How to cut carbon steer tube cleanly



Chuck731

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Nov 15, 2005
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How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies
 

capwater

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Sep 15, 2003
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Chuck731 said:
How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies
Hacksaw with a fine tooth blade will work.
 

fish156

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Mar 26, 2005
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Chuck731 said:
How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies
1. Use a cutting guide to insure a square end. Park makes a lovely one (Threadless Saw Guide - #SG-6), or, you can do it on the cheap and just use a hose clamp.

2. Hacksaw with a 32tpi blade.

3. Make sure you do not inhale any of the dust you create from the sawing. Get a ventilator mask and use it.

Easton and Park both have nice articles on cutting fork tubes:

http://www.eastonbike.com/downloadable_files/r&d_files/R&D-05-Carbon.pdf
http://www.parktool.com/repair/readhowto.asp?id=111
 

John M

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Jun 21, 2005
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Chuck731 said:
How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies

Do like the Easton site recommends for cutting carbon tubing (forks or bars) and wrap the area to be cut with masking tape to prevent carbon fiber splintering. I would also use a cutting guide or miter box and fine toothed hacksaw.
 

mitosis

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Jun 21, 2004
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Chuck731 said:
How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies

Use a guide (borrow from the bike shop where you bought the forks) and a hacksaw with a sharp coarse blade (24 tooth - It doesn't make the cut any less tidy and it doesn't clog).

If you are any good you can cut without the guide.

If you can't borrow a guide, make one out of 3 3x1's joined to make a u shape and with a wide kerf saw cut throught the two uprights that you use as your hacksaw guide (holding the steerer tube firmly in one corner as you cut).

If you are feeling a little timid (as I did before my first one) have a practice near the end of the steerer, well up from where you plan to make the real cut.

Cut it a little long and use spacers above the stem. You can always cut more off if you want but you can't lengthen it if you cut it too short.

Cut straight. :)
 

fish156

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Mar 26, 2005
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mitosis said:
Use a guide (borrow from the bike shop where you bought the forks) and a hacksaw with a sharp coarse blade (24 tooth - It doesn't make the cut any less tidy and it doesn't clog).
I'm just curious. Since one of the world's largest manufacturer of carbon forks - Easton, and the world's foremost manufacturer of bicycle specific tools - Park, both specifically say to use a 32tpi fine tooth hacksaw blade to cut a carbon steerer tube, why would you not follow their directions. What is it you know that they don't? Park advises to keep the blade wet so it does not clog.

Also, a 24tpi blade would be a medium. 18tpi is coarse.

With all due respect, your recommendations come off as only your opinion and it goes against documentation that the original manufacturer and tool makers' have provided. To suggest that "if you are any good you can cut without a guide" is just plain bad advice. For a headset to work properly you need to do everything you can to make sure the bearings get equal loading all the way around. This is why it's important to check head tube faces for parellelism and reface if necessary.
Cutting a tube with no guide almost guarantees that you will not get good, even loading on your bearings. While your technique may work, it certainly is not a good way to do the job and it goes against all published methods. If you have some source of validation for what you say, please share it with us all.
 

mitosis

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Jun 21, 2004
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fish156 said:
I'm just curious. Since one of the world's largest manufacturer of carbon forks - Easton, and the world's foremost manufacturer of bicycle specific tools - Park, both specifically say to use a 32tpi fine tooth hacksaw blade to cut a carbon steerer tube, why would you not follow their directions. What is it you know that they don't? Park advises to keep the blade wet so it does not clog.

Also, a 24tpi blade would be a medium. 18tpi is coarse.

With all due respect, your recommendations come off as only your opinion and it goes against documentation that the original manufacturer and tool makers' have provided. To suggest that "if you are any good you can cut without a guide" is just plain bad advice. For a headset to work properly you need to do everything you can to make sure the bearings get equal loading all the way around. This is why it's important to check head tube faces for parellelism and reface if necessary.
Cutting a tube with no guide almost guarantees that you will not get good, even loading on your bearings. While your technique may work, it certainly is not a good way to do the job and it goes against all published methods. If you have some source of validation for what you say, please share it with us all.

I usually use a 24 tooth blade for carbon fibre steerers and a 32 for aluminium. I have used an 18 on Carbon and it works well too. When I first cut a C fibre steerer I used a 32 tooth blade but realised that a coarser pitch would be an improvement. I made several cuts with different blades on steerer off-cuts to gain experience.

I've only cut one C fibre steerer free hand when I couldn't borrow my mate's guide, but not before having several practices on an off-cut to make sure I was up to it. If you mark the tube properly and are experienced at cutting there should be no problem. If you can borrow a guide use it.

If you don't believe any of this then I suggest you go down to your shed with hack saw blades and try for yourself on a C fibre off-cut. Its called learning from experience. If you are not confident get your lbs to do it. I've made dozens of cuts on both aluminium and carbon so I think I know what I am talking about.

Yes, a coarse blade is 18 tpi. Maybe I should have used the word coarser when referring to 24. Serious error that. :rolleyes:

The reason Park Tool recommend a 32 tooth blade is that is is supposed to produce a neater cut. By the time you touch up the end of the steerer with some wet and dry you won't see a difference.

