Drilling through stainless steel

[geoffa]

Good advice. Also spray the bit to keep it cool. And the bit generally work better with heavy downforce until you feel you are about to penetrate. I have found the best drill to be a quality portable device as tbis can provide the essential speed controls.
If you see smoke you have most likely work hardened the SS and damaged the bit. Stop and throw out the bit!

[smac999]

Do you really want holes in the tubing that goes underwater? It will fill up. And be heavy to lift back up. I would look at wrapping it with something?

[EasysailorSD]

Use cobalt drills.

[Lulabet]

Originally Posted by Bigjim

My transom swim ladder is made of hardy stainless steel tubing. It does not have wooden steps or rungs. So, it is difficult to climb out of the water.



I purchased some teak steps but when I tried drilling the holes for the machine screws the steel burned out two drill bits, a normal steel bit and a cobalt bit. I then bought a titanium one but it fared no better.

Anyone have a suggestion on what type of bit will work with this sturdy tubing?

Why not using these? instead of making holes?

[Aerides]

Many people stated that "work hardening" is a (or the main) problem. I believe this is incorrect. Work hardening is caused by an alteration of the metal's crystal (?) structure from repeated working, e.g. bending. With SS, the problem as I understand it, is the oxide layer that forms pretty much instantly. It is extremely hard and dulls tools. The reason for the high pressure and part of why a "lube" oil works, is that it helps isolate the cutting surface from oxygen. Higher pressure cuts below the hardened surface layer. This is also why you try to make a continuous cut--to keep the oxygen out and stay down in the soft metal. Most alloys of SS are actually rather soft. The reason for slow speed is because there are also limitations on overheating the tool with the high pressure. Too slow a feed and you're not taking enough of a bite, too fast and you're overheating the tool (which then softens *it*).

[Reefmagnet]

Originally Posted by Aerides

Many people stated that "work hardening" is a (or the main) problem. I believe this is incorrect. Work hardening is caused by an alteration of the metal's crystal (?) structure from repeated working, e.g. bending. With SS, the problem as I understand it, is the oxide layer that forms pretty much instantly. It is extremely hard and dulls tools. The reason for the high pressure and part of why a "lube" oil works, is that it helps isolate the cutting surface from oxygen. Higher pressure cuts below the hardened surface layer. This is also why you try to make a continuous cut--to keep the oxygen out and stay down in the soft metal. Most alloys of SS are actually rather soft. The reason for slow speed is because there are also limitations on overheating the tool with the high pressure. Too slow a feed and you're not taking enough of a bite, too fast and you're overheating the tool (which then softens *it*).

Incorrect. Austenitic stainless steels work harden through deformation. It's aluminium that has the hard oxide. Some sand papers use aluminium oxide as the abrasive.

[michaelkcowan]

Any one considered Techniglue - or similar product - on such a job...have used it on my boat and elsewhere...interesting and useful product...M K Cowan





https://www.carbatec.com.au/joinery-...-2-1-60a-500ml

[Fitsthebill]

There are those who sink money like water into solutions and then those hillbillies like myself who have the old ways. If you have cheap bits, sharpen them a LOT.... If not, drill and still sharpen.
Can't sharpen? Throw the boat away or it will steal your wallet. Oil is important but not store bought. Nothing on the commercial market works as well as bacon grease. Cook some bacon and save the grease. I don't care if you eat bacon or not... That is an oil that does not burn and smoke like others.
This is not a joke. You can sawsall through SS shaft and still have teeth left. Bacon grease is the key to drilling or sawing but clean up afterwards or the pets will come sniffing around and get fillings stuck between there teeth. A drill press is desired but you can drill through stainless by just resharpening. Fast speeds will harden SS too..
You need to clap securely!!! Either in a vice or using vice grips. You can lay the tubing in a piece of angle iron in a vice and then clamp it. Keeps the tubings straight.
Let me say it again, BACON GREASE IS MAGICAL STUFF. And figure to sharpen at least once, even with a new drill.

[Capt.Tom]

Originally Posted by Bigjim

My transom swim ladder is made of hardy stainless steel tubing. It does not have wooden steps or rungs. So, it is difficult to climb out of the water.



I purchased some teak steps but when I tried drilling the holes for the machine screws the steel burned out two drill bits, a normal steel bit and a cobalt bit. I then bought a titanium one but it fared no better.

Anyone have a suggestion on what type of bit will work with this sturdy tubing?

I would not drill into the stainless. Use two SS U bolts, with grip, on each step. The U bolts go around the SS pipe on your present step as drill holes in the teak steps you wish to attach.
You will need washers and have to cut the U bolts off and file then so you don't cut your feet.

If you must drill buy Dimond tipped drill bits.

[Eigenvector]

I was making some parts today and remembered this thread. Here's a picture drilling with proper chip loading. Do it right and your'e always below the work hardened zone. Manual feed (not CNC mode)

[coopec43]

Originally Posted by Woodland Hills

I am surprised that no one has recommended carbide drills over cheap cobalt and titanium oxide drills. They are much harder and will stand up to hard usage much longer.

Many people have commented before Slow speed (110 RPM optimum) and high pressure. If it stops cutting the steel will work harden. Always drill a pilot hole.

Now Carbide drills..... I once was trying to drill holes in my SS chain-plates and not having much success, Fortunately my B-I-L was riding past on his bicycle and asked how I was going and I told m the sad story.

He was a diesel fitter at the Caterpillar Agency and he said when they had to drill out broken engine block studs they used sharpened masonry drills with a huge pressure. We made up a stirrup type of device so we could secure one end through a hole in the deck and place a piece of 3 in X 2 in. length of timber which was used across the back of the drill to provide pressure. We had each hole drilled in two minutes flat!

Clive

[Wotname]

Originally Posted by Eigenvector

I was making some parts today and remembered this thread. Here's a picture drilling with proper chip loading. Do it right and your'e always below the work hardened zone. Manual feed (not CNC mode)

[Snowpetrel]

Originally Posted by Eigenvector

I was making some parts today and remembered this thread. Here's a picture drilling with proper chip loading. Do it right and your'e always below the work hardened zone. Manual feed (not CNC mode)

Very nice! Wish I could get a similar result with my hand drills!

[Wotname]

Originally Posted by Snowpetrel

Very nice! Wish I could get a similar result with my hand drills!

You must mean cordless, surely you are not drilling SS with a hand drill

But if you are, I

[Snowpetrel]

Originally Posted by Wotname

You must mean cordless, surely you are not drilling SS with a hand drill

But if you are, I [emoji144]

Ahh, thats a sophisticated hand drill, when I was a lad, all we had was one of these, had to drill through 18 inches of solid stainless before breakfast..