[Beezle]

I just tried the alum trick a few weeks ago on this part:



This was a 10-32 tap buried about .6" into the hole, broke flush.

The process did in fact dissolve the tap, but slowly. By the time the tap was nearly gone, the surface of the aluminum had enough damage that I scrapped the part. And I mean physical damage, not discoloration. This process took overnight.

[keen]

Wow - never knew you could dissolve a tap!

I either remove by making a small tool - or use my EDM. The small tool is a little key you make of tap drill diameter, with a cross slot sawed, or filed, or ground to suit the broken tap flute gaps, made out of tough steel eg allen key steel, tapped down over the broken tap, and unscrewed. Usually works and is quicker than EDM.

keen

[carlowens]

I just tried the alum trick a few weeks ago on this part:



This was a 10-32 tap buried about .6" into the hole, broke flush.

The process did in fact dissolve the tap, but slowly. By the time the tap was nearly gone, the surface of the aluminum had enough damage that I scrapped the part. And I mean physical damage, not discoloration. This process took overnight.

yeah that's why this process is usually the last one chosen when all else fails if tap extractors, picks and the welding rod methods fail and the part would be scrap anyway with the tap still in there. one other option is to use a counterbore with a pilot hole big enough for the tap to go into and bore around it then plug that hole and retap or use helicoil.