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Unread 24-06-2002, 00:04
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#0047 (ChiefDelphi)
 
Join Date: May 2001
Location: Pontiac, MI
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A very reliable method - trade secret?

Posted by Raul at 2/2/2001 9:06 PM EST


Engineer on team #111, Wildstang, from Rolling Meadows & Wheeling HS and Motorola.


In Reply to: Connecting hub sprockets to shafts
Posted by Patrick Dingle on 2/2/2001 7:17 PM EST:



I once considered what I am about to tell you somewhat of a trade secret. Considering that there may be others out there that have used this technique and because I feel bad hearing that so many people are having problems with keying hubs to shafts, I will tell you the best way to "key" a shaft to a hub that does not require a keyway:

It is called a "dutchman" key. You simply drill a hole through the shaft off-center such that it is tangent at the inner interface of the shaft and hub. Then press a dowel pin in the hole.

So why is this so much more reliable than just drilling a hole through the center? Because it is almost impossible to shear the pin. The failure mode is to compress the metal to the point that is has a little freeplay, but it will not break and will not come loose. The hub will crack from the pressure before you will get the pin to disintegrate. But that requires more force than you could possibly produce unless you use a shaft hub that is really small.

BTW, we only use this method on motor shafts or really tight spaces because we have better methods when we can just machine our own shafts. I won't tell you this one right now - just come see our bot at our pits and I will explain.

Raul



: Does anyone know the most reliable way to connect a hub sprocket to a rotating shaft (no keyway)? We are planning to drill and tap the hub, and bolt slightly into the shaft. Is this reliable, or are there better ways?

: Thanks
: Patrick


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