ARGUS oscillator

[Ramon WilsonParticipant @ramonwilson3]

Well there you go Dick – just goes to prove you can learn something every day.

 

Where I could, I think I would still make a small hollow cutter but that’s a matter of preference though its a tip worth knowing. I have seen the tip regarding Alum several times, though never tried it, but never heard of using Ferric chloride. I have a feeling that Alum only works in non ferrous material anyway

 

As a matter of interest how long would you expect the chemical reaction to take say on Petes 10BA tap and why wouldn’t the FC etch the surrounding material as it does in normal etching – that is any area exposed to it outside of the hole. Given this specific situation wouldn’t it be quite difficult to get sufficient down the flutes of a 10BA hole.

Thinking about it I guess you could mask the area – sellotape? – expose the hole then make a substantial ‘dam’ on the selotape and then try to get the fluid down the flutes and the trapped air out using a thin bit of wire?.

 

If – and hopefully it won’t  – too soon (fingers crossed)  – I have the same misfortune I will certainly try your method out 

 

Regards – Ramon

Edited By Ramon Wilson on 21/08/2010 10:26:16

[NJHParticipant @njh]

ARC Eurotrade sell diamond core drills – the smallest is 3mm. I used one of these recently when I broke off a tap in the Stent I am building. The drill was destroyed in the process but  it got the broken tap out !

Good luck

Norman

[Ian S CParticipant @iansc]

The base is mild steel, so any chemical method  is not going to work. If the tap is carbon steel it could possibly be heated the drilled out, other wise mechanical means must be used, or electrical. Ian S C

[Richard ParsonsParticipant @richardparsons61721]

 

Raymond,
I do not want to go into this problem too deeply. Reactive chemicals like Alum (Potassium Aluminium Sulphate), Ferric Chloride are intrinsically chemically reactive. They would all rather be some other compound with a higher energy barrier and so be more stable. 

To do the tap removal trick: –

1.    Degrease the tap and hole. This is important!

2.    Build a little dam around the hole using wax/modelling clay/shellac/PCB resist. Do not let any go down the hole.

3.    Use an eye dropper/pasture pipette or W.H.Y. drip in your reagent.

4.    Make sure you do not get air trapped in the hole.

5.    Let the reaction start. Wash out and refresh as needed.

Do not use acids they will not work well in this way.

Selotape (Durex for those who live upside down where the Cross hangs in the sky)  I have never used it. (U.K. stuff has semi-water soluble glue).

The last time I had to pull this stunt was in 1996 on a 12 BA tap (or there about) I used some candle wax (from a real ‘Frankie Randall’ not one of those smelly things the S.W.A.M.B.O’ have in the bathroom).  I like good old Carbolic anf a lump of bath brick -to get rid of any clinkers- my self

For small taps It works! And is cheaper than building a ‘Sparky’.

Good luck

Dick

Edited By Richard Parsons on 21/08/2010 12:55:08

[John OlsenParticipant @johnolsen79199]

Well here in New Zealand Durex is something you might want to take on a date if you had high hopes….I don’t know what it might be in Oz, they speak a different language over there.

[NJHParticipant @njh]

Good Grief John!

Presumably though they don’t go out on hot dates with a roll of sellotape in their pocket!

 

Sorry to have drifted off a bit here Peter but my justification is that if you have broken a tap off in your work anything that can raise a smile is good.

………………and why is it that disasters of this kind always seem to occur after considerable work has been carried out on the component and scrap & start again is not an option?

 

Norman

Edited By NJH on 21/08/2010 15:39:13

[Richard ParsonsParticipant @richardparsons61721]

John,

I think you have it in one!  I could tell how one from a land where one once needed a criminal record instesd of an enttry visa to get there  got his face slapped in a chain stationers – but I wont.  That ia enough of the traditional ritual insuts. so I will buy you all a beer and as you are not here I will have to drink it for you.

Dick 

Edited By Richard Parsons on 21/08/2010 15:43:07

[Ramon WilsonParticipant @ramonwilson3]

It’s called ‘Sods Law’ Norman –  surely it has to be one of our biggest ‘stress raisers’ on a job – a long worked at component with oodles of tapped holes and just one more left to do

 

Talking of Sods Law – after two days of searching for a set of car keys where I looked everywhere I found lurking in the back of a drawer the Dickson tool holder spanner which I was convinced I had thrown out with a pile of swarf several weeks ago. The keys? in a jacket pocket – where else

 

Hope you manage to get your tap out successfully Pete.

 

Ramon

 

 PS thanks for the info Dick – interesting alternative label on the sticky stuff!!

Edited By Ramon Wilson on 21/08/2010 18:28:20

[Charlie,Participant @charlie18171]

Hi Peter You could try using a left handed drill bit,(as if you would have one of those of the right size kicking around),A long shot but has been known to work,Good luck ,

[Peter HardingParticipant @peterharding54323]

Many thanks to all those who have responded to my little problem!

 

I don’t have internet at home so coming into work today was a nice surprise of all those willing to help.  As this tap is for one of the cylinder to base plate bolts and will be pretty much hidden by the steam chest I don’t have to overly worry about the looks of the repair.  I will take all of your practical methods on board and let you know what I have decided.  After walking some 22km this weekend I won’t be standing up at the lathe for a few more days

 

Also I recieved the first parts of my Blowfly locomotive this weekend. Frames, buffer beams and all stretchers for the locomotie aswell as the bogie sideframes and bolsters for the riding car.  All laser cut for less than I could get the plain metal for

 

Pete

[Sub MandrelParticipant @submandrel]

Jasper Carrott had a great routine about ASussies and Durex…

 

Neil

[Peter HardingParticipant @peterharding54323]

Well I emigrated to Australia in the 80’s and I’ve never seen Durex except at the chemists

 

Pete

[David Clark 13Participant @davidclark13]

Hi There

Can we stop talking about sellotape etc and get back on to model engineering?

regards David

 

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