I think I goofed

[JacksonH]

First of all, I have no idea what I'm doing, so I'm sorry if this is a dumb question.
 
I heated a piece of mild steel bar stock 1" X 1/4" X 12", bent the end to a 90 degree angle, then tried to drill a hole in it (yep, should have done that first), and I can't seem to get it done.  The drill bit doesn’t make much headway, then just becomes worthless.  I'm thinking that I may have inadvertently heat treated the metal by not cooling it properly.
 
My question is this:  How can I un-treat the metal so that it won't be so darned hard to drill?
 
Any help will be greatly appreciated.
 
Thanks

[swedefiddle]

Heat it back up and don't quench it. Let it cool slowly.

 

Neil

[jmccustomknives]

It's called annealing.  Heat it back up and let it cool slowly.  It shouldn't have hardened if it was mild steel.  You are probably suffering from DDS (Dull Drillbit Syndrome) :o   Start with good, sharp bits and give 'em a shot of cutting fluid (wd-40 will work in a pinch).

[Metalsmith21]

First question, is the drill bit deigned for metal? If so when was it last sharpened? Did you use any lubrication to aid the cutting process? To drill through any metal will take at least 5-10 times longer to drill than wood.

[JacksonH]

WOW! 3 answers in 6 minutes!  Thanks guys.

 

The drill bits are designed for metal, and were new.  I have drilled holes in this same metal without any problems, that's why I figured that I hardened it.  I didn't use any cutting oil, I'll try that.

 

sweedfiddle - you say to cool it slowly.  How slowly are you talking about.  If I just let it cool down in the air, will that do it?  Also, do I need to re-heat it to orange?

[Metalsmith21]

Take a file to it, if its been hardened the file will just skate across it, if it hasnt been hardned it will shave off some metal.

[Crazy Ivan]

It can also make a difference if you drill a pilot hole starting in a center punch mark. For example, if drilling a 1/4" hole, I start with a 1/8" bit first, then finish the hole to size. Also check on the speed your drill is spinning. Faster for smaller bits and slower for larger bits. There are drill charts out there for the proper rpm a drill should be used at. It will make for a better hole as well as extend the life of your bit.

-Crazy Ivan

[Steve Sells]

also need slower speed for metal than wood, too fast can dull a bit fast

[SoCal Dave]

I've purchased a harbor freight drill bit set for metal.  They are only good for one use before they become junk.  So, it depends on the quality of the drill bit.  Follow the instruction to anneal the metal, and get a good quality drill bit and I'm sure you will succeed.  Good luck.  

[DSW]

It shouldn't have hardened if it was mild steel.

 

 

 

Maybe, maybe not. I've had issues on occasion with some cheap imported "mild steel". I think a lot of it is remelted mystery mix. My guess is it 's sold as mild steel because  of minimum standards, ( if any standards at all) It wouldn't surprise me if some pieces of this hardened up if quenched. I seem to remember several instances where substandard Chinese made steel has ended up in the news over the last few years. Falsified chemical composition reports and materials that won't meet standards specified for jobs.

 

I've definitely seen a difference in Chinese pipe vs American made pipe in how it threads. I can cut nice clean threads in American black pipe, but the imported stuff tears and threads poorly even with dies that cut just fine before and after on better quality pipe.

[swedefiddle]

Jackson; Heat it up to above when it loses it's magnetism. Which will be a bright red / start of orange. (I have a speaker magnet hanging on a wire, near the forge. Wave the piece close to the magnet, if it is attracted, it is still too cold).

 

(1) You can let it cool in still air (will take 1/2 hour);   or (2)  Turn the gas off for your forge (close up all openings) and leave the piece inside the forge until the forge is cold (2-4 hours); or (3) bury your orange piece in a pail of garden lime or vermiculite insulation or fireplace ashes, until cold. or (4) Drive to the end of the block, stop and talk to your neighbour, have a cup of coffee (or wobbly pop), and forget there is a job to do :)  :) LOL

 

Learn how to grind drill bits. Make a cardboard or sheetmetal, drill angle gauge of 59 degrees and grind the two leading edges of the drill bit so the center of both sides is equal length. Don't buy a "Drill Doctor", do it by hand.

Drill slower than full speed of your drill.

