# Broke a Tap



## gredpe3 (Oct 11, 2014)

I broke a tap off in a part I have been working on for a couple evenings.It broke just as it was crowning the other end of the hole.I picked at alittle and chalked it up to the school of hard knocks.Should have drilled the hole a little bigger.Anyway more practice on layout and back to the mill.This time I will drill to nearest fractional size.Its not a load bearing fastener.I am making a hold down for a v-block.:angry::angry:


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## kd4gij (Oct 11, 2014)

What size tap and what materia is it in?


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## Shadowdog500 (Oct 11, 2014)

gredpe3 said:


> I broke a tap off in a part I have been working on for a couple evenings.It broke just as it was crowning the other end of the hole.I picked at alittle and chalked it up to the school of hard knocks.Should have drilled the hole a little bigger.Anyway more practice on layout and back to the mill.This time I will drill to nearest fractional size.Its not a load bearing fastener.I am making a hold down for a v-block.:angry::angry:



do you have a photo?  what material?

a broken tap sucks, but it isn't the end of the world.
There are ways to get the tap out.

chris


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## JimDawson (Oct 11, 2014)

On small holes, I would use a Dremel and a carbide burr.  It takes some time, but it works.  Sometimes it's possible to grind a couple of small dowel pins to fit down the flutes of the tap, then grab them with Vice-Grips and try to twist the broken tap out.  The problem with that is that many times, the tap ''explodes'' in the hole, so it wedges in the hole.  There are also some chemical methods of removing taps depending on the materials involved.


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## george wilson (Oct 11, 2014)

As I have mentioned before,I have a few sets of Chinese made carbide end mills,from about 1/32" to about 1/8" in assorted steps. They are probably metric. I have used them several times to mill out broken HSS taps when I was the toolmaker in Williamsburg museum. Others would bring their broken taps in gun springs(or other stuff they SHOULD have tapped before hardening!!) I ran the Bridgeport as fast as it would go. With the assorted carbide milling cutters,I could find a size that would mill out the tap,leaving the threads perfectly intact.

I used to buy these sets at a gun show from a guy who sold import tools. They were $10.00 for a box of 10 small carbide end mills. They are great little taps. I wish I could find more of these sets. They are well coated with TIN.


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## gredpe3 (Oct 11, 2014)

Got the part re-made,went and found a tap to replace the one I broke(10-32NF).In the morning I will drill and tap.Ace had the correct bit also.Here is the mistake.The part is just mild steel.I tried the carbide end mill thing and broke it also.


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## Round in circles (Oct 11, 2014)

I'd try get a decent socket set screwdriver bit  &  the brace or "T" bar set up from the  socket set , then grind a perfect screwdriver slot in the unbroken end  of the tap then , 
Gently  heat the whole item to boiling point , slip it in a vice that you can work at from above whilst  using the socket set screw driver set up ,give it a squirt of oil and use the screw driver and a socket set to gently but with firm pressure from above at the vertical try and unscrew the tap . You may find that the different coefficients of linear expansion of the block and the tap are enough to make a tiny workable clearance  to start movement .

 If there is no movement  heat the whole block to a nice cherry red to let it cool with out doing anything to it to anneal the metals .  Now try and unscrew it as above then using a made up mild steel drill guide clamped to item dot punch the tap once only , now drill it out using the drill guide jig & a cobalt drill  then re -temper or case harden the block AFTER  you have completed the tapping .

 You could also consider laying a lump of MS over the protruding tap end whilst it is on a solid surface and giving ONE ( only one )  fair smack on the M .S. with a one pound hammer  ..it may move the tap back a smidgeon ..just enough to enable you to do the unscrewing as indicated above . I'd do it before I cut the screw slot to reduce the chances of the tap shearing at  the end around  the slot . 

 Thinking a bit laterally about some of the things I've done to remove broken /sheared cylinder head bolts etc . ...  

Having cut the perfect screw slot in the tap end with a Dremmel type grinding blade you could use the drill press chuck to hold the screw driver bit at perfect right angles to the axis  and use the operating lever of the press to apply pressure to keep the bit in the slot whilst  turning the chuck gently but firmly by hand or very carefully with a pipe wrench etc. on the chuck part that is not moved when you use the chuck key . 

