There is a fair amount of torque that is required to put threads on a steerer as you push/pull the handles around, so it can be hard on the tool, especially if you get some racking movement in there as well. A good die should be able to handle the job repeatedly with a few mindfulls. Loosen up the die so it cuts the threads shallow first, then requires two re-adjustments and applications to cut the threads to the depth required. Frequently back off the tool to clear out the loose steel chips, maybe halfway down completely remove it and blow out the crud, then start again, and always provide adequate lubrication with thread cutting oil. Yes, it will take up some time to do it right. Any die will wear over time, but not using one for fear of wrecking it seems kind of lame to me. I think the guy who told you why he doesn't use one for threading, should consider the reason why the tool is expensive in the first place, minus the handle affair. Of course a tool that is only used to clear out threads will last longer, so credit where credit is due.
Just a few days ago threaded a steerer on a patina handled tool in
> Earlier this week I wrote in to ask advice on whether to cut a vintage
> Colnago fork. Survey said yes, overwhelmingly, that apparently forks
> were made to be cut.
> So since I don't have a saw guide or a machine shop, I called around
> to a few bike stores in town to ask about getting this cut down and
> the thread extended. And here's where things got strange. Nobody wants
> to do it.
> The basic line I got was that while cuttiing the fork is no problem,
> the threading is a pain. And one shop went so far as to say they
> don't, as a rule, do threading of steerers. Reason: because it's
> "murder on the $70 tool." It was odd, and I said, "so, what, you
> simply don't use your $70 fork threading tool for fear of ruining it?"
> And the guy said that the only use it to "clean" dirty threads;
> cutting the "ruins" the tool.
> Now I'm no expert, but it seems odd to me that a fork threading tool
> would get ruined by doing its job. And it seems odd that this is
> apparently a job nobody can do. Interestingly, the guy started talking
> to me about "making the switch" to threadless and how he could show me
> catalog with great threadless stems.
> Anyhow, am I being a ninny on this? Is it simply impossible to thread
> a fork these days? (I say that with tongue in cheek, because I really
> can't imagine it is).
> Corollary question: assuming that the laws of modern physics do indeed
> allow for fork cutting and threading, what's the going
> (post-Newtonian) rate for such a service? Or am I better off buying
> this famous $70 tool, doing it myself and then chucking the now ruined
> fork threading tool.
> Which reminds me, since when do companies like Park make a disposable
> line of tools designed to break with only one use?
> Ken Bensinger
> Brooklyn, NY