Chief Delphi - pic: Gold VexPro sprocket

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- - pic: Gold VexPro sprocket (http://www.chiefdelphi.com/forums/showthread.php?t=130572)

nathannfm

17-09-2014 23:59

pic: Gold VexPro sprocket

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Adrian Clark

18-09-2014 00:15

Re: pic: Gold VexPro sprocket

This reminds me of 2013. We used a press fit dead axle wheel assembly. To make assembly easier I put the shaft in a freezer and the sprockets on a hot plate, the sprockets would either get slightly lighter or turn a quite off putting green color.

It's worth noting that for aluminum to turn the color your sprocket did it needs to be heated to almost 2000F. Annealing aluminum on the other hand is done below 1000F. Just something to be aware of.

-Adrian

Akash Rastogi

18-09-2014 01:23

Re: pic: Gold VexPro sprocket

edited: nevermind, noticed grinding marks.

Michael Corsetto

18-09-2014 01:53

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by Adrian Clark (Post 1400457)

This reminds me of 2013. We used a press fit dead axle wheel assembly. To make assembly easier I put the shaft in a freezer and the sprockets on a hot plate, the sprockets would either get slightly lighter or turn a quite off putting green color.

"Easier" is one way to put it. I seem to remember you quickly putting two sprockets, a wheel, and the shaft in alignment, pouring on some green loctite, and hanging off a 5 ton arbor press in order to press the assembly together. With about a 50% success rate... :p

Good times!

-Mike

DampRobot

18-09-2014 02:35

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by Adrian Clark (Post 1400457)

It's worth noting that for aluminum to turn the color your sprocket did it needs to be heated to almost 2000F. Annealing aluminum on the other hand is done below 1000F. Just something to be aware of.

-Adrian

Is this because the chemical structure of the dye used in the ano changes at high temperatures, or because some kind of thin film interference varies due to head expansion between two layers?

FrankJ

18-09-2014 08:58

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by Adrian Clark (Post 1400457)

...
It's worth noting that for aluminum to turn the color your sprocket did it needs to be heated to almost 2000F. Annealing aluminum on the other hand is done below 1000F. Just something to be aware of.
-Adrian

At 2000 F your aluminum has turned into a puddle & no longer looks like a sprocket. Maybe even so at 1000F depending on the alloy. Anyway 1000 will have killed any age hardening. :]

JesseK

18-09-2014 09:08

Re: pic: Gold VexPro sprocket

I'm curious how you got the sprocket to hold its shape as the weld cooled - or was it a non-issue?

nathannfm

18-09-2014 11:14

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by JesseK (Post 1400480)

I'm curious how you got the sprocket to hold its shape as the weld cooled - or was it a non-issue?

I was not personally around for the welding but I don't believe they did anything special, nor did we instruct them to, and there is no warpage.

Adrian Clark

18-09-2014 13:34

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by FrankJ (Post 1400479)

At 2000 F your aluminum has turned into a puddle & no longer looks like a sprocket. Maybe even so at 1000F depending on the alloy. Anyway 1000 will have killed any age hardening. :]

Good catch, thanks! I got my metals mixed up, aluminum melts at ~1200F so disregard my previous comment.

-Adrian

JamesCH95

18-09-2014 14:46

Re: pic: Gold VexPro sprocket

Let us know how it holds up now that you've removed most, if not all, of the heat treatment!

Was this a 6061 or 7075 sprocket?

nathannfm

18-09-2014 16:05

Re: pic: Gold VexPro sprocket

Quote:

Originally Posted by JamesCH95 (Post 1400544)

Was this a 6061 or 7075 sprocket?

It is a #25 plate sprocket, VexPro specifies that they are originally 6061-T6 AL

Quote:

Originally Posted by JamesCH95 (Post 1400544)

Let us know how it holds up now that you've removed most, if not all, of the heat treatment!

I doubt we will see any wear as it is a prototype in an extremely low rpm application, but if something interesting happens I'll post it.

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