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Howard Lewis17/08/2019 21:52:01
2738 forum posts
2 photos

"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.


Nigel Graham 230/10/2019 19:30:30
461 forum posts

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 yet30/10/2019 20:11:43
3944 forum posts
15 photos

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 Jack31/10/2019 17:09:34
990 forum posts
137 photos

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?



John Rutzen01/11/2019 08:52:13
142 forum posts
1 photos

It's an easy job to get out with alum. It needs heating so put the job in a glass [pyrex] container and over a heat source. If you can't do that make a little dam around it and heat with a blowtorch. This takes patience . It took me a few days of occasional heating to get a 7ba tap out of my cylinder block this year. A friend broke a drill this year drilling his steam passages and got it out with the alum.

Trevorh01/11/2019 10:08:39
293 forum posts
84 photos

Hi Bill,

I have a set of them I picked up a couple of months ago just out of curiosity as to what they were

And like you when I used them they do work quite well


Cornish Jack01/11/2019 11:08:07
990 forum posts
137 photos

Trevor - presumably yours, like mine, are only suitable for 4 flute taps?



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