Witchcraft! ak.a know as quadralell.

[NeoTech]

I found this kinda nifty and seem to be simple enough to recreate.. =)

[awemawson]

That looks identical to a printers 'Quoin' used to clamp type letters in a printing frame.

[Pete W.]

That looks identical to a printers 'Quoin' used to clamp type letters in a printing frame.

If you'd asked me what a 'quoin' is, I'd have said it's a tapered house brick.  Or am I getting mixed-up with a 'squint quoin', a house brick with a skew end?

[flutedchamber]

I do the same thing with two sections of large diameter spur gear about an inch thick.

[awemawson]

A "Quoin" is a wedge, so the keystone in an arch is a quoin. In printing it is an expandable wedge used to hold the type in place

[NeoTech]

A "Quoin" is a wedge, so the keystone in an arch is a quoin. In printing it is an expandable wedge used to hold the type in place

Dont really seem to work same way. This got a ballbearing making two plates swivel against each other taking out odd angles when clamping. Not expandable at all actually.

[awemawson]

When I had my Adana 10x5 printing press the quoins were just as you describe pivoting on a ball but with the screw acting on the ball to tighten up. There were two dowel pins fixed in one half, and very loose in the other to allow a lot of out of parallel motion

Andrew

[NeoTech]

Ah ok..  Then i misunderstood your little picture there.. Well it seems like a valid way of clamping odd parts like.. car parts  and such that in some cases isnt always straight. =)

[AussieJimG]

I think that's just what I need for a task I am trying to do.

Thanks

Jim

[Meldonmech]

What is the maximum acute angle you can achieve?  Looks like a useful clamp.

                                                                             Cheers David

[rotorhead]

Hi Folks,

The quoin was originally used I believe, as a cannon gunners elevation piece, it was situated under the breech to aid rise and fall for a better aim.

I may be wrong again, but hey whatever.

[markball2]

Ok, I give.  How does a feller make the recess for that ball bearing?  The rest is fairly easy machining.

I have a project in mind & have been struggling with the work holding.  I think something like this will work pretty slick.

[awemawson]

Ball ended end mill, or form cutter

Andrew

[RussellT]

I wouldn't have thought it needs to be curved - a countersink type dimple ought to work just as well.

Russell

[Fergus OMore]

Actually it is a corruption of 'Coin' a French word for nothing odder than a  Corner. It gets hacked about  because none of us could spell or read or write but saying that- the French or most of them -- couldn't speak French anyway.

C'est vrai.

[mattinker]

Norm,

"Coin" not only means corner, but it means wedge. Funny, I can speak and read French and the French I'm surrounded by seem to be able to speak it quite well, they can even write it, which I can't!

Ça, c'est vrai!

[Fergus OMore]

Actually wedging is coincage( apologies for the lack of the c cedille) from the verb 'coincer' to wedge.

[mattinker]

Norm,

I didn't give your the etymology, the French for wedge is a coin, " n. m. instrument de forme prismatique (en bois, en métal) pour fondre des matériaux, serrer et assujettir certain choses." 

In this case, the coin refers to the object and not it's action!

Eh beh, "je te bouche un coin la mon pote"!

A plus, Matthew