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Roll Pins & Shear Pins

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petertha

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#1
I'm re-assembling my 14x40 & doing some head scratching.

My lead screw had a steel roll pin in it. According the parts manual, its supposed to be a #3 1" taper pin (material unspecified). My picture is showing a stick of black nylon, not using it, just sizing the hole. Anyway I assume this is supposed to be a shear pin designed to fail before taking out the expensive driveline & a steel roll pin probably is too strong? Should I make one out of say brass? The shaft hole isn't the best job, I really don't even think its tapered, or maybe not any more. Once the pin is installed there is a sleeve that goes over & held with a single set screw. I guess its job is to contain the & make for easy replacemnt. Seems fine to me, remember this point for below.

Now the clutch cup. Here the manual calls for a 5mm steel roll pin (which it has). Its not going to shear because of the clutch spring/ball mechanism is designed to disengage long before that if torque builds up. But the roll pin is a PITA to hammer in & out. OK, somewhat aggravated a bit by tight working quarters, odd angle & the usual non-centered (hand drilled?) hole issue typical of these machines. But this got me thinking - why break out the pin punch kit & all that hammering? Why not drop in a nice fitting steel pin & make a similar low profile sleeve like the clutch? Am I off base?
 

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Ulma Doctor

Infinitely Curious
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#2
Hi petertha,
you certainly can make a crosspin from brass or aluminum to prevent catastrophic failure,
just realize that it may need to be inspected more frequently.

the wonderful thing about having tools and a brain, is that you can do anything you wish to do!!!
if it sounds reasonable and you think it will work, try until it does work!!! :grin:
 

whitmore

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#3
I'm re-assembling my 14x40 & doing some head scratching.

My lead screw had a steel roll pin in it. According the parts manual, its supposed to be a #3 1" taper pin
The "#3 taper pin" only has 1/4" taper per foot, it's possible that you have a reamed hole for a taper
pin that someone 'repaired'. You don't want any slop in that joint, so the taper pin sounds like
a fine choice to me. The pins aren't pricey, but if you need to re-ream the hole, it will cost
for a tool to do that.
 

mikey

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#4
The pin on my Emco Super 11 is made from aluminum. It is soft and feels like the hardware store variety aluminum rod. It should shear before a gear goes, or at least that is the intent.
 
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