Broken tap solutions

[miestro_jerry]

I will have to try my Smith's Micro Torch with this trechnique. Thanks for posting it.

Jerry

[miestro_jerry]

Also, I agree with RRR, scrap the piece, it's salvage value maybe enough to pocket, but if I spend more than 10 to 15 minutes on an aluminum and steel situation, my time is wasted and I am not getting younger so my time is getting more valuable.

Jerry

[JIMinPHX]

I would like to see the proponents of any other theory try cooling a ~35" I.D. combination taper roller/thrust bearing that cost around $100K and fitting it to it's "stump" that also measures within 0.0001" of the bearing's I.D. on a 108" Bullard VTL.
Perhaps they are part of the "Get a Bigger Hammer" crowd?

That's a pretty big machine to be kicking around. Those things scare me a little.

[725]

For the first time ever, I broke a tap off inside a hole. !!!! Hanson 8-40 from Brownells. !!!! Had visions of a Winchester holding that tap forever. Took a long, slender punch and tapped the tap back out. It was deep enough to make it a pain but just shallow enough that I got a slight purchase on one flute. Kroil, prayers, and a gentle touch got it out.

[Nueces]

It's Miller Time!

Mark

[725]

You're not kinding.

[briang]

I find this topic very interesting, so interesting that I am going to run a tap into a piece of scrap AL and see if it gets any looser after a night in the freezer. Off to the shop I go.

[briang]

Alright, I decided it didn't need to be over night and 6 hours would be fine. I used I piece of unknown alloy but definitely AL .25 inches in thickness, that was the thickest I could find. I used a 12-26 tap going in and a .25-20 tap going out. I could wiggle both taps but could back neither out without tools. After freezing I still couldn't remove either tap by hand but I could wiggle both more than before. The freezing does seem to have loosened the hole to tap fit but I do not know if it as the hole growing or the tap shrinking. I guess I didn't really prove much of anything huh?

[jmorris]

http://www.electroarc.com/?gclid=CNa...FQIWFQodcirt3A

It will even take out carbide.

[yekcim]

If anyone (briang) who has changed steel cylinder liners in motorcycle blocks knows you put the block into a home kitchen oven for a a few minutes after you have the new liner into the refrigerator freezer compartment for a while. Take block out of oven, tap liner out of block. Replace block into oven for a few minutes and remove the new liner out of freezer, remove block from oven and quickly place the new liner into the block. You have a minute or two before the hole in the block shrinks back too small for liner to go in all the way. Like miestro jerry said politely a few times.Try it you will like it. Just like the tap. Just do it. Works for me. Don't know the scientific reason & don't care. Works for every mechanic I ever worked around, even me at home.

[longbow]

Well, recently I had some troubles along this line with a broken off tap in an engine block. It was awkward to get at for many of the solutions here, at least without removing the engine.

In the end, I decided to try a carbide bit in my Dremel. To top it off the only carbide bit I could find locally was for cutting ceramic tile.

It cost about $20.00 but considering the options I figured if it worked, it was a cheap solution and if it didn't well, it was a pretty cheap failure.

Short story is, much to my surprise it ate right through that tap. No acid, no heating, no welding, no freezing, just a few minutes with a Dremel held carefully and the broken tap was little bits.

So, I agree with John Taylor in post #13 ~ a carbide cutter, end mill or whatever is up to the task.

Not saying this is the best or only solution for all situations, just that it does work and does not require any special equipment.

Longbow

[jimkim]

Dang I'm low tech. The last one I broke was removed with a hairpin. I slid the hairpin in the flutes, stuck a long nail in the loop, and backed it out. I heated it with a small torch first.

[Heavy lead]

Dang I'm low tech. The last one I broke was removed with a hairpin. I slid the hairpin in the flutes, stuck a long nail in the loop, and back it out. I heated it with a small torch first.

Man, that's a deceivingly simple good idea, never thought about that.

[longbow]

I tried the hair pin idea only it was a bent loop of old bicycle spoke. If the tap isn't jammed that can work. Mine was jammed in a blind hole as well though.

