# Roll Pins & Shear Pins



## petertha (Dec 2, 2017)

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?


----------



## Ulma Doctor (Dec 2, 2017)

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!!!


----------



## whitmore (Dec 2, 2017)

petertha said:


> 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 (Dec 2, 2017)

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.


----------



## petertha (Dec 2, 2017)

I see tapered pins like at McMaster, but typically steel.
https://www.mcmaster.com/#taper-dowel-pins/=1ain0wd

Making one (or 6) sounds like the way to go.


----------

