GearHeads Forum

  I turned off the Root Wall and generated new G code. I ran another test and it was better. The old gear root averaged ~.053. The new gear measured .062 so that is pretty much the diameter of the EM. That improved the width of the involute tooth. The old measured ~.091  and the new measured .083.
So turning off the Root wall helps but is not perfect.. It was close enough that I reassembled the wiper transmission with the new gear and could not detect any noticeable backslash in the wiper mechanism. So I reassembled the whole unit into the Mercedes and it worked perfectly! It saved me a ton of money and was a fun project. I can now machine gears on a mill in addition to laser cutting them on my 100 W and 30 W lasers.
Let me know if you need any more tests while I have my 4th axis set up.
Dan Mauch



[quote="ArtF"]
Dan:

  The option "Root Wall" will take a slice on each side of the tooth to straighten its walls.
It may be buggy, turn it off and it may be better. I suspected a bug in there with Sky's tests
but I think in the end his worked ok, but if the bug I "thought' I saw really happened, it made the root too wide by about a full tool diameter.


  As to the feedrate, I put out the code with the expectation that the A axis would be used as a
circumferance object where the feedrate is the speed on the outside, so an F20 would be 20mm's per minute on the outside edge , not the actual angular speed. But thats all dependant on how Mach3 is setup. Ill make sure I look at that to option it in future.

Art




 

[/quote]

Hi guys:

  I think I see the confusion. the only numbers that should be used are those in the GCode file. The file starts with a statement on the blank radius and such.

Unfortunately, I wrote the screen to display the computed extents of the stock used in the drawing..which varies a bit for display reasons. Its designed so the Gcode was to declare the blank size and such.

Ill edit that and make them match...but the file is the correct information..

Thx
Art

Based on Dan's results I thought I would do some more testing with my setup and had some more questions.

I created a 25 tooth gear, DP 20.06 and Module 1.27.

The gear is listed on the Project screen as having 1.3457 Diameter
On the G-code Processing screen picture the stock width is listed at 1.3423, the height is 1.3447
On the G-code Processing menu, the material size is X 1.3776 and Y 1.3801.

I've always made the blanks the stock width or 1.3423 (at least I think I have).  But since I zero at the top of the stock, I see how this can be very critical.  Am I using the right number?  Why not make the Z the centerline of the A Axis instead of the top of the stock.  Maybe we could also have a function that trims the stock to the right diameter?

That way I get my stock close, and the mill does all the rest.

Dan:

  The option "Root Wall" will take a slice on each side of the tooth to straighten its walls.
It may be buggy, turn it off and it may be better. I suspected a bug in there with Sky's tests
but I think in the end his worked ok, but if the bug I "thought' I saw really happened, it made the root too wide by about a full tool diameter.


  As to the feedrate, I put out the code with the expectation that the A axis would be used as a
circumferance object where the feedrate is the speed on the outside, so an F20 would be 20mm's per minute on the outside edge , not the actual angular speed. But thats all dependant on how Mach3 is setup. Ill make sure I look at that to option it in future.

Art




 

The Axis is in the angular mode. I have the motoring tuning set up for 33.33333 steps per unit which is degrees for the A axis. So isn't the F20 mean 20 degrees per minute? On previous runs there wasn't the slow A axis just this latest test. Just the latest G code from GT. I made a new G code file to change the face width and make is wider. Since it wasn't a previous problem it may be a quirk on this latest test.
One other thing you are right that the teeth look a bit thin. I measured the old gear and the root width is .059 and the tooth width at it widest is .093. The new gear the root is .079 . The cutter is the .0615 so shouldn't the width of the root stay at ~.0615 with a single pass? Because it is making more than on pass is that what is thinning the teeth?
Dan Mauchg



[quote="ArtF"]
Dan:

  Nice to see. Re- your A axis going slow, are you in A axis radial mode? If so it should have revolved
at F20 as in 20mm/min on the circumferance..not in degrees..

Art

[/quote]

Dan:

  Nice to see. Re- your A axis going slow, are you in A axis radial mode? If so it should have revolved
at F20 as in 20mm/min on the circumferance..not in degrees..

Art

Hhttps://www.youtube.com/watch?v=Knb95tYQ5zo&feature=youtu.be
Here a video of the involute gear being machined.

Today I made a few changes and it looks like the 17tooth gear came out perfect. It meshes with no discernible backlash and there is clearance in the root. What do you think Art?
I plan to upload a video later today because I thing there are some things in the G code that you may want to take a look at. It seems like the X+ travel is excessive and the A axis at some point is really slow it  took m35 minutes to machine  a 20 IPM feed rate.
But overall this program is OUTSTANDING. And I can't thank you enough Art for all the help and for this great program.
Dan Mauch

BTW I post a link to the video later . My back was sore so I didn't want to lift my 8" rotary table so I used a cheap Chinese 4th axis that 1. Is low profile so it's easier to machine closer to the chuck, 2. seems to really lock the chuck tightly so there is no backlash or slop. 3 there are only 33.3333333 steps per degree. 4. it was pretty cheap



[quote="ArtF"]
Dan:

  Happens to all of us. :)

Im betting it looks better next run..

Art

[/quote]

Dan:

Ahh.. much better. Still looks a small,small,tiny bit wide in the space..but with small tools and small gears its not surprising, but they
easily look good enough to use.

  Look forward to your forensics.. good timing as over the next 3 months Ill be doing one heck of a lot of work
on all the G-Code outputs. Great to see it work out though, it means I wont have to reinvent the wheel on some
of the new code I need to do.

Art

Today I made a few changes and it looks like the 17tooth gear came out perfect. It meshes with no discernible backlash and there is clearance in the root. What do you think Art?
I plan to upload a video later today because I thing there are some things in the G code that you may want to take a look at. It seems like the X+ travel is excessive and the A axis at some point is really slow it  took m35 minutes to machine  a 20 IPM feed rate.
But overall this program is OUTSTANDING. And I can't thank you enough Art for all the help and for this great program.
Dan Mauch

BTW I post a link to the video later . My back was sore so I didn't want to lift my 8" rotary table so I used a cheap Chinese 4th axis that 1. Is low profile so it's easier to machine closer to the chuck, 2. seems to really lock the chuck tightly so there is no backlash or slop. 3 there are only 33.3333333 steps per degree. 4. it was pretty cheap