Use horizontal mill as saw for metal?

[ell81Participant @ell81]

I have just purchased a horizontal mill with an arbor and it obviously has spinning cutters similar to a circular saw, but can it be used to cut through thick metal? I assume you would have to do it in passes like a normal milling operation. Thanks.

[RobinParticipant @robin]

Bit shy on information…

“Thick”? “Metal”? You can probably go a lot deeper than you could with a slitting saw.

Choice of side and face cutter can be limited by what arbours you have and their keyways.

Sounds like fun 🙂

Robin

[noel shelleyParticipant @noelshelley55608]

As Robin says, we need more info ? Noel.

[Andrew CrowParticipant @andrewcrow91475]

Even without more information, using a sitting saw on a horizontal milling machine to cut through plate material is quite normal practice. How big obviously depends on the size of the machine and the cutter. I would recommend using slitting saws rather than side and face cutters for this operation. They cut better with several teeth in contact with the material that you are cutting.

Andy

[BazyleParticipant @bazyle]

Slitting saws are relatively expensive so not the best choice for bog standard hacking off metal. Look at the correct speed and feed for the slitting saw you are considering as you need to ensure each tooth is actually cutting an appropriate amount or it will break or rub then melt if not correct. The correct speed for a decent diameter is far slower than you expect and most mills cannot go very slow.
There are metal cut-off saws bit like the wood ones so look at the blades they use and the parameters that go with them.

[old martParticipant @oldmart]

Sounds like it could work well, using slow speeds. You may have to make an adaptor, but at the museum, we were given a number of slitting saws up to 8″ diameter with 1″ bores in widths of 1/32″ to 1/4″. I have used some on a custom R8 arbor successfully, but only have vertical mills, a horizontal spindle would work better.

What mill do you have and what spindle fitting doe’s it have?

[Roderick JenkinsParticipant @roderickjenkins93242]

Bazyle’s got it right.  When I bought my Sharp MkII milling machine, which has a horizontal milling option, I bought  a couple of 4″ diameter slitting saw blades thinking that they would go through steel bars like a knife through butter.  Wrong!  They blunted almost immediately.  You need to be  very aware of the correct feeds and speeds, which are much slower than you might think- a 4″ blade has a long perimeter.  A cheap bandsaw is much better.

Rod

[vintagengineerParticipant @vintagengineer]

You can use small T/C blades meant for circular saws.

[FulmenParticipant @fulmen]

You don’t even need a horizontal spindle:

 

No, I never turned it on *shudder*

[ell81]

On 7 April 2025 at 15:53 ell81 Said:

…can it be used to cut through thick metal? I assume you would have to do it in passes like a normal milling operation.

In a word yes. I regularly use slitting saws on a horizontal mill to slice off long lengths of hot rolled steel and extruded cast iron that won’t fit in the bandsaw. Maximum material thickness is around 75mm.

As stated above, I run the slitting saw slowly, usually 30/60rpm as they are the slowest speeds on my mill. Depth per pass is 10 to 15mm and feedrate is set by a chip load of around 0.1mm/tooth. Flood coolant is used, even on cast iron.

Good quality slitting saws are hollow ground so there shouldn’t be much rubbing of the cutter faces.

Julie

[RobCoxParticipant @robcox]

Yes, you can do it and I have a few times to cut sheet steel more accurately than using a shear.

BUT, it takes a deal of care. Using a conventional milling technique, the cutter tries to lift the material away from the mill table, so it must be well clamped down all along the length of the cut. If you try climb milling the cutter will push the material down but the backlash on my mill makes this a non starter as it feeds in fits and starts and threatens to break the saw.

If you’re going to cut thicker stock beware the cutter gullets filling up. You’d need fewer teeth with deep gullets for this.

I avoid doing this unless I have no better alternative.

Rob

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