Tapping threads onto a threadless steerer | Yay or Nay?

[andyz]

My back garden and black and decker workmate must be a proper engineering shop then ... ;-)

WD

Snap! You beat me to it!
Three of the bikes I ride have steerers threaded by myself using a borrowed tool and the workmate.

 

[pete_mcc]

My back garden and black and decker workmate must be a proper engineering shop then ... ;-)

To the OP - I can't guide you if it is safe or if it will work, but if you can borrow a tool, check out my how to guide here : viewtopic.php?f=1&t=282496&hilit=thread

WD

But you were only extending existing threads not cutting new ones into a blank ahead steerer with no existing threads to act as a guide. That is far, far harder to do well.

 

[andyz]

But you were only extending existing threads not cutting new ones into a blank ahead steerer with no existing threads to act as a guide. That is far, far harder to do well.

I was referring to blank steerers. The correct tool has a guide on it which holds the die in line with the steerer. It would be very difficult with a conventional die holder, and result in the problems mentioned.

The tool I've used was made by VAR, and has been used for many years in cycle workshops for threading blank steerers:

http://sheldonbrown.com/var/pages/var0021.html

 

[jinjrich]

My back garden and black and decker workmate must be a proper engineering shop then ... ;-)

WD

Snap! You beat me to it!
Three of the bikes I ride have steerers threaded by myself using a borrowed tool and the workmate.

I'd still not recommend that tool for anything other than extending threads.

To the OP: If you want a professional job get it done by an engineering shop. It shouldn't cost that much, you'll get a better result and it will probably cost less than the borrowed tool you just ruined on 'your workmate in the garden'

 

[WD Pro]

I still beg to differ ...

If I was starting on a blank steerer I would ensure it was a good inch or so longer than required (it should be as it's going from ahead to threaded).

I would reduce the OD of the steerer a little for the first half inch or so, just roughly with a file or even a grinder etc. This would give you a good / easy start for the die.

The centralising part of the tool would already be on good / true metal so by the time the die is cutting thread in the area that will get used, it will be doing so nice and true and in an identical way to extending an existing thread.

Once done, just shorten the steerer to the desired length removing the area that was used to get the die started.

If you have the competence to use the tool in the first place, this shouldn't be much different.

The greater the gap between the tools guide and the die, the easier this will be and the quicker the tool will cut straight.

WD

 

[pete_mcc]

So you'd beg to differ based on nothing more than what you reckon you might do. Cutting threads into a fork with existing threads like you have done is infinitely easier than cutting fresh threads into a blank, doing so with shitty tools and no knowledge is then compounding the difficulty further. It's not that hard to take something down to an engineering shop or frame builder and have it done professionally rather than trying to be an alpha male and hit it with stones.

 

[WD Pro]

No, I would beg do differ based on experience of cutting threads onto unthreaded material by hand, using a die and die holder without a guide to assist you

And why would the tools be shitty ? :?

Yeah, it's not hard to take it to an engineering shop and get them to do it but they can do it wrong to ... and you cant take any pride it doing it yourself ...

WD

 

[waddelblah]

My back garden and black and decker workmate must be a proper engineering shop then ... ;-)

To the OP - I can't guide you if it is safe or if it will work, but if you can borrow a tool, check out my how to guide here : viewtopic.php?f=1&t=282496&hilit=thread

WD

Clean work ! Nice one! Thanks for sharing

 

[cherrybomb]

Jeez!

Cutting threads isn't rocket science. I agree it can be easy to mess it up if you go at it like a mad man but I can't see an issue if you're using the right tool for the job.

The trick with cutting threads is to go slowly, use plenty of oil and back the tool up regularly to clear the swarf out of the cutter.

If you use a file to put a chamfer on the top edge (Or even some wet & dry) you'll get the cutter started a little easier and I'd agree about leaving the steerer long and cutting it down after to the correct length.

The difficult bit is getting hold of the right tool in the first place.

Chances are, if you take it to an engineering shop they'll cut it by hand just like you would, its less hassle than trying to clamp forks in a lathe!

Having said all that, when you work (or worked) in engineering it can be easy to think stuff like this is easy. You get plenty of practice.

I wouldn't be without my tap an die set though.

 

[Wold Ranger]

This is a yes and no answer, I used to do dozens of forks BITD and it was a very quick and simple job. BUT and it is a humongous but indeed, ONLY if you have a very good quality tool and these days they cost mega bucks.
When I was younger and dafter and more flush, I used to own a Campag steerer cutter die that was specifically designed just for this job. Many of the local roadies would buy better/new forks for their steeds and get me to die the steerers for them. Sadly I sold this years ago when kids arrived, it would take different sized dies also. They must be over a grand to buy now, if you can find one? :facepalm:
This automatically aligned the die and had a long taper to it, so each thread was gradually and progressively cut deeper.
I would take it to a good frame builder and ask his opinion.