1/2" BSW Split Die failure - Insufficient meat on the 1" O/D

Hi - I have just suffered a breakage of a 1/2" BSW split die when adjusting the centre screw to back off the cut which on reflection I think was due to the fact that the die had been manufactured with a 1" O/D resulting in an inherently weak design. Surely a die of this size should have been made on the next size up in the O/D series e.g. 1 and 5/16" to give the necessary meat around the periphery. There is no evidence of the name of the manufacturer on the die and so have had to put the whole thing down to experience. Thought it might be of some interest and perhaps a warning to other users.

I have had the same thing with a 12mm metric in 1" od ! Just not enough meat to allow for the stress of adjusting. You lear by your mistakes, as I did, and use a larger OD ! Noel.

Perhaps the holder was too loose through wear and tear or not being made to a good tolerance originally. I have some that are not steel and look like they could break if pushed too hard.

Martin C

Perhaps re-measure the die; I'm not doubting your die stock might be 1", but some of the imported dies are actually 25mm, and hence a loose unsupported fit in a 1" holder.

Bill

It's a trade-off:

the strength of the weak-section vs the force needed to open/close the die.

(Bit past the theory at my age but iirc the strength is proportional to area, the force needed is non-linear - cube-law seems to ring a bell)

Edited By Peter Greene on 21/11/2021 01:35:43

I've got one of those double split dies too.

Inclined to agree with peak4 that its a diestock issue. Some of the affordable ones are "less than precise". It was an inexpensive alloy one that did for mine. Bought in a 3 size set from a proper engineering tool shop too back in the mid 1970s so it wasn't a hopeless big box store or DIY house cheapy crappy. But with 20/20 hindsight and years of experience the fit isn't really good enough for large threads in small dies.

Identical die has worked fine in my tailstock die holder for many years. But the machined holder is a noticiably more precise fit. Probably doesn't hurt that the tailstock holder presents the die to the job in much better and more stable alignment than a hand die stock does. Coarse threads tend to rock as they cut the first thread due to the unbalanced load so you have to apply force to prevent that. Which probably isn't very kind to the die. Especially if its gone over a touch and needs pulling back on line.

Clive

I feel that putting a 1/2 Whit thread in a 1” die is pushing things a bit, it is a fairly coarse thread which will require a fair amount of torque applied to cut. A larger OD for the die will require a larger stock which will have longer handles and make the job easier. I wonder whether putting large threads in a small die means they should only really be used for cleaning up threads rather than cutting a thread from scratch. Dormer put a thread of that size in a 1 5/16” or 1 1/2” die, Tracy list a 1/2” Whit die in a 1”, 1 5/16” or 1 1/2” OD die. I think I would not go smaller than 1 5/16” as this is a much meatier item than the 1”, the dies also get thicker as the OD increases.

Mike

Edited By Mike Poole on 21/11/2021 11:17:44

It has to be said that if the manufacturer didn’t put there name on it they had the perfect get out clause!!

No name?

Ashamed of producing such rubbish and don't want to put their name to it.

I'm always wary of nameless goods.

Brings to mind really crappy toys marked "Empire made" (probably Hong Kong) when I was a kid. Other junk marked "Foreign". Short term gain giving the culprits a bad reputation. Not good.

Hi, I think that Empire made and Foreign were both for political reasons rather than rubbish stuff. I've got quite a few tools that were my father's with Foreign on them and all though they are not high end, they are certainly not rubbish. The old company that I work for sold some of their products to certain foreign countries in either plain brown or plain white paper sacks and the only thing printed on them was a batch number that the baggers had to stamp onto them, and this was purely due to politics, the quality was exactly the same as any other customer had.

Regards Nick.

And named goods too. All too often reassuringly expensive household names are used to separate naive buyers from their money.

The awful truth is brand-names guarantee nothing. Neither does country of origin. Apart from fakes and seconds escaping into the market, brand value depends entirely on whatever the owner decides, and ownership changes in complicated ways.

For example, RCA was a much respected US Brand. However, it's been through difficult times. It was formed in 1919 as a patent trust between GE, Westinghouse, AT&T and the United Fruit Company. RCA became an independent company after being prosecuted under anti-trust laws by the US government, after which embarrassment they were hugely successful until 1970, when competition proved too much.

