Broken Tap ...

[Phat3R]

So last weekend I was drilling and tapping the R6 swingarm to fit the GP lifters and sharks fin. I was in a bit of a rush towards the end as I had an appointment to get to. Big mistake, I was extracting the 6mm tap from the last hole I had drilled ... and it broke.

It was firmly in there maybe 20mm in a blind hole. Farq!

So I walked away from it and did some research over the week. I found out about a watchmakers trick that uses alum to dissolve HSS without destroying the aluminium. Talk about a lucky find.

IMG20181013185349.jpg IMG20181013185401.jpg

I bought 1kg of lab grade (98% pure) alum and have started the process. It's still bubbling away.



I have a small hot plate I am going to hook up tomorrow to get the temp up to get a faster reaction.

[Turbo]

WOW!! I actually had a not too different experience not long ago. I had a good look down the Alum rabbit hole but was never game to try it.
I ended up getting a thread repair dude, that specialises in bolt extraction, to work it out. That basically amounted to a diamond tip bur followed by a heli-coil!
Still, a lot better of a job than I was doing with cobalt drill bits and blind fury!!

VERY keen to see how you go...

[Phat3R]

Alum looks like pretty low risk ... AvE used it as well ... just needs patience (I just used it with water, not acid like some sugegst)


Ole mate here used your suggested method ...



There also the welding method ... which is way faster ... and although I have been doing lessons ... this looks a little advanced for me still ... but I will try out on some scrap before commencing with swingarms!

[Ruckos87]

Very cool!!!!!


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[Phat3R]

Quick update just so as not to leave this technique dangling.

The alum did dissolve most of the tap after 2 weeks of sitting on a little hot plate at 70C. There was maybe 3mm at the bottom, out of 20mm that it just couldn't seem to shift.

I suspect it's because it's a blind hole and the gasses from the process form a bubble around it, and the deeper you go the slower the bubble dissipates.

It did help though so I dropped it off at Greg Ball Motorcycle Engineering and they drilled out the last of it. The process did eat away some of the thread of the hole that the tap was in, so it needed a super duper helicoil. Ben from GBME said having the deep hole to guide it made drilling it out much easier.

That said I probably wouldn't go this route again, just straight to GBME to get them to sort it.

I've thrown away my cheap assed Chinese taps and bought some quality Sutton / Goliath ones for all the sizes from 5mm to 14mm, (which were not cheap).

[Turbo]

Good to know you've tried it. Agree if you can get it to a professional bolt extractor, they're awesome at what they do.
Hard to know exactly when tho. With a good diamond burr, a drill press, and a heli-coil there's not much you can't rescue!!