Yet another iron in the fire...

[BobWarfield]

Yeah, it's the same style brake as the pic you posted. The plans were in the Metalworking Vol 2 book. The pic you posted was finished a lot nicer than the one in the book. We'll see how mine turns out. I'm scaling it up a bit, to 24" instead of 17. This was the picture:



I'm doing the split cotters the way Lautard describes them, with a flange to hold them while you bore, then you turn the flange back off again. So far so good. I'm waiting for some steel to arrive before I can do the broing operation.

You're going to need an English Wheel if you want to make fenders. I'd love to play with one of those. I liked the one that was featured in the magazines recently.

Best,

BW

[Mcgyver]

Thats the one - it was made by Gary Hart who posts at the hsm board. he did a beautiful job of it, makes it compelling to have a go at it.

most times with the cotters, I thread the cotter, then use a piece of ready-rod and a nut to hold it in place tight against the bottom of its hole while the intersecting hole is drilled/reamed. face a bit of the cottered end for clearance, then face the cotter to length - same idea as what you described, but saves having to turn the shoulder

[Geof]

Originally Posted by BobWarfield .....I'm doing the split cotters.....

Originally Posted by Mcgyver .....most times with the cotters.....

Excuse the butting in question but you both used the word 'cotter'; what's a cotter? The context in which you use the word and the description for making it does not jibe with my understanding of the word.

[philbur]

A cotter pin looks like this.

Originally Posted by Geof Excuse the butting in question but you both used the word 'cotter'; what's a cotter? The context in which you use the word and the description for making it does not jibe with my understanding of the word.

[Mcgyver]

Geof, yeah like Phils pic. here's two i did recently, one on the shaft holding the tooth rest and the other the shaft holding the drill stop. I'm betting someone of your experience has seen/made dozens of these before? i've only ever known them as cotters from plans and books from both here and England, don't know if they're called anything else.

[Geof]

Thank you to philbur and Mcgyver and apologies to Bob for the hijack. I hope you find it worth reading.

Cotter Pins; an overview by Geof

The first picture shows my technicolor rendition of what I was taught is a cotter pin some 50 years ago; a round shaft with a smaller diameter thread on the end and a flat going from the thread diameter to the shaft diameter. My bicycle had cotter pins holding the pedal crank onto the pedal shaft which had a flat for the flat on the cotter pin.

I went Googling and found this: titled "semcycle cranks and cotter pins"

The nut is just to retain the cotter pin and does not add extra tension to it. To tighten a cotter pin, the pin should be tapped with a small hammer from the opposite side to the retainer nut. The nut should then be tightened (taking up the slack). Then tap the pin in again and tighten the nut, Repeat until the pin can no longer be tightened.

I could not find any pictures but you can see that this description matches my pretty picture. The source was this; http://www.unicycling.org/unicycling...mail/2354.html and the 'hypermail' threw me until I noticed the date; Wed, 13 Sep 1995 17:43:27 +0100 (BST) and the poster was in Cambridge, UK.

So obviously my senile old memory is not so senile after all; this is what I considered to be a cotter pin prior to arriving in Canada. My Googling also turned up what I discovered was a cotter pin in Canada which is the second picture. For obvious reasons I call this a split pin.

Now you guys have really thrown me into a loop. I am very familiar with your 'cotter pin', actually I should say a version of it shown in the third picture. We make these and use them for clamping aluminum fittings we make onto 7/8"stainless steel tube in a manner that gives a grip of about 40lb-ft torque, which will slip when overloaded but will not mar the tube; our name for them is Pinch Clamp (I know, not at all original, sorry). I based this design on the clamps used to hold round toolholders in the turret toolpost on Herbert Turret Lathes. I am sure the Herbert manuals did not use the name cotter pin for these clamps but I cannot check because I tossed them all out five years ago.

Incidentally Mcgyver you would win the bet and then some. My Pinch Clamp was designed and first made in 1986. To date I guess we have made around 100,000 and our current production rate is about 10,000 a year.

PS: My memory tells me somewhere I read that cotter pins, the bicycle version, where derived from steam engines with the cotter pin being used to secure the cotter arm to the cotter shaft with this assembly something to do with the steam valve on the cylinder; specifically the mechanism used to alter the point of cut-off. Google let me down on this one.

[Mcgyver]

well i would have been surprised if it was a new one on you....pic # 2 is what i would call a cotter pin, pic three a cotter or split cotter (no pin), although you've refreshed my memory with pic 1, also what i'd call a cotter or wedge. I've seen the term on plans and in books from both England and NA, perhaps the term is incorrectly being applied, but what the heck if everyone is doing it. as often as not, to streamline production, I'll just go with a half cotter, half of what's shown in pic 3, it would have to be half a split pin by your parlance

I can't remember a specific part of a valve gear called a cotter, but that isn't saying much - there are lots of valve gear types and I'm not a expert. on multi cylinder engines there are definitely places like the where the cranks or lifts mount to the reversing shaft that could use wedge cotters (often tapers on models) and that would put a cotter as part of cut off mechanism - these would be high stressed areas like a bike crank - but for all i know cotter shaft is another name for reversing shaft. some of the big ends on the connecting rods had square holes with bearings secured by wedges - these may well also be call cotters