TAPS, spiral or std

[Anonymous]

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

[Bob MurrayParticipant @bobmurray]

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

[petro1headParticipant @petro1head]

Posted by JasonB on 01/05/2017 16:05:36:

Posted by petro1head on 01/05/2017 13:57:59:

So have I wasted my money now

 

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.

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

[Antony PowellParticipant @antonypowell28169]

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

[JasonBModerator @jasonb]

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

[John ReeseParticipant @johnreese12848]

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.

[JasonBModerator @jasonb]

T, P & B

[JellyParticipant @jelly]

HSS taps are a “nice to have”, so I wouldn’t call it a waste of money.

I tend to get CS taps or dies for one-off tasks because they’re inexpensive, and HSS if I foresee using them lots (either repeatively on one job or over time).

Best advice I ever got on tapping was to get a piece of scrap steel and practice tapping holes in it until I got the feel of it. I was told to start with worn taps out of the scrap tooling tub (this is a luxury you may not have, but buying a dubiously cheap set off the net would substitute), and not worry too much about breaking them then buy myself a sharp set once I had a feel for how much force would cause breakage.

[Enough!Participant @enough]

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.

[John ReeseParticipant @johnreese12848]

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.

[Anonymous]

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

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 02/05/2017 11:06:26:

…

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.

…

Andrew

Good tip. I would never have thought of that!

Thanks,

Dave

[JAParticipant @ja]

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

[petro1headParticipant @petro1head]

Posted by JA on 02/05/2017 17:17:42:

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

[modeng2000Participant @modeng2000]

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

[Mike PooleParticipant @mikepoole82104]

Posted by modeng2000 on 02/05/2017 19:45:43:

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

[Anonymous]

What about those of us who use both hands to tap? Get tired, just swap hands and carry on.

Andrew

[John ReeseParticipant @johnreese12848]

Take off your shoes and hold the guide with your feet.

[Anonymous]

It's bad enough hopping around the house because of slivers of swarf; no way I'm going to be in the workshop without shoes.

Andrew

[HopperParticipant @hopper]

Posted by JA on 02/05/2017 17:17:42:

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

Yes this works well. I have a piece of BMS about 1" thick and 2" x 4" big with a variety of holes drilled in it to suit various size taps that has been kicking around my toolbox for years. Very very handy. Getting the tap straight is a no-brainer (which suits me perfectly.)

[petro1headParticipant @petro1head]

Posted by Andrew Johnston on 02/05/2017 22:09:04:

It's bad enough hopping around the house because of slivers of swarf; no way I'm going to be in the workshop without shoes.

Andrew

I am always getting into bother from "her in doors" because of the bits of swarf I drag into the house. The other day there was swarf on the toilet seet

[MWParticipant @mw27036]

Posted by John Reese on 02/05/2017 20:55:41:

Take off your shoes and hold the guide with your feet.

I prefer using my teeth.

[Brian OldfordParticipant @brianoldford70365]

Posted by Andrew Johnston on 02/05/2017 22:09:04:

It's bad enough hopping around the house because of slivers of swarf; no way I'm going to be in the workshop without shoes.

Andrew

Almost as bad as treading on a piece of the grandson's Lego without any footwear.

[Howard LewisParticipant @howardlewis46836]

Once, I was told that a lot of taps break because they dislike being subjected to bending.

Consequently, I have made / bought a variety of devices to hold the Tap square to the job. Some are drill chucks that locate in the Morse taper in the Mill – Drill, or Lathe Tailstock. One is a spare drill chuck on a spindle mounted oi what was once the stand for a pistol drill, (A very poor imitation of the G H Thomas Pillar Tool)

Even with ER collets, (A home made ER25 collet chuck sliding on an arbor held in the Tailstock) if the tap tries to stick, the chuck will slip around the plain shank, rather than break the Tap. (That ALWAYS happens in the very last hole in the job!!!!!!!).

For Metric threads, the rule of thumb for a tapping drill is (Nominal size – pitch). If in doubt drill slightly oversize.

My advice, FWIW, use plenty of lubricant, (Trefolex, Rocol STD, or even Bacon fat), and do back off frequently to break the swarf and prevent it packing in the flutes.

My preference is HSS rather than CS since it seems less prone to breakage; or maybe it's just my clumsiness? S

I try:

Not to use a large Wrench on a small tap, but to try to match the size to the tap.

To use both hands on the wrench, or as a Tee wrench, to minimise bending moment on the Tap

If in ANY doubt, to remove the Tap frequently, and clear swarf from the hole by shaking / blowing / banging the work on a piece of wood/ clearing with matchstick or scriber.

Ignoring my own advice cost me a M10 first cut tap! Fortunately, I was able to remove the broken stub, so most of the harm done was to my pride.

My favourite Tap for M6 is a spiral flute, because it cuts at one pass (so less risk of my heavy hands breaking it!)

Risking calamity; since using the various Tapping Aids, have not broken any Taps; (not even 10 BA) but now, that may not last for much longer!

And I thought I was alone in being told off for dropping swarf around the house! Obviously SWMBO does not like sparkly carpets.

Howard

[petro1headParticipant @petro1head]

I have been using Lithium Grease, is this wrong?

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