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might try a left hand drill bit if its flat enough for the drill to bite
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Man, I spent many hours making a part and then when I was tapping it manually, the tap broke with a lot stuck in and not a lot sticking out to unthread it.
How do you remove taps?
Heat it up then try unthread it?
People have fancy methods like using EDM but I dont have that. The tap I believe is hardened carbon steel with titanium nitride coating. Presumably I can run a carbide end mill right down the center as its harder to cut it out. The problem also is the tap is super small. I dont think I have any carbide end mills that size, let alone that size to throw out.
Any tricks?
might try a left hand drill bit if its flat enough for the drill to bite
Saw a simple EDM arrangement for such cases somewhere on the net.
Here's a link to a thread in another forum
Home Made EDM
If the part is aluminum you can dissolve the tap by boiling the part in an alum solution.
Tap out.
You make a small dam of some putty around the tap, place tap out in the dam, after some period of time depending on tap size, the acid eats the tap away enough for it to fall right out.
Here is one version of it
http://www.chemical-supermarket.com/product.php?productid=574
If the part is aluminum or stainless....
Clean the hole and tap thoroughly.
20% solution of nitric acid in tap water poured into hole with a clay (or suitable putty-like substance) as a dam and leave to soak. It could take a day or two....
It'll bubble and smoke, and periodically you'll want to replenish the solution with fresh... and keep picking the pieces out with a dental pick or some such..
If you have a low voltage power supply, hook up some aligator clips to the part and the tap to accelerate the process.
,,,,,,,,,,,, If you're patient and brave and have a carbide mill, you can mill it out. I've only managed to break the mill along with the tap.. so I don't do that. Some guys are really good at it. I ain't.
The tool broke not with a flat surface. Yeah its a 6061 part. The tool is probably tool steel but TiN coated on the business end.
I dont have any of those chemical methods right now and wanted quick solutions. So I broke a couple of tools trying a few things.
Found a 1mm diameter carbide end mill. Plunge in is the only space I can do to fit in the space. Plunge in from the broken and not TiN coated end of tool. End mill broke right away.
Put in a diamond coated grinding tool. Grinded for a while and it worked, but on deeper plunges in the cnc, tool started defecting around broken geometry and then broke.
I then manually grinded the top flat with a ball nose diamond coated grinder. then tried to drill it in. Wouldnt budge since its similar material and hardness of course so backed off.
All the while this has been probably work hardenining the tool more if its not already hard enough.
I made a make shift approach to discharge machine it with a copper wire as the sinker. It worked but painfully slow. After a hour I can see a tiny hole eroded away, but at this rate it will take forever.
I also broke another tap while trying to finish the other holes while figuring a solution to get the tap out.
So now the part has 2 broken taps.
Probably better to just remake the part and go real easy on the hole tapping where ill back off with the slightest resistance.
Where do you guys buy the fluid for get rid of the taps? Theres a mechanical solution too like walton tap extractors (where 4, 3 or 2 pins are inserted into the gap depending on the design of tap to help unthread it), any tried them?
I have had very poor luck with the fingered tap extractors. If you plan to break a lot of taps, look for a machine called a tap burner. Works similar to manual sinker EDM with a tungsten electrode, but no coolant. Alternative is to keep a lot of small 4 flute carbide end mills on hand. At least one for every tap you break. The most cost effective solution is to learn how to tap without breaking the tap. This is one of many skills that cannot really be described with words effectively. Even when demonstrated, it is a physical skill that has to be learned. Some people have some natural abilities to learn the "feel" of tapping. Many do not.
http://www.kirkcon.com/
In my experience of breaking of smaller taps in the bore I came to realise that its false economy and headbanging to buy cheap taps in the smaller range and is best to buy the best in these taps.
some cheaper taps are very brittle material and are prone to snap in aluminium because of the nature of aluminium.
I normally use carbide ground into a spade style end, held in a collet , taking very small pecks at Max, Spindle speed
Rockcliff Machine Inc.
www.rockcliffmachine.com
Where I work broken taps are a common occurrence.
Through the years I have tried just about every method of removal.
Sometimes peck drilling with a carbide end mill works but usually ends up chewing up the end mill by the time you reach the finished depth. I like to circle mill the taps out using a helical clockwise (Not Counter Clockwise) motion. It doesn't need to be much of an offset motion but best not to feed more than .005 per pass. High rpm plenty of flush coolant even a blast of air occasionally. Remember that the direction you fed the tap in there is not the direction you want to cut it out. Once the tap does decide to let go you don't want it screwing out and breaking your end mill. Good Luck !
Originally Posted by bebob1
if you are having issues tapping on a manual mill that used like r8 collets and such, a good trick is to leave it just a little bit loose so when it torques out, it spins in the collet instead of breaking the tap. then you can back out and tap back in like peck tapping.
as for getting the tap out, usually we use a dull small carbide endmill since most sharpening companies wont touch anything under 3/8" due to replacement price. take it really slow with air blast and you can easily work it out.
also, you might wanna look at a tapping fluid like anchor lube or tap magic or rapid tap. i highly reccommend anchor lube for stainless steels..
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