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Gremmy

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I’ve recently acquired a very large set of taps and dies. Plug taps, taper taps all sizes.
In - metric, BSW, BSF, BSP, UNF, UNC.
I’m set for life essentially.

I’m just getting into renovating old woodworking equipment, and seem to need a good supply of BSW/F bolts at present.
They are actually quite expensive per unit to buy off shelf, unless in quantity.

Are there such a thing as bolt blanks - whereby I can cut my own threads of my choosing on stock blank bolts? So if I needed a different thread I could do it myself rather than buying off the shelf?

Google shows a few companies with stock lists, but no prices.
Before I investigate further by emailing those companies, does anyone here do this? Or are there obvious reasons why not to?

Your thoughts would be welcome.

Best.
 

Jelly

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I don't believe that this is a thing (certainly it's not common), as bolts will be heat-treated post machining to achieve their specified strength characteristics, and are generally rolled rather than cut (which means that blanks from bolt production are not suitable for cutting threads into).

The closest you would get is buying lengths of hot-rolled hex bar, but because the BSW/BSF head sizes don't meet up with the standard sizes of either fractional inch or metric stock, you'd still need to machine a little bit off the heads.

Best option would be to buy a couple of sizes of cold-rolled bar in EN8 or EN19, and a hexagon collet-block, then you can turn blanks and mill the heads as required. If you were looking at higher stress applications hot-rolled bar would be better, but you would want to use a propane or oxy-acetylene torch (or dedicated oven) to heat-treat and anneal to reach the correct characterisics.



On a point of curiosity, when you say "all sizes" how far up the range does your tap & die collection go? Mine tops out at about BSW 1¾" (which is also my biggest spanner), which is frankly ludicrous to actually cut by hand.
 
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Cheshirechappie

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Over the last three decades or so, I've done a lot of restoration work on vintage equipment, mostly on a heritage railway. From that experience, I would suggest either accepting the cost of buying in finished fasteners as you need them, or machining them from bar stock as Jelly suggested - though I would suggest that for woodworking machinery, free-cutting mild steel would be adequate stock bar - I doubt most old wood machines used high-tensile bolts. More likely to use larger diameter mild steel, or if old enough, even wrought iron.

Using BSW dies is OK for finishing a thread roughed out by screwcutting, but it's not a great way to cut threads from round bar - the BSW threadform is so coarse that the effort required to cut a thread is excessive. There's also the challenge of starting the die such that the resulting thread is square to the bar, and not 'drunken'. Tapping steel with BSW threads is bad enough - use plenty of threading compound or heavy cutting oil!

Best keep the dies for cleaning up rusted threads on existing bolts, and replace worn or damaged bolts with either new bought-in examples or new bolts machined in-house from barstock.
 

kenledger

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I don't believe that this is a thing (certainly it's not common), as bolts will be heat-treated post machining to achieve their specified strength characteristics, and are generally rolled rather than cut (which means that blanks from bolt production are not suitable for cutting threads into).

The closest you would get is buying lengths of hot-rolled hex bar, but because the BSW/BSF head sizes don't meet up with the standard sizes of either fractional inch or metric stock, you'd still need to machine a little bit off the heads.

Best option would be to buy a couple of sizes of cold-rolled bar in EN8 or EN19, and a hexagon collet-block, then you can turn blanks and mill the heads as required. If you were looking at higher stress applications hot-rolled bar would be better, but you would want to use a propane or oxy-acetylene torch (or dedicated oven) to heat-treat and anneal to reach the correct characterisics.



On a point of curiosity, when you say "all sizes" how far up the range does your tap & die collection go? Mine tops out at about BSW 1¾" (which is also my biggest spanner), which is frankly ludicrous to actually cut by hand.

I used to steel melting furnaces, the inductors that hung off them had aligning pins, 2in diameter, We used 6ft long scaffold pipes each side to tap the hole. That was the biggest tap i have ever seen lol
 

Gremmy

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I don't believe that this is a thing (certainly it's not common), as bolts will be heat-treated post machining to achieve their specified strength characteristics, and are generally rolled rather than cut (which means that blanks from bolt production are not suitable for cutting threads into).

The closest you would get is buying lengths of hot-rolled hex bar, but because the BSW/BSF head sizes don't meet up with the standard sizes of either fractional inch or metric stock, you'd still need to machine a little bit off the heads.

Best option would be to buy a couple of sizes of cold-rolled bar in EN8 or EN19, and a hexagon collet-block, then you can turn blanks and mill the heads as required. If you were looking at higher stress applications hot-rolled bar would be better, but you would want to use a propane or oxy-acetylene torch (or dedicated oven) to heat-treat and anneal to reach the correct characterisics.



On a point of curiosity, when you say "all sizes" how far up the range does your tap & die collection go? Mine tops out at about BSW 1¾" (which is also my biggest spanner), which is frankly ludicrous to actually cut by hand.
Many thanks for your response Jelly, I think I’ve tried to be a bit too clever with an idea without thinking it through fully..!
The Huge set of taps and dies was actually free from a friends fathers estate, so I was probably subconsciously trying to create a use for them.

