What is the best bit to drill thu 316 stainless plate

[Mr. Sandman]

I destroyed a few including new Cobolt and Ti bits already

[likwid]

Normal bits work fine.

Go slow, use cutting oil, GO SLOW!!!

Just like G10.

SLOW DOWN!



The real problem now is where you've been drilling you've probably work hardened and need to have it machined.

[Fishpart]

We do a lot of machining of 316 almost all with HSS coated with TiN. Key is slow and steady and plenty of lubricant. If you can control the drilling, $olid carbide i$ best but very brittle so you can't dril by hand.

[JohnR]

Cobalt bits and LOTS of cutting fluid. If you see smoke you don't have enough fluid.

The smaller the bit the faster you need to go. For example, I was doing some 1.3mm holes the other day (depth about 6mm) and I'm using 3K RPM. After I used a centering bit to start the hole.

Hi Ed

[leptar]

Norseman or CTD --- Magnum super premium 135degree split point... by either company do well...
Bits made to drill SS do so... Use thick cutting fluid not thin tapping fluid..

Have a Fastenal near by? you can get either mfg bit from them...

Get mechanic length for hand drilling.

[Nebe]

Likwid is correct
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[ProfessorM]

Like stated above slow. HSS is my preference. I hate everything to do with stainless, drilling, coolant, rpm's, etc... Sorry breaks over time to go drill something. Have fun.
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[Adam_777]

I am assuming the plate is too thick to punch holes in.

[Mr. Sandman]

Slow is not working. I ordered new bits as directed above along with better cutting fluid.

T-316/316L STAINLESS STEEL SHEET / PLATE 3/16" T-316-2B Annealed
is what I am working with.

I am using it to back up two stern cleats on the transom. I need something that looks nice, will not rust when directly exposed to the elements, is stiff and will spread the load over more square inches than a few washers and with acorn nuts (which was there).

This stuff seems to laugh at drill bits. Need to drill 8, 5/16" holes. Have 2.5 drilled and have gone thru 6 bits. It is maddening. I thought this would take 15 minutes...Jezzzus, this is turning into a project itself now.


Moved on to more electrical work, will get back to this when the bits arrive. (nobody sells that stuff where I live, everything comes from the internet)

I ordered some bits made for hardened SS and will adjust the drillpress belts for the highest speed it can deliver, will go slow and lube this up like a dried out New Bedford hooker on a Friday night.

[likwid]

Aluminum would have worked fine. Get it anodized or powder coated.

You're load spreading, not creating a lifting point.
Hell, the lifting points on my boat are just glassed in plywood, and they've survived fine.

[Saltheart]

Do it on a drill press if possible and do go slow. 300 series stainless is Austenitic which means it will work harden if you try to go too fast or take too big a bite. Best would be a drill with a mechanically controlled down feed.

Now you do want to be cutting a chip so if you go toooo slow , the bit just sits there working the metal and it gets harder.

If I were you I would slowly drill a small pilot hole then go in with the larger bit.

[leptar]

low rpm and minimal pressure for little time... You don't want to heat up the bit or the part.

Do not go super fast with hardened bits..that is an accident waiting to happen... These bits will shatter, especially on the press drilling SS at high RPM...

[ProfessorM]

2 holes 6 bits your fired. Probably cheap bits. I don't think I have ruined 6 drill bits in 35 years of drilling hard metals. Too bad you live on that little island or I'd do it for you. If you go too fast you will just melt the drill bit. Are you center drilling the hole first? It would probably help. Low rpms and steady firm feed. Don't let it ride on the material with out a firm feed. If your drill press has a feed stop that would help too as you don't want to hang on the handle when you break thru. Fun isn't it.

[likwid]

Originally Posted by ProfessorM

2 holes 6 bits your fired. Probably cheap bits. I don't think I have ruined 6 drill bits in 35 years of drilling hard metals. Too bad you live on that little island or I'd do it for you. If you go too fast you will just melt the drill bit. Are you center drilling the hole first? It would probably help. Low rpms and steady firm feed. Don't let it ride on the material with out a firm feed. If your drill press has a feed stop that would help too as you don't want to hang on the handle when you break thru. Fun isn't it.

Bet the stainless is harder than hell too.

[ProfessorM]

Lots of pretty colors too
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[Mr. Sandman]

I normally don't use that many bits either, ...maybe break one per year. But I got carried away with this.

I may abandon these plates and start again with fresh material, bits, and a new perspective.


I have to figure this out because I have another project where I have first make 6 bends then drill a doz or so small holes thru 1/2" SS 316 tubing ( I am also buying some Al tubing just in case this turns out bad but I would prefer using SS)

[Mr. Sandman]

Ok...Thank you for your advice. I have it working now.
I did it slowly reduced rpm, light pressure and in 3 steps increasing the bit size, and lubed. No smoke, no damage to bits. It took a little while but it's went thru and the bits still cut.

thanks

[ProfessorM]

Called a learning curve. Not laughing at you but with you. I have broken tools pretty much every way possible over the years Some pretty embarrassing ways too All we do all day long is bust balls so I just did the usual. If you ever get stuck just ship them to the mainland and I will help if I can.
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[Sgranata73]

I did just the same thing tonight. I used an 1/8" cobalt drill bit to start. Then I used a Lenox (two cutting points) step drill bit to increase the size of the hole to the required dimension. I was drilling 316 ss, used lots of oil, and went slow.

Thanks, Stefano.