Thread: A 12-20 tap & die set

What a great adventure getting a metal lathe is Ian . What model is yours? Ill look it up . Just interested to see it . Ive always paid extra attention when you show or mention the stuff you do on your lathe.

The manual being wrong! That would be a head scratcher!

With no indexer do you have to keep it engaged and reverse for threading?

Ive got an old Hercus now . Its a little bit worn on the bed. Does a great job though . I'm Learning all the time about how to do things with it . Turned my first 5/8 BSW thread for a machine part in 4140 steel about 8 months back . I was so amazed by it I slept with it on my bedside table that night. Couldn't stop handling it. 4140 is beautiful stuff. So is Brass and Bronze. .

Rob, compared with a Hercus, even an old one, my lathe is a toy! It is a much older model of this one. The new model looks sleeker, and has better specs as well as being a bit heavier, which would be a good thing. I made the usual mistake, I went for the minimum that I thought would make the few simple bits I envisaged making with it. But as you have discovered, they can suck you in, real quick, so it wasn't very long before I was pushing the limits of its capabilies & sometimes wishing I'd spent a bit more!

If you know what you are doing, they can do some pretty amazing work. I discovered a whole forum devoted to mini-lathes & the stuff some blokes manage to make is very impressive. Mind you, they usually start by stripping the things & rebuilding them to much tighter tolerances than original.

The little lathe has done all the jobs I originally wanted it to do, plus a couple I never expected to tackle. It handles brass & aluminium no sweat (particularly after I bought a decent set of tools, the ones that came with it were really poor and barely fit for purpose). It's fine with steel as long as you are patient & stick to light cuts (there's too much deflection in the cross-slide under heavy cuts). Because of its limitations, it hasn't distracted me too much from my real love (making sawdust & shavings ), so I guess you can say in some ways, I made the right decision....

Cheers,

Originally Posted by oldBruce

Sorry to barge in on a question directed at Ian, but the 12 is 12 Gauge (which in bolt terms is .216 inches, or 5.5mm, or near as dammit to 7/32 inch outer diameter). The 20 is TPI (so same TPI as a 1/4 UNC, just thinner diameter).

Thanks Bruce. Ive been thinking about the 12-20 question ever since I first read this thread, wondering if I should ask. I was thinking "its got to be obvious". But no it wasn't. 12 Gauge , Ill look into gauge sizes .

Originally Posted by oldBruce

I think that I have made most of the usual errors when playing this game... and I may have even learnt from some of them.

learning by errors. Its great to have the insight of a few good errors when learning . Seems to me we are designed to work that way .

Originally Posted by IanW

Rob, compared with a Hercus, even an old one, my lathe is a toy! It is a much older model of this one. The new model looks sleeker, and has better specs as well as being a bit heavier, which would be a good thing. I made the usual mistake, I went for the minimum that I thought would make the few simple bits I envisaged making with it. But as you have discovered, they can suck you in, real quick, so it wasn't very long before I was pushing the limits of its capabilies & sometimes wishing I'd spent a bit more!

Nice lathe Ian . Its really amazing what even smaller ones can do.
Yeah they do suck you in quick . Nothing like getting one to start learning and just go for it .
I should have got one that size ten years earlier as I now know it would have made the next step up a LOT easier and sooner as well.

You ever watched this girl? Similar sized lathe. Smart, precise and straight to the point. Her lathe with gears changed the same way is probably a step larger than yours.
Blondihacks - YouTube

Originally Posted by IanW

Because of its limitations, it hasn't distracted me too much from my real love (making sawdust & shavings )

One thing for sure . Sawdust and shavings is Bliss compared to cleaning the mess a metal lathe leaves .

Originally Posted by auscab

Nice lathe Ian . Its really amazing what even smaller ones can do.
Yeah they do suck you in quick . Nothing like getting one to start learning and just go for it .
I should have got one that size ten years earlier as I now know it would have made the next step up a LOT easier and sooner as well.

You ever watched this girl? Similar sized lathe. Smart, precise and straight to the point. Her lathe with gears changed the same way is probably a step larger than yours.
Blondihacks - YouTube



One thing for sure . Sawdust and shavings is Bliss compared to cleaning the mess a metal lathe leaves .

A second for Blondie hacks, she is an excellent instructor, an gives woodies a bit of stick from time too time.

Cheers Matt.

Auscab: You are entirely correct: the traditional solution would be to grind your own HSS bit to cut the Whitworth thread. However, I admit that I am a convert to carbide inserts for my small lathe jobs, and standard 60 degree thread-cutting inserts/tips are just so easy and available. The same can't be said for 55 degree tips, so we get back to your solution. But using a button die is even easier, and simplicity has a certain appeal...
But going back to one of Ian's comments: the tolerances on Stanley rods and plane bodies are not terribly exact, and an AF (60 degree) thread form will fit over 90% of them, but may have just a little more play.

