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Julien M




Location: London
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PostPosted: Tue 21 Jan, 2014 5:52 am    Post subject: Drilling mild steel         Reply with quote

Ok. I'm trying to make a peen block and that's the one last thing I need to complete this sword project:
http://www.myArmoury.com/talk/viewtopic.php?t=21636

I need to drill a hole in a piece of likely mild steel I got from a pile of scrap at Owen Bush's forge some time ago.

Sounds simple right...well not so much!

I have a vice, I have a cheap drill, and I bought cobalt and titane bits (2mm, and 2.5mm).

I broke 4 trying to do it holding the drill myself.

I bought a column/press to hold the drill vertical, I now have a bi gaz welding kit that I used to heat the metal red, and let it cool by air...just in case it was hardened. Just tried again, nothing. The bit barely leaves a tiny cone shaped mark on the surface, nothing more. I got impatient and tried the percussion mode...I think I broke my drill, plus another bit down the drain too, most likely.

I'm quiet frustrated (to say the least, the all neighbourhood likely hear me cursing at this thing). Any suggestions? (yeah I might just buy a piece of certified mild steel somewhere...)

I don't understand why the heck this does not work (slow speed, checked, oil, checked)

Help!

Julien
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Kai Lawson




Location: Madison, WI
Joined: 26 Aug 2010
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PostPosted: Tue 21 Jan, 2014 7:02 am    Post subject:         Reply with quote

I had a similar issue, where the bit wouldn't bit and just ended up burning the steel. It might be the drill/drill press or the particular piece of steel. Maybe get a new piece?

I've definitely been waiting for the results of this project! Looks fantastic!

"And they crossed swords."
--William Goldman, alias S. Morgenstern
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Bjorn Hagstrom




Location: Höör, Skane
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PostPosted: Tue 21 Jan, 2014 7:05 am    Post subject:         Reply with quote

Owen made some Kryptonite? Wink
You think you could have got some other alloy than expected?
I mean, since the normalization did not help, and it really should if it was mild steel.

There is nothing quite as sad as a one man conga-line...
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Dean F. Marino




Location: Midland MI USA
Joined: 24 Aug 2011

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PostPosted: Tue 21 Jan, 2014 7:13 am    Post subject:         Reply with quote

hmmmm - you're sure this isn't a chunk of WELD, right? Cobalt bits will work well on GUN steel. The only time I've had problems is when I have tried to drill through a weld: NOTHING will "bite", just spins happily away & makes a polished spot Happy.
In edhil, hai edhil. In edain, hai edain.
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Matthew Bunker




Location: Somerset UK
Joined: 02 Apr 2009

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PostPosted: Tue 21 Jan, 2014 7:15 am    Post subject:         Reply with quote

Try drilling on a slower speed with a bit of cutting oil?

If you've heated it, punched it and it still won't drill..it's not mild steel.

"If a Greek can do it, two Englishman certainly can !"
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Radovan Geist




Location: Slovakia
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PostPosted: Tue 21 Jan, 2014 7:16 am    Post subject:         Reply with quote

Hi Julien, from what you write it seems that it´s just that steel - it does not sound like a mild steel for sure. My suggestion would be to get a different block. Breaking 4 Co-Ti bits is too high a price...
You can still do a simple (and inaccurate:)) hardness test - get a piece of steel which you know is a mild steel, and scratch it with a file, then scratch your mysterious piece, applying the same (more or less) force, and compare.
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Sean Flynt
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PostPosted: Tue 21 Jan, 2014 7:26 am    Post subject:         Reply with quote

I just spun bits on a hardened steel helmet until I put much of my weight behind the hand drill and just barely let the drill turn. I also found that oil helps.
-Sean

"Everywhere I have searched for peace and nowhere found it, except in a corner with a book"- Thomas a Kempis (d. 1471)
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Daniel Wallace




Location: Pennsylvania USA
Joined: 07 Aug 2011

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PostPosted: Tue 21 Jan, 2014 9:30 am    Post subject:         Reply with quote

hmm, even hardened mild steel wouldn't be all that tuff to break bits. but 2 mm is a pretty small bit, if I'm drilling something of that diameter, I'm only doing it on very thin sheet metal. I've broken many of my 1/16 - 1/8th in bits on just 22 gage mild steel.
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Norman McCormick





Joined: 17 Jan 2007

Posts: 117

PostPosted: Tue 21 Jan, 2014 9:47 am    Post subject:         Reply with quote

Hi,
I have had similar issues using small diameter bits, hard but very brittle. My solution, which worked for me when using small diameter bits, was to insert the bit deep into the chuck so that only 2-3 mm protruded, I was then able to exert a lot of downward pressure on my drill press without breaking the bit. I then remounted the bit 4-5 mm protruding and so on until I reached the required depth. So far this has worked every time for me. Hope this is of some help.
Regards,
Norman.
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Leo Todeschini
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Location: Oxford, UK
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PostPosted: Tue 21 Jan, 2014 10:17 am    Post subject:         Reply with quote

When drilling any material, imagine a point at the edge of the bit and imagine how fast it spins.

