beng1

Hi all. Does anyone know of a source of a lower-priced die for cutting the threads on a one-inch fork? I have a fork that I want to cut down a little to fit a shorter frame, and before I cut it I wanted to cut the threads down further. The Park Tool for this job is about $250, I was hoping to just buy a die alone for about a tenth that much as I will probably never need it again. My local bike shop said they never used their tool for this job and got rid of it.

Andrew R Stewart 

Most of the "threading dies" the bike industry sees are more a chasing of existing threads type then cutting new threads types. What's the difference? The reduction of pulling/pealing off the thread form from the steerer. Especially with the stringy nature of 4130 (and related bike tube alloys) a die can easily tear off the threads it's trying to cut.

Yes nice sharp and well ground cutting edges help to reduce this. But that is not what cheap/used tools are generally about If one were only needing a few more threads i would consider this (and I have access to Park, Campy and Var dies/handles/guides). But for more than the threaded race will need i would pass on this job.

So we don't know about the steerer in play, the amount of added threads needed and your location to possible offer help... Andy

bulgie 

Short answer:
$13.50 on ebay (+ free ship) cheap enough for ya? Not endorsing that product or seller, just the first hit that came up in a brief search.

Longer answer: don't do it on a fork you care about... unless you really wanna!

What Andrew said. It's likely to rip out all the threads, both the new ones you just cut and the original ones too.

Not always though. Sometimes you get lucky get good threads. I think one of the main variables is how many new threads you add (aka how far down the steerer), with a shorter distance more likely to succeed. I'm unlikely to try it on a fork I like, for more than maybe 1.5 cm. 10 mm is probably even a lot safer than that. Is that the kind of range you're talking? More threads than that can be added by a machinist a couple different ways, but unless you have a buddy who'll do it for a 6-pack, getting a busy machine shop to do this for you is impractical and $$$. Shop for a new fork.

Another issue, if you shorten a steerer by a lot, make sure you know where the butt begins. It doesn't go to the full butt thickness all at once, there's a tapered transition. And where that taper starts can be a little tricky to tell exactly. But it's super important that a quill stem not be allowed to touch even the beginning of that taper. If it tightens in the taper, then it can easily come loose and cause a crash.

Mark B

Jeff Neese

I've had it done once. There was only one shop in our area that had the tool and the experience doing it. Some of the other shops in the area just referred people to them and I had to drive across town. Call around. If no luck in your area, you may need to send it off to be done. Don't undervalue the experience part - find a guy that's done it a few times before.

unterhausen

I had a bad experience extending threads (bad experience as in new steerer time) and that was with a good die. You have to be careful at the transition from old threads to new, and I wasn't careful enough so I lost a thread. Of course that thread is exactly where the headset would go. It's the threaded version of cutting the steerer too short. Also careless framebuilding not checking where the threads are going to end up.

beng1

Thank-you for the input.

I am not going to know exactly how much to shorten the fork until I am done shortening the frame. It is a 26" Schwinn frame, I am going to shorten it to somewhere between 24" and 25". The head tube on it is only a fraction of an inch longer than some 25" bikes I have checked, I will be shortening the head tube by an inch or more. There are a couple other bike shops in my area I will check with when I get a chance to see if they have the park tool.

I went to school for tool and die and worked as a machinist etc. so am not worried about cutting threads myself if it comes to that, I will just make sure I have the Park tool or the right high-speed steel die if I end up doing it myself.

bulgie 

OK I have just one more word of advice, thread cutting with a die is more likely to succeed if you reduce the diameter just a bit in the area where the threads will go. Can be done with a flat file, or shoe-shining with abrasive cloth strip. Super important if the steerer is chrome plated, remove the plating where the threads need to go. If you only take the diameter down in the threaded part, then you're not reducing the strength any, no downside. Proper thread form is a little truncated anyway, as you know from your schooling.

Reynolds 531 

I would recommend a cheap "split die" rather than a cheap solid die. The cheap (nothing wrong with that) solid dies are actually a teeeeny bit smaller than the actual spec, and most if not all proper headsets will be a loose fit. We talking thousandths here.