Heat treating wouldn’t be a problem, but it would start to add up time wise against buying off the shelf.
I think I was particularly frustrated when I needed some 3/8th bolt and the week wait of time from the supplier got the creative cogs thinking.

The largest I’ve got in my set is 1” BSW. Never say never, but I doubt I’ll ever use it!
 

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Gremmy

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Over the last three decades or so, I've done a lot of restoration work on vintage equipment, mostly on a heritage railway. From that experience, I would suggest either accepting the cost of buying in finished fasteners as you need them, or machining them from bar stock as Jelly suggested - though I would suggest that for woodworking machinery, free-cutting mild steel would be adequate stock bar - I doubt most old wood machines used high-tensile bolts. More likely to use larger diameter mild steel, or if old enough, even wrought iron.

Using BSW dies is OK for finishing a thread roughed out by screwcutting, but it's not a great way to cut threads from round bar - the BSW threadform is so coarse that the effort required to cut a thread is excessive. There's also the challenge of starting the die such that the resulting thread is square to the bar, and not 'drunken'. Tapping steel with BSW threads is bad enough - use plenty of threading compound or heavy cutting oil!

Best keep the dies for cleaning up rusted threads on existing bolts, and replace worn or damaged bolts with either new bought-in examples or new bolts machined in-house from barstock.
Hi Cheshirechappie,

Many thanks for your response also. As I put in my reply to Jelly, I don’t think I’d thought through things enough.
“If” blanks in mild steel were available and then aligning the thread correctly, ensuring it wasn’t drunken, adding in heat treating it adds up massively in time and I’d be better off buying off shelf.

I must have been having a bit of moment!
Machining from bar stock could be an option going forward, I’ve got a lathe fund on the go, the wife does not know about it 😉

Thanks for your time.
 

AES

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+1 for the comments above Gremmy.

Personally I've never heard of "bolt blanks" being available off the shelf. "Maybe" a good idea for some enterprising business to get into - perhaps.

But as already been pointed out, particularly with coarse threads like BSW and BSG, as soon as you get above about three quarter inch OD, the amount of torque needed to cut threads (both male and female) is huge - I can well believe the tale above about using a length of scaffold tube as a tommy bar!

And as has also been pointed out, to get a big-ish coarse thread to start square so that you end up with a decent thread and not a drunken jobby is, IME, VERY difficult and often takes several goes - or a much shorter bolt than was originally planned (DAMHIKT)!

I'd also echo the above comments for keeping the above taps & dies for use as just "chasers" - e.g. for recovering damaged fasteners - you'll probably only use one or two sizes during your whole lifetime, but what a life-saver when you need it.
 

Gremmy

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Hi AES,

Without wanting to seem as I’m defending my original position and just for a bit of background info to my “thought processes”.
Just had a first son a month back so had “free time” at the most unghastly hour. I stumbled upon these while googling my thoughts and then came up with my proposal without too much more thought..! 😂


I’ve generally found I’m in need 1/4”or 3/8” BSW or BSF of various lengths relatively frequently, as what I’ve pulled out of my renovations have been in need of replacement.
Just got a bit peed off with having to order enough to either justify free postage or enough quantity to make the purchase worthwhile + wait time for postage etc..

I have very limited knowledge on the subject so thank you all again for your response (s)!

I’ll keep squirrelling for another few months for a Myford 7 lathe or similar as a welcome to the world “gift” to my son 😜

Thanks for your time
 
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AES

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Well first of Gremmy, many congratulations on your first son - and to "Mrs Gremmy" too of course.

A new "engineer-in-the making" perhaps? Certainly, when you find a Myford it's definitely something you'll be able to pass on to him (just as a BTW, I never remember my Dad and I playing football when I was a kid - I think he almost hated it then it as much as I do now - but I DO have memories going back to a very early age of "helping" him and watching him at work on his lathe in his home workshop - also a Myford). Perhaps that's at least one of the reasons why I started down the engineering path). But I digress, sorry.

I wasn't belittling your idea in any way (I hope you didn't think I was) and as you've now seen, whilst at first sight your idea of bolt blanks (thanks for that link BTW, bookmarked, as was previously unknown to me), you'll also have seen from everyone else's responses that the practicalities don't really work for the average "hobbyist".

BUT if you "only" want quarter and three eighth inch sizes generally, especially if "only" BSF most of the time, they shouldn't be too hard to cut by hand using normal taps and dies - and especially if you "only" need MS and not high tensile steel, just as Jelly has already suggested above.

I can also understand you getting fed up with paying postage (bolts can be pretty heavy things) but would suggest you keep an eye out locally for either an old-fashioned hardware store (like the place shown in the Two Ronnies "Fork 'andles" sketch, NOT B&Q or something!), or possibly, for a model engineering "shop".

Both quite hard to find these days, but I suggest for a start you look through the web site for the "Model Engineer" and "Model Engineer's Workshop" magazines for possible "local" suppliers - www.model-engineer.co.uk.

Cheers
 

Wildman

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