 

Absolute #1 thing!!!! Smile and make holeage. :) :)

 

 

Neil

[Anachronist58]

Once again, lots of well-thought replies.

 

And my 2 cents: Improper Speed and Feed can work-harden the hole you are drilling. Sounds like you didn't have that problem: 

 

"The drill bits are designed for metal, and were new.  I have drilled holes in this same metal without any problems, that's why I figured that I hardened it.  I didn't use any cutting oil, I'll try that."

 

Lubrication of the cut is indeed a wonderful idea. even spit is better than nothing.

 

Robert Taylor

[JacksonH]

Holeage has been accomplished.  I re-heated the metal to orange color then cooled it very slowly in a warm wood stove.  When it was cooled down I took it to the drill press, put on a drop of cutting oil, slowed down the drill press speed, put my Harbor Freight :( drill bit in the chuck, and had no problem drilling my holes.

 

Thanks for all the great advice.  You guys rock. :)

 

Jackson

 

P.S.  I found a great drill speed chart online, which I will laminate and hang by the drill press.

[the iron dwarf]

sharp drills drill easy, blunt drills get hot and get soft so you have to cut off a good bit before sharpening them again.

 

good quality drill bits work out a lot cheaper.

a friend only uses cheap ones and had a job drilling hundreds of holes in 1" plate, he got through a bucket full of drills and it took him days, a similar number of holes in stainless just as thick took me 2 drills and half a day ( my drill bits cost 10 times what his cost each but his cost more than 10 times what mine cost in total even without the extra days work allowed for ).

 

also get a chart of cutting angles to sharpen drill too and laminate it ;) 

[Rich Hale]

I drill a lot of eighth or smaller holes in knife quality stainless steel. I almost use HF cheap bits for everything and maybe once a year will toss one and grab a new from the drawer. I don't use a lube on them. Key is correct speed. in drill press. 

And for larger drill bits,,you can take to hex nuts..lay them side by each and one side of each will meet..there will also be sides that meet at an angle,,that angle is correct for the shape on cutting end of drill bit. You could tack weld the nuts together so you can hold them up to light..or maybe even super glue,,if you lay them on plastic so they will lift off,

If you have a tough time visualizing wot I am typing..go to shop and don't over think it..put two nuts together and look...Use larger or smaller nuts to fit the bits you are wanting to sharpen. I don't sharpen anything eighth inch or smaller...New ones are cheap.

[JacksonH]

I think that the two hex bolts idea is a great way to get a 60 degree angle so that one can check the angle of the drill bit cutting edge. Thanks.

[vapremac]

JacksonH........Glad to hear you were able to accomplish what you set out to do in the first place.

DSW.........I agree 100%, there is quite a bit of "mild steel mystery metal" floating around among the
material suppliers, run in to right often.

118 degree split point jobber length drills are the most commonly sold twist drills and cover a
wide range of typical applications in the shop. The correct grind angle is 59 degrees (118/2=59).
I hand grind so it could end up 5+- degrees. The critical areas of twist drill grinding is to
maintain proper web length and web center. Probably the most neglected angle when putting a
fresh grind on a twist drill is the positive rake (the land should gently slope downward from the
cutting edge). This allows the cutting edge to do it intended job of cutting, run cooler,evacuate
the chips and speed up the whole process. A cutting oil will dramatically extend drill life and
regrinds.
Each material classification (1018,4140,316SS) has it own set of drilling specs known as
surface feet per minute for a high speed steel or a carbide twist drill. Once the material class is
known,the SFM and the diameter of the twist drill,a few calculations preformed and that will give
you the proper RPM at which to set your machine.
Like Rich Hale mentioned,cutting speeds are crucial to long tool life,use the hex nuts for a
point gauge,it takes a little time to learn to properly put a good grind on a twist drill.
So,even though you believe you hardened the material, changing some of the drilling parameters
would have let you bore the hole.

[JacksonH]

vapremac,

 

I looked into how to re-grind drills, and like you said, there is a lot to it.  The cutting oil that I used was for aluminum, but it seemed to work just fine.  I may pick up some that is meant for steel.  I never really paid any attention to the speed of the drill press, or used cutting oil very much, but I definitely will in the future.

 

What's your take on good vs cheap drills?