In your case you have a 2mm bit spinning at say 200rpm (if that is what you mean by slow)

so, 2 mm x 3.142 x 200 = 1257mm = cutting edge moving through the material at 1256mm per minute

now lets imagine a 10mm bit doing the same thing

10 x 3.142 x 200 = 12570mm per minute

I don't actually know what the rpm of a 10mm bit through mild is, but I would guess it should in fact be around 450rpm.

So if you keep the rpm the same, then the bigger the bit the faster the edge velocity, but as you are in fact cutting the same material you should in fact be heading toward the same edge velocity whatever the bit size. This is of course different to the rpm being the same.

So run large bits slow and small bits fast - that is what they are designed for and you are likely having problems because your speed is far too slow.

Big bits too fast overheat the edges and soften them, small bits too slow catch, judder and shatter.

The biggest mistake people make with drills is running them too fast for the bit size so they run DIY drills at 2500rpm using 6mm bits and so they die......

As you can see from this chart (scroll down) your bits should be running at around 2000rpm ie around the top speed of your drill. http://www.garagejournal.com/forum/showthread.php?t=229661

If you are using cobalt bits which are really for hard materials like springs then you do run slower and use more force and do not let up during the cut, but for mild a cobalt bit or ordinary HSS bit will glide through.

If a file will readily mark your metal then a drill will drill it.

So in a nutshell Julien look at the rpm on your drill which is likely around 2500, and run it just below max speed. For the record I only bother to use fluid on hard materials and I get through a drill set a year.

Good luck

Tod

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Julien M




Location: London
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PostPosted: Tue 21 Jan, 2014 12:09 pm    Post subject:         Reply with quote

Hi all,

Thanks all for the input, much appreciated. Tod that's quiet a write up, way too technical for me Happy but I'll stick to your conclusions and will drill at full speed, if that piece of C*** of a drill (Aldi again!) can do that before it falls apart.

Norman I like your tip thanks, I will do it that way as even with the drill stand I can see the drill bit go sideways as I push harder on the all thing. I have no doubt that I would break yet another one if I pushed harder, and yes Radovan, 4 cobalt drill bits starts to add up for such a tiny piece of steel (just mentioning that again pisses me off Happy). I did the file test, and yes the steel marks on the mysterious piece but another certified mild piece does feel softer under the file, that's why I thought normalizing would be the end of it. Maybe I did not do it correctly. I have a bi gas kit, and I heated the tip red (just the tip, the piece is 30 cm long), and tried to drill that area. On that topic I have a full size guard blank I need to soften and normalize. As long as I get it red bit by bits it will work right? I used to do that in one of Owen's gas forge, that would get the all piece bright red in no time. That day I was on the clock, and I stupidly dipped the piece in water in order to take off without having this thing burning my car carpet. So I have a harden guard I can't further shape...

Dean F. Marino wrote:
drill through a weld: NOTHING will "bite", just spins happily away & makes a polished spot Happy.


That's interesting as I drilled through a weld spot without any issues with the same set up! (a filled tang hole on a pommel).

Anyway I have a few more options to try before I give up and look for a certified piece of mild steel.

What a bloody waste of time!!

J
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Dean F. Marino




Location: Midland MI USA
Joined: 24 Aug 2011

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PostPosted: Tue 21 Jan, 2014 2:37 pm    Post subject:         Reply with quote

I also noticed (late) that you were making a peen block - small piece.

Ever thought of just buying a steel NUT, hole about the right size for the tang stub, then drilling & smoothing off the nut edges? I've turned nuts into things you would never recognize as nuts Happy - often, it requires no more than a dremmel tool Happy.

In edhil, hai edhil. In edain, hai edain.
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Glen A Cleeton




Location: Nipmuc USA
Joined: 21 Aug 2003

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PostPosted: Tue 21 Jan, 2014 3:27 pm    Post subject:         Reply with quote

Matthew Bunker wrote:
Try drilling on a slower speed with a bit of cutting oil?

If you've heated it, punched it and it still won't drill..it's not mild steel.

Also use pilot drills, the width of the larger bit's cutting tip.

Fwiw

GC
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Bruce Tordoff
Industry Professional




Joined: 13 Aug 2007

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PostPosted: Wed 22 Jan, 2014 10:15 am    Post subject: drilling mild steel         Reply with quote

A) What Matt and Leo said.

and B) that really doesn't sound like mild steel in my experience.

Your other option could be this;

Domestic/ DIY tools are not always up to the task we try using them for. whether its the power tool or the bits themselves the same applies.

So this being the case, I would suggest a trip to your nearest engineering company, ie, any type of company that does, machining or welding/fabrication type work.
They would A; probably have many choices of scrap mild steel for you to choose from and B; would be able to drill it to your specs for a very nominal fee, Using pro equipment.