Sorry all: I hadn't flicked to the second page of the thread, and seen that Ian had already said all that. D'Oh!

Originally Posted by oldBruce

Sorry all: I hadn't flicked to the second page of the thread, and seen that Ian had already said all that. D'Oh!

Don't feel bad Bruce, I've been caught like that more than once! And if you are a slow typist like I am, you canl spend 10 minutes typing out a reply, hit 'send' & discover you've been upstaged 9 minutes ago, by someone who can type at an acceptable speed....

oldBruce, you need to clear out your personal message inbox. It's full so you won't receive any new messages.

Sorry Umar. I am still learning the system. All good now, though.

Comment from a Yank here: the more common term in the U.S. nowadays for what y'all are calling "gauge" sizes in screws is "machine screws." Good practice here calls for putting a "#" meaning "number" in front of the size: so this would be a #12-20 tap and die (and you'd say it that way, too: "Number 12-20"). Otherwise, it's easy to read it wrong and hand over a 1/2"-20 tap/die when the customer asks.

Bill, my comment wasn't to denigrate the US system. It's just that the number system for small machine bolts died out here by my time, or was maybe never used all that much in the first place. So it was something I was unfamiliar with when I first encountered it, but it didn't take long to cotton onto, back when I still had a memory. The term 'gauge' can lead to some confusion too, given that sheet-metal gauges are quite a different thing (& work in reverse!).

We started to "metrify" in the 70s, but it's been a bit of a bumpy ride. Many hardware items are now a "proper" metric size, not just Imperial sizes re-badged to a metric equivalent (which can result in some curious numbers). Nails have been sold by metric diameter for quite a while, but until recently, wood screws were still sold by the old Imperial gauge size. I notice the odd maker is giving the metric diameter now, so maybe that will change in the next 20 years.

In the range of sizes I work with, metric trumps all, I reckon, simple & intuitive. Metric bolts are sold here as "M" with the diameter following, e.g. "M5", or "M12", etc. You know exactly what you are getting because the fine metric thread is very uncommon & you have to get those from specialist suppliers. The pitch of standard metric threads tends to fall between the coarse & fine Imperial thread pitches for the same diameters, a sort of one-size-fits-all compromise so unless the finer threads become common, for an old git like me, life has become simpler....

Cheers,

Hi all,

Came across this thread whilst looking for a Stanley #12 x 20 tap and die.

An Australian specialty supplier who makes #12 x 20 taps. I've ordered but asked him to hold off manufacture to Friday 20/1 in case anyone else wants to get a set made quickly and tack on to my place in the queue.

Pricing as per the below, no affiliation, yada yada, just letting you know.

If you want a tap/die, please call or email the below. They're a small toolshop so don't have much time on the phone.
[admin - please delete if not allowed. ]

Cheers,

eddie

...............

Re your enquiry special tooling.

Whitworth 55° thread 12g x 20 as per original Stanley/Singer threads.

1 only 12g x 20 Bottom Tap @ $62.00 + GST Del 2 Days
1 only 12g x 20 intermediate tap @ $62.00 + GST Del 2 days
1 only 12g x 20 taper Tap @ $62.00 + GST Del 2 Days
1 Only 12g x 20 x 1" O/D die @ $95.00 + GST Del 2 Weeks

Postage $18.00 + GST

Thanks


Garry

Capital Cutting Tools Pty Ltd
37 Hammond Street, Hamilton, VIC, 3300

Ph: (03) 5571 1772
Fax: (03) 5571 1774
Email: [email protected]

Hi Eddie;

Why are you picking a Whitworth threadform of 55 degrees? Americans quickly ditched Whitworth in the last quarter of the 19th century and standardised on 60 degree threads as the tooling is much easier to produce. American National and Unified threads all used 60 degrees, if you look at the picture of Ian's tap and die set you'll clearly see the letters "UN" etched on the die.

I've just pulled a couple of frog mounting screws out of a Sweetheart era rebate plane and they are definitely 60 degree threads according to my Moore & Wright thread gauges. I also checked the screws on a post-WW2/pre '57 Record where if anybody would have used Whit it would have been Record but they are also UN.

I note there is a statement by Old Bruce in post #13 where he refers to Whitworth but I don't know where that came from. Yes you can force 55 and 60 degree threadforms together so long as the pitches match; but only in the same way that you can mash Philips screwdrivers into Pozidrive screwheads and butter knives into slot headed screwheads.