Is its says really, how ot go about getting a snapped tap out of an ali head.....

ouch, anything sticking out at all?
I used a small watch making type screwdriver to gently tap the broken lip of a bolt anticlockwise. Worked with patience.
Im guessing its in tight to break?

Right in the bottom, was cleaning the thread up after extracting a broken bolt!

is it a flush snap or are there any jagged edges

I use a range of Tungsten Carbide ball burrs for such. You cannot buy a set of them you just have to search around ebay and the like. Autojumbles are good for them.

example: http://uk.farnell.com/jsp/displayProduct.jsp?sku=1773748&CMP=e-2072-00001000&gross_price=true

Iv got some of them, never used them, how do you for such?

Well now you do have a little challenge.

When I was a boy, long long time ago, I had an air rifle that was only held in the
stock with 2 out of three screws. After talking to my Metal Work Teacher at the time,
He suggested that I remove the barrel and take the 'compressor part' to school and he would have a look.

He found that there was a bit of a tap in the hole, and said " The only way to remove these is to 'shatter' them".

He ground a center punch so that it would go into the hole without damaging the remaing thread and
kept 'tapping' it with a hammer. It eventually broke into small enough pieces to be withdrawn.

Have fun.

Len.

Not sure where to get them, but you can buy tap extractors. A sort of three pronged tool with a tee handle. The only other way without damaging the thread is by spark errosion, try searching yellow pages.

Do you have a picture?

What kind of tap, high carbon steel or HSS?

If it's HSS don't even waste your time trying it with a carbide burr, no idea how carbide will fair against high carbon steel.

If you broke it because it was tight in the hole e.g. you bottomed it out or jammed it with cuttings then there is no chance that a "tap extractor" will take it out. If you sheared it off because something fell on it etc but tap wasn't tight before it broke then you may have success with this method.

Smashing it to bits in the bottom of the hole works if the surrounding material is strong enough to take the abuse, it will knacker all the threads the tap covers

Do you have burning gear?

If you have burning gear and can get the tap nice and red (you may damage the ali at the top of the hole) then welding something to it while hot sometimes works.

Broken tap in alloy is pretty much the worst case scenario

Cheers
Davie

Aluminium sticks to the tap, so you need to back off religiously every half turn, as it builds up in the flutes it wedges solid in the hole.

I think you have zero chance of getting it out and leaving the thread intact, be prepared to helicoil, if its the RV8 another head may be the cheapest least frustrating option.

I have got many a tap out by 'drilling' them out with a carbide endmill. Though the BEST way as said is spark erosion. It really is a choice of how accurate (tidy) you want it removed.

I welded a nut to the remains of the tap, the thermal shock should get it out, I had to do it twice to get it out, the tap was flush with the hole.

Came out a treat in the end, then I ran a fresh tap down the threads to clean up any nicks and stuff

Cheers
David

If the previous suggestions don't work take it to a machine shop that does spark eroding.
The hardness of the tap material will not matter then.

· Don't know if this little tip works with ally but it may be worth a try, taken from Hints and tips for using a lathe

Busted a tap in a bit of brass? - Here’s a great tip - build a plasticene "dam" around the bit of tap to be removed, then mix up a strong solution of ‘alum’ (available from the local chemist for treatment of bed sores). Pour this into the dam and put the whole lot in the airing cupboard. I don’t know if the action is electrolytic, or why it works, but the alum attacks the steel leaving the brass completely unscathed. After a day, a carbon-steel tap will have become loose enough to wiggle out; H.S.S. takes about a week.

HTH

Last time I did something like this - long, long time ago - I took it to a local engineering shop and asked them to use their spark eroder on it. Takes a few hours, but it's something they can set up and leave alone, so very low labour involved.

This was the cylinder block for my 5" steam loco and I'd finished all the other machining, so there was probably 50 hours of my time invested in it - I really didn't to start again, or mess it up trying to get the tap out!

It cost me £5 into their tea/coffee fund - I can't guarantee that you'll get the same price!

Rusty Nuts may be on to a winner - just check to see if alum reacts with aluminium before you try it...

http://www.cromwell.co.uk/index.php?search_all=tap+extractors&search.x=0&search.y=0&p=advancedsearch&q=0

A number of options available from Cromwells. I've got a few of various sizes. These actually work, but may need patience and care, depending on tapped material.

Cheers,
Nev.

A local engineer to me ground a tungsten tipped SDS bit to replical the same angle as a high speed steel bit and drilled mine out, he said it can be done with any tungsten tipped masonery bit just drilled really slow.

Not read all the replys as im off to bed, but heres what id do.
Find a metal tube thats small enought to get in the hole and protect the thread, but big enough to get a drill bit into,
Measure the depth of the hole in a clear adacjent stud hole so you dont drill the head, then drill down the hole with the tap in, hopefully you can drill it enough so it colapses and can be cleaned out.

Yes that does usually work quite well, I have done it many times in the past, it is worth making sure that you use a good quality masonry drill as the cheap ones tend to be brittle and can snap the carbide off making matters worse.You do need to be able to grind a drill successfully though and would need a green grit wheel as normal grinding wheels struggle to grind carbide.
Paul

quote:

---

Originally posted by austin man
A local engineer to me ground a tungsten tipped SDS bit to replical the same angle as a high speed steel bit and drilled mine out, he said it can be done with any tungsten tipped masonery bit just drilled really slow.

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As somebody already said you have the worse case scenario, spark errosion or get another head.

Ok, here you go, best picture I could get...



And, the offending tap....



Thought I'd done well to get the stud out! The last thing I wanted to do was an engine rebuild....

I am reluctant to post on this one with all the really good advice already given on the subject.

It is obvious from the picture most of the hard bit of the tap is still in there!

However as the hss tap remaining is not far down the hole I think if I had the problem I would be tempted to mig down the hole to create a bead of weld on top of that broken tap. That may achieve two things:

1) The heat alone may solve your problem by releasing the tap.

2) If not released then you have some workable metal to cut a slot in down the hole with a dremmel.

Once you have a slot in that tap and released by the heat I think it would come out with a screwdriver.

No doubt I will be slagged for my non professional approach but I do feel for you with this one, it is a bitch!

Its Out!!

Used a small (5mm) milling piece and a large lump hammer, smashed it to bits and after about an hour hammering away and picking bits out theres only a tiny bit right in the end that I've probably hammered into the bottom!

Threads are Ok as well, just a bit slack for the first 4 but it goes in 11 threads and is nice and tight.

I'll be getting a stud conversion and glueing that one if just to make sure

Back on track!

Time to buy a lottery ticket

Well done.

Len.

phewww