Drilling advice needed.

[Molly Brown]

I usually somehow manage to remove a broken bolt but in this instance
that is not an option so I need to drill it out. The bolt is probably
hardened steel and I am using a drill press at 300 RPM, a cobalt bit,
and metal cutting oil. I have had the drill press arm bungee tied for
the past few hours and all I got was about a millimeter. Is this
normal or am I doing something wrong?

[alb...@att.net]

Are you sure the bit is sharp? Or just try a smaller "new" bit to start with.

[Stormin Mormon]

Does your drill press do left? Can you use a reverse fluted drill bit?

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Molly Brown" <recycl...@gmail.com> wrote in message
news:7d5e9fa8-4f49-4b56...@dg7g2000vbb.googlegroups.com...

[Molly Brown]

After doing extensive research here is how I drilled-out a hardened
steel bolt:

1. Use a drill press that has a vise. It says to use a hydraulic chuck
instead of a clamping chuck but I didn’t have a hydraulic chuck; maybe
I got lucky that it worked for me.
2. Set the drill for 220 RPM
3. Use lots of cutting oil.
4. Feed the drill VERY slowly and no more than several seconds at a
time. Clean out bits of steel with a paper towel between periods of
cutting; maybe it’s not necessary but doesn’t hurt. Keep the room as
quit as possible so you can hear it cutting.
5. Use a solid carbide bit. Not carbide coated or carbide tipped but
solid carbide which costs about $22.00 for a ¼” diameter bit. The bit
is very brittle and will break very easily and can never be sharpened.
Do not expect it to give at all. You will not find a solid carbide bit
in any hardware store so don’t even ask because they won’t even know
what you’re talking about. You will need to go to an industrial tool
supplier or the internet.

I must be the first to post these instructions on the internet because
I haven’t seen another one with this much detail. Bully for me.

[croy]

Sounds like it's time for EDM.

http://en.wikipedia.org/wiki/Electrical_discharge_machining

Some automotive machine shops provide the service.

--
croy

[DanG]

I doubt that your bolt is hardened. It may well be stainless steel
which can be vicious to drill. It is regrettable that you have work
hardened the bolt by "grinding" it. Really slow speed, lots of
pressure. If the bit is not cutting chips or curls, stop! continuing
to work harden only makes things worse. Stainless steel is VERY prone
to gauling and once it happens cannot/will not thread in or out. Drill
and retap or alternate assembly become the only choices.

--


___________________________________

Keep the whole world singing . . .
Dan G
remove the seven

[Molly Brown]

I know it was hardened steel and not stainless steel because stainless
steel is barely magnetic and this bolt was held firmly by a magnet
when I tested it after removing it.
I know it was hardened because even though I used completely new
cobalt bits in different sizes none of them could make more than a
scratch on it.
I am not familiar with the word “gauling”. What does it mean?

[Stormin Mormon]

Not a single thing.

However, it sounds a bit like "galling"
http://www.thefreedictionary.com/galling
2. Obsolete rubbing painfully; chafing

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Molly Brown" <recycl...@gmail.com> wrote in message

news:8f178270-0a57-4cf1...@ns1g2000pbc.googlegroups.com...

> to work harden only makes things worse. Stainless steel is VERY prone
> to gauling and once it happens cannot/will not thread in or out.
>

> Keep the whole world singing . . .
> Dan G
> remove the seven

[Ralph Mowery]

"Molly Brown" <recycl...@gmail.com> wrote in message
news:8f178270-0a57-4cf1...@ns1g2000pbc.googlegroups.com...

>I am not familiar with the word “gauling”. What does it mean?

It is spelled galling. Difficult for me to explain, but it is when the
threads sort of lock up and almost 'cold weld' to the bolt hole.

http://www.estainlesssteel.com/gallingofstainless.html

While it hapens to other materials, stainless steel is the most common seem
one that has this as a major problem.

[k...@att.bizzzzzzzzzzzz]

Not all grades of stainless are non-magnetic. Not a good test.

>I know it was hardened because even though I used completely new
>cobalt bits in different sizes none of them could make more than a
>scratch on it.
>I am not familiar with the word “gauling”. What does it mean?

Kinda like spaulling. ;-)

[Jules Richardson]

On Tue, 15 May 2012 15:48:30 -0700, Molly Brown wrote:

> On May 13, 5:55 pm, Molly Brown <recyclebin...@gmail.com> wrote:
>> I usually somehow manage to remove a broken bolt but in this instance
>> that is not an option so I need to drill it out. The bolt is probably
>> hardened steel and I am using a drill press at 300 RPM, a cobalt bit,
>> and metal cutting oil. I have had the drill press arm bungee tied for
>> the past few hours and all I got was about a millimeter. Is this normal
>> or am I doing something wrong?
>
> After doing extensive research here is how I drilled-out a hardened
> steel bolt:
>
> 1. Use a drill press that has a vise.

Yes, the more solid the thing you're trying to drill into, the better
(not that drilling metal without having the workpiece clamped is ever a
good idea, anyway).

> 4. Feed the drill VERY slowly and no more than several seconds at a
> time.

