degull

Looking at tig welding a unicrown fork with a 1” threadless steerer tube. The fork blades are Columbus. Wondering what suitable steer tube?

unterhausen

What country are you in?

degull

Oh Canada eh!

unterhausen

Okay so your supply choices are some limited domestically. It doesn't really matter what you get but I wouldn't go with the super light steers that you can get nowadays. There is a history of steerers breaking in unicrown forks, so lightweight parts aren't a good idea

degull

Great, I have a Columbus 2.3/1.55 wall steerer that I originally planned to use.
Paragon Machine Works makes a 1 1/8” steerer tube with a beefy end where the blades are welded to. That made me wonder if a regular steerer would be strong enough. Thanks.

unterhausen

The paragon part has the advantage that you don't need to add a crown race or a sleeve for the blades to attach to.

Andrew R Stewart 

If paragon is sold out of this steerer one can have a sleeve turned out on a lathe than brazed onto the steerer's bottom end.



BTW the small notch in the crown race seat ring is to have drift punch clearance for when one wants to remove the race. Andy

degull

Paragon does not make a 1” steerer. What is the sleeve for? My 2.3mm wall Columbus steerer is not thick enough?
The notch on bottom for removing the crown race is genius!

Andrew R Stewart 

The sleeve both reinforces the area the blades attach to and provide a headset race seat. Is it needed for strength? I don't know but I felt better with it

Will the blades fit the 1' steerer well? Andy

degull

The blades are 1” at the crown end and would definitely look better on larger sized steerer. I like the idea of reinforcing the fork and providing a seat for the crown race at the same time. I have some 1.125 .058 that should fit over the end of the 1” steerer. Thank you!

bulgie 

But you said TIG, is that still the plan? You can't weld over a brazed sleeve. If your weld gets good penetration, you'll have a brass volcano coming up through your weld puddle. Makes the weld all frothy, weak and brittle.

Millions of 1" unicrowns have been made with the blades welded directly to the steerer, with just a ring above the blades for the headset.

I don't like seeing that ring welded on, if the headset size will be the Campy "standard" 26.4 mm. That leaves the 26.4 mm "shim" connected to the heavier ring below only by a too-thin edge. So either stick with 27 mm headsets, or braze the headset ring on after welding is done. I prefer the latter, but a lot of welding guys try to avoid any brazing...

Mark B

degull

I didn’t realize tig welding over a brazed sleeve is a no no. Thanks for that.
My plan is to Tig weld directly to the steerer now. I’ll braze the ring on after.

degull

I didn’t realize that welding to a brazed sleeve is a no no. I’ll stick to the original plan of tig welding directly to the steerer and then braze the ring on last. Thank you!

bulgie 

If you don't already have rings for the headset, Harry Havnoonian is selling them cheap on his ebay store. I think it was something like $12 for a 5-pack and free shipping (though probably not free to Canada).

guy153

Could you just tack the sleeve on with the TIG first. Then weld the arms. Then braze the sleeve.

pwyg

Guy has your procedure right. Although I do not see an issue with the sleeve being being brazed to the steerer first. Since the sleeve will be for sake of ease 1 1/8 x 058 that is plenty of steel between your braze material and the Tig weld. Unless you have too much over penetration when you Tig the legs on that could mix in with your gas filler material. Either way you can use the sleeve as your press shelf for the crown race once done. As for the steer tube you can buy a threadless one or depending on the amount of steer tube you need you can use a longer threaded and cut off the threaded portion. Just make sure it is 4130 steel since that alloy is best for Tig application if you weld them directly to the steer tube.

degull

The thought of using a long regular steerer and cutting off the threads never crossed my mind, thanks for that!
I have a fork with an extra long steerer and some 1.125 .058 wall tubing. I will play with that before I burn some real tubes.

Andrew R Stewart 

Danger tangent ahead... I had a need to look through my stash of fork crowns yesterday. I found this one.




No where near a Tig bead but pretty cool anyway. Andy

degull

That lug is something you don’t see everyday! Very cool!