Broken tiny tap in aluminium

[Wongster]

Hi guys,

Me again seeking help...

I was onto my last piece and last tap hole making endstop holders for a Kossel Mini 3D printer that the tiny M2.5 tap broke in the hole.  I googled around for solution(s) but couldn't find something I can try.  There was one I found that talked about dissolving the tap but I'm unable to get the chemical here in SG.

Here's the pic:



This is what I am trying to make.  Completed 2 without problem.  The hole I was tapping is the last hole before the ops on the flip side.



Hope I can avoid doing the last piece all over again and move on to the next part.

Thank you in advance.

[NormanV]

Apparently Alum is your friend. Can't you buy it on Ebay for import to Singapore?

[Dr Stan]

I've tried alum W/O and success.  Try a carbide ball end endmill the same size as the tap drill running at full speed while peck drilling.  It will destroy the endmill so consider the cost of the cutting tool V making the part again.

The best cutting compound I've ever used for tapping in aluminum is pork lard.  If that is not to your liking try solid vegetable  oil.  In the States Crisco is the leading brand. Penetrating oil such as WD40 is also excellent.

[TomG]

If it's a through hole, just drive it out with a punch and replace it with a helical insert.

Tom

[Vinny]

Are there any EDM shops there? They should be able to burn it out.

[Roadracer_Al]

If you have a TIG welder, you may be able to tack a piece of welding rod to the tap and back it out while it's still warm.

Another expedient from the welding shop is to use an oxy-acetylene cutting torch and burn it out. The steel is very small, and will heat quite quickly to red hot, then hit it with the oxygen and the thing will disappear almost instantly. Theoretically, the part should be unharmed.

[Mike E.]

(09-07-2016, 02:58 PM)Dr Stan Wrote: ................. The best cutting compound I've ever used for tapping in aluminum is pork lard. ...........................

" Lacquer Thinner " used as a cutting fluid in tapping aluminium will produce perfect razor sharp threads; also, it evaporates quickly leaving a clean hole. I've used it with fine results on tapping holes as small as 2-56 tpi.  Learned this trick from a machinist at Lockheed aircraft back in the 1970's. Try it.

[Highpower]

I've not heard of that one before. I'm going to have to give that a try. Thanks Mike.

[flosi]

Alcohol, any kind, is also good for cutting al. Leaves no residue and is less hazardous than than thinner.

[Dr Stan]

(09-08-2016, 04:40 AM)Mike E. Wrote:

(09-07-2016, 02:58 PM)Dr Stan Wrote: ................. The best cutting compound I've ever used for tapping in aluminum is pork lard. ...........................

" Lacquer Thinner " used as a cutting fluid in tapping aluminium will produce perfect razor sharp threads; also, it evaporates quickly leaving a clean hole. I've used it with fine results on tapping holes as small as 2-56 tpi.  Learned this trick from a machinist at Lockheed aircraft back in the 1970's. Try it.

Thanks for the info.