I realise this is all opinion but it is one expressed as a result of experience. Unless I have some knowledge or experience that I think will help someone I don't bother posting (unless I can think of a smart arsed comment of course). You are free to take my suggestions or leave them. :)
 

mitosis

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Jun 21, 2004
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jimmer23 said:
Use 32tpi for sure. You don't want to even risk splintering.

Don't know where you got the idea about splintering. I've cut carbon fibre steerer tube with a mortising saw (just to see what happened) and made a straight clean cut. Splintering? ;)

It pays to know what you are talking about.
 

sarah_pdx

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Oct 22, 2009
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fish156 said:
Cutting a tube with no guide almost guarantees that you will not get good, even loading on your bearings.

As far as I can tell, this has nothing to do with bearing loading. There are no compressive forces on the top of the steerer tube. One leaves a ~2mm gap between the top of the steerer and the top of the stem. The only reason a vaguely square cut is required is so you can put pulling pressure on the steerer tube to snug down the headset without a portion of the steerer bumping into the top cap. I suppose you could go the other way too and cut it uneven where portions of the steerer are "too short". That would mean your stem is clamped to slightly less steerer tube, which doesn't seem like the end of the world.

Seems to me that as long as you're not off by more than 2mm (and check to make sure you're not bumping into the top cap) you'll be fine.

Still, if you have a miter box or a saw guide, I'd definitely use it!
 

sideshow_bob

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Apr 26, 2005
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sarah_pdx said:
Seems to me that as long as you're not off by more than 2mm (and check to make sure you're not bumping into the top cap) you'll be fine.

Still, if you have a miter box or a saw guide, I'd definitely use it!

That's exactly right, there's generally no functional requirement to have a perfect cut. Having said that I do prefer to have a nice clean and straight cut.

I do all mine (carbon and aluminium) with a drop saw using a cut-off wheel. The saw has a built in clamp to ensure a cut at right angles to the walls of the steerer tube, just clamp and cut. If you are doing many of these, a drop saw at $100 isn't a bad investment.
 

rparedes

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Jul 21, 2007
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Chuck731 said:
How do I cut the carbon steer tube to the right length cleanly? Can I use a hacksaw? Or would I need some special tool?

Thanks for the replies

I taped the steerer where the cut was going to be (masking tape), used an old stem as a guide and used a hacksaw with a tile cutting blade (it's really more like an abrasive narrow rod). Finished off the edges with very fine sandpaper. Almost like a factory edge!
 

frenchyge

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Apr 3, 2005
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I use a $5 tube cutter like this that I bought at the Home Depot and it works great without any clamps, guides, tape or what-have-you. Works for seatposts, too. Of course, this tool was specifically designed for square cuts on thin-walled tubing.

base_media
 

alienator

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Jun 10, 2004
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Ask any manufacturer or composites expert, and they will tell you NOT to use a tubing cutter. They don't cut fiber cleanly. It's not what they're designed for. They crush and tear tubing and do nasty things to the resin. In short, they don't do kind things for the CF matrix.

Such advise is uniform across manufacturers.
 

tonyzackery

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Dec 23, 2006
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Always nice to revive an almost 4yo thread...Nevertheless, the info should come in handy to someone out there...

Tool of the trade - carpentry trade, that is - will do the job nicely. It's called a miter saw or chop saw - maybe the same as the "drop saw" that I saw referenced in a previous reply. Never heard it called that though - may be a regional term or something...

Anyway, with the correct blade (the more teeth the better) a miter saw will make short and easy work of cutting the carbon steer tube on your fork. I've done several myself with excellent results. Speed kills...your hand sawing will never do the job as cleanly as the electric saw and its high speed will...

Ask around...one of your buddies may just own one...if that fails, take it to your local hardware store or lumber yard as they may have one available and do the job pro bono...
 

frenchyge

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Apr 3, 2005
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alienator said:
Ask any manufacturer or composites expert, and they will tell you NOT to use a tubing cutter. They don't cut fiber cleanly. It's not what they're designed for. They crush and tear tubing and do nasty things to the resin. In short, they don't do kind things for the CF matrix.

Such advise is uniform across manufacturers.

Hmmm. Good to know.... thanks.:)
 

Akadat

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Sep 12, 2006
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In my experience...

- Tube cutters work best on metal, the cut is square and leaves an inwards crimp. Carbon fibre cannot crimp and will splinter on the inside.

- Hand saws must have at least 2 teeth in contact with the wall thickness. If sawing with 2 teeth in contact then light pressure is best. If 3 or more teeth are in contact then heavier pressure can be used.

- Drop saws = high-speed machine cutting. The cut will be square and the tooth count is overwhelmed by the RPM. Anything will do from an abrasive wheel to a coarse saw...just take it slow on the drop!
 

David Beacham

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Jul 26, 2013
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Originally Posted by frenchyge .

Quote:
Originally Posted by alienator . Ask any manufacturer or composites expert, and they will tell you NOT to use a tubing cutter. They don't cut fiber cleanly. It's not what they're designed for. They crush and tear tubing and do nasty things to the resin. In short, they don't do kind things for the CF matrix.

Such advise is uniform across manufacturers.
Hmmm. Good to know.... thanks./img/vbsmilies/smilies/smile.gif
I wasn't sure it would be a good idea, i'll get the hacksaw out now!