I am building a 3D printer and I have bought steel rods which I'm going to have to cut to size. I have already got a rotary tool at home which works. I have only ever used it to cut wood however, so all the blades I have are specific to wood.

Anyone have any tips on what type of cutting disc is suitable for cutting the steel rods? For reference, the max diameter of these rods is 1.2cm (approx 1/2").


Depends on you, as much as anything.

First off, don't forget eye protection and to work in a location where the sparks flung won't set your house on fire (sometimes hours later, if they get off into a nice cozy bed of lint or shavings in a corner.)

All cutoff discs are consumable, in the sense that they either break or wear down too small to be of use, so buy them in multi-packs.

Very thin discs are easier to break, but cut faster since they remove less metal. If you have a steady hand so you don't break them so much, they work well.

Thicker "reinforced" discs cut slower, since they remove more metal, but are somewhat harder (though not impossible) to break.

  • 1
    If threaded rods, placing a nut on, before cutting, can clean up cut threads.
    – crip659
    Jan 20 '21 at 21:42
  • @crip659 thanks for the tip. I have both smooth and threaded rods to cut, so i will try with a nut at the limit to guide me. Thanks for Jan 20 '21 at 23:11
  • 1
    Use a vice or something to clamp rods solid. No fun holding rod and tool with hands. Cut from top so cut piece does not bind cutting disc as it bends down.
    – crip659
    Jan 20 '21 at 23:29

“Steel rods “ is very vague. Are they tool steel, heat treated, what diameter? If it’s just some soft bar stock you would want to use a thin cut off disc. Sometimes labeled “bimetal” a thick disco is typically used for grinding and de burring. Grab a file so you can break the edge or chamfer your threaded rod.


This really depends. If the cut doesn't have to be spot on perfect I cut steel rods all the time with an angle grinder and the cheapest flap disk (pack of 20 at HF for $3-4) I can find. Why cheap discs? Because they get me 10 or so 1/2 inch cuts. While the $20 diamond coated (one disc) gives me 50-60... but after 10 it isn't useful for things I need a diamond blade for (tile).

Angle grinders are messy and can be dangerous in the wrong hands. If you want safety and a cleaner cut use a chop saw with a fine tooth metal blade. This is the more expensive route as the blades will be $12-15 and don't last forever.

The other thing you have to think about is where you are cutting the rods. The angle grinder goes anywhere, you take the rods to the chop saw.

  • Your definition of "flap disk" and mine must be very different. When I hear "flap disk" I think of a sanding disk. Would you mind linking to the HF "flap disk" you use for cutting? I'd be really interested in learning something new (plus, any excuse to buy more toys, er... tools at HF!)
    – FreeMan
    Jan 21 '21 at 12:37

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