Well, on the one hand you don't want to overheat it - but on the other,
doesn't most drill bit wear occur when first getting the bit to 'bite',
rather than once it's cutting? So perhaps stopping frequently is actually
a bad thing in terms of the life of the bit.

> 5. Use a solid carbide bit.

I've not tried those, but I do have some cobalt bits which have been
serving me well - for the larger diameters it's necessary to start out
with a smaller bit and work up to the desired diameter, though.

cheers

Jules

[Oren]

On Wed, 16 May 2012 21:12:24 -0400, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:

>
>Not all grades of stainless are non-magnetic. Not a good test.

I didn't know that. How would one test for the better grade of SS?

[k...@att.bizzzzzzzzzzzz]

Define "better". ;-)

[Oren]

On Thu, 17 May 2012 12:31:06 -0400, "k...@att.bizzzzzzzzzzzz"

<k...@att.bizzzzzzzzzzzz> wrote:

>>>Not all grades of stainless are non-magnetic. Not a good test.
>>
>>I didn't know that. How would one test for the better grade of SS?
>
>Define "better". ;-)

... 'more gooder' ...

[bob haller]

non magnetic stanless doesnt rust.....

non magnetic is the better stainless

I have wondered if they make non magnetic stainless rebar for wet
applications like dams?

rusting rebar expands and cause concrete to spall....

[Oren]

On Thu, 17 May 2012 12:45:03 -0700 (PDT), bob haller <hal...@aol.com>

wrote:

>> >>>Not all grades of stainless are non-magnetic.  Not a good test.
>>
>> >>I didn't know that.  How would one test for the better grade of SS?
>>
>> >Define "better".  ;-)
>>
>> ... 'more gooder' ...
>
>non magnetic stanless doesnt rust.....
>
>non magnetic is the better stainless

Yes sir, correct.


My pistol will wash in a dishwasher. Never miss a lick.

[Larry W]

In article <kknar7lv1o4r30jki...@4ax.com>,

Oren <Or...@127.0.0.1> wrote:
>On Thu, 17 May 2012 12:45:03 -0700 (PDT), bob haller <hal...@aol.com>
>wrote:
>
>>> >>>Not all grades of stainless are non-magnetic.  Not a good test.
>>>
>>> >>I didn't know that.  How would one test for the better grade of SS?
>>>
>>> >Define "better".  ;-)
>>>
>>> ... 'more gooder' ...
>>
>>non magnetic stanless doesnt rust.....
>>
>>non magnetic is the better stainless
>
>Yes sir, correct.
>
>

While in general the non-magnetic stainless steels have greater corrosion
resistance than the magnetic varieties, "better" is relevant to the
intended use. The magnetic stainless steels are often harder, stronger,
or have other characteristics that make them preferable in a specific
application. It would be incorrect to say one type is better than another
only on the basis of magnetism without also considering how it will be
used.


--
The best argument against democracy is a five-minute conversation
with the average voter. (Winston Churchill)

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

[Sjouke Burry]

Oren <Or...@127.0.0.1> wrote in news:fq8ar7d5enjq8elaivbo5l1f9jk619bcbm@
4ax.com:

Use a magnet and choose the non-magnetic.

[k...@att.bizzzzzzzzzzzz]

Insufficient information. Non-magnetic may be gooder. On a different day,
magnetic may be even more gooder.

[k...@att.bizzzzzzzzzzzz]

I suppose after you take it out, you lubricate it with WD-40, too.

[Existential Angst]

"Molly Brown" <recycl...@gmail.com> wrote in message

news:7d5e9fa8-4f49-4b56...@dg7g2000vbb.googlegroups.com...

Sometimes shit can be spectacularly and anomalously hard. For example, I
was trying to drill/tap some holes in the ends of a dumbbell for an eyebolt.
One drilled fine, the other was like glass, absolutely un-drillable.

A carbide bit might help, but maybe you just have to heat the thing red hot,
and let it cool slowly (cover with sand or sumpn), to anneal.

Also, some stuff is superhard, but just on the surface, as in
case-hardening, while the interior is softer, sometimes very soft. If you
try grinding away 1/16 inch or so, you might find it much easier to drill.

I wonder if they make a "grinding drill", which would basically be a rod
coated with aluminum oxide, to just grind a hole through.... which could be
a very slow process. You could run this idea by the folks at
rec.crafts.metalworking.

I doubt a bungee cord is doing anything but dulling the bit.
--
EA

[croy]

On Wed, 16 May 2012 06:47:23 -0700 (PDT), Molly Brown
<recycl...@gmail.com> wrote:

>I know it was hardened steel and not stainless steel because stainless
>steel is barely magnetic and this bolt was held firmly by a magnet
>when I tested it after removing it.
>I know it was hardened because even though I used completely new
>cobalt bits in different sizes none of them could make more than a
>scratch on it.
>I am not familiar with the word “gauling”. What does it mean?

Some info on "stainless steel" and "galling" is available
here:

http://www.estainlesssteel.com/


More good stuff here:

http://www.aksteel.com/pdf/markets_products/stainless/Stainless_Steel_Comparator.pdf

--
croy