I try and be as self sufficient in my own workshop as my skills and equipment allow., but there have been occasions when I have needed to 'farm' something out. Most companies are usually quite amenable, especially as a small job like yours would take little time.
Good luck.
Bruce
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Julien M




Location: London
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PostPosted: Wed 22 Jan, 2014 10:42 am    Post subject:         Reply with quote

Thanks for the advice Bruce - that's an idea though I would not know where to begin to find such a company here around Paris. I did bother my local garage for a couple of welds a few weeks back though, nice chaps really.

I tried again yesterday with the bit pushed as far as possible in the drill, high speed and then low speed too. The drill did not break, which is good. Otherwise nothing happened. Took the drill set off the vertical stand to be able to lean my weight on it. Nothing. I now believe that this piece of scrap metal is home to some malignant evil that has a will of it's own. It's going straight to the bin and will torment somebody else when it's collected by some poor chap in a scrapyard at the far end of the world...

To make a long story short, I'm getting a piece of mild steel Happy (to the question why didn't you do it before, well, I like to keep things simple, and searching for mild steel on ebay uk will return plenty of result, dirt cheap (same for brass), and behold on ebay France. "acier doux" will return nothing save some useless shower handle...same for brass. I have no clue why). I know of a shop that deals with metals in Paris, so I'll have to go just for that.

To be continued...
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Fabrice Cognot
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Location: Dijon
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PostPosted: Wed 22 Jan, 2014 11:41 am    Post subject:         Reply with quote

Julien, if you need advice/addresses/suppliers and all in France, why don't you just ask ? Wink

I don't know them all, but I sure know a few useful places....

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Robert Rootslane




Location: Estonia
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PostPosted: Wed 22 Jan, 2014 7:22 pm    Post subject:         Reply with quote

Must admit that the only items that i have encountered to have such hardness are different military helmets that our guys often use as training helmets when they have added a visor.

A few things i have noticed when drilling through that very hard steel:

* for some reason, good steel bits have worked better for me than cobalt ones when drilling that kind of steel.
* sometimes it helps to make a small dent in the material with a punch so the drill has something to start from
*if you can heat it to red hot as you said, you may want to try to just punch through it.

Anyway, if the peace of steel is so badass than you can make something cool out of it. Like an indestructible knife or something.


R
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Julien M




Location: London
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PostPosted: Thu 23 Jan, 2014 12:06 am    Post subject:         Reply with quote

Fabrice Cognot wrote:
Julien, if you need advice/addresses/suppliers and all in France, why don't you just ask ? Wink
I don't know them all, but I sure know a few useful places....


Thanks Fabrice! I have not forgotten about you and I will have questions for you sooner of later no worries Happy

Fellow forum member Mathieu H provided me with much information on suppliers in Paris, but I'm the lazy type and the web remains my preferred way to get things done, especially ebay. So I really can't explain the pletoric wealth of the offering for such things in the UK and why there is nothing in france. Try "mild steel bar", or "mild steel flat bar" or even "brass sheet" in the uk, then go "barre acier doux" in ebay fr, that's pretty eloquent. I begin to wonder if there is some ebay regulation prohibiting such sales on this side of the channel...

Sure there are plenty of specialized industrial companies that cutlers use to supply themselves here: all you'll find on their website is a un-user friendly and lengthy pdf spreadsheets with cryptic technical info and no prices...and I hate to pick up my phone. Fabrice if you have an address to share that can list mild steel bits, provides dimensions and prices and allows to shop online, I'll take it!

Robert Rootslane wrote:
Anyway, if the peace of steel is so badass than you can make something cool out of it. Like an indestructible knife or something.R


Yeah, and I shall call this blade "drill's bane", a well deserved name!
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Julien M




Location: London
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PostPosted: Thu 30 Jan, 2014 5:30 am    Post subject:         Reply with quote

Ok I broke 2 more bits...yeah! And this time on a mild steel bolt that I reshaped. I also heated it red and attempted to punch with little success but I know now where my problem is. Checking video of dudes drilling through 1cm thick steel plates with cordless drills and a drop of oil made me realize I was not looking at the problem correctly and oversaw to thoroughly check the main component: the drill itself.

With the drill on the stand I was looking at it drilling sideways, I realized that the barrel was not rotating properly around it's axis, it's loose or simply broken. I've tried to fasten it with no results. As said, it was dirt cheap lidl/aldi quality gear.
I bought a new drill online, with new bits (german stuff, also cheap but highly rated). I think that will be the end of this rather ridiculous and not too glorious episode in my learning path...
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Kai Lawson




Location: Madison, WI
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PostPosted: Thu 30 Jan, 2014 7:42 am    Post subject:         Reply with quote

Your record for broken bits is both saddening and amazing…here's some not-quite-congratulations.
"And they crossed swords."
--William Goldman, alias S. Morgenstern
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