TAPS, spiral or std

Not necessarily. The key phrase is "decent quality". Fifty plus years ago commercial tap manufacturers made both carbon steel and HSS taps. Carbon steel taps would have been cut, HSS steel ones ground. I don't think any commercial tap manufacturer makes carbon steel taps now. So if you want good taps from a commercial manufacturer you need to go for HSS.

Andrew

Not at all - I learned a few things too. (Thanks chaps)

Don't be surprised to break small taps, it's not that unusual. How to remove a broken tap from the hole is a popular forum topic too!

Painful experience has taught me that a gallon of patience is needed for every teaspoon full of cutting fluid. I'm not a natural in the workshop and find that the problem is often me rather than the tool. I improve slowly with practice. I'd suggest starting with inexpensive new taps (provided they're sharp) on brass. M4 is big enough to take a bit of abuse: if you break one it's probably bad technique. My taps mostly come from Tracy Tools and have met my hobby requirements well.

It's useful to experiment with different sized holes. Unless it's critical I usually drill tap holes a tad bigger than recommended in the tables, e.g 3.5mm rather than 3.3 for M4. This weakens the fastening slightly, but reduces the strain on the tap enormously. A trick learned on this forum.

The metal being tapped makes a big difference too. Tapping M4 in a 3.5mm hole is brass is easy. Tapping M4 in a 3.2mm hole in steel is much harder. Aluminium is deceptively soft but the swarf tends to stay in the hole and jam the tap, snap! Copper is horrible - it tears.

Take care to remove swarf and always apply lashings of cutting fluid, CT90 works for me.

Dave

Edited By SillyOldDuffer on 01/05/2017 15:14:27

I have used Bergen taps without problems in the past. Rarely use anything smaller than M6, and when I do, it'll be M4. I always drill M4 at 3.5mm and use cutting paste. So far (firmly touching my head as there's a fair bit of wood in there) I've not broken an M4 tap.

Will say I tend to get Bergen for some of the odder sizes I use, like 3/8 BS Cycle (26 tpi), as they are cheap enough for rarely used sizes to be viable and not break the bank.

Regards

Richard.

No, you will have a set of 3 good quality M2.5 taps that will cut well. Given that the hole you intend to use them for is to take a Torx screw for an insert I would not go larger than 2.1mm for the tapping drill as there is not much length to these screws and we tend to wind them in quite tight.

You will also be able to use them in situations where you cant assure there is support for the other end directly above the work which is where a taper tap will be easier to start true into the hole.

This is the swarf you get from a spiral flute tap in a ductile material (low carbon steel):

The steel offcut will be a gauge for the screwcut external threads on the brass pipe connectors. The drilled hole is a little small at 17.5mm, but that's the nearest drill I could find.

Note the name stamped on the tap wrench; made by my father as part of his apprenticeship at RAE Farnborough, probably around 1940/41.

Andrew

Use a tap guide to start and keep the tap vertical. For your tap, a 2.6mm hole through a 6mm piece of steel that can be clamped to the work should be sufficient. Harold Hall's book of workshop projects has a couple of more elegant solutions.

Regards,

Bob

Jason, I was refering to buying a full set of Volkel taps not the 2.5 ones

Cheers for all the tips guys, they will be put to good use

Edited By petro1head on 01/05/2017 17:06:08

No you have bought decent kit

There is a big difference between opinions - but there is also a big difference between using something daily and using it once in a blue moon, using it on a bit of copper or brass and using it on harder metals

you will never get a perfect answer

only individual opinion.....

Tony

On other way to protect small taps is to hold them by the shank, that way if thighs should tighten up hopefully the tap wrench will slip before the tap goes ping!

These are M2.5 Volkel ones like I linked to this morning doing blind holes in 2.5mm thick brass

Also has the benifit of making it easier to support the end of the tap with a female ctr as someone mentioned earlier

I have a question about the 3 tap sets:

Are they serial taps where each tap in the set cuts slightly larger than the previous tap, the last one finishing the hole?

Or are they taper, plug. and bottoming?

I much prefer the spiral point or spiral flute taps over conventional taps.

T, P & B

One of the best small tools I bought for my shop was a tap holder like this. Haven't broken a tap since. They can be used in the mill or drill or lathe and fully support the end of the tap-wrench. You don't have to worry about tap alignment and can concentrate on the "feel" of the tap (when in doubt, back it out). You can still use the tap-wrench freehand if you wish (I avoid that like the plague).

I bought the first one but then modified all my other tap-wrenches. It's trivially easy.

Bandersnatch, I agree that is a great tool. I made the mistake of buying cheap Chinese imitations that were junk. I do use spring loaded tap guides that engage the center pop in the top of the tap. They also work quite well. When I am using the T type tap wrench, not guided by the machine, I like to leave the chuck a bit loose. That way if my hands wobble a bit the slack keeps me from breaking the tap.

And at the end of the tapping process the swarf is nearly a foot long:

I have a range of the T-handle tap holders and extensions, albeit from the cheaper end of the market. I used them a lot, but eventually found them rather heavy and, to me, clumsy. So I now use ordinary tap wrenches. I have a selection, custom made although not by me, ranging from 2" to 12".

When hand tapping a good finish on the part has the advantage that you see a reflection of the tap in the material. If the tap and reflection are in line then carry on, if not tweak the tap angle. Personally I've never bothered with tapping guides. Either I use the mill/lathe to start the tap, or I freehand tap with no guide and judge the angle by eye.

Andrew

Good tip. I would never have thought of that!

Thanks,

Dave

Many years ago I started using tapping guides with small taps.

I have happily tapped 12BA threads into mild steel and, recent, 8BA into aluminium bronze. You just keep the guide pressed against the surface using your left hand and tap with your right.

Simple (or have I missed something?).

JA

Edited By JA on 02/05/2017 17:18:31

Thats a good idea

Is it possible to tap holes if you hold the guide with your right hand?

Only if you are one of those left handed people with their brain in upside down

Mike