Replacing a steerer?

The steerer on my 72 year old bike is cracked, the forks are quite nice looking so I don’t want to replace them.
The plan is:
Cut off the top of the cracked fork,
Cut of the top of another 1” fork I have,
Chamfer the joining ends,
Drill some holes through the steerer,
Put a 50mm length of tube inside the steerer, with a chartered edge to the inside,
Push it all together,
Clamp it with some angle iron,
Mig weld the holes,
Mig weld the joint,
File it all smooth,
Job done?
Does this sound the right way to go?
I’ve even done a little drawing, that’s got to be worth some points?
I’m pretty confident about my mig welding, but nobody uses mig on bike stuff.
I could give it to a mate to have it TIGed, but it’ll sit in his garage for quite awhile, we’ll at least until he’s finished the motorcycle header he’s building.
Another option is to send it to somebody who knows what they’re doing.
Cheers Ta.

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Nice bike I’d go for your last option or buy another really nice fork

Why is the fork cracked? Doesn't sound like something you'd want to weld.
I have extended/replaces loads of steerers but mostly on newer forks. I'd be worried about this vintage steel. What happens when welded? Also I would not MIG it.

Thanks both.
The crack is really more a split. The top of the fork has been cut to use a more modern headset, but it’s been cut VERY! badly. It’s not only sloping, but also a little bit V’ed. This was not done by me, I promise! So it’s split down the steerer I didn’t notice when I got it, but 500miles in and it’s made itself known. It stops at the bottom of the threaded bit.
@Hulsroy the unknownness of the steel that made me ask, so I’ll defer to your concerns.
I think I’ll have to just use the other fork I’ve got until I find a nice replacement.

Like @Hulsroy I’ve done a fair few steerer extensions. The age of the steel isn’t something that would concern me but that could be foolhardy stupidity rather than anything scientific.

If you have room to slug it and still get a quill stem in it then I say go for it. Are you remembering that the existing steerer will be butted? Your diagram makes it look like you’ll be working at the very bottom of the existing steerer where the butt will be.

There are builders who will say this is the wrong way to do this and would want to sweat out the old steerer and braze in a new one but my personal feeling is that you’re safer slugging and extending than whacking all that heat into a crown and hoping that the silver doesn’t melt out the leg sockets as it melts out the steerer one. Again, I have nothing scientific to back this up.

Yeah, I was thinking of making the cut about 40mm up the steerer, using a 50mm internal tube. Meaning I’d only loose 65mm of space for the stem. The steerer is around 200mm so should be fine for clearance.
I’m normally of the same mindset as you, with a it’ll be fine, but last time a fork failed on me, the drop out ripped out of a carbon/aluminium fork, I woke up in A&E 8 hours later. But maybe MIG is a step too far.

But maybe MIG is a step too far.

That's for you to decide really. I'd braze it because that's what I have/do.

Why not have the full steerer replaced? You'd need to repaint the forks and the very worst.
Cheaper than Turkey teeth.

Hey @Chaley.

Ping us a DM, we can take a look for a fellow bike tagger!

Cheers Amy, I’m on a course today will DM when I get home.

https://youtu.be/TtOeCtNBUwg?si=VNsTXGyM2B9bCMm_

This seems a good solution, and simple lathe made insert, drilled holes that are plug welded are a good addition too

Cool to know I’m on the right track, although I have professional help on hand now.

I took it apart earlier and popped on another fork. Which meant another longer drop brake, but I can ride to work on Monday now at least. Here’s a pic of the split.
And the place holder fork.

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A massive thank you to team @RunRabbitRun especially Barbara for sorting this out for me. Another bike saved from the scrap bin x

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Great job. Nice to avoid a fork respray, too.

Welded extension?

I believe Gavin sleeved and TIGed it, he cut it so that the fork serial number is intact on the bit that was cut off. For posterity. Absolutely flawless job, I recommend them 100%

Is the slight colour change what looks to be about an inch from the bottom of the thread the join? Or is it right down just above the crown?

As you say, flawless work. Must have chucked it on the lathe after to get it looking so consistent.

That was my first thought, but the joint is way further down the tube than that.

The Steerer has been cut and joined at the line drawn on the attached picture, it's where the butt ends on the original steerer tube. That kind of dictates where the splice needs to happen, as this was a threaded steerer for a quill stem, I tried to keep the join as low as possible for maximum stem insertion. There is a 4130 chromoly insert where the join is, as per the Brodie video posted further up the page. Both ends of the tubes being joined are heavily chamfered and then clamped in a big V block whilst they were TIG welded together, The welds were filed flush, which makes everything look nice but also ensures the crown race can be removed/refitted. Everything was then 'shoeshined' with 120 grit and scotchbrite so it all looks seamless.

It was a pleasure to sort it for you @Chaley , always good to keep something out of the scrap bin! It was also awesome to meet Dolly!

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Master class work.

Thank You!

So no lathe?

Outstanding level of finish on it, would never have been able to spot it.

Thank you!

Well, I used the lathe to cut the replacement steerer to the correct length and to turn the insert to the correct diameter, but all the finish work was done by hand.

I guess nearly a decade of doing this stuff on bikes and 20 years prior, doing similar stuff for sports cars has paid off!

I probably didn't charge half as much as most builders would these days either!

Edit - I just noticed where you can see a slight change in the colour of the metal 20mm or so under the threads, That and the threads were clamped in a wooden tube block so didn't get hit with scotchbrite!

That looks bloody good, BITD that would have been a whole new steerer tube an worries about the fork crown...