Washroom partitions just arrived on site and will be installed in a week when tile work is finished. The partitions are clad in stainless steel. I know from previous commercial bathroom installs I’ve done that I’ll be drilling 1/4″ through holes in order to mount them. I’ve never worked with stainless panels before, though, just laminated ones.
There are 8 panels altogether, plus pilasters that will need pilot holes when fastening the mounting hardware. I figure 32 or more 1/4″ holes plus at least that many again in pilot holes by the time I’m done with all the latches, TP holders and other hardware. Seems to me I’ll be wearing out a lot of drill bits if I just use regular twist bits, stainless is a lot harder than mild steel. Has anyone seen a bit specific for stainless sheet? I have a unibit (step bit) which works great on regular steel doors, but I don’t know if it will be durable enough to last on stainless – and at $50 for the unibit, that’s an expensive experiment.
My best guess right now is use a a cobalt twist bit at lower speed and dribble some cutting lube on it from time to time. Anyone got other suggestions?
Replies
I don't know what kind of SS those stalls are made of but SS screws are only a little stronger than brass. Much weaker than steel screws.
You are talking about brittleness. They are more brittle, but SS is harder than normal steel, which is what is at question when drilling it.
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Unless those partitions were ordered for the Nuc power plant I would bet that the SS overlay is not too thick.
slykarma,
Your guess is right on. Cobalt bit, drill slow, cutting oil. You don't want to heat up the SS and work harden the metal.
KK
titanium ?
we where doing a project a few years back where I had a bunch of steel to drill and I bought some titanium bits , they worked well.
The "titanium" bits sold in stores are tool steel with a titanium nitride coating. The TiN coating is very hard, but it's less than a thousanth of an inch thick and when it chips or wears off, the underlying steel is exposed.Titanium metal is a poor choice for any cutting tool because it can't hold an edge like steel. The earlier advice - use a quality cobalt-steel bit, lots of oil and slow RPMs - is best for stainless.
Cobalt bits because they withstand the heat better but standard M2 HSS are likely good enough and at a third the price you can have backups if, when the first goes south. Another thing to consider is to use a good quality masonry bit, or two. The carbide it tough.
All the bits can be sharpened. The carbide demands a green wheel unless you willing to groove a standard grey one. Greys are cheap, especially the ones that normally come with the grinders.
Standard cutting oil, Tap Magic are good but any decent cutting oil will help. Even light motor oil or WD-40.
Most of this is in other posts.
The one important thing I can add is to really bear down on the bit. Short of breaking the bit it is hard to overestimate how much pressure you need to use. You have to keep the bit engaged and cutting. If it spins it heats up fast. Spin it much and the best cobalt bit with the finest cutting oil won't survive for long. Keep it cutting and square and even a cheap, but good quality, M2 HSS bit will drill quite a few holes before dulling.
Also helps if you don't tilt or wobble. Much more than simple straight pressure in line, which the bits are designed to endure, this sort of motion quickly galls, chips and snaps bits.
All this points out that if at all possible any drilling of stainless beyond a couple of small holes is best done on a drill press. Where a lot of pressure can be applied square to the piece with very little wobble or effort. Most bits last longer used in a drill press.
So now I'm plotting how to make a table of some sort and take my little 8" drill press to the site. It's going to be a slow install, usually you just drill everything in place once it's all spaced correctly off the floor and levelled. And here I was thinking that having done the hardware on all the steel doors that my metalworking phase was over....
Thanks everyone for the replies,
Wally
Lignum est bonum.
Having the drill press in the truck in case it is needed sounds like a decent idea but if it too much trouble go ahead and try to drill it in place first. M2 bits are pretty cheap. Go ahead and buy a half dozen or so. They might be cheaper at a supply house because they buy them in bulk packs without the packaging. Last I got in quarter inch were about $.75 each compared with the $1.75 at the box. Assuming you use the size a lot get a handful. You know your going to use them in time. Having multiple bits allows you to sharpen a bunch and change them out as they get a little dull. Too many people run bits until they are scrap metal. Easy to sharpen a moderately dulled bit. Once they are burnt they are too far gone.A lot of how difficult it is to drill stainless has to do with the thickness your drilling and the grade of steel your shooting through. Some grades are tougher and gummier. Other grades are softer and about as easy to drill as any good quality mild steel.
140 degree modified split point should be best, good luck finding them.
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My best luck with stainless was to use the cheap jobbing bits. Like the other posts say don't let them heat up, keep a steady pressure on them. Luck.
I bought some titanium aluminum nitride (TiAlN) coated drill bits for the guys in my maintenance shop to drill heavy gauge stainless steel sheet metal. They said they worked a lot better than standard drill bits.
Both TiAlN and TiCN (titanium carbonitride), but not TiN (titanium nitride) are recommended for stainless steel.
