Heartbroken!

[Brian HParticipant @brianh50089]

As is the 8BA Plug tap that is broken in a 1/8" inch deep blind hole!

Any (sensible) suggestions welcome, as is an offer of spark erosion near Mansfield with a financial contribution from me.

Please don't suggest heating it to red (it's a carbon steel tap) because it's in a silver soldered assembly!

Brian

Edited By Brian H on 16/08/2019 15:25:43

[Brian HParticipant @brianh50089]

[Dave Smith 14Participant @davesmith14]

Brian

This comes up on an internet search.

Address

Meden Square

Pleasley

Mansfield

NG19 7SQ

United Kingdom

Website

**LINK**

[KWILParticipant @kwil]

You do not say what metal the tap is in.

[GoCreateParticipant @gocreate]

I broke a 7 BA tap in a blind hole the other day, I managed to grind away the tap using a small diamond coated burrs with a Dremel. I basically ground away the centre portion of the tap after initially grinding the top surface reasonably flat to get a good start. I used a fine pointed burr and a very small spherical burr, alternating between the two.

I did this with the aid of a desk illuminated desk magnifying glass.

It took 15 – 20 minutes and I was surprised how well the it went. 8ba is a little smaller though but I think manageable by this method.

Nigel

[old martParticipant @oldmart]

Take the offer of spark erosion and cough up the money.

[Trevor Drabble 1Participant @trevordrabble1]

My suggestion would be either carbide drill from M A Tooling on Attercliffe in Sheffield on 07973843152 or a carbide burr from J B Cutting Tools in Dronfield on 01246 418110 . I got some minature burrs from J B at last year's Midlands show , and they are very good . Also , if you visiting Meadowhall in the near future , Took Shed in The Lanes has a small stock of Proxxon carbide burrs . Hope t all helps . Please post your progress so we may all learn . Trevor.

[Brian HParticipant @brianh50089]

Many thanks for the suggestions all. The material that the broken tap is in is a mixture of brass and gunmetal.

I seem to remember that there is a chemical solution that has been mentioned before on here, that disolves the steel, but I can't remember what it is.

Brian

[Rod RenshawParticipant @rodrenshaw28584]

Memory suggests that the chemical is alum, as used in cooking, but I can't remember the details. I seem to remember it takes quite a long time.

[Roderick JenkinsParticipant @roderickjenkins93242]

With respect, you wouldn't need to heat the fabrication up to red heat in order to soften a carbon steel tap. Tools are usually considered to be spoiled if they get to blue, which is about 300C. You've another 300C to play with before the silver solder starts to soften – and that's ignoring any liquation effect which will raise the solder melting temperature even further.

Cheers,

Rod

[TomfileryParticipant @tomfilery]

Brian,

The chemical you mention is Alum, however, I managed to get a broken small drill (1.5mm dia) out of a brass item by leaving it soaking overnight in citric acid. The next day the drill had basically turned to rust and could be poked out with a scriber.

If you use clean citric acid, rather than some which has had copper in it, you won't get a deposit of copper on your item.

Good luck.

Regards Tom

[SamsarandaParticipant @samsaranda]

If you need Alum it is readily available on the internet, when I ordered some it took only a day to arrive, can’t remember where I ordered it from but there are plenty of suppliers..

Dave W

[ianjParticipant @ians]

recently I broke a No. 50 drill in a block of Aluminuim . Some time ago I bought a product called BTR-10-broken tap remover, (Translunar technology Ltd , Bucks) it contains 33% aluminum sulphate.

The instructions say to dissolve a quantity in water in a aluminum /glass container and simmer the part . It states no action occurs at a lower temp.

After approx 1 hour enough of the drill had been dissolved and it just fell out.

[norman royds 2Participant @normanroyds2]

the chemical I use is hydrochric acid it dissolved carbon taps the problem is tirying to buy these days regards norm

[John ReeseParticipant @johnreese12848]

Is alum safe on copper alloys?

[peak4Participant @peak4]

BrianH, whereabouts in Derbyshire are you?

