Drilling through SS?

[druid]

OK, I'm on my 3rd hour and 3rd bit, trying to drill a 1/4" hole in an 1/8" piece of Stainless Steel. The advice from others was "slow and hard" so I'm drilling about 60rpm (1 rev/sec), with about half my body-weight (100 lb) on the drill. My first two bits were titanium, the last was cobalt, and the cobalt seemed to "bite" a bit better than the titanium.

Barring any other advice, I'll buy another cobalt bit and try again tomorrow.

Any advice?
druid

 

[Roger Long]

A drill press will make an incredible difference and you'll find it one of the most useful things you ever bought if you like to make things for your boat. The instant the bit slips, it work hardens the stainless and almost nothing will go through it. The drill press helps maintain the steady consistent pressure that keeps the bit biting.

I bought a cheap one at Home Depot for about $125 and am amazed at how it's held up and what I've done with it. One of the best and most useful purchases I ever made. Even has laser sights for spotting the drill. There's a reason why our kids won't be able to get jobs without being able to speak Chinese.

Even where I've had to hand drill because the pieces were too large, I've never had problems like you are describing. I don't know what you are doing wrong.

 

[Tim R.]

The way I do it is as follows:

Low RPM(120) with cutting oil on the bit
Initially press hard for just a second
Repeat this until the bit starts to bite into the SS
Now you should be able to drill through.

Unfortunately you have probably already heat hardened the SS you are trying to drill. That will make it even harder for you to drill it. Hopefully you have another piece to start on again.

Roger, you let me know when that drill press quits on you. I have a bench top model from Woodworkers Warehouse that is about 5 years old that I am selling(along with most all of my shop tools)

 

[Maine Sail]

Druid,

Sounds like you stopped before getting all the way through and did not use cutting oil. As Tim eluded you have now most likely work hardened the SS and will use a number of bits getting the rest of the way through as the stock you are drilling is closer to the hardness of the drill than it originally was.

You need lube, and a slow speed with SS, and a constant one shot method. If you did not use cutting oil and then took a break, which allowed it to cool and work harden, you'll probably want to buy some stock in the drill manufacturer as you'll certainly raise their share price getting the rest of the way through..

 

[RichH]

Drill press is almost 'required' when drilling stainless

BEST is to keep the tip of the drill bit as cool as possible with water (soap water) or light weight cutting oil - dont electrocute yourself when cooling with water.

Slow drill tip speed, moderate pressure, (if possible, continually cool the bit tip with water or oil) ..... and DONT STOP drilling until the hole is 'through'.

Other:
get a drill bit with the proper (shallow) 'face cutting angles' for cutting *hard metals*. These will be 'shallow' face angles .... not the relatively 'sharp' face angles found on hardware store 'general purpose' drill bits. A drill bit shaped for cutting hard metals (eg. stainless) will almost 'look flat' at the 'sharp end' of the drill bit.

Home Despot and other 'consumer' sources (of cheap asian crap) usually do not have drill bits for 'hard' metals; get thee to an 'industrial supply' or order online from such as www.granger.com, etc.

 

[tommays]

Buy a split point #21 or other small drill to go through as this should have taken about 30 seconds and as said above you may have a work harden issue

I prefer and on/off cycle with at a few hundred RPM to control the heat

auto store white spray grease works very for good drilling and tapping in boats as it does not run all over into places that you cant clean up like oil

 

[Ross]

60 RPM is much too slow for a 1/4 inch bit. I turn a bit brace faster than that. Steady feed pressure a bit of lube oil and you should have no problem with a Bosch bit. I use about 600 rpm with a 1/2 inch bit in a drill press.

 

[RichH]

60 RPM is much too slow for a 1/4 inch bit. I turn a bit brace faster than that. Steady feed pressure a bit of lube oil and you should have no problem with a Bosch bit. I use about 600 rpm with a 1/2 inch bit in a drill press.

ummmm
not in stainless steel you dont; unless you know how to constantly sharpen a drill bit.

HARD metals such as Monel, Inconel, Hastalloy, HC Steel, STAINLESS, etc. (should) require about 60-100 rpm for drilling ... and need a low face angle (for hard metal) drill bit. Hardware store drill bits ('general purpose' cutting angle profiles @ 58° per flute = 118° tot. angle) are for drilling plastic, wall board, wood, SOFT metals (mild steel, aluminum, etc.), etc. Not that you 'cant' drill a hard material with a gen. purpose bit .... but it certainly wont stay sharp very long - especially at above low to moderate rpms.

 

[druid]

Yeah... a drill press would be nice. Tell me: how do you get the boat under the drill press? (as you know, ANY work done on a boat is with you on your back, legs tucked up, one elbow pressing on something while you're pushing the drill "up" and backwards, with the shavings falling into your eyes...)

This one is actually quite easy - I can stand up and push the drill DOWN. I'd have to take the pedestal apart to get the piece under a press, though.

