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Maybe keeping such things in one place will prove helpful? Maybe not.

Anyway, to get the ball rolling, does anyone have a technique for removing a snapped off 4-40 tap from extruded aluminum side rails? Maybe the sort of kit one uses for removing stripped screws would work, but there is no head, essentially. Any other thoughts?

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How to dissolve a tap embedded in aluminum: http://www.forkrobotics.com/2013/04/dissolve-a-tap-broken-in-makerslide/

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Maybe keeping such things in one place will prove helpful? Maybe not.

Anyway, to get the ball rolling, does anyone have a technique for removing a snapped off 4-40 tap from extruded aluminum side rails? Maybe the sort of kit one uses for removing stripped screws would work, but there is no head, essentially. Any other thoughts?

If I am understanding you correctly, you have a broken tap trapped in aluminum and need to remove it. In the past what I have done is to use a very small drill bit to drill a small hole into the trapped tap. Then I use a broken bolt kit to remove. Been years since I have done this, so, there may be better ways of doing it now.

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If you have access to an ultrasonic cell disruptor,

Unfortunately, I don't know any Romulans, Klingons, or Cardassians from whom to borrow a disruptor.

I do have the sense this is a lost cause as it is pretty tiny, and as you say, quite brittle. Note to self, tap cases before having them machined, rather than after :( And, replace taps when they seem like they might be worn rather than trying to eek out one more case.

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Maybe I'll learn something to help my meager skills.

Best thing I've learned is to farm out casework to professionals whenever I can :)

I once had success with needle-nose pliers and worried the tap out, but the tap size was larger..

It is broken pretty flush to the case. But, there is a little wiggle, and the tap tip is fluted, so I may be able to stick some thin metal bits down these channels and turn it just enough to expose enough to grab with some small pliers.

Maybe some vibration would cause it to extract itself? I could put it on a UPS truck for an afternoon.

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Putting it on a UPS truck, it would likely return with far more pressing problems than a broken tap...

A 4-40 tap would be pretty small to try to drill into, and as Kevin noted, hard and brittle. If you have some really sharp pointed tweezers, maybe try to work it around to loosen it enough so there is something to grab onto? Good luck! And good thread idea as well.

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There are a lot of different techniques you can find by googling. This situation happened to me once, and I succeded using a technique that surprisingly I cant' find anywhere:

I put a very small amount of loctite on the top of a flat barrel of a diameter slightly smaller that the tap, and carefully introduce it into the hole until it makes contact with the broken tap. Then I wait 2 min while maintaining the pressure to make sure the two are glued. Then I unscrew gently...voilĂ .

Problem is you can glue everything together, and then you are screwed, but if you are careful enough, and have a steady hand, it should work.

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One of the problems with tapping holes is the methodology.

I usually turn the tap about 1 turn then retract half a turn to break the swarf.

If you don't do this usually the tap gets stuck on the hole and sometimes breaks in the attempt to extract it.

Some tips:-

http://www.spaco.org/taptips.htm

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I've been thinking about getting into DIY powder coating. The professional metal finishers around here want ridiculous prices for small jobs. Looks like you can get started for about $300. Anyone have any experience in this area?

I think this thread is a good idea. Half the reason I build stuff is the craft, creativity, and artistic expression that goes into i the casework.

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I've heard good things about the Eastwood powder coating kit. You'll definitely want to purchase a separate oven for this, as the oven can no longer be used for food after powder coating. The good thing is that used ovens with burnt out stove top elements are usually had pretty cheap.

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  • 1 month later...

you could try to weld something onto the tap and use that to extract it. But you might just end up kind of arc welding the tap into the hole....

if you can get any sort of grip on the tap, you can try heating the aluminum to a few hundred degrees in your home oven and then dripping some freeze-mist on the tap (or butane, or "Canned Air" CFC liquid- be careful with any flammables)

That might make it possible to remove it....

The other possibility is to carve out the aluminum around the tap with a small Dremel tip, then grab the tap. You'll have to fill in the hole you carved out.... can be done in various ways, including inert gas welding.......

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  • 3 months later...

That's a thick front panel. So you blind tap a few holes at the back of that thing, and mount a second thinner plate on it. Then use the second plate to mount the switch.

You could still mount the switch directly to the front panel with the blind tapped holes, you wouldn't necessarily need the second plate.
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