Half a Gear

Well there is it. My one of my favorite machines at the college machine shop. Also the machine I made 'snoopy' on. It is a 5 axis Charmilles wire EDM. Electrical Discharge Machining has its advantages over other forms of machining because of its ability to cut just about anything that conducts electricity and of just about any shape and size that will physically fit in the machine. I thought of using this machine as a way to make gears for my evil bidding (aka all those weird gear related projects I like to do but never have the right equipment) a couple years ago and have done a couple (square gears, etc.) but haven't had a lot of time to just poke at it and see just how good of a gear you can make on this machine. I would like to determine what sort of gear quality I can get by EDM. So, I designed a simple planetary gear train to get things rolling.

I will be curious to see just how well the EDM does with the elemental parts of the gear teeth. Correct profile, lead, PD size, even things like finish. How well they run with each other which will depend on things like correct tooth spacing, runout, as well as everything listed above. I might not be able to check all these things but I will do what I can. I am almost more curious about the quality of the gears than anything else in this project.

I ran a test part through the wire and size held within about .0003. Not too bad. I can see it getting a lot worse though with something that has a lot of geometry (like the gears). One of the biggest things is the finish. Surface finish from this EDM isn't the greatest but We'll see what we end up with.

Tons of fun :)

Update: 11-5-08

I have cut a few gears on the EDM and they actually ended up really good! Nice profile, a tiny bit of lead error (taper), and decent dual flank composite variation results. Better than expected! yay!