You may be right about work hardening - the first bit got a bit hot despite the oil. And forgive me if I stop after 5 minutes - I'm not in that great shape! As for industrial bits: it's Saturday and the "good shops" aren't open. I'll try KMS - they may be open Sat, otherwise Home Depot is the best I can get.

Thanks for the input!
druid

 

[Ross]

ummmm
not in stainless steel you dont; unless you know how to constantly sharpen a drill bit.

HARD metals such as Monel, Inconel, Hastalloy, HC Steel, STAINLESS, etc. (should) require about 60-100 rpm for drilling ... and need a low face angle (for hard metal) drill bit. Hardware store drill bits (general purpose cutting angle profiles) are for drilling plastic, wall board, wood, SOFT metals (mild steel, aluminum, etc.), etc. Not that you 'cant' drill a hard material with a gen. purpose bit .... but it certainly wont stay sharp very long - especially at above low to moderate rpms.

I ran the spinnerette shop for Firestoine Fibers for 4 years. we routinely drilled 316 ss 204 holes 1/8 inch diameter 2 inches deep. And finished with a .008 hole through the last .060 thickness. I do know a little bit about drilling stainless steel

 

[rardiH36]

As tommays suggested, you might start again in the same hole but first with a much smaller bit ... say 3/32". Apply firm pressure but be careful not to bend and break it. Go all the way through. Then increase maybe to a 5/32 or a 3/16 bit, then finally the 1/4. For years around the house, I've found this method works well using a hand held electric drill to get to larger diameter holes in various metals. And since getting into sailing a few years ago, I've used it to drill a number of holes in SS tubing and various other pieces of SS metal stock. I've used vanadium and colbot hardened bits or whatever comes out of my drill bit box. I must say that my drill bit sharpener gets more use than it used to!

 

[RichH]

I ran the spinnerette shop for Firestoine Fibers for 4 years. we routinely drilled 316 ss 204 holes 1/8 inch diameter 2 inches deep. And finished with a .008 hole through the last .060 thickness. I do know a little bit about drilling stainless steel

http://www.custompartnet.com/calculator/drilling-speed-and-feed

 

[RichH]

I ran the spinnerette shop for Firestoine Fibers for 4 years. we routinely drilled 316 ss 204 holes 1/8 inch diameter 2 inches deep. And finished with a .008 hole through the last .060 thickness. I do know a little bit about drilling stainless steel

http://www.custompartnet.com/calculator/drilling-speed-and-feed

ditto the info from a standard "Machinery Handbook".

You *drilled* .008"Ø holes in stainless? ..... oh, come on now.

 

[Ross]

http://www.custompartnet.com/calculator/drilling-speed-and-feed

ditto the info from a standard "Machinery Handbook".

You *drilled* .008"Ø holes in stainless? ..... oh, come on now.

Tools supplied by National Jet Drill company in Cumberland MD . Don't know if they are still in business They made fuel injecters amoung other things .
How do you think they make spinnerettes? we were just starting to use electric spark methods when I left.

Link: http://www.najet.com/

 

[Bob S]

Cutting stainless steel is tricky because it work hardens. The reason why a drill press works better is you can put much more pressure on the cutting tool. Using cutting oil will lengthen the life of your tool. Definitely use a cobalt or any industrial grade high speed drill. Split point will reduce the amount of pressure you'll need to push. Don't buy your drills from Home Depot or the like. Use a local industrial supply house as the quality is better.

 

[Mario G]

The caption reads "Honey please hand me up the drill press"

I broke the first bit and only got in 1/4 inch. Its a good thing Its easy to drop my mast.

 

[Don12364]

Druid,
You don't say what you are trying to drill but is it possible to start from the other side? The opposite surface of the steel might not be work hardened yet.
Also a smaller pilot drill will allow the pressure you apply to be concentrated on a smaller point so improving the chances of penetration.
In any drilling operation one MUST see swarf coming from the drill immediately it begins to rotate and starting with a good sized centre punch dimple gives the drill a fighting chance. If at any time the drill stops making swarf stop immediately as the steel will harden in just two or three 'rubbing' - rather than cutting - revolutions.

Lastly, if you cannot get to the back of the piece I just wonder if one of those diamond powder coated drills used with water for tile drilling would help.
Anyone tried this as I am keen to learn if this is the way AFTER one has work hardened the workpiece?

 

[dscribner]

I went thru about $100 worth of drill bits (no, really) building my trailer. Ther was a bunch of spring steel on it. Finally, I followed the advide of a young fellow in the office. I bought a step drill. I'll never go back. I'm not sure about the physics behind them, but they cut differently than standard drills. It starts by drilling a 1/8" hole, then a 1/4, 3/8 and so on. I don't know how this would work on SS, butnon spring steel it was the bomb. On stainless . . . feeds and speeds.

 

[Bill Roosa]

Try using oil

Cutting oil is used by most professionals when drilling almost any metal. It does provide for better cutting.

 

[Ross]

Re: Try using oil

Drilling a pilot hole is always a big help.