cutting steel 2

[Teguci]

Need to cut a 3/8" thick mild steel plate but don't want to cut the beam flange it sits on. Burning through will not work and would like to leave the 25'-0" long plate in place. The cut needs to be straight and clean.

Is there a process that is appropriate for this type of cutting?

 

[ishvaaag]

Diamond rotary sawing? If you can fit the cutting device to tolerance you leave some fraction of a mm, fatigue it to extraction and then grind.

 

[MiketheEngineer]

A very big hacksaw??

 

[Ron]

Metal cutting wheel on a circular saw or side grinder. It will be slow and sparky, but will work as you wanted.

 

[racookpe1978]

I cannot tell the plate configuration from your description, but you should be able to use a 120v electric powered bandsaw to cut the plate while not touching the beam web.

These are commercially available (my own can cut up to a plate 6 inch across; they are at Home Depot, Lowes, and Sears personally; and MSC, Fastenal, etc commercially for around $90.00 to $150.00.)

With its upper handle, the bandsaw is (roughly) 8 inches tall - you will need to verify there is enough room to get it in place above the plate. Width of cut (kerf) is the blade with - just a few thousands. With the saw held hrizontally, the excess depth of the cut is zero. You may want to stop a few thousands above the beam just to avoid scarring the beam amyway, then prying apart the residue.

Now, if the beam (plate) is wider than what the bandsaw can tackle, use it as much as possible; then, use a simple 4-1/2" 13,500 rpm hand grinder with a 1/16 metal cutting blade. (Remember all your PPE, and avoid twisting the grinder wheel in the cut to avoid breaking the wheel.) I have a fairly good touch with a hand grinder, and I do trust myself not to grind through the plate into the beam surface.

Are others at your jobsite as careful? You will have determine that yourself.

I recommend a 1/16 cutting wheel because it takes the shortest time, leaves the smallest kerf, and is lightest. A 1/8 thick grinding wheel would work also, and would be more forgiving if you twisted the grinder in the slot. A 1/4 grinding wheel is a bit of an overkill. The grinding whell can cut away any weld between the plate and beam as well, again, without touching the surface of the beam.

I would not ever consider using my diamond saws in any metal at any time. They are only used for concrete, rock, and granite and hard ceramics.