The secret of it all is a continuous gently downward force applied to a well fitting quality Diamond coated cobalt or titanium screw driver tip that fits perfectly in  the cut slot , turned with a constant  smooth rotational pressure/ movement .


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## pdentrem (Oct 11, 2014)

I use diamond burrs in a Dremel to grind out the broken taps. I use light oil or water to lube and cool the burr.
Pierre


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## gredpe3 (Oct 11, 2014)

I still have it,years ago that part would be at the bottom of the pond.I have a little room to take  the top down some.I think I'm gonna try and mill around it and expose it a little.Then maybe slot it or something.


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## savarin (Oct 11, 2014)

you need one of these. http://www.homemodelenginemachinist.com/downloads/files/Easy_Spark_Eroder.pdf
The circuit is very simple but works well.
I lashed up mine using wood for the slides, square steel tube for the post, an old chuck from a broken drill and powered it from the transformer of an old welder giving 40V to drive it.
The down feed was a bit of all thread with a handle. In practice the vibration from its operation self feeds the head.
Some very rough pics here of mine (from post 19)and more links further down
http://www.hobby-machinist.com/showthread.php/10122-tumbler-reverse?highlight=savarin


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## chips&more (Oct 11, 2014)

Your pictures show you maybe used the old 4 flute tap style? That style of tap does not do a very good job of dealing with the chips it makes. And so can bind up with chips very easily and break. The gun tap is my tap of choice. As it cuts the threads the chips are directed to the front of the tap. No real need to cut CW and then back off CCW like you would with the old style. You can just feed the tap in all the way with no fear of chip build up and use cutting fluid where applicable, Also, maybe the gun tap is a little stronger because of its two flute design…Good Luck


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## GarageGuy (Oct 11, 2014)

I don't do too much tapping... just every once in awhile.  I have what I think is a good quality tap and die set (Hanson) that I bought back in the late 1970's.  I was tapping a 3/8-16 through a 11/32" hole in mild steel, and it just wasn't working well.  I had it nice and straight using a T handle with a live center in the tailstock, and used plenty of cutting oil.  I even double checked the drill size to make sure I had drilled the right size hole.  It was right at the point where I thought the tap was ready to break, so I backed it out of the unfinished hole, and went to the tool box to see if I had another tap.  As luck would have it, I had recently acquired one in a tooling lot purchase.  I didn't know it's history, but I mounted it up, and it cut just as smooth and nice as could be.  I couldn't believe my original tap could have been that dull, but it obviously was.  I chucked it into the scrap tooling bin (HSS that I save to cut new tools from), and bought a new one to replace it.  Next time I won't fight it as long before trying a new tap.

GG


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## Frank Ford (Oct 12, 2014)

If you have never tried a high speed steel spiral point tap, you should.  The difference between them and hardware store Hanson or Ace taps is nothing short of un-f-ing-believable.

After I made the "discovery" for myself, I literally gave away all my carbon steel taps, and have not looked back!


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## gredpe3 (Oct 12, 2014)

Everthing went good this morning,I had things lined up better.To start with I had the correct drill to use for the tap.So new drill bit /new tap and job went well.I go to put the screw in ans its to loose.Turns out there is a metric screw that fits closely to the thread gauge in the standard set.I had a metric screw the whole time.I went and got the correct screw and now all is good.Rookies , God help us.


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## gredpe3 (Oct 12, 2014)

I have yet to get the broke tap out of the other part.Dont think Im gonna mess with it,since I now have what I was going for.


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## savarin (Oct 12, 2014)

Since I built my spark eroder I've used it 4 times. Very handy indeed particularly knowing I can make the repair there and then.
I will be playing with larger copper electrodes and square and triangular shaped ones for shaped holes.
Maybe hex to make my own socket screws who knows.


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## Round in circles (Oct 12, 2014)

Now look what you've gone and made me put on my " To Do " list  Savarin ........."  Build a spark erosion machine , using my old stick welder " ( 90 volt open circuit ) 

 It's *ONLY*  number 57 on the list .:man:


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## Round in circles (Oct 12, 2014)

savarin said:


> Since I built my spark eroder I've used it 4 times. Very handy indeed particularly knowing I can make the repair there and then.
> I will be playing with larger copper electrodes and square and triangular shaped ones for shaped holes.
> Maybe hex to make my own socket screws who knows.



