Wiggles_dad

I'm trying to cut/shorten some Velo Orange steel fenders (I have good reasons). Is it possible to do this cleanly? What would be the best tool to do this, a dremel? A hack saw?

Aubergine 

I used a hacksaw to cut a Honjo fender. It was perfectly clean and needed just a bit of sanding to remove tiny burrs.

Plimogz

I expect that both a dremel w/ cutting disc or a hacksaw would do an OK job. In my experience, when cutting such thin material, the main trick to doing a clean job is holding the work securely. A bench vise, with well chosen jaw fittings to hold the work without damaging it, is extremely handy in such situations.

If doing this on the bike (For Shame!) I would stuff something between the fender and another solid section (tire, frame, fork, etc...) and securely bind everything together -- anything to hold the fender still while you are hacking into it.

And a little filing and sanding erases much in the way of less than perfect cuts.

jyl

A dremel with cutting disc will do it easily. Put some making tape on the fender, draw the desired cut line, and trace it with the disc. If you make a light groove on the surface and then deepen it to cut through, the fender shouldn't vibrate much and you can make any curved cut you like. If you come at it from the edge of the fender and simply bury the disc, there may be more vibration and the flat disc will make it hard to cut a sharp curve.

Phil_gretz

Mark the fender while on the bike. Remove to do the cutting. There's no reason to spray metal shavings near your drivetrain, or wheels.

Dremel and cutting wheel are the preferred combination. Use a sanding barrel to finish off the edgs.

OP, why are you cutting a fender, to split around a tight fork crown or bridge?

Homebrew01

Good quality tin snips should work too. Finish with a sanding block.

Classtime 

I used a Dremel to notch my Bertoud fenders for my bottle generator.

dsbrantjr

"Aviation" snips do a quick, clean job on straight or gentle curves. Shop Stanley 1.18-in 60CrV Snip at Lowes.com
If you need to make tight radius cuts a "nibbler" works well and will distort the material less than the snips: Robot Check

speedy25

ANY kind of snips will distort the edges badly. Use them as a last resort. Hacksaw would be next best, but a dremel cutting wheel will give you the best cut on thin sheet metal. Follow jyl's instructions.

-SP

elcraft

Jeweler's Saw!! But it takes a little practice to be able to use. The fender must be definitely off the bike! A jewelers saw is used like a woodworker's "coping saw". They cut on the down stroke. See:
https://m.youtube.com/watch?v=uQJ4NUKmFaA

fietsbob

or a Jewelers Hand saw if you are not in a hurry and want to follow a very precise line.

they saw pulling down .. they sell the blades in packs of a dozen for a reason.

to have a hardened steel for the cutting teeth they Break if not careful , because of the tempering.


What will you do with the sharp edge to not cut yourself later, touching it?

1nterceptor

I've cut metal items plenty of times with just a hacksaw.