Broke a 6-32 tap off in an aluminum heat sink, ideas?

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zombiess

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So one thing I've learned for sure is me and metal working don't get along well. I don't seem to have the knack for it. With that established, I managed to break off a tap in my brand new heat sink I'm planning to use in a controller build. Tap is broken flush. I tried pliers, but it's bound up. Next I tried freezing it with canned air and using a punch to shatter it, that was a no go.

Any ideas? I've looked through youtube and seen some machinist suggestions, but my tap is pretty small.

The tap broke because I'm a goof and forgot to use oil when making the cut. 100% my fault. I was using the chuck on my mini mill to keep the tap straight while I turned it by hand. Had I remembered oil I probably would not be posting this.

Good news is I have a spare heat sink, but I'd like to save this one if possible. Otherwise It will have to be re purposed for a smaller, lower power build.
 
first put a washer on top over the tap, with inside hole smaller than the tap and then weld the washer to the tap inside the hole.

then weld a nut to the surface of the washer and unscrew the nut.

this technique is pretty famous. he had broken off a bolt in the surface of this huge steel plate. yours is tiny.

otherwise you will have to layout the surface of the heat sink again so the tap is not in the way.
 
try to make a slot in it with a dremel tool and a thin cut-off wheel, and unscrew it with a flat-head screwdriver.

use wd-40 before unscrewing
 
If all else fails look for a company that does spark erosion. That's how professionals get them out.
 
if the hole goes all the way through, use a punch and large hammer to push it through, it will destroy threads, but you can then use a helicoil. If not all the way through drill from other side to meet it.

Always use lubricating oil and go 1/2 turn in, half turn out and clear shavings out of the hole regularly next time you tap something.
 
Sounds like this is a more expensive problem than is worth fixing. I'm unable to weld, and even if I could do basic welding I doubt I would have the skill to weld a washer to a tiny little tap. The hole does not go all the way through and drilling from the other side will most likely not work due to the fins being in the way. The heat sink has a 0.3xx" thick base. Adding a slot to it with a dremel will not work either as there is not enough room to use a cut off wheel without destroying the heat sink surface. I've already managed to mangle it up pretty good and I haven't even used a drill :lol:

Looks like I'm stuck and have to start over on a new heat sink. It would be awesome if there was a local shop that could do this kind of work, but I can't find any shop willing to take on jobs for less than $5k. The oil industry and the high cost of living prevents many businesses from taking on small jobs. Back in Vegas I had 4 shops I could have probably asked for help with this, but even then the labor would cost more than the $30 the heat sink cost. I'd have to buy several to make the $50 shipping cost worth while.
 
Without a pic to add more details, I'd consider using a dremel to cut a slot in the stub of the tap, then but it in boiling water.

The aluminum will expand more than the steel, and it "might be enough" to make the extraction easier.
 
2nd. If you can put it in the oven or hot plate ( ? Maybe ) for a while pull it out and get a vise grip on it. Or cut the slot then heat it. Now how hot ?
 
take it to a muffler shop with the small washer and nut.

not a corporate shop, but a owner operated type where you can talk to the guy since they can weld almost anything and have the skills and welders to work in such a tiny space.
 
nieles said:
try to make a slot in it with a dremel tool and a thin cut-off wheel, and unscrew it with a flat-head screwdriver.
Click to expand...
+1
A 6-32 tap is pretty tiny. The slot trick will work but be sure to use a (new) thin cutoff wheel as recommended and not one of the fiber-mesh variety (way too thick).

If you don't have a Dremel - it's about time....
 
If you have access to nitric acid you can remove it chemically in a few hours as per the attachment.
 

Attachments

  • Broken tap removal.pdf
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Great tips on removal above. All the methods I know are already listed. ...and I sure feel for you, been there and done that many times. I use TapMagic-Aluminum now for all my hand taps in aluminum, and I have not broken a tap since changing to that fluid.
 