I like the idea of putting in square holes , especially on round bars turned up out of square bar that fits the tool post , either in the end square on  or ...at an angle as a small single leg fly cutter or on the side for that could make a fantastic boring bar tip holder .

 Do you use a single set shaped electrode/tip or  is it a series of small electrodes strategically placed  in a round hole to get the square one   ?

Do you have any idea of the smallest square hole we can expect to obtain using the spark erosion technique? 

 Another thing about it is that I may be able use spark erosion techniques to make some small steel moulds to free or centrifugally cast some aluminium or wax parts  as I don't have a mill ( Yet  ! ) 
........  Do I " Darling ",  :whistle:says Dave to his wife < who has just popped int othe room and peeked at what he's typing .  ) :happyhappy:


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## Shadowdog500 (Oct 12, 2014)

george wilson said:


> As I have mentioned before,I have a few sets of Chinese made carbide end mills,from about 1/32" to about 1/8" in assorted steps. They are probably metric. I have used them several times to mill out broken HSS taps when I was the toolmaker in Williamsburg museum. Others would bring their broken taps in gun springs(or other stuff they SHOULD have tapped before hardening!!) I ran the Bridgeport as fast as it would go. With the assorted carbide milling cutters,I could find a size that would mill out the tap,leaving the threads perfectly intact.
> 
> I used to buy these sets at a gun show from a guy who sold import tools. They were $10.00 for a box of 10 small carbide end mills. They are great little taps. I wish I could find more of these sets. They are well coated with TIN.




Do you have a photo of the packaging, bits, or remember the name of the manufacturer or tool dealer. Even if the dealer died, his unused website can stay up for years.(if he had one)

I will try to hunt these down.

Thanks,

Chris


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## bfd (Oct 30, 2016)

welcome to machining if you haven't broken a tap you have never tapped a hole bill


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## Christian Poulsen (Nov 1, 2016)

It happens...as a retire I still have access to EDM sinkers (naner, naner!) to burn out my blunders when bkn tap removers, picking and breaking, heating up the surrounding steel with a torch (yada, yada) don't work...Note: For small taps (6-32 down to about a #2), always drill around .004 to .005 bigger diameter than called for depending also on % of depth of thread you need (how hard you're gonna' crank on that screw)... and of course only a quarter to a half turn (or less!) before backing out to break that chip  and keep blowing out those chips and I prefer using the old "watery" rapid tap (rather than some of the new "syrup") on small taped holes...and don't forget to put a small lead in (out? lol) on the back side of the hole too (too get rid of any break through burr left from the drill)


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## tq60 (Nov 1, 2016)

Since tap is sticking out bottom gently tap it with a hammer as that will unseat it a bit.

Use a hand grinder to make flats so you can grab it with pliers.

Some oil will help if dripped in from bottom but keep tip dry.

If cannot grab it try gently offset turning it by placing very sharp punch on the side and tapping it to unscrew it and use multiple angles.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## milomilo (Nov 1, 2016)

Use a Walton tap extractor to remove a broken tap. They work very well.

http://www.waltontools.com/products/remvtap.htm


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## kingmt01 (Nov 2, 2016)

Was that from power tapping? I've decided it's faster to hand tap then to remove broken taps or rebuild parts. I'll power tap the first couple of threads to make sure the tap is started straight then hand tap it with a ratchet the rest of the way. I break less that way. Power tapping seems like I only get 4 holes then they snap even if I'm doing the 5th one by hand. I will power them back out of a hole but that too seems to weaken them.


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## 4GSR (Nov 2, 2016)

bfd said:


> welcome to machining if you haven't broken a tap you have never tapped a hole bill


You also learn over the years your limits on pushing a tap, too.  When to toss out a worn tap and what tapping fluid works the best, and using higher quality taps too!  Among other things, new cuss words, a big respect to tapping holes.  Ken

BTW-You sure can't beat an new old stock Card or Butterfield tap when you can find them!  They seem to tolerate a little more stressing before snapping off compared to many of the newer ones today.


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