[Dan C]

Try rubbing sidewalk chalk on the area before you drill it.  That and slowing down the drill has worked for me.

[DSW]

Don't buy a "Drill Doctor", do it by hand.

 

 

If you get the better Drill Doctors and learn how to use them, they work quite well. I will admit that at 1st I had a few issues using one, but the problem was how I was setting the bit, not the unit itself. I will say that once you understand how to set the bits up correctly in the machine, it's really easy to sharpen bits. My helper would never have been able to quickly learn how to sharpen bits by hand. However after watching me set the machine up and me helping him with the 1st few, I could basically walk away and have him sharpen bits, no problem. Every few months when we'd finish up early, or when we'd have rain that would unexpectedly shut down our job, I'd finish out the day cleaning out the truck and doing small misc projects that we'd never seem to find time for. Among them was having the helper go thru the box of dull bits and sharpen them on the Drill Doctor and put them back in the drill index. 90%+ of the ones he did worked very well.

 

 

The drill doctor doesn't work for really large bits however. Those I'd still have to do by hand. Small bits under say 1/4" weren't really worth the hassle to sharpen and the vast majority of the time we wouldn't dull the bits, but break them. The big bits I'd still have to do by hand, but the DD limited the number I'd have to deal with myself.

 

For the pro who needs to sharpen bit regularly they really either need a commercial machine like a Durex, or they need to learn to do it by hand on the bench grinder. For the small home hobbyist, I think the Drill Doctor works just fine.

[Anachronist58]

DSW: Well spoken.  I don't see anything you've said that I don't agree with: A pretty square hit.

 

The trouble with drills is that not everyone can master the offhand technique. 

 

I am no good at upholstery. 

 

Some people can be taught how to grind drills for others it's not so easy. 

 

Everyone should learn to recondition their drills offhand, and it sure helps to be coached.  Learning hand grinding unlocks some of the 'mystery' of how a twist drill works, and it also helps when it's time to use a Drill Doctor, et cetera.

 

I used to run a Stirling, and it would do up to 2" Diameter twist drills. I was in the habit of bringing the tools to rough then near finish by hand, leaving only about .010" for the machine. I had to assume every drill I reconned would be used for close tolerance work. 

 

With the various machines, I hand roughed virtually all the drills, then machine finished.  I have no doubt that as roughed most of them would have cut just fine.

 

R. Taylor (er ah, drill grinding is a heat-treating topic, yes? :huh: )

 

 

 

[vapremac]

JacksonH,

IMHO good drills and cheap both have their place in the shop, alot of the decision process
when determining which brand or quality to purchase is the level of precision you are trying to
achieve.
The lower price drills,Harbor Freight ones,I use them and can get them to hold a decent grind
over an extended period of time (with proper speeds and cutting oil). The issue that I have with the
cheaper drills is that they do not run concentric, meaning they don't rotate in true circle but more of
an oval. If that is of no big concern to the type of work you are doing then they will be fine. With the
cheaper drills you won't feel to bad when one breaks or honing your grinding skills.
When my jobs call for precision tolerance, I leave the cheap ones in the tool room.
For this I prefer morse taper shank twist drills, American made , more expensive but a whole
lot more peace of mind.
So my take on both.........each have their place,depends on the task at hand as to the quality
of choice.
Hope that helps.............

[JacksonH]

Thanks vapremac, that does help.

[swedefiddle]

Good Morning,

 

I wasn't meaning that the Drill Doctor doesn't work, It does quite well (I have and use one). What I was trying to say is that it shouldn't be a MUST HAVE tool. It is better if you can walk up to a bench grinder and know how to grind a drill bit. I teach grinding drill bits in my Beginners Blacksmith Class. :) :)

 

Neil

[Anachronist58]

Yes, Mr. Swedefiddle, Exactly. 

 

So glad to read that you are teaching a skill that a student will carry away from your shop - and will serve him/her for a lifetime. 

 

Can there be anything more rewarding than to be able to solve your own problems with such a ubiquitously necessary tool as the twist drill - restore the geometry and get back to work!

 

Understanding how the end of a twist drill works is KEY to nearly every other rotating tool out there - Milling Cutters & Saws, Reamers, even Gun Drills..... 

 

R. Taylor