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Cutting a carbon steerer

daniel_bdaniel_b Posts: 9,610
edited May 2014 in Workshop
So as I will soon be tackling two steerers, I thought I would have a look on t'internet.

Found this video, but to me the cut looks pretty unlevel - is it just me or is that less than acceptable?

Just wondering what degree of levelness I should be aiming for (before I give up and take it to the lbs), and I was thinking more than in the below video.

I have bought a cutting guide and a carbon specific saw that someone on here kindly posted.

https://www.youtube.com/watch?v=f-mfV2vZyfQ
Felt F70 05 (Turbo)
Marin Palisades Trail 91 and 06
Scott CR1 SL 12
Cannondale Synapse Adventure 15 & 16 Di2
Scott Foil 18

Posts

  • simonjsimonj Posts: 346
    Doesn't look very neat or professional, but since nothing comes into contact with it you can get away with it as long as all of it is recessed by a mm or two. I'd not be happy and would probably file it a bit or do a better job first time using a park tool thing. What's the carbon specific saw by the way? I've tried this with what I though was an appropriate hack saw but it always wanted to track away from the guide.
  • mitchgixer6mitchgixer6 Posts: 729
    Doesn't need to be perfect as mentioned above it doesn't touch anything. Try and get it as flat as possible with sandpaper and you'll be fine.
  • ugo.santaluciaugo.santalucia Posts: 26,441
    Carbon fibre = expensive wood

    treat as such
  • simonjsimonj Posts: 346
    Also practice, try cutting off a cm or so first before cutting right down to size, else you may end up with a low front end! If you can't practice on a fork, maybe a seat post.
  • ugo.santaluciaugo.santalucia Posts: 26,441
    simonj wrote:
    If you can't practice on a fork, maybe a seat post.

    Or a chair...
  • veronese68veronese68 Posts: 24,660 Lives Here
    Carbon fibre = expensive wood

    treat as such
    This pretty much covers how I treated mine. I used a spare stem with an old spacer as a guide and cut against that. Be careful as you get to the end so it doesn't splinter as you finish, much like wood. I just used a regular fine toothed hacksaw blade. I cut mine so that it finishes a fraction above the stem to ensure maximum clamping surface from the stem and use a slim spacer on top. Worked a treat. Didn't need to finish it with sandpaper as it's not an exposed end.
  • buckmulliganbuckmulligan Posts: 1,031
    Reminds me of the time i bought some MTB forks off eBay (thankfully not carbon), which looked as though the previous owner had hacked the steerer down with a steak knife. Took ages to file it down, but I guess you've only got one shot with carbon!

    The 'old stem' trick sounds good, you could always temporarily glue a spacer on top of it and use that as a saw blade guide if you're worried about knackering a stem. Good luck!
  • daniel_bdaniel_b Posts: 9,610
    edited May 2014
    Thanks for the replies,

    This is the saw that another poster on here suggested:
    http://www.carbonmods.co.uk/Products/Perma-Grit-152mm-Rodsaw-with-Junior-Hacksaw__TC2.aspx

    I was planning to try a cut right up the top initially to have a practice cut and to see how it goes, so good to know that is a sound plan.

    Cheers

    Dan
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • simonjsimonj Posts: 346
    Not sure if it's just me being rubbish, but I did not get on great with a junior saw, even with a miter block. I then bought a park tools guide and it still tried to drift, the park tool kept it in place, but cut was not great or perfectly straight. I think a full size one may be easier to handle, less back and forth etc and longer strokes may mean a cleaner cut with less drift. I think using a junior contributed to needing a few attempts on a few jobs.
  • sandyballssandyballs Posts: 577
    The issue with most junior hacksaws is the inability to get real tension in the blade that's why it try's to track away, it's the deflection in the blade. As long as you have good tension (they do take a lot) and use gentle sawing pressure unlike forcing a knife through the stroke you should be fine.
  • bernithebikerbernithebiker Posts: 4,148
    If you want to get a perfectly straight cut, use a pipe cutter.

    They're fairly cheap, and your cut will be perfect.

    Scaremongers will say don't use one near carbon, but if you increase the pressure only very slightly on each rev, and the round cutting blade is new and sharp, you won't have any issues. Keep rotating it, and keep increasing pressure a tiny amount each turn.

    When you have a good line scored all the way round, take the pipe cutter off and use a junior hacksaw to finish. As it now has a groove to sit in, you'd have to be really hamfisted to mess up now.
  • mallorcajeffmallorcajeff Posts: 1,489
    As a guide i slipped two jubilee clips on mine and left a saw blade thickness gap between the two and then passed the saw between for a perfect square cut.
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