Long skinny needle nose pliers can sometimes do it as well it the tips are small enough to get into the flutes.

[jimkim]

Did you heat it first? Use the largest hairpin that will fit. The large flat ones don't flex as much. I guess to be accurate I should call them Bobby pins.

[longbow]

Man you must be as old as I am to know what a Bobby pin is!

Yes, I did try heating but no go. She was jammed badly. I couldn't get it to budge. I honestly didn't think the carbide bit would survive but it did. I guess if you don't have a Dremel it isn't such a simple solution but then I don't have a TIG welder, couldn't put the engine in a freezer, didn't have a bottle of liquid nitrogen, no mercury on hand ~ what did I miss?

Necessity is the mother of invention and it is interesting to see how many different solutions there are to a problem like this.

Longbow

[Boz330]

I broke a 6-48 off in a blind hole for a scope in a brand new barrel couple months back and couldn't budge it with a broken tap extractor. Put the barrel in the freezer for a couple days and the extractor took it out. I was right at the point that I thought it might break but it let go. I had a box of dental burrs and a Dremel but that hole was so small that I was concerned about buggering the hole for good. At this point the gun hadn't even been fired yet.
+1 on the freezer method.

Bob

[dominicfortune00]

I haven't seen this trick mentioned yet, so here goes:

If you're going to scrap the part anyway, try burning the tap out with a cutting torch. The "Smoke Wrench" will preferentially eat the steel and for the most part leave the Aluminum alone.

One of the guys at work used to be a mechanic on bulldozers and other big equipment, and he said he used a torch to burn a hole through the middle of those long pins that were galled in, like on the track of a bulldozer. He said that the heat would loosen up the pin and then it could be tapped out.

As an aside, I fixed some stripped out allen bolts on an old Ponsness Warren 12GA reloader by TIG welding an old hex to them.

To get out stripped head allens, I just tap a Torx bit in that is a little bit bigger in diameter than the allen recess in the bolt head. The six ribs of the Torx cut into the allen bolt head and have enough gripping power to allow the bolt to be turned out of the hole. Works very well on those button head allens, the head of which strips out if you look at them funny.

[Morrison Machine Shop]

I use a carbide end mill on the mill, cuts like butter.

[BeeMan]

Since I broke a tap in aluminum last week I'll bite. Remaking the workpiece wasn't practical.

Chips may interfere with backing out a tap if they lock it in place. No joy here for my project as the tap was firmly jammed and too small for an extractor.

Shattering a carbon steel tap has worked before but this was a high speed steel tap so shattering was out. The machinists at work use a carbide end mill but I did not have one, nor a burr for a Dremel. No liquid nitrogen or CO2 was available so I tried chemical removal.

Make a saturated solution of alum in hot water. Alum is used for making old fashioned pickles and is potassium aluminum sulfate. A Google search will explain why the steel is etched away, but aluminum is not affected.

Soak the aluminum work piece until enough of the steel tap dissolves to remove the remainder of the tap. This may take several hours to more than a day, depending on the concentration of alum and the temperature. No paid machinist is likely to consider this method. It is slow but it works well for a home project without damaging the aluminum workpiece.

Floodgate nailed why relative thermal expansion of aluminum and steel loosens a steel tap in an aluminum part. Restrain a material from dimensional changes it normally makes with a change in temperature and it will yield in the restrained axis but grow in another direction.

In this case the aluminum yields when the steel in the hole prevents the aluminum (and the hole in it) from shrinking. When the workpiece warms back up, both expand. The aluminum expands more and is now loose around the steel.

Last, someone mentioned special size taps for features machined before heat treat so that dimensions are correct in the hardened part. This is not a co-efficient of expansion effect. The part is machined at room temperature and the dimension after all is done is measured at room temperature.

The post heat treat dimension change is due to the various forms of compounds formed by the alloying elements in the steel. Quenching, normalizing, annealing, and tempering all have differing effects on which compounds are formed and when. Find a good explanation of steel heat treat - I don't recall for sure but Machinery's Handbook may cover this.

BeeMan