It was bought by GE, which by this time had become a US based multinational, and they managed the decline until selling the trademarks to Technicolor SA in 1982. Technicolor SA was a rebranding of Thomson SA which was a French based multinational with ownership roots back to the UK's GEC and Marconi as well as French firms.

At one point the RCA trademarks were owned by Britain's Carlton Television, part of the Carlton Group, now ITV plc, but they went back to Thomson who resold them to TLC in 2004. No-one's ever heard of TLC, but they're the largest manufacturer of televisions in the world, plus a lot of other stuff from mobile phones to washing machines. TLC is Chinese, and their various outputs are sold with whatever brand-name makes purchasers happy.

Point is, manufacturing isn't simple. The Radio Corporation of America has been American, French, British, multi-national and Chinese. Not unusual. It's family firms paying master craftsmen to produce quality goods with a trustworthy trade-name who are few on the ground. They've been replaced by a mesh of multinational financial arrangements where companies and brands move between different owners. Multinational products are made wherever in the world happens to be most profitable. Consumers rarely know who owns brands, where stuff is made, or exactly what the brand represents.

In 1940 buying an RCA radio was a no-brainer - they were well-made and good value. Buying one in 1980 was risky; by this time they were over-priced compared with the competition and as they went into decline late models were too cheaply made. Today the RCA brand could be resurrected at any quality level the owners wanted to. The brand could be exploited to sell rubbish or to badge top of the range goods.

When buying, it can't be assumed that brand-names are still meaningful. You have to check standards have been maintained. Often all is well because trusted brands are valuable, but there's no guarantee. Anything can happen when companies change hands. Caveat emptor!

Dave

Plus one for that Nicholas I think it was for non commonwealth goods.

Probably was not enough room for the maker's name

I'm also wondering whey the die needed opening up to back it out, either blunt or the two side screws were not tight when the thread was cut allowing it to spring and then be tight on the work.

Thats an interesting comment Jason. It would be interesting to ask if the die broke when adjusting or when backing off the job. If the side screws were not tight then any ingress of swarf when reversing the die from the job could exert far more pressure on the die than the adjusting screw.

regards Martin

I am afraid that I cannot offer any clarification on the circumstance under which the failed as the event took place some weeks/months ago and I only discovered the broken die wheh I came to re-use the die holder and the die fell out in two pieces! Have now ordered a replacement itwm having a 1 5/16" O/D which should prevent any further problems.

SOD, I remember that during the 1980’s RCA (Radio Corporation of America) were contractors at what was Fylingdales the early warning radar station in Yorkshire. Dave W

After decades of stationary engine restoration ,recently I decided to get a new set of whit taps and dies, only snag was the outside diameter of the dies,the 1/2 inch die was the similar in size to the broken one,so will only fit in a smalldieholder when a lot larger dieholder is required to as it requires a good force to thread 1/2 inch whit, so the small o/dia dies get used in tailstock die die holders, The set was not cheap and the first time I used one of the taps it shattered,this was replaced by the supplier. Stationary engines and steam work also require a good range of BSP taps and dies ,and I usually buy individually if I need a new die now I enquire first about the o/dia before purchase. I have had for a long time ,a WDept set of 1/2 to 1inch whit taps and dies English made of course,each die has its own sub holder which then fits into a very large die holder,this allows the dies to be adjusted to size and and the size is held by the sub holder.The tap wrench is a superb sliding block type in polished steel and still rust free, carbon steel which cuts as good as modern hss ,probably cost a lot of money even in 1939 .

I'm sure I remember reading that "Foreign" was used on German products between the wars as British customers could be reluctant to buy "Made in Germany".

Brian G

Foreign was definitely marked on items that came from japan at least in the 50s but seemed to change when the dinky transistors came out and had (Made in Japan) on the back.

Have suffered one or two broken dies, mainly due to overtighting the centre grubscrew to expand it.

But, 1/2 BSW in a 1" die leaves little metal to take the load.

With a thin wall like that, probably pays to treat it like a Tap and back off every half turn, to break the swarf.

Howard