extending fork/steerer threads?

[horsefarmer]

I'm unclear on if you actually cut fresh threads on the junk fork. If you did how does the Schwinn cone fit over the new threads? Part of what controls the fit of threads is how much material the die has to remove and the material alloy, so the cone should fit more snug on the fresh threads has they have had the most metal removed. also the Schwinn tube is .007" bigger dia. so the cone should fit tighter on the larger tube.
It would be best to get an adjustable die and open it up so it cuts as little as possible and test the fit. To help the die start, run the Schwinn cone a ways down the Schwinn fork, then grind a chamfer on the end of the steerer tube. When you remove the cone it will chase the threads then the die should start. Opening up the die will also let it start easier.

As the text under the last illustration says you can always adjust the die by closing it up and cutting more metal away to make the cone fit looser but you can't add it back.

 

[GuitarlCarl]

He already has a die, so buying an "adjustable one" is a little after the fact. Obviously the Schwinn and the other fork are not the same threads. His die fits the other fork. He wanted to thread the Schwinn down to fit what he needed. I believe he has two practical choices. One, find a different fork or two rethread the Schwinn. It will probably work, but you will likely have to use the headset from the other fork when you're done. It'll be a lot of work but you'll probably be able to do it. Maybe... I wouldn't try it if you're not willing to trash the fork if you fail. Or you can spend a bunch more on an adjustable die and do it right. Me, I'm a stubborn ratter, I'd screw that die right down on the Schwinn threads cut me some new ones right on past what I think I'd need, about a half inch to be sure.

Carl.

 

[Phil Fink]

I have a fixed size die that would spin on and off by hand on one fork but was difficult to even start on another.
I was thinking about adapting it to be a makeshift adjustable die by cutting through one side, and making angled shim pieces to force the hard steel die open.

 

[ParkRNDL]

I have a fixed size die that would spin on and off by hand on one fork but was difficult to even start on another.
I was thinking about adapting it to be a makeshift adjustable die by cutting through one side, and making angled shim pieces to force the hard steel die open.

This is the exact situation I am in. And the fork I want to cut the threads on is the one I can't get it started on.

I'm unclear on if you actually cut fresh threads on the junk fork. If you did how does the Schwinn cone fit over the new threads? Part of what controls the fit of threads is how much material the die has to remove and the material alloy, so the cone should fit more snug on the fresh threads has they have had the most metal removed. also the Schwinn tube is .007" bigger dia. so the cone should fit tighter on the larger tube.
It would be best to get an adjustable die and open it up so it cuts as little as possible and test the fit. To help the die start, run the Schwinn cone a ways down the Schwinn fork, then grind a chamfer on the end of the steerer tube. When you remove the cone it will chase the threads then the die should start. Opening up the die will also let it start easier.

As the text under the last illustration says you can always adjust the die by closing it up and cutting more metal away to make the cone fit looser but you can't add it back.

Yeah, I didn't really explain clearly: I did not cut new threads on the junk fork; I was just playing around to see how the thing fit and get a feel for it. When I got near the bottom of the threads on the junk fork, I had to install the handle and put some effort into it; I guess the threads weren't cut as deep that far down. I decided that if the tool is cutting threads the size of the junk fork, and the Schwinn hardware is loose on the junk fork, and I want to use the Schwinn hardware, then I shouldn't cut the threads with that tool. I have talked to the friend locally who has a die and he says it is in fact a split one, so I will get with him and continue from there.

He already has a die, so buying an "adjustable one" is a little after the fact. Obviously the Schwinn and the other fork are not the same threads. His die fits the other fork. He wanted to thread the Schwinn down to fit what he needed. I believe he has two practical choices. One, find a different fork or two rethread the Schwinn. It will probably work, but you will likely have to use the headset from the other fork when you're done. It'll be a lot of work but you'll probably be able to do it. Maybe... I wouldn't try it if you're not willing to trash the fork if you fail. Or you can spend a bunch more on an adjustable die and do it right. Me, I'm a stubborn ratter, I'd screw that die right down on the Schwinn threads cut me some new ones right on past what I think I'd need, about a half inch to be sure.

Carl.

Yeah, it irks the heck out of me to have bought this tool that isn't doing what I want it to do, but it's winter so I'm not in a hurry and I know someone who has a tool that might solve the problem, so I'm gonna wait it out till I can try his.

 

[horsefarmer]

There is usually a taper built into dies so there is a chamfer on one side and this side starts cutting on the tube. As the die progresses it cuts a little more so it will be tighter fit towards the bottom of the threads. Worth remembering to look for an adjustable die when shopping.

 

[RustyGold]

I see a bunch of air between your caliper blade and the fork tube on your 25.3mm measurement. It looks substantially smaller than 1".