Removing a broken tap
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Help Support Home Model Engine Machinist Forum:
Diymania said:
Diymania, look up Alum on Wikipedia and it will tell you the chemical name, if that will help you.
Here in the USA it's used for cooking. We buy it at the grocery store. It's kept in the spice section. You can also get it at a drug store or a from supplier of regent chemicals.
kellswaterri
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Hi all, here is the recipe for the alum...it was in an other forum I am in...
Re: REMOVING BROKEN TAP
« Reply #7 on 2/21/06 at 17:09 »
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Hello Folks,
to continue the saga of ''the broken Tap'', after the collective brain picking of this Forum and others, one in particular [the american horological society], the final result was to remove it with the use of ''ALUM'' i/e...aluminium potassium sulphate...this chemical is commonly used in the clock repair trade for removing rusted or broken screws from out of rare or antique clocks or watches when all else fails.
The process is slow but very sure as I have just proved.
During the tapping of a considerable number of 7ba threads, I managed to snap the Tap leaving approximately 3/8'' of broken tap in a blind hole.
The removal of the broken piece involved the use of a large sauce pan, a pyrex bowl, and 'ALUM', the pyrex bowl was filled with boiling water enough to cover the cylinder with broken tap by about 2'' of liquid, 'ALUM' powder was then poured into the bowl of boiling water until no more powder could be absorbed by the water, the bowl of liquid 'ALUM' was then put into the large saucepan which already had boiling water in it and left to simmer at just under boiling point for 15 hours over yesterday and today, that is what I mean by 'slow but sure', the gunmetal casting was not affected in any way and the remains of the broken tap had vanished.
It was amazing to watch the constant stream of tiny little bubbles erupting from hole where the broken bit of tap was being eaten away with the chemical.
For anyone who has never used this process before [like myself] I would heartily endorse it as an excellent ''MODEL ENGINEERS '' tool
and a little about ''ALUM''
''ALUM'' quite a few of us on occasion have had to use this substance, but how of its History...
1470: Alum (previously known in the Middle East) is discovered in Europe
for the first time, specifically Tuscany. It was first found between
1300 and 1310 in Rocca (Syria). The mineral Alum is
the double sulphate of aluminum and potassium, AlK(SO4)2 + 12 H2O,
is a common compound of Aluminum, which was not isolated until
1825 by Hans Christian Oersted (although anticipated and named in 1807
by Sir Humphrey Davy). Alum comes to be used for dyeing, leathermaking,
medicine, paper sizing, and fireproofing.
Europe's problem since Roman times had been a chronic imbalance of trade. Bullion drained out of northern Europe into Italy and thence through the Middle East to the Far East, to pay for imports of alum, grain, oil, and wine, and luxury goods like silk and pepper. In exceptional times and places this problem did not apply. For example, the fur and slave trade through Russia that was run by the Vikings and then by the Russians themselves resulted in a flow of silver north of the Black Sea into northern Europe. But this did not last for very long, and did not affect southern Europe very much. Venetian merchants were always reminding their agents in the east to use barter wherever they could, but they were usually required to pay in silver and gold; failing that, in copper, tin, or lead.
http://www.wovepaper.co.uk/alumessay1.html
Just a few snippets of its history, for those interested the web site gives an excellent review but a little long winded to down load...
All the best for now,
John.
« Last Edit: 3/27/08 at 9:44 by lancelot » Link
Re: REMOVING BROKEN TAP
« Reply #7 on 2/21/06 at 17:09 »
--------------------------------------------------------------------------------
Hello Folks,
to continue the saga of ''the broken Tap'', after the collective brain picking of this Forum and others, one in particular [the american horological society], the final result was to remove it with the use of ''ALUM'' i/e...aluminium potassium sulphate...this chemical is commonly used in the clock repair trade for removing rusted or broken screws from out of rare or antique clocks or watches when all else fails.
The process is slow but very sure as I have just proved.
