Cycling UK Forum

Hi Mick

Try putting your test piece in the freezer overnight, along with another block of something that will soak up the cold. in the morning put the block in the jaws of your vice and let it chill them down a few degrees. with a hot air blower or blow lamp Warm the outer bit you want to get off. That should expand while the inner core is kept chilled.

Good luck

Malc

Thanks Malc,
That sounds good.
A weekend job I think.

If the whole thing is thoroughly very cold, and the boss is heated very quickly, it could work.
I got the impression the other day that the heat gun on max wasn't focussed enough and was heating the whole thing.
I have a blowlamp, so that might be better.

No doubt a pair of stillsons would shift it, but it would end up marked terribly.

Theres always the crank removal advice using a cloth wrapped around the sleeve and a dousing of boiling water after removal from the freezer.
I'd loan you my uncles screwdriver which may also be an apprentice piece. He was a technician in the fleet air arm. But i don't think its big enough.

Mick F wrote:Thanks Malc,
That sounds good.
A weekend job I think.

If the whole thing is thoroughly very cold, and the boss is heated very quickly, it could work.
I got the impression the other day that the heat gun on max wasn't focussed enough and was heating the whole thing.
I have a blowlamp, so that might be better.

No doubt a pair of stillsons would shift it, but it would end up marked terribly.

pop a couple of jubilee clips round it before using the "Stillies" they could help it grip and take the brunt of the teeth marks.

Going out into the workshop shortly. May have a cuppa first.
Been thinking about what I have that'll help twist the boss.

Malc, good idea about Jubilee Clips.
I have a strap wrench. Canvas tough strap with a half-inch socket hole for undoing car oil filters.
That should wrap round and grip, and being canvas, may hold boiling water, if not, it's get the boss hot (whilst everything else is cold) and it might shift.

Also, the brass nut is a coarse thread. If I screw that on and turn the boss clockwise, I can grip the hex brass nut in the vice to hold it all tight.

Back later to this in an hour or two. Fingers crossed, one of this things will work.

Never mind all that, what time are you popping out to the Rising sun?
Or is it staying closed like a few pubs around here!

No way is this going to shift without "mechanical means".

Jubilee Clip won't grip, neither will the oil filter strap wrench, let alone the vice. It's smooth and well finished, and is slippery.
The only grip-able thing is the hex nut and even with it "upside down" with the hex in the vice, the boss still won't shift as there's nothing to grip.

In order to shift it, it needs gripping so tight it'll mark it considerably.
Four-jaw chuck would do it, but you'd need two ..... one at each end counter rotated.

By freezing the whole thing and then heating just the boss, the whole steel structure heats up too from basic heat conduction.
If they dissimilar metals, like an alu crank on a steel bottom bracket they would release ........... but both are the same steel made from the same basic lump.

philvantwo wrote:Never mind all that, what time are you popping out to the Rising sun?
Or is it staying closed like a few pubs around here!

Opening at 12, closing at 11pm.

I'll be walking the doggie about noon for an hour, then calling in en-route. Meeting a friend or two there as well.
Stand by for a report this afternoon!

Perhaps you could build a replica to avoid damaging the original
Might the replica be better?

Doubt if mick f has got a lathe etc in his shed/workshop to make another one.

1. Sailor the Doggie enjoyed the walk.
2. I enjoyed the walk.
3. We both called in at the Rising Sun and it was a few minutes after 1pm. I was the sixth customer in.
4. The beer was poured for me as we walked in the door. Dartmoor Legend.
5. Mate of mine came in soon after me and by that time, there were eight or nine of us.
6. People signed in and out and left contact details, but we all knew each other anyway.

--------------------------------------------------------

Any road up, back to the subject in hand.

I woke up this morning with an idea.
Any tool to try to turn the boss is in danger of marking it ........... so protect it!

Wrap gaffa tape round and round and round, and wrap something tough (metal?) within the wrap too, then wrap more gaffa tape.
Then use Stillsons whilst it's held tightly in the soft jaws of the vice.

Going out to the workshop shortly ......................

Tried it.

I really swung off the Stillsons, but it didn't shift one iota. The Stillsons bit into the gafffa and it gave a little which probably detracted from their efficacy.

No damage done, so that's a plus.

Morning Mick

what about a clamp plate the go around the fixed boss that would help hold it in the vice, larger surface area of contact etc. I could knock up something out of my scrap box? what the OD of the fixed boss ?

FW, you are a star as usual!
The grip in the vice doesn't seem to be a problem, but gipping the boss is difficult.

I reckon the the boss would expand away from the whole unit if it was heated very quickly before the whole thing warmed up.
Needs a quick blast from a welding torch methinks.

Going to chat to a very good mate who works with South Devon Railway in the next few days. His father is a retired engineer with an equipped workshop, and the two of them could do something.

https://www.southdevonrailway.co.uk

Mick F wrote:FW, you are a star as usual!
The grip in the vice doesn't seem to be a problem, but gipping the boss is difficult.

I reckon the the boss would expand away from the whole unit if it was heated very quickly before the whole thing warmed up.
Needs a quick blast from a welding torch methinks.

Going to chat to a very good mate who works with South Devon Railway in the next few days. His father is a retired engineer with an equipped workshop, and the two of them could do something.

https://www.southdevonrailway.co.uk

sounds like a plan rapid heating should do the trick, good luck

FW

Had a chat with my mate yesterday afternoon and showed him the job.
He said he'd get it to his dad's place to do it.

He said that what they do at the railway for shifting stuff like that - and they do this sort of thing many times - is to get a piece of metal to white hot and touch the job with it. The expansion will be sudden and highly localised, and off it'll come.

I'll get back to this, if and when there's a result!