Working with stainless steel

[mick]

I have a 30cm by 20cm piece of 2mm stainless sheet which I need to cut in half. I also need to drill several 6mm holes in it. Any tips?

 

[FlyingDutchman]

It is not difficult, you can use a normal metal saw and normal drills. Just make sure not to create heat as this will harden the stainless steel. Slow speeds are essential as is the use of a coolant (water will do). Drill with enough pressure (a lot!) to create drill chips.

 

[maxi77]

The sawing is best doen with a new blade.

 

[sailorman]

jig-saw metal cutting blade slo spd loadsa lube.
i have done 6 m/m that way

 

[boatmike]

Buy good tools. Bimetal hacksaw blades not just HSS. Top quality drill bits and keep them sharp. Blunt tools will work harden the steel. Also cut with even pressure and not too fast.

 

[bazobeleza]

cobalt steel drillbits and hacksaws, available cheaply from screwfix.
keep your cutting speed very slow, pressure high and even and workpiece cooled with oil or wd40, resharpen regularly. You should have no trouble.

 

[Norman_E]

Important safety tip. When the drill breaks through it will probably grab the metal and spin it. Do the drilling in a drill press, not with a hand held drill, as the drill press lets you apply enough pressure to keep the drill cutting and not rubbing. Hold the metal by clamping it firmly to the drill table and keep your hands well out of the way. My preferred method with thin stainless like that is to clamp it down with a piece of thicker ordinary mild steel beneath it, and drill through it into the mild steel. That way the drill will not grab the stainless as it breaks through

 

[mick]

Thanks, all.

 

[30boat]

One very important point.Drill speed is relative to size.If you are drilling small diameters you will need faster speeds.For instance for 3mm you should use around 3000rpm.If you keep speeds low the torque is to high and the bit will break.Keep good pressure and use cutting oil wich lubricates and cools the tip of the drill bit.This is even more important with stainless than with mild steel.

 

[alexrunic]

i was a sheet metal worker at one time. i would use a cutting disk on a grinder (make sure it is an iron free one suitable for stainless) i have never tried a jigsaw on stainless but don't see why not with plenty of oil for coolant/ lubrication. as regards drilling not too fast but you need plenty of pressure on the drill otherwise you will burn out the end of the drill and in the worst case you will end up with bits of drill bit in the hole then in is impossible to drill. also plenty of lubrication / coolant.

 

[sailorman]

i made a collar + backing collar to go around the mast of my Co32 to transfer the halliard loads out of 6 m/m s/s no probs with the Jig-Saw. i did use propriety cutting paste

 

[mhouse]

Its also worth keeping an eye on good old ALDI last year they were selling packs of 4" cutting discs for S/S

 

[matelot]

If the sheet is thin and shiny, then its very likely to have been cold rolled and will already be work hardened. That being the case I wouldnt even try to cut with a hacksaw - use a disc cutter instead.

As for drilling, get new sharp drills of good quality, use a cutting lubricant and a fair pressure on the drill turning slowly. You need to cut rather than skid on the surface or you will harden it even more.

 

[seaesta]

Some good advice above - main point is to make sure you cut slowly and evenly. You must cut and nut rub because friction will work harden the material rapidly. I have found that Titanium nitride coated drills (which are much harder than normal HSS ones) give you more room for error if you have to use a hand drill.
Apart from the cutting aspect you need to have in mind that you should try not to cause rust. The surface of stainless is "passive" or corrosion resistant because of a thin chromic oxide layer which forms at the surface. When you break this layer it dloes not always re-form quickly and if you get free iron on the surface then it will rust or stain for ages. Free iron can be in the filings and chips that arise as you cut so sweep or wash them away promptly.I would avoid grinding type cutting discs at all costs as the dust that emerges is very prone to creating corrosion which seems to last forever (unless you can passivate the surface with acid).
Cheers
Martin

 

[Cliveshep]

Wear goggles FIRST, cut sheet to size using Inox 1 or 1.5mm blades (from Screwfix) in a mini-grinder. Any other blade will cause burn marks on the metal. You must hold the tool steady as these inox blades are thin but they cut like a knife through butter. Drilling with lubrication is a must, centre "popping" the hole stops the bit wandering, and use Cobalt tipped bits or you'll burn them out. Once you master it you'll be wanting to make all sorts of things. A Jig saw very slow with sharp blades and lubrication/cooling will cut but it is tedious and not very satisfactory. I learnt from watching my friend's guys on site working in stainless on handrails etc, they make it look easy but the secret is in these blades. Use a sander disc in the grinder to de-burr the cut although the burr is very small.

 

[NormanS]

You wont be able to use an ordinary hacksaw with a sheet as wide as 20cm. Just use a cutting disc in an angle grinder. For drilling, do as others say, slow speed, cutting fluid, or even just some oil, and most important, SHARP drills.