During the tapping of a considerable number of 7ba threads, I managed to snap the Tap leaving approximately 3/8'' of broken tap in a blind hole.
The removal of the broken piece involved the use of a large sauce pan, a pyrex bowl, and 'ALUM', the pyrex bowl was filled with boiling water enough to cover the cylinder with broken tap by about 2'' of liquid, 'ALUM' powder was then poured into the bowl of boiling water until no more powder could be absorbed by the water, the bowl of liquid 'ALUM' was then put into the large saucepan which already had boiling water in it and left to simmer at just under boiling point for 15 hours over yesterday and today, that is what I mean by 'slow but sure', the gunmetal casting was not affected in any way and the remains of the broken tap had vanished.
It was amazing to watch the constant stream of tiny little bubbles erupting from hole where the broken bit of tap was being eaten away with the chemical.
For anyone who has never used this process before [like myself] I would heartily endorse it as an excellent ''MODEL ENGINEERS '' tool
and a little about ''ALUM''
''ALUM'' quite a few of us on occasion have had to use this substance, but how of its History...
1470: Alum (previously known in the Middle East) is discovered in Europe
for the first time, specifically Tuscany. It was first found between
1300 and 1310 in Rocca (Syria). The mineral Alum is
the double sulphate of aluminum and potassium, AlK(SO4)2 + 12 H2O,
is a common compound of Aluminum, which was not isolated until
1825 by Hans Christian Oersted (although anticipated and named in 1807
by Sir Humphrey Davy). Alum comes to be used for dyeing, leathermaking,
medicine, paper sizing, and fireproofing.
Europe's problem since Roman times had been a chronic imbalance of trade. Bullion drained out of northern Europe into Italy and thence through the Middle East to the Far East, to pay for imports of alum, grain, oil, and wine, and luxury goods like silk and pepper. In exceptional times and places this problem did not apply. For example, the fur and slave trade through Russia that was run by the Vikings and then by the Russians themselves resulted in a flow of silver north of the Black Sea into northern Europe. But this did not last for very long, and did not affect southern Europe very much. Venetian merchants were always reminding their agents in the east to use barter wherever they could, but they were usually required to pay in silver and gold; failing that, in copper, tin, or lead.
http://www.wovepaper.co.uk/alumessay1.html
Just a few snippets of its history, for those interested the web site gives an excellent review but a little long winded to down load...
All the best for now,
John.
« Last Edit: 3/27/08 at 9:44 by lancelot » Link
rake60
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4wheels said:
I was a licensed taxidermist at the age of 16.
I bought alum by the pound at that time to cure deer hides for mounts.
Every night I had to pull those hides out of the alum baths to work them over
a wooden beam. It was to keep them from hardening of shrinking.
It was a little tough on the hands. A lot of cracked and split skin on the knuckles.
I didn't know at that time alum could serve a better purpose down the road.
I dumped enough of it in the woods behind the house to dissolve hundreds of taps.
Rick
Well
A Heartfelt thanks to all of you who actively participated in this wonderful animated lesson on Broken tap removal.
I was taken from the taxidermists, then on to chemistry school and in to the deep dark woods.
Thanks again for some wonderful information.
p.s.
I know of a resting place where we can all take our embedded taps into the the dark. dark woods.
Cheers
Phil
A Heartfelt thanks to all of you who actively participated in this wonderful animated lesson on Broken tap removal.
I was taken from the taxidermists, then on to chemistry school and in to the deep dark woods.
Thanks again for some wonderful information.
p.s.
I know of a resting place where we can all take our embedded taps into the the dark. dark woods.
Cheers
Phil
Hi Phil,
You can buy the stuff at Bunnings in the pool section. It's called a flocculent and the active ingredient is Aluminium Sulphate. I spent ages trying to track some down here in OZ. Finally went to bunnings and found 1kg for about $15. Chemists were charging $15 for 10grams. I mixed my brew up in an old rice cooker to keep it warm and it took 3 hours to completely dissolve a 3mm tap in aluminium.
