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

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

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?

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

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

As others have said, the correct rpm is going to be much less than what most might think. I’d calculate that rpm from the recommended speeds for any metal type, and then drop down to at least 20%-30% less that that for what blade tip material your using. Maximum rpm is calculated for production and most you might find probably assume flood cooling. Tool replacement costs for us are a lot more important, so a bit slower is cheaper. Feed rate is also going to be much faster than most might think with any high tooth count saw blade. I’d start with about .002″-.004″ feed rate per tooth. So those cutting rpms verses the blade diameter, the exact tooth counts, and the correct feed rate are going to be pretty important to be 100% sure of what your doing.

I’ve read that for the thinner slitting and slotting blades it’s better to take multiple cuts for slicing the metal right through so that’s how I do it. Something like screw head slots I’d do in one pass at full depth. As the blade cutting width increases, the saw blade becomes much more rigid, so deeper depths of cuts are possible if the machine has enough HP. Depending on the blade type and width, that machine HP and rigidity, it’s probably something that can’t have any real recommendations for the optimum depth of cut for saw type blades. I try to be fairly conservative, and especially so for rpm. Heat and abrasion from any cutting tip rubbing is what destroys cutting tools the quickest. Deeper in softer metals, less for harder. Brass and cast iron because of the small chips are in my opinion much easier than steel. Thin slitting saws are extremely delicate, and your going to ruin some before you learn what they won’t do. I can’t prove it, but making an initial light cut first seems to help keep the thinner slitting blades tracking in the same saw kerf better for the next cuts. Cutting oil also reduces the abrasion and helps to lower the heat build up. Oil is cheap, cutting tools aren’t.

I see the mistake made often on YT videos, but sawing or even drilling unneeded material away so it’s still slightly oversized whenever possible, and then making the last few finishing cuts to size is usually multiple times faster and cheaper than using an end mill to slowly do the same.