Fork crown brazing
#1
Fork crown brazing
Do you braze your blades and steerer at the same time? Here's a Brent Steelman vid of what I mean:
Also, why are the crown blade openings not fluxed before inserting the blades?
thanks, Brian
Also, why are the crown blade openings not fluxed before inserting the blades?
thanks, Brian
#5
Senior Member
Joined: Dec 2012
Posts: 148
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From: Puyallup, WA
Bikes: Many... Up to 9 in the stable now
Couple things to note:
* He does have flux in the crown already, along with some brass. He knows when the steerer/crown joint is up to temp when he can see the brass flowing out the crown race seat end (bottom).
* He's using a "big ass tip" (a small rosebud). That's pouring a lot of heat into the crown in a short time.
I think it also depends on how your jigging works. What access you have, etc.
My method: I generally do a two-step process (well, three, because I'll often put a plate on the bottom of the steerer to close that off). Brass on the steerer to crown, and then silver on blades to crown. I use a #4 tip with oxy/propane, and it gets the job done. I like to be able to feed brass into the crown/steerer joint through the blade openings. I also drill the steerer to vent through the crown.
* He does have flux in the crown already, along with some brass. He knows when the steerer/crown joint is up to temp when he can see the brass flowing out the crown race seat end (bottom).
* He's using a "big ass tip" (a small rosebud). That's pouring a lot of heat into the crown in a short time.
I think it also depends on how your jigging works. What access you have, etc.
My method: I generally do a two-step process (well, three, because I'll often put a plate on the bottom of the steerer to close that off). Brass on the steerer to crown, and then silver on blades to crown. I use a #4 tip with oxy/propane, and it gets the job done. I like to be able to feed brass into the crown/steerer joint through the blade openings. I also drill the steerer to vent through the crown.
#6
Couple things to note:
* He does have flux in the crown already, along with some brass. He knows when the steerer/crown joint is up to temp when he can see the brass flowing out the (bottom).
* He's using a "big ass tip" (a small rosebud). That's pouring a lot of heat into the crown in a short time.
* He does have flux in the crown already, along with some brass. He knows when the steerer/crown joint is up to temp when he can see the brass flowing out the (bottom).
* He's using a "big ass tip" (a small rosebud). That's pouring a lot of heat into the crown in a short time.
Yes he's using a rosebud, not sure what difference that makes in the brazing sequence, just up to temp quicker.
Thanks, Brian
#7
Randomhead
Joined: Aug 2008
Posts: 25,930
Likes: 4,825
From: Happy Valley, Pennsylvania
I feel like brass is a little less sensitive to the presence of flux, and some probably wicks in there when he is heating it up.
I really like building forks. I have a pile of forks in my shop, waiting for frames.
I do the fork crown first with silver and then the blades. I like to see that the silver has created a fillet in the windows in the crown. I pull the silver through from one side to the other, so there are always fillets, but it makes me happy to see them.
I go back and heat up the first blade when I'm done with the second. It doesn't take that much, I don't get it red or anything. Never had to set a fork or file a dropout either.
I really like building forks. I have a pile of forks in my shop, waiting for frames.
I do the fork crown first with silver and then the blades. I like to see that the silver has created a fillet in the windows in the crown. I pull the silver through from one side to the other, so there are always fillets, but it makes me happy to see them.
I go back and heat up the first blade when I'm done with the second. It doesn't take that much, I don't get it red or anything. Never had to set a fork or file a dropout either.
#8
Senior Member


Joined: Aug 2012
Posts: 680
Likes: 283
From: Seattle
I have same process as Unterhausen - silver the crown to steerer. I actually leave a bit of extra flux in the sockets when putting the crown on the steerer so I can scoop it out and put more on as I'm going around the crown. I use a #4 which is about the max my tanks will handle. After the crown is on, I cut the headset race, then I flux up the sockets and dropouts and assemble in the jig. Then I do the dropouts and finally the sockets.
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Last edited by duanedr; 01-13-18 at 01:47 AM.
#9
Senior Member

Joined: Jan 2013
Posts: 2,379
Likes: 937
From: South Jersey
Do you do the left leg second? My fork fixture allows some movement of the steerer tube in the clamp. I found that the expansion, from brazing the first leg, pushed the crown and steerer up slightly and had the effect of pulling the other leg out of the crown a small amount. This caused the second leg to be slightly longer than the first. The fix was to evenly heat both legs until they were close to brazing temp and then do each one individually.
#10
Senior Member


Joined: Aug 2012
Posts: 680
Likes: 283
From: Seattle
Do you do the left leg second? My fork fixture allows some movement of the steerer tube in the clamp. I found that the expansion, from brazing the first leg, pushed the crown and steerer up slightly and had the effect of pulling the other leg out of the crown a small amount. This caused the second leg to be slightly longer than the first. The fix was to evenly heat both legs until they were close to brazing temp and then do each one individually.
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