You can buy the stuff at Bunnings in the pool section. It's called a flocculent and the active ingredient is Aluminium Sulphate. I spent ages trying to track some down here in OZ. Finally went to bunnings and found 1kg for about $15. Chemists were charging $15 for 10grams. I mixed my brew up in an old rice cooker to keep it warm and it took 3 hours to completely dissolve a 3mm tap in aluminium.
Removing a broken 2mm tap from a piece of 1/2" x 5/8" x 1 1/2" brass
Here are my observations after having purchased some Flocculent (active constituent:-Aluminium Sulphate) from Bunnings Warehouse Australia in the pool section.
Cost
2Kg refill pack $9.60 from Bunnings Warehouse
100 gram from local pharmacy quoted $16.00 ( equals $192.00 for equivalent amount)
Method
Made up a Saturated solution of approximately 300 millilitres of water
and placed in to an old Aluminium saucepan, placed on kitchen stove,brought to high heat then reduced to a low heat
After a few minutes, large (2mm) bubbles began coming from the broken tap area.
Used a shiny Stainless steel spoon for stirring the mixture.
At 15 minutes,
the shiny stainless steel spoon became a dull stainless steel spoon, Wife not happy( could be useful for making a Satin finish)
The old Aluminium saucepan became a cleaner Aluminium Saucepan. Wife not impressed. ( could be useful for cleaning oxidised Aluminium) Metal stove top can become discoloured if spillages occur. Didn't alert wife to this.
At 30 mins
Small (less than 0.2mm) Bubbles still escaping from broken tap area.
Will give final results when completed
Phil
Here are my observations after having purchased some Flocculent (active constituent:-Aluminium Sulphate) from Bunnings Warehouse Australia in the pool section.
Cost
2Kg refill pack $9.60 from Bunnings Warehouse
100 gram from local pharmacy quoted $16.00 ( equals $192.00 for equivalent amount)
Method
Made up a Saturated solution of approximately 300 millilitres of water
and placed in to an old Aluminium saucepan, placed on kitchen stove,brought to high heat then reduced to a low heat
After a few minutes, large (2mm) bubbles began coming from the broken tap area.
Used a shiny Stainless steel spoon for stirring the mixture.
At 15 minutes,
the shiny stainless steel spoon became a dull stainless steel spoon, Wife not happy( could be useful for making a Satin finish)
The old Aluminium saucepan became a cleaner Aluminium Saucepan. Wife not impressed. ( could be useful for cleaning oxidised Aluminium) Metal stove top can become discoloured if spillages occur. Didn't alert wife to this.
At 30 mins
Small (less than 0.2mm) Bubbles still escaping from broken tap area.
Will give final results when completed
Phil
Wow, Bunnings is selling something useful that is hard to get elsewhere.
That's got to be a first.
I've not broken a tap yet but I'm sure I will at some point.
I've been thinking about buying one of those bench top ovens with a hob on top of it for curing paint and having a go at jappaning.
This has just given me another reason to get one.
That's got to be a first.
I've not broken a tap yet but I'm sure I will at some point.
I've been thinking about buying one of those bench top ovens with a hob on top of it for curing paint and having a go at jappaning.
This has just given me another reason to get one.
Good one Phil but I think you had better find another heat source while you can still walk. :big: Not worth upsetting SWMBO.
Good price too. That's cheaper than what I saw it going for.
Someone gave me an old rice cooker an I used that. They'd broken the glass lid which is why they had given it to me but I stretched a bit of plastc over the top to cut down on evaporation. I've seen these rice cookers going at Aldi for $19
Good price too. That's cheaper than what I saw it going for.
Someone gave me an old rice cooker an I used that. They'd broken the glass lid which is why they had given it to me but I stretched a bit of plastc over the top to cut down on evaporation. I've seen these rice cookers going at Aldi for $19
at 1 hr and 45 minutes, added more water as some has evaporated.
I can now poke a toothpick in to one of the holes where the tap used to be in the vertical hole.
