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Gunsmithing Broken Tap in Ar15 lower I

junglejim23

Private
Full Member
Minuteman
Feb 22, 2008
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Santee,California PRK
Wile taping lower for take down pin detent spring mod the tap broke in the lower it is a 4_40 recessed about 4 threads the pices is maybe 6-10 threads long


Any Ideas on getting it out ?
 
Re: Broken Tap in Ar15 lower I

they make broken tap removers, not sure if one that small but i know they make them. check with Mac or Snap On tools.
 
Re: Broken Tap in Ar15 lower I

Do a search on ar15 in the build section. It has been posted before. Somebody makes a liquid that will eat the steel (tap) and not the aluminum. Cost $6-15.
 
Re: Broken Tap in Ar15 lower I

if you have a mill:

1/16, 4F carb EM@4000rpm will eat it. Use oil and feed w/ the knee.

I've also been able to use air hardening TIG rod to make a little bead to build the tap back up enough to back it out w/pliers. Its a biche, but it works too.

Soak the part in kroil or kerosene after to loosen the chip weld.

Good luck.

C.
 
Re: Broken Tap in Ar15 lower I

If the above mentioned ideas do not work for you find a local machine shop that has an EDM machine, they can burn it out.
 
Re: Broken Tap in Ar15 lower I

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: toolmaker64</div><div class="ubbcode-body">If the above mentioned ideas do not work for you find a local machine shop that has an EDM machine, they can burn it out. </div></div>

Most shops ( at least the ones I've worked in/visited) will have a machine called.. wait for it... a 'Tap Burner' its like an EDM without the tech.

Basically it's a low tech EDM. I used to loose taps all the time and would have to burn them out and then heli-coil or jump up a tap size. Cheap and easy.
 
I've removed a few with a Dremel tool, carbide or diamond bit will work wonders...you'll want the flex shaft for this job.
 
The tap extractor would be the easiest, least expensive way , so long as it was a straight flute style tap. The extractors are designed for the specific number of flutes too. Patience and a little back and forth turning very lightly will be your best method and constantly blow the chip out as you turn. Taps usually fracture near the top where they break and if you don't clean the fragments they will wedge in the threads and cause more problems. Small picks, magnets and airpressure will help get them out. Good luck!
 
If it were mine I would try the McMaster tap remover first, but stop if the tap didn't come out easily. Best way is to take it to a machine shop with an EDM machine. While one of the other methods might work, they are more likely to make a bad situation worse.

OFG
 
I have used tap extractors before with limited success, IMHO it isn't going to do you a great deal of good. The tap is very small, and if it is really tight, and being in anodized aluminum it is certainly most likely tight, it's going to be nigh impossible.
Tapping those small holes is a real PITA, small fragile tap in an anodized hole on aluminum- bad news. LOTS of cutting oil and slow and easy, breaking the chip as you go.
Good luck! Small carbide drill bit as above mentioned is best bet. I would normally try to break it out were it steel with a punch- being in aluminum it would REALLY booger up the hole, BAD.
 
This thread is nearly 2 years old. Hopefully the OP will let us know how it worked out. My guess is it didn't.

A 4-40 tap, broken off 4 or 5 threads below flush? Good luck!