pic: 968 - Even more unfinished parts!!

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I don’t think these are hard to distinguish at all, so I won’t even bother making you guys guess. I wanted to show a finished delrin side plate and one of the 7075 gears with dog cutouts. The ‘numbers’ say the delrin should hold up just fine… we’ll see.

The caliper is there to show the plates relative size… somehow it got a lot smaller than last year!

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That is niceee. I wouldn’t expect anything less from 968 and 254.:slight_smile:

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Grats Travis to yet another shiny piece of metal (seriously, 968 rawks)!

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Wow, 968 and 254 are going all out this year with their robots. 7075, 7068, Delrin. Is your frame made from welded 2024 by chance? :rolleyes:

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are you running two CIMS or one and a FP? I think you guys said you’d never run the FPs again, is that true?

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Yes!! FP = :ahh:

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Hrrm, I’ve seen this somewhere before. Oh yes, last night when I was holding my breath making sure we didn’t crash the CNC. :smiley: Anyhow, this particular plate has something special that you can’t see. :wink: thank goodness

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Very, very nice.

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Looks very nice,:yikes:

I just have a couple of questions.

How are you guys cutting the teeth?

Whats gonna be the pitch on those aluminum gears?

Those plates are very nice and I bet this gearbox is gonna be supper light.:ahh:

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They will be hobbed.

That gear will be 20 DP. The initial reduction is 32 DP.

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Just out of curiosity, what kind of machinery will it take to hob those gears?

The only experience I have with hobbing is with the half-million dollar CNC hobbing machines they use at GM where I work.

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These will be hobbed on generic hobbing machines whose sole purpose is cutting gear teeth. They are relatively simple machines - purely mechanical.

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This past year, I made a gear hobbing attachment for a generic bridgeport milling machine. So far we have cut type 35 and type 25 aluminum sprockets from 6061 and 7068 as well as cut a few 20 DP and 32 DP gears in both steel and aluminum.

Unlike an indexing method where you cut one tooth at a time and reindex, a hobber spins the gear blank and proceeds to cut all the teeth as they revolve under the cutter.

Sorry, I don’t know how to post pictures, but there are a couple on our website showing the hobbing attachment making a 25 DP cluster sprocket and a type 35 sprocket.

http://www.mckinleyrobotics.org/2007/gallery/week3/images/0120-01.jpg

http://www.mckinleyrobotics.org/2007/gallery/week2/images/0119-02.jpg

http://www.mckinleyrobotics.org/2007/gallery/week2/images/0118-06.jpg

Basically, I put an optical encoder on the spindle of the mill which runs through an adjustable divider circuit which in turn provides step and direction pulses to a servo driver which turns the gear/sprocket blank at the exact speed to cut whatever number of teeth we want. The gear or spocket blank needs to turn at the spindle speed divided by the number of teeth you want to cut. Whats nice about this set up is that I can stop the mill midway, check measurements and start it up again without losing sync.

Unfortunately the pictures do not show the servo drive on the 5c collet spindle. Maybe the next time I set it up we will take some better pictures.

If there is enough interest, I might write up a white paper or something at the end of the season.

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Most definitely!

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Wait a minute, you made your own hob? Please explain, because that would also would be a very worthy white paper too!

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Here’s some video too if people are interested.

http://mckinleyrobotics.org/2007/videos/sprocket/sprocket_med.htm