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mill pins


Paul Amey

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Posted (edited)

I should chuck it after three and hope they don't throw it back!  But none the less James Paddock refers to a roll pin as a mills pin. Can you use split pins is my question?

Edited by Paul Amey
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Thank you, Paul, I didn't know that a "Mills pin" was a thing!   I find from an old post on the TRR board that "A "Mills pin" is a solid tapered pin so you need to tap it out from the tapered end with a small drift.. A roll pin is slit down the side to compress slightly when tapped in to hold in place. These can be tapped out from either end with a small drift and then compressed with a pair of pliers to withdraw the rest of the way."   Thank you, "Stuart"!

So my apologies, Paul, for the mock!   A split pin is intentionally soft, so I'd use a pin.

John

 

Edited by JohnD
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there are a good few rocker shaft end caps held on with split pins   probably used a lot on early   and roll pin was a mod introduced at some time .

there is little wear it does hold the end cap on cant see a split pin failing here .

Pete

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Surely a split pin would let the oil leak out of the end caps where it’s all needed at the rockers

A roll pin fills the hole out and leakage would be miniminal 

The last rocker shaft I brought a couple of years ago had end caps that were an interference fit really damned hard to get on

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Posted (edited)

Thank you chaps, don't worry about the humour, all taken is good stead! Opinions on both sides there, so I still don't know for sure. I can say the end caps needed a fair tug to get off though. So, I suppose my next question would be is a roll pin as good as a mills pin? 

Edited by Paul Amey
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8 hours ago, Peter Truman said:

The last rocker shaft I brought a couple of years ago had end caps that were an interference fit really damned hard to get on

The last one I bought a few years ago had internal fixed end caps. I hoped there wasn't any crap left in there. All the rockers were dripping oil from their holes when fitted. Had the cover off the other day and no oil dripping from the top holes on front rockers 1-10, apart from no 2 (so assume has oil pressure along the full length?). Oil drippling from the bottom of all but one of the rockers and pooling around the pushrod holes. Maybe some crap has been pushed along to the front the shaft by the oil and blocking oil access at the top off the further along rocker top holes? ?.

I understand some of rockers didn't have the top holes anyway, and I cant be bothered worrying about it!

Edited by daverclasper
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Historical Note:- ( or perhaps Hysterical?)

The solid Tapered pins, John refered to, where in frequent use in factory machinery in the past. In order to get the correct fit the holes where reamed with a tapered reamer, the pin driven in for an interferance fit and frequently peened on the small end to prevent them coming loose. The method was a hammer (large) on the larger end and a small ball peen hammer used (ball) to "mushroom" the small end. Also fitted as "sheer" pins, when removal, post failure, meant aligning the shaft/wheel/cog/cam whatever before the old broken pin could be removed and a new one inserted. Somewhat tricky laid on one`s back halfway into a machine.

It`s too cold/wet/dark to go check , but I think I still have some smaller one`s and the taper reamers somewhere in the dim receses of my garage?.

Pete.

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I have a variety of old rivet stems that I use to drive them out; always plenty lying about of different sizes.

I nipped out to check just now; all my Herald rockers are roll pins, I have two 6-cylinder rocker shafts, one is roll pin and one split pin, but no idea of the age of either to try to pin them to any model. 

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