AGGGH!! Broken tap becomes a need to remove the headset bearings.

[Lanzecki]

After removing some stuck bottle carrier bolts and re-tapping one hole then breaking the tap in the second hole I need to dissolve the tap from the Ali frame using the tried and trusted method of hot Alum. But to be this, and allow for the new paint job I was planning for winter (now moved forwards ) I need to remove everything.

And it's all out, except the headset bearings. I'm not overly familiar with these new fangled integrated bearings. They maybe semi-integrated if I'm honest

If it was an older style headset I'd just drive out the cups with a special tool (a foot long pole and a hammer)

But if possible I'd like to reuse the bearings since they are smooth. Here's a picture. They don't pop out of the frame, and seem to be in some sort of cup. Can I just drift them out?

 

[400bhp]

Shouldn't really need drifting out, but likelihood is it's got stuck with gunk.

A gentle tap should shift it.

Make sure you keep the bit that sits on top of the forks - can't remember the technical term. It's like an oversized washer. It's not something you get with replacement headsets.

 

[Lanzecki]

Shouldn't really need drifting out, but likelihood is it's got stuck with gunk.

A gentle tap should shift it.

Make sure you keep the bit that sits on top of the forks - can't remember the technical term. It's like an oversized washer. It's not something you get with replacement headsets.

The part that sits on top of the item in the picture but below the spacers? Yup cleaned and in a labeled bag. OCD can help sometimes I was disapointed to see the inside of the head tube was poorly painted though

 

[400bhp]

Crown race

 

[Lanzecki]

Crown race

Which one?> The part in the pic or the part that sits on top?

And just to confirm, that entire black part that the bearing sits in should come out? Similar to the cup of an older design?

 

[accountantpete]

Which one?> The part in the pic or the part that sits on top?

And just to confirm, that entire black part that the bearing sits in should come out? Similar to the cup of an older design?

You are correct - that looks like a semi-integrated headset which is very much like the old traditional headsets except that the cup sits right into the headtube.

Some of these had a reasonably tight fit so you will probably need to gently knock them out.

 

[sidevalve]

Question here - how did you dissolve a steel tap from an alloy frame ?

 

[the_mikey]

2nd question: What size thread were you tapping?

 

[Tim Hall]

Question here - how did you dissolve a steel tap from an alloy frame ?

Like he says, using hot alum. It's a nifty bit of chemistry. zigzag did it as described here

 

[TonyEnjoyD]

I was disapointed to see the inside of the head tube was poorly painted though

Thats just overspray from the hand or factory applied primer/basecoats.

 

[Lanzecki]

Using dissolved Potash of Alum (Potassium Ammonium Sulphate) in near boiling water. Dissolved as much as possible. Cover the item that need dissolving in the solution and keep at temp. wait several hours. No more tap. I haven't done it yet as the local chemists has so far looked blankly at me. "Why would we sell that?". "You are a chemist..." It'll work on any ferrous metal such as taps and drill bits. BUT don't use on a steel frame. "Look I got rid of the tap. And 1/2 the frame".


To be honest this is secondary school chemistry. Here's one, To remove rust dissolve a load of salt in water. stick a sheet of metal to act as a conductor and apply voltage across rusty part and the conductor. Rust removal that doesn't hurt the good metal. Replace the conductor with zync and reverse the polarity and you get a zinc coating.

it was a m5 x 0.8 Tap to tap out the bottle mounts. Everything was properly done with the correct cutting fluid.

Like he says, using hot alum. It's a nifty bit of chemistry. zigzag did it as described here

Missed that one. Thanks.

To digress an old engineer friend cuts a small groove in his tap near the handle. This creates a weakness. The idea being that the top breaks at a place you can get to instead if inside the hole.

 

[Lanzecki]

(Potassium Ammonium Sulphate)[/QUOTE]

Sorry brain fade, it's

Potassium aluminum Sulfate. KAl(SO4)2

 

[Lanzecki]

Thats just overspray from the hand or factory applied primer/basecoats.

That's really not good enough you know.

 

[Lanzecki]

Update. I found some Potash. Turns out that crystal grown kits are Potash of Alum. After some negotiation with number 2 child she supplied me with one of her crystal making colours she didn't care for.

Near boiling water, enough crystals so they stop dissolving and heat :

No it's not blood. The fizzing was from the broken tap I chucked in.

1.5 hours later.

The top is the same size tap before application to the now called 'juice'. To say the least it's effective.

Now to rig something to make W. Heath Robinson proud since the stuck tap is in the down tube.

The vicious colour changed to purple, Brown and eventually a gray. The contents of the pyrex jug at the end were small flecks of metal and a load of grey sludge. It doesn't appear that eh colour stained anything.

 

[sidevalve]

Now that is seriously usefull to know. Live and learn eh.