Bolt threading on Challange Gordon
I need to make a replacement platen bolt for a 10x15 Challenge Gordon. While I have the dimensions from an original a nagging inner voice says “Are those Whitworth threads?” Shouldn’t be, but… (about the only difference is thread angle, 60 vs 55 degrees.) Anyone have a good word for this?
Unfortunately, I don’t have a bolt in hand to check; it’s 25 miles away in the press.
I used to have a 8x12 Challenge Gordon with a broken impression bolt, and back in the ’80s, a retired machinist made a replacement. And at a certain depth going in, it would bind up, so I had to adjust the good bolts to match this new bolt. I always thought he had got the pitch slightly off, but your suspicion of Whitworth threads is a real possibility.
I have a Gally Universal Parallel platen press from the 1870’s. I found that the threads are off by one from the standard of today.
1/2-14 tpi instead of 1/2-13, and 5/8-12 tpi instead of 5/8-11. Fortunately, taps and dies for just about any thread are readily available.
Right, what was once a common thread (before the auto) is now designated National-Special. Even so, any mis-matched thread pitch would not go in two revolutions before binding. My replacement bolt went MOST of the way before binding, so thread angle sounds possible to me.
I did check the thread pitch with a thread gauge and have some modern nuts that freely turn on an original bolt, so I’m confident on that part.
The only real question is the angle. If I can’t get an accurate measurement, maybe I’ll have them done at 55 deg since that should turn into a 60 deg opening.
A 60 degree center gauge is inexpensive and would help determine the angle. You could probably find it or a 55 degree version on eBay.
centergauge.jpg
Food for though, I have a 8x12 new style, low series number of 50100 (or there about..going by my weak memory) I needed some bolts but they were 1/2 12 not 14. I got them from a donor press. Bud
At the pioneer village where I volunteer we have a press which is probably either a 7X11 “Clipper” made in Palmyra NY, or a Canadian knock-off of one (since it is in Canada). I needed some 1/2-12 bolts for that and got some Whitworth bolts from England, but as you said, the bolts only go in so far before binding. Those bolts were to bolt the bracket which holds the ink disc, to the press. Luckily, they went in far enough to hold the bracket OK.
The following is probably overkill, but there are companies out there like this:
https://westportcorp.com/pages/custom-made-taps-dies
which I just found on the internet. I know nothing more about them. I don’t know but maybe if you sent them the bolt they could make you a die so you could make your bolt or have a machinist make it for you. Under their “Popular special taps and dies (inches)” section they might even have it already made. Since they are specialists I would think they would get it right.
Another thought is maybe you could have one 3D printed. I don’t know how strong that would be but if you could try it and make sure it was right, then you could have one machined to the same specs.
I’m sure a 3-d printed wouldn’t last ten impressions even if it was printed metal.
For my need, a friend offered to cut a couple of the replacements on a lathe, so any thread angle or TPI is possible :D. Cost is something like the 12” of hex steel bar (<$15) and a six pack.
And yes, some older machine bolts are just whacky threads; my Kelsey has a few (IIRC 1/2”x14 where x13 is modern standard). Always measure.
The simple fact is that truly standard thread sizes weren’t developed until after WWII (Unified Thread Standard was adopted in 1949). Unified threads were based on designs going back to the 1860s, but there were changes over the years so a modern UTS bolt won’t necessarily fit in something made to William Sellers’ original specs, even though that’s what UTS was based on. Plus, there were dozens of competing “standards”, different tolerance requrements over the years, random in-house thread designs, and just general screwing chaos. For anything older than about mid-20th-century, you’re probably going to have to custom manufacture the parts. If you wind up doing much of this kind of thing, you’ll probably be best served buying a small lathe and learning how to do single-point threading yourself.
—
Michael Hurley
Titivilus Press
Memphis, TN
If I need a bolt with an ancient way back when thread, I go to my local heritage steam railway, not only do they understand this sort of thing,( have to for safety reasons but can actually re-create what \I need, they have the knowhow and a big lathe to make it. Nice guys too and some know about Edmondsons tickets, and he was a compositor originally!.
Making the bolt isn’t much of a problem. As I’ve mentioned, I have access to people who will do the work and a fairly-well equipped shop. (I’m a member of a steam hobbyist group, we have lathes from maybe 18” bed to almost 18’ bed :).)
z!
Just for the record :)
A piece of raw stock and the finished replacement. I won’t be able to actually try it before mid-next-week.
z!
replacement-bolt.jpg
that’s a nice looking bolt there
Oh, ya- it fit perfectly. Platen is level to a couple of thousandths and I’ll recheck it in a few weeks before we run anything.
a quick background which may be of interest to some
www.printaction.com/the-importance-of-uniform-world-standards/
Some historical background, which may be of interest to some
www.printaction.com/the-importance-of-uniform-world-standards/