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What to do when a tap breaks in a hole??
- Thread starter va2fsq
- Start date
Chicken lights
Forum Pony Express Driver
They have tap removal tools, or at least I’ve seen them in the past, they fit in the flutes
How bad do you need it? A shop with a EDM machine can burn the tap out. That is a last resort I think. I've seen turn wright on you tube build up a bead of weld one little blob at a time till he had enough sticking up to be a handle. It was not on such a tiny thread though. tap removal tools... somebody on here should have a good suggestion.
Drill it out and use a kit similar to https://www.princessauto.com/en/detail/48-pc-metric-thread-repair-coil-inserts/A-p8391708e
to install a M3 insert in a M4 or M5 hole. This kit does not have those sizes but gives you an idea.
to install a M3 insert in a M4 or M5 hole. This kit does not have those sizes but gives you an idea.
Chicken lights
Forum Pony Express Driver
Hmm not for M3 but you get the idea
Yes. Make a difference?
Johnwa
Ultra Member
If you’re lucky you can drive it out with a punch.
As Chicken lights states, they do make broken tap removal tools that go into the flutes. They look like this (there are others):
i don’t have any metric ones.
lots of times they don’t work because you can’t get them into the flutes because they are jammed up with chips (the reason the tap probably broke in the first place [one of the main reasons anyway]).
That leaves two options: as Janger suggests - EDM. Or, use a carbide drill bit and drill the tap out. The problem is carbide will shatter if it sees too much of an interrupted cut - as in coming out sideways of the tap while drilling. The key would be to drill straight though the tap leaving the wall thin enough that it can be collapsed, then you create enough room for the threaded portion of the tap to disengage from your part and pick the pieces out bit by bit. You will most likely damage the original threads; if you can go to M4, no problem. If you can’t, maybe a M3 Helicoil could help afterwards. Or, just machine all the bad threads out oversize and make a plug you can locktite in and then re-thread it M3.
Whatever you decide to do - you will need loads of patience!
i don’t have any metric ones.
lots of times they don’t work because you can’t get them into the flutes because they are jammed up with chips (the reason the tap probably broke in the first place [one of the main reasons anyway]).
That leaves two options: as Janger suggests - EDM. Or, use a carbide drill bit and drill the tap out. The problem is carbide will shatter if it sees too much of an interrupted cut - as in coming out sideways of the tap while drilling. The key would be to drill straight though the tap leaving the wall thin enough that it can be collapsed, then you create enough room for the threaded portion of the tap to disengage from your part and pick the pieces out bit by bit. You will most likely damage the original threads; if you can go to M4, no problem. If you can’t, maybe a M3 Helicoil could help afterwards. Or, just machine all the bad threads out oversize and make a plug you can locktite in and then re-thread it M3.
Whatever you decide to do - you will need loads of patience!
I’ve been there. Patience, dental picks, hot cup of tea, Top Gun playing on Netflix, Kroil penetrating oil and more patience.
Try to get the picks into two of the flutes and then turn like you were picking a lock.
I spent 2 hours and then “it moved” like a couple thou. More oil and more practice......
I won!
Sent from my iPad using Tapatalk
Try to get the picks into two of the flutes and then turn like you were picking a lock.
I spent 2 hours and then “it moved” like a couple thou. More oil and more practice......
I won!
Sent from my iPad using Tapatalk
When I was a teenager, I would go to the pharmacy down the street...I could buy anything, Nitric acid, sulfuric acid, you name it. I once bought Sulfur, Saltpeter and granulated carbon.... Mixed up a batch and succeeded in burning a hole through our back porch....
Could have been worse I guess...
Anyways, I tried a larger drill and succeeded in drilling to the side of it. So, it's a write off. I am going to fill the hole with something black so it looks nice and reprint the part with the mounting holes shifted away. Then I am going to take much more care tapping the hole.
Thanks for all the replies. I'll keep this thread in mind for the future.
Bets regards, Tom
Could have been worse I guess...
Anyways, I tried a larger drill and succeeded in drilling to the side of it. So, it's a write off. I am going to fill the hole with something black so it looks nice and reprint the part with the mounting holes shifted away. Then I am going to take much more care tapping the hole.
Thanks for all the replies. I'll keep this thread in mind for the future.
Bets regards, Tom
Wells thats the most useful thing I've learned today.
I've seen the YouTube videos & heard the same advice on alum solution. There seem to be 2 results: 1) works 2) doesn't work. I was in the camp #2. Despite following the concentration & heating instructions & very encouraging looking bubbles streaming out of the hole, it made a complete mess of my (2024 aluminum) radial crankcase which has a broken M3 tap stuck it a blind hole. Results may have been attributed to the tap itself. It was HSS based but was coated (Sowa blue ring type) as opposed to conventional bright. Possibly the solution had a tougher time etching the tap before all the rest of the aluminum started looking like it sank beside the Titanic. Or related to 2024 alloy vs 6061? I dunno. I would never attempt it again on a part I cared about.
It ended up being junked which was an unhappy day, but I did work away at the tap with other methods just for future education. If its a small tap or landed in tight or well packed with chips or spral flutes vs linear ... it makes the typical tools & picks & methods that much more difficult. I had a tough time milling down on the tap even with a carbide end mill, both flat & ball ended. I made something like an annular cutter from O1 with the idea to just drill past it & not through it. I made some practice holes on aluminum & then somehow managed to lose the cutter (along with interest) so never did get to try it on the stuck tap. I had to peck drill because its not efficient to remove chips but I think it would have worked. In hindsight a simple D-bit type edge is probably all one requires. To fill the hole just Loctite in a matching aluminum plug which probably has to be done in any event.
An EDM is probably the best solution but I have no direct experience using or making one.
It ended up being junked which was an unhappy day, but I did work away at the tap with other methods just for future education. If its a small tap or landed in tight or well packed with chips or spral flutes vs linear ... it makes the typical tools & picks & methods that much more difficult. I had a tough time milling down on the tap even with a carbide end mill, both flat & ball ended. I made something like an annular cutter from O1 with the idea to just drill past it & not through it. I made some practice holes on aluminum & then somehow managed to lose the cutter (along with interest) so never did get to try it on the stuck tap. I had to peck drill because its not efficient to remove chips but I think it would have worked. In hindsight a simple D-bit type edge is probably all one requires. To fill the hole just Loctite in a matching aluminum plug which probably has to be done in any event.
An EDM is probably the best solution but I have no direct experience using or making one.
Dabbler
ersatz engineer
You can fake an EDM in a temporary way with an aquarium pump, distilled water, a plastic pan, a 12v battery charger, and a very steady hand. The bigger the charger, the better. You are only eroding the centre web of the tap.
It is more tedious than TIG welding, but you can erode away the tap with an arrangement like this. I did this only once, about 30 years ago. It took 5+ hours for a 1/4 tap, but it saved the part. I can't remember how I grounded it, but the current CANNOT pass between the tap and the aluminum hole or you're sunk. I think I used a copper wire to touch off on the tap. The electrode can be anything, but I used a piece of copper coated steel welding rod intended for oxy-acetylene.
It is more tedious than TIG welding, but you can erode away the tap with an arrangement like this. I did this only once, about 30 years ago. It took 5+ hours for a 1/4 tap, but it saved the part. I can't remember how I grounded it, but the current CANNOT pass between the tap and the aluminum hole or you're sunk. I think I used a copper wire to touch off on the tap. The electrode can be anything, but I used a piece of copper coated steel welding rod intended for oxy-acetylene.