If you're in easy reach of Buxton, I had some Alum arrive a month or so ago off ebay, You're welcome to a bit.

I bought it ready for when I brake a tap in a bit of motorbike one day.

Bill

[Ian S CParticipant @iansc]

Alum is usually available in garden shops, and the cooking dept of the super market.

Ian S C

[Mick B1Participant @mickb1]

Have you an option to move the hole and drill and tap elsewhere?

You can see the attempted expiation of my sin in the position of the LH bearing strap retaining bolt (also due to a broken 8BA tap) here:-

[Anthony KnightsParticipant @anthonyknights16741]

Hi Norman. Hydrochloric acid is the main constituent of B&Q's Brick Cleaner.

[Brian HParticipant @brianh50089]

Many thanks to all on here for the suggestions and offers. I've now managed to secure a small amount.

I first came across alum as a young apprentice with Crossley-Premier Engines. One of my first jobs was to pressure test valve guides which where hollow cast iron castings with water passages to cool the valves on diesel and gas engines.

They were tested to 25psi (as I remember) and any porosity or leaks were fixed by the addition of a teaspoonful of alum which VERY quickly rusted any defects so that a second pressure test could be carried out to ensure no leaks.

Brian

[Brian HParticipant @brianh50089]

Just discovered that I needn't have made the holes blind! They will just go through without leaving a witness in the mating parts.

Also realised tht the two holes that I broke a tap in,needn't have been put in at all.

Must get my brain in gear next time.

Brian

[Howard LewisParticipant @howardlewis46836]

"Experience is what allows you to recognise the mistake, the next time that you make it!"

A hard taskmaster, but makes the memory work better!

Gunmetal will expand faster than steel, so maybe a session in boiling water may ease things enough, if you can grip the remains, to uncsrew it. Hopefully, after the first 1/4 turn things will become easier!,

Hope you get it fixed.

Howard

[Nigel Graham 2Participant @nigelgraham2]

That BTR-10 is Alum then. (Aluminium Sulphate). Well, a third of it is. The rest might include a surfactant to break through grease and minimise bubbles shrouding the metal.

Citric acid: easy enough _ I bought some recently in Wilko's.

Hydrochloric Acid: try a stockist of swimming-pool additives. It's used as a descaler and pH corrector in pools and spas. Nasty stuff though…. it emits a corrosive vapour the moment you take the cap off the container.

+

Incidentally, other swimming-pool additives of potential engineering use include "Dry Acid" (granular Sodium Bisulphate), Sodium Carbonate (aka washing soda), and algaecides that are mainly strong Copper Sulphate solutions.. The first two are pH correctors.

Also various water-testing devices ranging from paper test-trips to more sophisticated electronic reagent-colour comparators. These measure Chlorine, pH, Total Dissolved Solids, and Hardness, probably accurately enough for keeping boilers healthy though fairly obviously, none test for tannin % levels. (Easy to make your own sample-colour comparator though: just seal known-concentration samples of the water-treatment compound in suitable vials, read the test sample in a similar vial, against them by eye, in day-light.)

[not done it yetParticipant @notdoneityet]

Alum is not aluminium sulphate. It is the double salt aluminium ammonium sulphate, probably along with a lot of water of hydration.

I recently broke a tap in a brass feed-screw nut – my first tap breakage for years and where I didn’t really need to put in a second securing pin – and virtually boiling in a concentrated solution solved the problem in time. The reaction slows very rapidly below 100 degrees Celsius.

I wish I had put the part in a beaker in an old aluminium pressure cooker to speed things up!

[Cornish JackParticipant @cornishjack]

Having just broken an 8mm tap (best quality Chinese black chocolate!), this thread offered various 'escape' options. However, from the dim recesses of my remaining brain cell, I recalled a couple of oddments from 40 or so years back – see pic below.

The smaller of the two was adjusted to fit and … Bingo! . It unscrewed easy-peasy!

I cannot recall having seen these mentioned previously nor seen them advertised. Anyone else own or use one?

rgds

Bill

[Author]

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