18-09-2014 00:15

Adrian Clark

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

18-09-2014 01:23

Akash Rastogi

Re: pic: Gold VexPro sprocket

edited: nevermind, noticed grinding marks.

18-09-2014 01:53

Michael Corsetto

Re: pic: Gold VexPro sprocket

"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...

Good times!

-Mike

18-09-2014 02:35

DampRobot

Re: pic: Gold VexPro sprocket

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?

18-09-2014 08:58

FrankJ

Re: pic: Gold VexPro sprocket

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.

18-09-2014 09:08

JesseK

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?

18-09-2014 11:14

nathannfm

Re: pic: Gold VexPro sprocket

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.

18-09-2014 13:34

Adrian Clark

Re: pic: Gold VexPro sprocket

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

-Adrian

18-09-2014 14:46

JamesCH95

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?

18-09-2014 16:05

nathannfm

Re: pic: Gold VexPro sprocket

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

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.