Cutting Tetrix gears

[Forhire]

I re-wrote the slitting saw code in python so I could generate some g-code to play with. This is neat stuff. The rendering is a bit odd looking because of the zero is on the outside edge of the blank and the A axis rotates around the X. It appears to work. I wrote my version to automatically calculate the blank diameter based on the gear tooth count and module making it very simple. Enter the module, tooth count, blank width, and the cutter details, it then spits out g-code.This is a good starting point to play with. I'm definitely going to modify this code to handle standard profile gear cutters also.

The render is for a mod 3.0, 38 tooth gear, and a 30mm face width. The cutter is 60mm diameter and 2mm thick. Similar to the gear in the original video.

[asid61]

I really look forward to seeing this in action!
If you had standard profile gear cutters, wouldn't that be considerably simpler code?

[Forhire]

Originally Posted by asid61

I really look forward to seeing this in action!
If you had standard profile gear cutters, wouldn't that be considerably simpler code?

Yes. For milling gears the set of 8 profile cutters is likely the easiest. I'd have to look but I think my code for cutting gears is only about 5 or 10 lines long. The formulas are easy enough to do by hand. Rolling the formulas into a quick python script allows for the code creation with just a few variables.

Milling gears with the slitting saw is just interesting. For me it's a novelty. But, it is very similar to what Sandvik is doing with their Invomilling, so it may well be the future. I think this will be a fun project to play with in the fall. A great introduction to 4th axis programming.

We used Gearotic last season to calculate the gear dimension. Looking at it this morning it appears to also support gear milling. I'll have to play with that some more.

I sorted out the 4th axis at the school last year but I haven't mounted a chuck or center on it yet. Now that we have a use I'll have to get cracking on the 4th axis accessories.

If you don't have a 4th axis, or even if you just have a manual mill you can still cut gears with an indexer. Manual indexers do most counts but are tedious. My Haas indexer is nice because all you do is press a button (or the cnc pulses it).

You can build one using a rotary table and a stepper motor. Here's an Arduino Sherline Rotary Table controller my friend built.
http://www.cnczone.com/forums/arduino/215402-cnc.html

Last year when I needed to cut a replacement 93 tooth back gear for my Lagun I couldn't get my Haas to do it correctly, so I made a new control for it. The 7 wire Haas indexers are steppers and super simple to drive. I ended up using Pacific Scientific 6420 stepper indexer and Python with pySerial. Worked perfectly. The URL below also has some images of making many of the gear cutting accessories required.
http://weldingweb.com/showthread.php...indexer-driver

After all that I discovered the Haas supported circle division but it was a few months after I built my new control.