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 Post subject: Re:
PostPosted: Wed Aug 12, 2020 9:37 pm 
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Joined: Sun Jun 28, 2015 9:54 pm
Posts: 1005
Wow, i thought some of my projects were rusty :shock:

what's the plan for this frame?


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 Post subject: Re: Proper Barn Find
PostPosted: Wed Aug 12, 2020 9:55 pm 
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Location: Colchester, Essex
Peachy! wrote:
Evening David,
You’ve probably already got this worked out, but just in case this a new thing for you, gentle build up heat to the fork steerer so that the heat has traveled down the fork tube. When it’s as hot as you can get it, squirt that freezer kit down into the aluminium stem, then twist/hit it as hard as you dare... sorry if that’s teaching you to suck eggs... :wink: :lol:

Ok thanks, yes your right, not tried this before. I was planing to cool first then heat up. My logic being the aluminium will contract more than the steel and if I did it the other way round it could be counter productive. Was planning to empty the stem of +gas then put back in the vice as shown. Fill the stem with the freezing agent and wrap the remainder of the stem sticking out with the blanket and add more from the can. if the didn't release it then heat the crown sending heat down the tube first. I still need to get the wedge nut out as the little tang in the crown is stopping it currently, would like to preserve that too if I can.

I think/hope as I can get half a turn on this even now I will not need much assistant to get it out. I am hoping for just enough to get it to start moving out as well as round. Going to let it soak a wile longer. There is evidence of +gas traveling down the stem when turned so if all else fails I'll go back to brute force.


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 Post subject: Re: Proper Barn Find
PostPosted: Wed Aug 12, 2020 10:50 pm 
BoTM | rBoTM | rider
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Joined: Wed Jan 17, 2018 8:42 pm
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Location: VCC Member 5558 East Riding of Yorkshire
Ahh, well, speaking as someone who tried both ways, I found that even with the aluminium stem (which obviously is inside the steerer tube) frozen first, that when I applied the heat it takes too long to make a difference, the heat just transfers though the steel tube and into the frozen aluminium and just de-frosts it in quiet a slow way.. remember the cold has also transferred into the steel. It just doesn’t work.
This worked for me;
1. Hold the frame upside down in the vice, well away from the headtube as the vice acts as a heat sink
2. Apply heat down into the fork steerer (I used a heat gun)
3. Using the long tube that comes with the freeze kit, squirt the CO2 (or whatever it is) deep down into the aluminium stem.
4. I had made a timber lever (two 1-1/4” holes drilled into a length of timber to go over the fork legs) and an old MTB flat bar clamped at the very end in the stem. And cracked them in opposite directions.
I think what made this work was the rapid shock temperature change you get from the spray is so much faster than the heating up from the heat gun as you cant get the heat directly where you want it, but the freeze spray goes straight to the problem, shrinking the aluminium before the cold transfers to the hot steel.


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 Post subject: Re: Proper Barn Find
PostPosted: Wed Aug 12, 2020 11:03 pm 
Gold Trader / PoTM Winner / RB Rider
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Joined: Fri Jul 23, 2010 4:13 pm
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Location: Royal Forest of Dean (Still looking for the Bear !)
It think your all nutz - is there really anything worth saving here


But that’s the beauty of this place 99% of all projects don’t stack when measured with time/money or effort V’s value of end product

It’s ace !


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 Post subject: Re: Proper Barn Find
PostPosted: Thu Aug 13, 2020 6:35 am 
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Joined: Tue Jul 07, 2015 10:52 am
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Location: Colchester, Essex
Peachy! wrote:
Ahh, well, speaking as someone who tried both ways, I found that even with the aluminium stem (which obviously is inside the steerer tube) frozen first, that when I applied the heat it takes too long to make a difference, the heat just transfers though the steel tube and into the frozen aluminium and just de-frosts it in quiet a slow way.. remember the cold has also transferred into the steel. It just doesn’t work.
This worked for me;
1. Hold the frame upside down in the vice, well away from the headtube as the vice acts as a heat sink
2. Apply heat down into the fork steerer (I used a heat gun)
3. Using the long tube that comes with the freeze kit, squirt the CO2 (or whatever it is) deep down into the aluminium stem.
4. I had made a timber lever (two 1-1/4” holes drilled into a length of timber to go over the fork legs) and an old MTB flat bar clamped at the very end in the stem. And cracked them in opposite directions.
I think what made this work was the rapid shock temperature change you get from the spray is so much faster than the heating up from the heat gun as you cant get the heat directly where you want it, but the freeze spray goes straight to the problem, shrinking the aluminium before the cold transfers to the hot steel.

I am assuming this was with stem still stuck and not moving? I can already get half a turn and 1/4 turn is easy to move. I am hoping freezing alone will do the job now. What is your heat gun? I have a small Camping Gaz blow torch I was intending to use.


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 Post subject: Re: Proper Barn Find
PostPosted: Thu Aug 13, 2020 6:45 am 
BoTM | rBoTM | rider
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Joined: Wed Jan 17, 2018 8:42 pm
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Location: VCC Member 5558 East Riding of Yorkshire
I’ve got a BOSCH GHG 23-66, it’s a bit of a beast - 660degrees!


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 Post subject: Re: Proper Barn Find
PostPosted: Thu Aug 13, 2020 7:03 am 
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Peachy! wrote:
I’ve got a BOSCH GHG 23-66, it’s a bit of a beast - 660degrees!

Interesting, a more general heat I guess with the air. The blow torch I have isn't hot enough to braze with, but can remove lugs with a bit of mechanical help. My be a bit more localised too perhaps.

I'll give it some more thought while soaking it longer. I was hoping that now I have it on the move the +gas would do the job. May be worth sticking with that a bit longer and give it a move each day.


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 Post subject: Re: Proper Barn Find
PostPosted: Thu Aug 13, 2020 7:20 am 
BoTM | rBoTM | rider
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Location: VCC Member 5558 East Riding of Yorkshire
You should be able to get 2 hits out of the CO2 can, so perhaps try one without heat first?


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 Post subject: Re: Proper Barn Find
PostPosted: Thu Aug 13, 2020 7:25 am 
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Joined: Tue Jul 07, 2015 10:52 am
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Location: Colchester, Essex
Peachy! wrote:
You should be able to get 2 hits out of the CO2 can, so perhaps try one without heat first?

Ok, that good to know


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 Post subject: Re: Re:
PostPosted: Thu Aug 13, 2020 7:28 am 
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Location: Colchester, Essex
enc wrote:
Wow, i thought some of my projects were rusty :shock:

what's the plan for this frame?

Clean it up carefully, paint it up and probably rebuild the bike with some of the old components salvaged. I was going to use it as a winter bike, but as it was pointed out to me this could be a bit too good for that. Could be my first something like original bike as I have tended to make them more retro up to now.


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