Moderators: Random Orbital Bob, nev, CHJ, Noel, Charley

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By Pete Maddex
Get the sizes you need not a set, I would only get HSS not carbon steel.
Most of mine came from car boot sales.

By Inspector
Worth mention that solid hex dies are usually for thread chasing and split round dies meant for cutting new threads. There are of course rules to every exception.

By MusicMan
Lots of good advice there. Just a couple of points:

1. When getting taps it is really useful to get so-called 'progressive' or 'graduated' sets. The starter tap is not only more tapered at the start but is a thinner diameter, and they progress as you get to the final size. Sometimes hard to determine from an advert. The set below is graduated and was cheap on eBay though there is no indication on the box!
taps n dies - 1.jpg

2. Brass is very easy to tap or thread, aluminium is harder (lubricate with WD40) steel and cast iron are not too bad (use cutting fluid), stainless steel is terrible (cutting fluid and good quality sets). For a nice looking and smooth plane adjuster I suggest getting a bronze rod (bit stronger than brass, but that would be second best.

3. When tapping, get used to taking a half-turn cut, then backing off the tap till you feel the back of the flutes on the tap cutting off the scarf (hard to describe, easy to feel). Otherwise it will clog up and jam, and ruin the thread.

4. When die cutting (much harder to get a uniform thread rather than a drunkard's walk) make sure you have a good tapered lead-in to the thread. Don't rely on the taper of the die itself. You can always start with a longer piece and cut off the taper afterwards.

5. Where possible use a machine of some sort to keep it all square, especially when starting and especially with a die. A lathe with dedicated tap/die holder is ideal, but drills and even a vice can be used if you have to.

Note that I am Welsh, and a couple can be anything up to 50 ;-).

By MusicMan
Inspector wrote:Worth mention that solid hex dies are usually for thread chasing and split round dies meant for cutting new threads. There are of course rules to every exception.


True. You start the die thread with a split die, mounted so as to be as wide open as possible. Then close down and repeat. The equivalent of graduated taps.

If you buy the wrong sort, it's easy to slit a sold die with a Dremel and thin slitting wheel.
By J-G
MusicMan wrote:2. ... aluminium is harder (lubricate with WD40)...

Most of that is good advice but I must take exception to the WD40 suggestion ! (hammer) (hammer)

WD40 is a water repellent not a lubricant.

Lubricate Aluminium with paraffin.
J-G wrote, QUOTE: WD40 is a water repellent not a lubricant. UNQUOTE:

and Music Man wrote, QUOTE: I would not use WD40 for lubricating anything but aluminium, but it is good for that, in my experience. UNQUOTE:

The first statement about WD 40 comes up so many times, but sorry, it's just plain wrong. Q: What is a "lubricant"? A: ANY liquid (or semi liquid/paste/slimy stuff) which will keep 2 pieces of metal apart while they're rotating or sliding or rubbing. In other words, water (OFTEN used as a lubricant, AND fuel of various types) and even raspberry jam COULD be used as a lubricant - though perhaps there are better uses for raspberry jam (my wife's is lovely)!

And although WD 40 IS primarily a water dispersant, it definitely IS also a lubricant - and maybe even better than raspberry jam for that purpose! Seriously, in certain special applications, WD 40 is a very GOOD lubricant and for some special purposes (in aviation for example) it's sometimes specified for exactly that purpose.

Coming back to the practical hobby workshop world. Music Man (amongst others) is perfectly correct when he states that although you'll find paraffin (kerosene) specified as lubricant for ali in all the text books, WD 40 works just as well as paraffin for cutting ali - that includes threading and lathe turning when you're after a fine finish. In addition, when turning brass, (which always "squeals" at you) though it's impossible to stop that squeal completely, a judicious squirt of WD 40 does a lot to at least reduce the teeth-jarring frequencies!

I also use WD 40 as a cleaner/lubricant for all my garden tools, with and without cutting edges. Some of these tools live in the relative warm/dry cellar workshop, the bigger ones such as the lawn mower and tree lopper live outside year round in a small timber tool store (unheated but with a small high level ventilator). In all cases cutting edges remain clean, sharp, and untarnished, and there is no rust at all on any tools, stored inside or out. And WD 40 is ALWAYS used (a quick squirt) as a lubricant on the pivot points on my wife's secateurs before and after use.

The "trick" of course is that after the "carrier fluid" has evaporated off, WD 40 leaves a thin film of silicon, which I think is why its use is frowned on in many wood working applications (where I understand silicon can adversely affect many traditional wood finishes).

But to say WD 40 is not a lubricant is just plain wrong, sorry - and to repeat, in some (limited) special applications it is actually specified as the only lubricant to use.
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By PaddyRedman
As has been said, HSS for cutting threads, carbon steel for chasing threads. The amount of carbon steel taps I've snapped cutting threads is beyond the reasonable mark. Once snapped you've then got to try and get it out....
I always use a bit of drilling / cutting paste on steel, helps to ease the friction and makes the bit glide smoothly. Generally don't use aluminium so don't know what will work best on that.
GT85 smells nicer than WD40, and Ive found seems to last longer and work better.
By Rorschach
PaddyRedman wrote:GT85 smells nicer than WD40, and Ive found seems to last longer and work better.

I find it doesn't clean as well as WD40 but it does lubricate better and longer as you say.
I keep both on hand and use the GT85 mostly on our bicycles, it's a great water disperser for chains and sprockets and the lubricating properties easily last for the duration of a ride which is all I need.