Presto taps

[Lonsdale73]

No previous experience of taps and dies but told that's what I need to put a thread in some aluminium. Can anyone tell me how this http://www.ebay.co.uk/itm/Brand-NEW...281487?hash=item25bc7fca8f:g:aUcAAOSw-vlVl9Q4 differs from this http://www.ebay.co.uk/itm/Presto-M8...040364?hash=item51b8fe8aac:g:7WIAAOxydlFS-I7P, besides price?

Thanks in advance.

 

[galleywood]

The 2nd set are High Speed Steel - the 1st are not stated, but even if they are only carbon steel, which is unlikely, they will be fine for Aluminium.

 

[Lonsdale73]

The 2nd set are High Speed Steel - the 1st are not stated, but even if they are only carbon steel, which is unlikely, they will be fine for Aluminium.

Brilliant thanks

 

[sunnybob]

When you come to thread the piece, DONT just wind the tap (or die) straight in like a bolt. They will break.

Turn a quarter to half turn, and back it out half of that. repeat for the first few turns. then go to a whole turn and back it out a half.

Use a lubricant thats sticky, even butter would work rather than a spray on. If you do use spray on, use it constantly to clear the thread swarf.

 

[AES]

++1 for the above comments Lonsdale.

Note that Presto is a good, made in GB brand (used to be good anyway), so assuming both vendors are really offering Presto like they show, personally I'd go for the half price one. As already said above, even if the cheap set is "only" carbon steel they'll be plenty good enough taps for ali.

Also agree about backing off regularly during the thread cut. What you really need to do is develop a "feel" - basically, A) as soon as you feel the tap getting a bit stiffer to turn you back off; and B) you need to back off until it feels "unstiff" again. Depending on the grade of ali and the thickness of the job that could well be more turns than the usually quoted quarter/half turn.

And sunnybob is right about cutting lubricant, although butter would not really be my 1st choice! The recommended standard is paraffin, though WD40 will do just fine; even normal 3in1 works too - remember that ali is "soft & sticky" and gets stuck on to the cutting edges of the tap, making a poorly cut thread unless you back off regularly, as above, and (as the actress said to the bishop) unless you use some lubricant now and then.

Finally, I assume it's 8 mm x 1.25 mm pitch you want (I'm not sure if you're repairing something or making something new)? That thread is the ISO standard "metric coarse" and is very common over here. But there are also 2 ISO standard "metric fine" 8 mm dia threads - either 1.0 mm pitch or 0.75 mm pitch. Pretty rare but if you're repairing something, suggest you double check.

HTH

AES

 

[AndyT]

There's another diffetence, if the illustrations are right.

The cheaper set will tap holes that go right through and also tap blind holes.

The dearer set won't tap blind holes, only holes right through the work, but you get three taps to wear out - not very likely on a one-off job in aluminium.

 

[Lonsdale73]

There's another diffetence, if the illustrations are right.

The cheaper set will tap holes that go right through and also tap blind .

Good point, hadn't realised dearer set was three identical cutters, thought it was one each of the three types I'd llearned of via Wiki and the indispensible youtube. Not knowing what holes I might need and following all your suggestions I've ordered the cheaper set, working on an assumption M8 has a "standard" pitch of 1.25mm? Got paraffin, WD40, 3-in-One and butter! Going to need a tap wrench though, any recommendations?

 

[sunnybob]

I did mention butter as a last resort....(g). But I'm not a fan of wd 40 on thread cutting as it runs away so quickly. After all, thats what its designed to do. Any thing that will stick for more 10 seconds will work.
back in the day we used white tallow when cutting threads by hand, but I expect theres a health and safety issue on it nowadays.

A tap wrench is a tap wrench, especially if you are only going to use it on alli. i have often used pipe grips when the wrench was hiding deep in a tool box somewhere.

 

[AES]

Blimey sunnybob, I haven't seen (or smelled) tallow for a LONG time! And yes, I realised that butter was a joke

Personally I've never had any trouble with WD40 and I've not found it runs away any quicker than paraffin does. But I guess it may depend on how deep Lonsdale's thread must be.

