Cutting a thread on a 1 1/4" threadless steerer
- Thread starter shawnb
- Start date
The Bear":185szgo2 said:
Cheers for the info... trouble is it's bonded in a crown (manitou 2). Just one of a couple of options, this being the easiest.
Other option is to use an adjustable reamer to take the inside of a 1 1/8" (28.575mm) ahead stem out to 1 1/4" (31.75mm) - there's enough meat in the alloy aheadstem to do this..... :?
integerspin
Senior Retro Guru
Do the stanchions come out?
If they do, it's still easy to hold the yoke to cut the thread on a lathe.
If the stanchions don't come out I could still do it, but I would
have to knock up a pretty stout centre to hold and drive it the yoke.
I was going to do this to re-thread a pair of rigid forks, then three pairs
the right length fell off ebay into my garage;-)
If they do, it's still easy to hold the yoke to cut the thread on a lathe.
If the stanchions don't come out I could still do it, but I would
have to knock up a pretty stout centre to hold and drive it the yoke.
I was going to do this to re-thread a pair of rigid forks, then three pairs
the right length fell off ebay into my garage;-)
integerspin":f0t6aggf said:
Hmmm sounds like you know what you're talking about
Ideally I would like to have a thread cut onto a 1 1/4" ahead steerer, the route of reaming out a 1 1/8" ahead stem to 1 1/4" on second thoughts is not a go-er... the stanchions do indeed come out so I'd be left with the crown and steerer to thread. The reason I need to do it to these forks is they are original to the bike and I have a nice 1 1/4" quill stem I want to use as it's more suited to the bike/year, also I don't have the patience to wait for a set of manitou 2's in 1 1/4" threaded 
If you'tr going to give it a go yourself........
The trick is to get the die started square to the steerer. Don't even try starting it with the handle on. Put the die on the top of the steerer, lead in side down. Check that it's sitting flat and perpendicular to the steerer with a toolmarker's square (or equivalent) around the steerer at 90 deg. positions. Tap the top of the top of the die lightly to get it to seat and grip the steerer. Check the squareness again. Put the handle on and cut a half turn of thread. remove the handle and check the squarenss again. If it's out a bit, now is the time to tap the high edge of the die to bring it back to square. Put the handle back on ad cut another half turn. Remove handle and check squareness again, tapping it back square if needed. Put handle back on and do a full turn (you should start breaking the chip @ 1/4 turns now). Check squareness again. You should now be able to cut the full thread reasonably square. Use plenty of tapping fluid and break the chips (I like Kool Tool, but it's banned now. any oil is better than none). The thread may be tight after the first pass due to tool spring back. If the cup or lockring of your headset are tight on the thread, do another pass (chase) the thread with the die. If it's still tight, turn the adjusting screw on the die in 1/8 turn and repeat.
Yes, the constant checking for squareness is a PITA, but you only get one shot.
The trick is to get the die started square to the steerer. Don't even try starting it with the handle on. Put the die on the top of the steerer, lead in side down. Check that it's sitting flat and perpendicular to the steerer with a toolmarker's square (or equivalent) around the steerer at 90 deg. positions. Tap the top of the top of the die lightly to get it to seat and grip the steerer. Check the squareness again. Put the handle on and cut a half turn of thread. remove the handle and check the squarenss again. If it's out a bit, now is the time to tap the high edge of the die to bring it back to square. Put the handle back on ad cut another half turn. Remove handle and check squareness again, tapping it back square if needed. Put handle back on and do a full turn (you should start breaking the chip @ 1/4 turns now). Check squareness again. You should now be able to cut the full thread reasonably square. Use plenty of tapping fluid and break the chips (I like Kool Tool, but it's banned now. any oil is better than none). The thread may be tight after the first pass due to tool spring back. If the cup or lockring of your headset are tight on the thread, do another pass (chase) the thread with the die. If it's still tight, turn the adjusting screw on the die in 1/8 turn and repeat.
Yes, the constant checking for squareness is a PITA, but you only get one shot.
