Cutting and fitting SS

Date 12-23-2010 04:19

If you are close enough to a facility that has the equipment, water jetting sounds like exactly what you are looking for. It can cut any shape that can be drawn, and the people that do it around here will guarantee +/- .020 in. per inch of thickness.

By G.S.Crisi (****)

Date 12-28-2010 18:09

I agree, John. I've always seen cutting disks and saws being cooled down with water.
Giovanni S. Crisi
Sao Paulo - Brazil

By DaveBoyer (*****)

Date 12-23-2010 04:36

I would try a masonary [silicon carbide] wheel in the chopsaw, and see what happens. It is a slightly harder but more fryable abrasive, and may break down fast enough to keep cutting. Don't expect good wheel life, but at this point You just need to get the job done without burning up the saw. You have much more wheel in contact with the work than that type saw, or the wheels available for it are made for.

A good bi metal bandsaw blade with coarse teeth [I like Lenox] is probably the best bet, but a Portaband might run too fast at full speed. I don't know what You have available, My Milwakee is set up so that anything other than 90 degree cuts take some serious jury rigging.

By G.S.Crisi (****)

Date 12-28-2010 18:14

Let me disagree with you, Dave, with all due respect, of course.
For cutting stainless steel, silicon carbide disks should not be used because they'll leave traces of carbon within the stainless, which may originate intergranular corrosion.
For stainless steel, alumina (aluminum oxyde) disks should be used.
Alumina and silicon carbide have the same hardness in Mohs scale: 9.
Giovanni S. Crisi

By DaveBoyer (*****)

Date 12-29-2010 02:14

On the Knoop scale, aluminum oxide is 2500 and silicon carbide is 2800 if I remember correctly. The silicon carbide abrasive grains themselves fracture quite a bit more readily, giving a "sharper" wheel. I think there will be considerable grinding after the initial cut, this can be done with an aluminum oxide wheel.

The machine He is using is a little power tool resembling a miter saw used in woodworking. They don't have the power or rigidity to do this heavy a work, better suited to angle iron & tube [section thickness 3/8" or less].

I don't even know if the masonry wheel will work, but I do know from experience trying to cut large sections with a similar machine that the normal aluminum oxide wheel glazes up and doesn't cut worth a hoot. You can press harder, but then the smoke comes out of the motor, and everyone knows a motor won't run after the smoke escapes.

By G.S.Crisi (****)

Date 12-29-2010 13:54

The Knoop scale is more precise than the Mohs one, that's the reason of the difference.
What about cutting with a silicon carbide disk and then giving a pass with an alumina disk to remove the carbon left by the first disk? I'd say that a light pass, sufficient to remove a few tenths of a millimeter, would do.
I insist on the alumina disk, it's a well known fact that silicon carbide leaves traces of carbon that may originate intergranular corrosion.
Giovanni S. Crisi

By rlitman (***)

Date 12-29-2010 17:21

That's a new one to me, but a lesson I'll try to remember.
I've always had better luck with silicon carbide abrasive belts over aluminum oxide for steel, when zirconium oxide isn't available (that's always my first choice).

Silicon carbide fractures into large chunks with sharp corners. Aluminum oxide breaks off in small pieces, so it rounds over, and dulls faster.

By G.S.Crisi (****)

Date 12-29-2010 18:59 Edited 12-29-2010 19:02

Bob,
Take into account that we're talking of stainless steel. Silicon carbide is fine on carbon steel but not on stainless.
I can show you the Piping Specs issued by first class engineering companies like M W Kellogg, Lummus and others, that preclude the use of silicon carbide disks on stainless steels. They also preclude the use of carbon steel brushes, stailess steel brushes must be used instead.
Of course, zirconium oxyde is also fine on stainless, I forgot to mention it on my first posting.
Giovanni S. Crisi

By rlitman (***)

Date 12-29-2010 21:02

Yes. I don't work too much on stainless, so I never really thought about it. I know all about carbon steel brushes, and have seen how they can start corrosion. All of my brushes are stainless now, but I keep them marked; some for steel or whatever, some for stainless only, some for aluminum only.
I'll just have to remember that silicon carbide on stainless is a no-no now.

I love zirconia, but I've only seen it in belts and flap wheels (although google tells me that some cutoff wheels do indeed use it). It WAY outlasts alumina or silicon carbide, staying sharp much longer as well. The increase in lifetime is several times the increase in cost.
Still, a cloth backed abrasive works very differently than a wheel. With a belt, you're relying on the outer layer to be frangible (rather than friable), and fracture to keep a toothy surface.
My favorite cutoff wheels from Metabo are aluminum oxide, but unlike a belt, a good grinding wheel will shed whole particles from its outer layer to expose fresh abrasive underneath (if a belt did that, you'd be left with nothing but cloth in just a few seconds). I guess in that scenario, it is how the adhesive allows grit to be expelled, that prevents a wheel from glazing, and while a franging abrasive might help, the wheel's ability to lose diameter is how it really stay's aggressive.

By DaveBoyer (*****)

Date 12-30-2010 03:21

The cut off disks are harder [stronger] bonded than what You would want for cutting heavy sections. The reason for this is that they are designed to provide good life cutting thin materials like steel studs, garage door track and thin wall "EMT" conduit. These saws are designed for the building trades, and the wheels designed for what most guys cut with these saws.

These saws work OK on sch.40 pipe, square tube and structural sections that are up to 1/8" thick, but performance falls off in thicker sections.

By DaveBoyer (*****)

Date 12-30-2010 03:04

I agree that any contamination would be removed with even a light grinding with an aluminum oxide wheel.

By weldwade (***)

Date 12-24-2010 02:52

I use my Metabo for cuts like that. You can go through several slicer blades but it is WAY faster than a chop saw IMO.