As a beginner in the noble art of thread cutting I wouldn't suggest that Lansdale uses a pipe wrench - - very difficult to start the thread off square to the axis of the hole unless you've had a bit of experience first, which I guess you have by the sound of things. But as you say, any tap wrench will do really, and 8 mm isn't as difficult first time around as, say, a 3 or 4 mm thread.

But Lonsdale, I suggest you get one that's not too big - my own normal everyday tap wrench has 2 equal length arms of about 4.5 inches each. Should do you fine for everything unless you get into really small (or huge) diameter threads.

Yes Lonsdale, the 8 mm x 1.25 mm pitch is the ISO standard metric coarse thread. Even in UK you should find nuts & bolts with that thread everywhere (I guess - not been in UK for yonks).

AES

 

[sunnybob]

1964, gas board gas fitting apprentice. up to 6" iron pipe, cut and threaded by hand (4 men needed to swing the 6" die holder, 2 men needed to lift it off the ground!), LOTS of tallow needed on those buggers.

Tap wrenches are so cheap and basic, its not a big deal to get a small one to start and a bigger later if the need arises.

Youre right, the pipe wrench wasnt a recommendation, just a way of showing that the tool doesnt need to be gold plated to do a job with it.

8 x 1.25 is the standard in the uk and almost all the world now. Even America is waking up to metric (slowly mind).

 

[Phil Pascoe]

What about serial taps?
http://www.arceurotrade.co.uk/Catalogue ... ric-Coarse

 

[Phil Pascoe]

http://www.ebay.co.uk/itm/Half-kilo-tub ... Swv0tVcMGX

Still around.

 

[AndyT]

http://www.ebay.co.uk/itm/Half-kilo-tub-of-Monument-tallow-Steady-lube-thread-cutting-lube-new-/222222028462?hash=item33bd770eae:g:IMAAAOSwv0tVcMGX

Still around.

and not hard to find from a mainstream supplier -

http://www.toolstation.com/shop/p90610?table=no

 

[AES]

Blimey folks (about tallow), I'm really surprised to hear that. I remember using it during my apprenticeship in the shop on a hot day - stunk to high heaven (a bit like rancid pork dripping or something)!

And I don't doubt that it took 10 men and a dog to thread those gas pipes sunnybob. I have a small "domestic" set (up to 2 inch if I remember correctly) for threading iron pipes. So far I've never had to use the biggest, but it was a MAJOR job to hold the inch and a quarter/inch and a half bit of pipe in the vice, plus a long lever on the die stock, when I had to thread a new bit of water pipe for a replacement at home (although built in the late '60s, all our internal house water pipes are iron here).

@phil.p. I quite agree that Arc Euro is a good company, and I've always had good stuff from them. But the 3 cheapest Presto taps Lonsdale linked to were about 6+ quid if I remember right, whereas the Arc taps you linked to were nearly 6 quid each (if I read it correctly). I really don't think he can go wrong with 3 off Presto taps at under 7 quid for the 3 (assuming they really are Presto, and that Presto is still the same as "when I were a lad")! Hence my recommendation.

AES

 

[sunnybob]

We had a door jamb vice for threading up to 1" pipe. which we had to carry over our shoulders on the push bikes. With two old style canvas tool bags across the handlebars, it was hard work pedalling up hills.
That vice made a mess of nice woodwork, it would never be accepted in any ones house today.

up to 3/4" pipe we usually threaded on the ground. 12" footprint grips in the left hand, die threader in the right, pipe between the legs, and pretend youre doing push ups.
The mains pipes (1 1/2" and up) were delivered by lorry, and threaded on a towed work trailer with pipe vice.
kids today...... dont know theyre born.

 

[AES]

"Aye" sunnybob - "don't know they're born do they?" (You forgot the Hovis accent mate)

AES

 

[Phil Pascoe]

AES - no, that price was for the set. I wasn't so much recommending the firm as maybe the type of tap as opposed to the normal three, or suggesting they were as good or better than Presto. They seem to me to be a more logical way of tapping a through hole.

 

[AES]

OK phil.p, agreed. My (v quick look) suggested the price was per tap, my mistake, sorry. But I think we're too late, Lonsdale says somewhere above that he's ordered, but if not, those Arc taps would be better (Note to self: "Engage eyes before operating mouth/or keyboard").

AES