If I have this right ; I envision a round hole in aluminum stock, in which there is a broken piece of threaded tool steel with an X shaped cross section. I would soak with a 50/50 mix of Dextron ATF and Acetone. Then I would sharpen the tip of a center punch to the shape of a pencil point. Secure the heat sink in a soft face vise. Use a hammer and punch on the sides of the tap flutes ,alternating from flute to flute, to start it to turn. Turn both directions, a little at a time. Flush out, and refill with 50/50 mix. as you go along. Good Luck !
 
You can mail me the heatsink and I will weld a washer to it, and weld a nut to the washer and turn it out and mail it back.
 
liveforphysics said:
You can mail me the heatsink and I will weld a washer to it, and weld a nut to the washer and turn it out and mail it back.
Click to expand...

Sadly there is nothing to weld to, it's below the surface.
 
I just screwed up my 2nd heat sink when my drill bit broke off in it. Now it's in the same place my other one is, but there is a drill bit instead of a tap broken off. There is NOTHING to grab on to, it's broken off below the surface.

I need 3 of these with all the holes drilled and tapped, but now I only have 2 of them left. I think I've successfully established that I"m not going to be able to do this task. The mill I have is about as good as a drill press anyways. It measures in 0.0625" per turn which is just stupid. The conversion math isn't hard, but the measurement wheel sometimes moves when moving the table losing it's setting. This makes measuring distance about as good as eyeballing it.

I'm pretty good at a lot of things, but metal working is not one. Probably because I don't desire to be good at it. It's something I view as a hurdle to making stuff I want.
 
zombiess said:
It would be awesome if there was a local shop that could do this kind of work, but I can't find any shop willing to take on jobs for less than $5k.
Click to expand...
That's because you're looking for a 'machine shop' instead of a shop with machine tools....

For small machining jobs I go to an 'auto machine shop' (see the Yellow Pages). Same CNC gear, etc as a regular machine shop except they work on engines and stuff, but milling/boring/turning is all the same. Excellent work with just a verbal description or pencil sketch - and pretty inexpensive. With CNC gear, they're happy to make small runs. If you are stymied with the heatsinks, take them by and see what they can do. Mention the weld and slot tricks.

Turnaround varies but a day for something simple isn't unusual.

All shops are different of course, but just a thought....
 
One thing I have not seen mentioned yet... have you tried spiraled flute extractors yet? I have had luck about 50% of the time with them, the other 50% of the time they break off as well, haha.
 
Good news is I have been able to outsource this work.
I started this thinking it was going to be fairly easy, but I ended up with a bag full of fail due to my lack of skill and equipment issues (mainly me) :lol:

It's been a while since I have experienced this level of failure.
 
if this is for the mosfets, why not consider using a bar for the clamp instead of putting a screw and bushing in through the tab.

i think the bar clamp is better because it makes the surface behind the device flatter against the heat sink surface imo, so better contact.

then you could still use these heat sinks but drill a hole all the way through in between each pair of mosfets so you can have a screw and nut to hold the bar onto the devices. 2 at a time.
 
http://www.amazon.com/Walton-10063-Flute-Extractor-Square/dp/B0006N8DFK/ref=sr_1_5?ie=UTF8&qid=1434779617&sr=8-5&keywords=Tap+Extractor
 
ecycler said:
One thing I have not seen mentioned yet... have you tried spiraled flute extractors yet? I have had luck about 50% of the time with them, the other 50% of the time they break off as well, haha.
Click to expand...

You'd need a solid carbide bit to drill the hole to start one and then you might as well just drill the tap out ;)
 
Punx0r said:
ecycler said:
One thing I have not seen mentioned yet... have you tried spiraled flute extractors yet? I have had luck about 50% of the time with them, the other 50% of the time they break off as well, haha.
Click to expand...

You'd need a solid carbide bit to drill the hole to start one and then you might as well just drill the tap out ;)
Click to expand...

I've tried a spiraled flute extrators in the past and had no success. This was on a much larger tap than a 6-32. 6-32 is tiny, think #36 drill bit small or about 0.100"

It looks like I found someone to help me on my future interactions with metal. I wish I would have gotten the metal working gene sometimes. I was an OK car mechanic but I knew I would never be "really good" since I viewed the work as something between myself and what I wanted to enjoy. I tolerated it :lol:
 
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