You can read about it on page 2276 of the current catalog on http://www.mcmaster.com.
You can order from them, too. On their site search for "drill bits coated".
Thanks everyone for the replies. The other fun part will be drilling 3/4" dia holes into the floor tiles for the expansion anchors that hold the pilasters in place. I have a diamond hole saw (acquired on previous bathroom installs) but it's always tricky getting the hole started without slippage as this style of bit does not use a pilot bit. I use scrap plywood bored out at 3/4" as a guide but it is still tricky to get through the glaze without things vibrating off line. On the plus side, the washroom floors are not sloped so that makes things a little easier.
WallyLignum est bonum.
Instead of using 3/4" plybd, try using a 2x4 long enough so that you can stand on both ends after centering the hole in the correct position.
Drilled many holes using that technique and all the holes were drilled without any problems.
butch
Already thought of that one a couple jobs back. My piece of ply is big enough to stand on, and there are several pilot holes drilled along edges and in corners to let me work in corners and against walls. And ya still gotta be careful things don't vibrate off line.Lignum est bonum.
Since you're experience the drill bit not being restrained in the desired location because it's moving upward, the 2x material, being twice the thickness of the 3/4" ply, provides more vertical restraint than the plybd.
As for working along the edges and corners of slabs, the limiting factor will be the physical size of your drill with its offsets from the centerline of the drill bit.
butch
Seems to me if you were to place something like gum rubber on you drill guide where you step might prevent it from vibrating or other wise drifting from the desired location. Perhaps something as simple as a half dozen rubber bands or a few beads of silicon caulk, allowed to harden of course, but I'm thinking the best material would be a couple of small pieces of anti-slip mat sold to hold work pieces in place when using a router.They sell a very similar material in Wally World as foam shelf liner and, even cheaper, some of their placemats. Another advantage to adding this to the under side of your guide is that the rubber or foam would tend to prevent tipping on uneven surfaces. This with the greater resistance to slipping may save a bit and help assure the holes go where you want them.
It went fairly well today, should finish them all tomorrow. I put a couple of layers of masking tape in the underside of the plywood, that seemed to keep things stable. Cobalt bit worked pretty well on the panels; they must be fairly light gauge. Found I didn't even need the cutting compound. I brought out my old B&D 1/2" drill because it runs at 650 rpm max. Only broke one 1/8" bit too, I was expecting worse.
WallyLignum est bonum.
Use cobalt bits to drill stainless steel, you do not need a cutting fluid if the stainless is thinner than 3/16". If you find you need cutting fluid,vinegar works okay.
Mark the hole out on the ceramic tile, take a hammer and center punch, break the glazing on the holes perimeter.Now set your template and drill.Once you puncture the glazing the drill goes in easily.
mike
HI Sly! My best advise is to stay cool! (You & your workpieces that is).
You have received some excellent advice so far & shouldn't have too much trouble. The truth is that SS (MY VERY BEST & FAVOURITE MATERIAL OF ALL TIME FROM WHENCE MY CHOSEN MONIKER WAS BORN !) is available in many diferent grades. Generally speaking the architectural grades are of the 300 Series,ie:303, 304,308,309,316 etc. easier to machine than the 400 series but not quite up to the strengths and hardnesses obtainable by heat treating (which the 300 series can't be hardened by doing.)
Generally speaking the 300 series (& the unhardenable types in the 400 series) types of SS are more trouble to machine not because they are initially any harder than mild steel but because they are tough and WORK HARDEN. Chips tend to be stringy and don't break like mild steel. If a twist drill is not sharp it will tend to rub rather than cut your SS & this rubbing is what actually hardens the material and makes it even tougher to drill. Try not to let your drill bit spin for even a short time without cutting as the SS will work harden & quickly dull or ruin your drill bit's edge. The advice for cutting oil and heavy end thrust while drilling are excellent suggestions.
A supply of new (read SHARP) twist drills is likewise an excellent piece of advice. I might also suggest pre-drilling with a smaller size, say 1/8" or 3/16" to reduce the thrust required to push the 1/4" bit through. Be carefull, however, to reduce the thrust as the bit breaks through as it will tend to grab & possibly break as the hole is nearly completed and the pushing gets noticeably easier. A center-punch or prick-punch makes a good starting point to keep your twist drill from walking all over your workpiece too.( Just keep in mind the work hardening attribute), hammering the heck out of your work piece with a punch will harden it exactly where you want to drill it!
I LOVE SS! I figure if it was easy for everyone to work with, I couldn't get to charge a premium to make things out of it! Once you learn the tricks to using it, it's not that much more trouble to use than mild steel.
You get paid more for your knowledge and experience than the other guy/gal, and thats what sets you apart rather than working longer hours. Some very bright person said it is better to work smart than to work hard. (How about hard & smart?)
Good luck