Note
There are two broken taps in this rectangular piece. One is vertical on the part and the other is horizontal, 75% of the vertical tap has been dissolved, however the horizontal tap is still intact. The vertical tap seems to be more affected by this process and I would now suggest this may be the preffered way to help dissolve the part i/e Place the part in the pot so the broken tap is upright.
Aluminium pot has become somewhat scummy , probably remains of some of the dissolved HSS tap. Pot which is in contact with the solution is verty clean. Wife still not impressed.
At 2 Hrs, the horizontal tap has now begun to bubble. Rearranged the part in the pot so that other broken tap is now sitting vertically.
In order to still have the part covered, I needed to add extra water ( approx extra 300 Ml. Now I suspect that the solution is no longer saturated so may need to add extra Alum and re saturate the solution. ( add extra Alum until it will no longer dissolve)
I am now also thinking that because of the effects on the Aluminium pot and the Stainless steel spoon that perhaps I should not be using these materials for trying to dissolve the part as some of the active ingredients are actually dissolving the parts I dont need to be dissolved. Perhaps a brass pot with a plastic or brass spoon or even better a pyrex pot may speed up the process and use up less Alum.
I can now poke a toothpick in to one of the holes where the tap used to be in the vertical hole.
Note
There are two broken taps in this rectangular piece. One is vertical on the part and the other is horizontal, 75% of the vertical tap has been dissolved, however the horizontal tap is still intact. The vertical tap seems to be more affected by this process and I would now suggest this may be the preffered way to help dissolve the part i/e Place the part in the pot so the broken tap is upright.
Aluminium pot has become somewhat scummy , probably remains of some of the dissolved HSS tap. Pot which is in contact with the solution is verty clean. Wife still not impressed.
At 2 Hrs, the horizontal tap has now begun to bubble. Rearranged the part in the pot so that other broken tap is now sitting vertically.
In order to still have the part covered, I needed to add extra water ( approx extra 300 Ml. Now I suspect that the solution is no longer saturated so may need to add extra Alum and re saturate the solution. ( add extra Alum until it will no longer dissolve)
I am now also thinking that because of the effects on the Aluminium pot and the Stainless steel spoon that perhaps I should not be using these materials for trying to dissolve the part as some of the active ingredients are actually dissolving the parts I dont need to be dissolved. Perhaps a brass pot with a plastic or brass spoon or even better a pyrex pot may speed up the process and use up less Alum.
Melbourne_Phil said:
The cooker I used was one of those teflon coated ones.
I had a bit of blackish ozidisation on my part after I was finished but it cleaned off easily.
Just drape a bit of Gladwrap or clear shopping bag loosely over your pot so it hangs lower in the middle. Poke a couple of small holes in it to help release the pressure. That way when the water evaporates it will drip back into the pot and cut down on your evaporation.
FWIW, heat is not actually required; it just speeds the process. When I had to get a drill out of a brass block, I made the solution hot, then stuck the part and solution in a covered jam jar and left it there, shaking occasionally, for a couple days and the drill was gone. Lots of Alum crystals formed in the process as the solution cooled but didn't seem to hurt anything.
Thanks Wannabee2 and Shred both good tips especially as I dont want to dull any more stainless steel spoons.
Left the part overnight on stove top turned off.
Both Taps are now completely dissolved and was able to put a screw in the hole without any further tapping required. I must have been at the bottom of each hole when the taps broke.
Highly Recommend this method of broken tap removal. Am now trying to remove a broken tap from an Alumiinium block from my v-4 Oscillatong cylinder engine from 20 years ago.
Left the part overnight on stove top turned off.
Both Taps are now completely dissolved and was able to put a screw in the hole without any further tapping required. I must have been at the bottom of each hole when the taps broke.
Highly Recommend this method of broken tap removal. Am now trying to remove a broken tap from an Alumiinium block from my v-4 Oscillatong cylinder engine from 20 years ago.
wm460
Member
Very interesting link, Glad to see that Alum is readily available in Aust.
