Cornerstone versus Challenge Hi-speed Quoins

The standard Cornerstone quoins use a square key (the same as a “1” Wickersham quoin). Despite their being made from “Duralumin”, I wouldn’t think they are as durable as a steel quoin; the screws tend to strip out the threads of the wedge when over-tightened. They should be fine for a tabletop press though, especially the “midget” variety (you could also use the smaller “0” Wickershams).
Challenge Hi-speed quoins, in the appropriate lengths, would also work fine, and are still made. Used quoins are easily found too, though the short lengths are sometimes priced higher because of demand. Key has unique five-point spline.

I’ve just edited my post because I incorrectly assumed you were in the UK when you referred to Cornerstone Quoins; but your post is timely because I was thinking about the pros and cons of Cornerstones and Challenge hi-speed only yesterday and wanted to field a similar question:

I’ve always used Cornerstone quoins and spring-loaded Harrild quoins here in the UK but have recently got hold of some Challenge hi-speed quoins. Whereas the former have a smooth expansion action, the Challenge quoins are obviously ratcheted, expanding notch by notch as you turn the key. Can you leave the quoin tightened at mid-notch or is it likely to slip?

The clicks in the Hi-speed quoin are from an internal spring. Each click is one point expansion. I doubt that a mid-click setting will make any difference to lockup; it’s only a half-point, even if it were to slip. The Hi-speed quoins also work without the springs (they break, best to remove the pieces), haven’t had one loosen on me.
Similar to the Cornerstone quoins are the Notting and the Hancock quoins, using the same key and having a similar wedge design. These are all steel; the Nottings are my favorite quoins. There’s also the Tru-forme, make of a light metal more like the Cornerstones. Never saw a Harriild quoin—does it have a wedge, or a cam like the Wickersham?
Cornerstone procucts weren’t unheard of here in the US. They were imported by American Printing Equipment.

Right, that’s all useful information - thanks.

It looks like a cam mechanism on the Harrild - overtighten and it springs shut…

IMG_4283.jpg

I would appear the Harrild follows the Wickersham design.

Short of a LOT of use, there’s no reason to have quoins wear out, especially the little ones. I’ve always felt that the most pressure on the quoin key should be that you can apply with just your thumb and forefinger, and this for quoins up to 6” Hi-Speeds. More than that leave you wrecking the key (on Hi-Speeds), stripping threads on Cornerstones or having the quoin bulge out and eventuall crack into two (Wickersham/Harrild). Maybe a couple more quoins or a tighter lockup would serve better.

New Hi-Speed style quoins are over $50 each (!)

Thanks for your collective help!