Troublesome Chrono Pusher

[KOwatch]

Looking for next step advice with a chrono pusher. 2.5mm/20tpi pusher sleeve has external splines. Spline tool removed one pusher fine, on the second one the splines are stripped so it can't get a grip. Tried cutting broaches to get a grip from the inside, all these did was widen the hole. So now I've got a 2.3mm hole in a 2.5mm pusher sleeve. The outside end of the pusher sleeve is somewhat recessed, so I can't get a grip with pliers. The pusher sleeve looks brass and the case is stainless steel.

Options include:

Another, larger set of cutting broaches, and then perhaps a tap to clean out the threads. I'm concerned I'll mangle the threads on the case and have to re-tap it larger.

Dissolve the brass inside the stainless steel case? Like the alum-on-steel trick, but with a different solvent for brass-on-stainless.

Suggestions or any other ideas?

[Tudor]

Left handed drill bit? Maybe difficult now that you’ve reduced the wall but if you can make it even thinner, you can probably collapse the tube with needle nose or perhaps even some manly tweezers. Then twist it once one wall collapses and it should come right out. 
 

If you want to soak it, PB Blaster works well as a penetrating lubricant. 

[Klassiker]

Try alternating heat (soldering iron) and cold (ice).

[KOwatch]

@Tudor what's your source for left-handed drill bits? I haven't seen any at 2.4mm sizes

[Tudor]

That’s 0.095”. But you can use a bit larger like 1/8 (0.125”) since the idea is not to drill necessarily; but for it to grab and unscrew. 

They can be had (in any size just about) from industrial supply such as McMaster-Carr or MSC. I think I got a cheesy set from Harbor Freight. Those should be good enough. 

[rodabod]

I’ve cut a slot in them before. Or clean and then glue a rod inside. 

[fixermole]

If they make a screw extractor that size, maybe that would work?

As rodabod suggested, I've also cut a slot in something similar and simply unscrewed it.

[KOwatch]

Success!

Here's my procedure:

spline tool: fail, splines stripped

penetrating lubricant

cutting broach: fail, just widened internal diameter

more penetrating lubricant

several hot & cold cycles (soldering iron & freezer)

cut slot (carefully drilled sideways with 1/32" bit) & 4mm screwdriver FTW

Thanks for all the suggestions! @rodabod, the slot cut was the winning tip (and most accessible without buying more new tools), I was getting ready to try epoxying in a rod or screw as a next step.

The outer spline flange was already in bad shape and I didn't have the 3.5mm thin-blade screwdriver it really required, but I had a cruder 4mm that did the job. Ultimately it made a mess of the  spline flange but still got enough purchase to get the job done. The case may have acquired an extra ding during the process, fortunately it has a lot of pre-existing company.

 

[Tudor]

Nice! Don’t forget to chase the threads before you install the new tube!

A drop of purple locktite will help hold and seal it. 

[KOwatch]

@TudorI was hoping to avoid buying the tap for this. Is chasing the threads a good idea or a "will fail if you don't" situation?

[Tudor]

Check with a 10x loupe and wash with acetone on a q-tip at least.