don't know how to attach to this post.

Thanks,
Scott

[BobL]

Hi Scott;

Have you viewed the 4th Axis Milling Tangential Shaving and CAM features of Gearotic on Youtube?  Perhaps this may help to shed some light... 

http://www.youtube.com/watch?v=UndFcWc38Wk


Cheers
Bob

[Scott Pancheau]

Bob,
Thanks for your reply. Yes, I have viewed the video. As I stated the first cuts at A 0 position are just what you would expect. Here is the code sequence. The last line of code at A 0 position is g1x-40 y0 z-.32 A0.
The very next line of code is go x-.4 y-.150 z-.4429 A7.3279. The next line of code is x+.40. This does just what you would think, it takes a full depth of cut deeper than the last correct cut and wipes out the blank at a position just outside of the last proper cut. I would expect z to return to the clearance plane before A rotates to the next machining position. I cannot see how this could be a proper code generation.

Thanks again
Scott

[Mooselake]

Scott, to attach a gcode file you'll need to zip it first.  When you reply click on the additional options below the reply window, scroll down if necessary, then use the Browse button next to "Attach:".  You can attach any of the files with extensions listed after "allowed file types" without zipping them first.

Art might like to see the gth project file, so you should attach that also.

Kirk

[Scott Pancheau]

Thanks Kirk
I think I have the code attached. Thanks for your help.
Scott

[ArtF]

Hi Guys:

Sorry for the delay, I wasnt getting notifications lately.. Ill check this out and reply back. ( Are you sure the A is goign correct direction, thats usually
the issue.. but Ill analyse and check..

Art

[ArtF]

Scott:

  These are notoriously hard to troubleshoot form the numbers, it does look correct to me though... but if your
A axis is rotating backwards, you'd see the symptom your seeing.. Can you tell me what direction it rotates when you rotate
it ++ when viewed from X++ looking down towards x--?
  While the numbers look correct I cant verify it as yet. Im assuming its the old rotation issue. Make sure your 4th axis position is
selected correctly and the A axis rotates counter clockwise ( when chuck faces X++, and is viewed from X++ looking down X-- direction)
when it turns in a ++ direction....

Within a week or so I hope to have the new version out which will show a simulation of the toolpath as you generate it.
So at least soon you'll be able to see exactly what you SHOULD see on your machine..

Art

[Scott Pancheau]

Art,
I did not even think of that as a possibility. If I am correctly understanding your description then I think my rotary is turning the wrong way. I will swap it around tonight and then get back. Thank you so much for your help. On that vein - this is a home made gantry and I have it set up such that the X axis moves toward the rotary when moving in + direction. Is that correct for the way code is written ?

Thank you
Scott

[ArtF]

Scott:

  The default code is written for the chuck being in the X-- direction.. But in the options you can select the direction you face.

Its not unusual for the rotary to be backwards, few peopel follow the spec for that and youd only really notice on gear cutting.

Art

[SEOSearch [Crawler]]

Why don't you just reverse the direction of the motor in Mach3?
Dan

Art,
I did not even think of that as a possibility. If I am correctly understanding your description then I think my rotary is turning the wrong way. I will swap it around tonight and then get back. Thank you so much for your help. On that vein - this is a home made gantry and I have it set up such that the X axis moves toward the rotary when moving in + direction. Is that correct for the way code is written ?

Thank you
Scott