[OT] machining stainless steel

I've a use for an M10 stainless bolt with a short M5 (about 5mm) thread
tapped into the middle of the head.

unfortunately, the first attempt to achieve this has got me an M10 stainless
bolt (A4-70) with the broken end of a rather inferior M5 tap in the middle
of the head.

part of the problem was an inferior grade of drill which didn't like
drilling it and likesay the tap was not in the best condition, so I'm not
unduly surprised at the outcome.

I've now ordered some decent drills in the correct size from the tool porn
dogalogue (http://www.jlindustrial.co.uk), and replacement M5 taps... so in
a day or so I can try it again...

I imagine that stainless is more workable with lubricant, any
recommendations as to what's the best lubricant to use?
--
Austin Shackles. www.ddol-las.net my opinions are just that
"For when the One Great Scorer comes to write against your name,
He marks - not that you won or lost - but how you played the game"
Grantland Rice (1880-1954). my opinions are just that

Austin Shackles wrote:
> I've a use for an M10 stainless bolt with a short M5 (about 5mm) thread
> tapped into the middle of the head.
>
> unfortunately, the first attempt to achieve this has got me an M10 stainless
> bolt (A4-70) with the broken end of a rather inferior M5 tap in the middle
> of the head.
>
> part of the problem was an inferior grade of drill which didn't like
> drilling it and likesay the tap was not in the best condition, so I'm not
> unduly surprised at the outcome.
>
> I've now ordered some decent drills in the correct size from the tool porn
> dogalogue (http://www.jlindustrial.co.uk), and replacement M5 taps... so in
> a day or so I can try it again...
>
> I imagine that stainless is more workable with lubricant, any
> recommendations as to what's the best lubricant to use?


'Rapid Tap' - we use it all the time for stainless machining and it
works well. You'll have to find a UK supplier - but a link to a US site
selling it is below.

http://www.melbran.com/relton.htm

--
EMB

Austin Shackles wrote:

>I imagine that stainless is more workable with lubricant, any
>recommendations as to what's the best lubricant to use?
>
>
Morris Supercut G

http://www.morrislubricants.co.uk/images/products/Supercut G.pdf



Lizzy

LizzyTaylor wrote:
> Austin Shackles wrote:
>
>> I imagine that stainless is more workable with lubricant, any
>> recommendations as to what's the best lubricant to use?
>>
>>
> Morris Supercut G
>
> http://www.morrislubricants.co.uk/images/products/Supercut G.pdf
>
>
>
> Lizzy

Re-lion tapping fluid.

Steve

On Thu, 15 Jun 2006 13:48:13 +0100, Austin Shackles
<[email protected]> wrote:

>
>I've a use for an M10 stainless bolt with a short M5 (about 5mm) thread
>tapped into the middle of the head.
>
>unfortunately, the first attempt to achieve this has got me an M10 stainless
>bolt (A4-70) with the broken end of a rather inferior M5 tap in the middle
>of the head.
>
>part of the problem was an inferior grade of drill which didn't like
>drilling it and likesay the tap was not in the best condition, so I'm not
>unduly surprised at the outcome.
>
>I've now ordered some decent drills in the correct size from the tool porn
>dogalogue (http://www.jlindustrial.co.uk), and replacement M5 taps... so in
>a day or so I can try it again...
>
>I imagine that stainless is more workable with lubricant, any
>recommendations as to what's the best lubricant to use?

Stainless work hardens really easily. Once you start drilling keep
going and don'y allow drill to rub and build up temperature. Keep
drills really sharp and use cutting lubricants as above to keep
temperatures down.

If you do end up creating local hard spots when you drill, even good
taps will suffer.

David

rads wrote:

> Stainless work hardens really easily. Once you start drilling keep
> going and don'y allow drill to rub and build up temperature. Keep
> drills really sharp and use cutting lubricants as above to keep
> temperatures down.

Using a seconds tap rather than a taper tap helps too.

Steve

On or around Thu, 15 Jun 2006 15:13:15 +0100, Steve Taylor
<[email protected]> enlightened us thusly:

>rads wrote:
>
>> Stainless work hardens really easily. Once you start drilling keep
>> going and don'y allow drill to rub and build up temperature. Keep
>> drills really sharp and use cutting lubricants as above to keep
>> temperatures down.
>
>Using a seconds tap rather than a taper tap helps too.

ta for the useful info, all.

I started off with a sharp drill, but it was a cheapo anonymous "HSS" one,
which although it might've been HSS obviously ain't correctly heat treated.
I've ordered some decent ones.

what about cutting speeds, for drilling? is it better to run it slower than
for e.g. mild steel?

The tapping will be done by hand... I don't rate my chances much of doing
5mm depth on the lathe...
--
Austin Shackles. www.ddol-las.net my opinions are just that
Appearances: You don't really need make-up. Celebrate your authentic
face by frightening people in the street.
from the Little Book of Complete B***ocks by Alistair Beaton.

Austin Shackles wrote:

> what about cutting speeds, for drilling? is it better to run it slower than
> for e.g. mild steel?

MUCH slower for sure.

>
> The tapping will be done by hand... I don't rate my chances much of doing
> 5mm depth on the lathe...

Use the lathe to hold the tap perpendicular, but dont' do it under
power. Re-lion is very good on stainless, much better than Trefolex.

Steve

On or around Thu, 15 Jun 2006 19:05:52 +0100, steve
<[email protected]> enlightened us thusly:

>Austin Shackles wrote:
>
>> what about cutting speeds, for drilling? is it better to run it slower than
>> for e.g. mild steel?
>
>MUCH slower for sure.
>
>>
>> The tapping will be done by hand... I don't rate my chances much of doing
>> 5mm depth on the lathe...
>
>Use the lathe to hold the tap perpendicular, but dont' do it under
>power. Re-lion is very good on stainless, much better than Trefolex.

yeah, probably will. point noted about speed. I've never done much with
stainless. will how it goes with the cutting stuff I've got, as it's a very
small job and ain't gonna happen more than about once every 6 months, I
shouldn't think. not really worth hunting special cutting fluid if I can
manage without.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Beyond the horizon of the place we lived when we were young / In a world
of magnets and miracles / Our thoughts strayed constantly and without
boundary / The ringing of the Division bell had begun. Pink Floyd (1994)

Austin Shackles wrote:
> not really worth hunting special cutting fluid if I can
> manage without.
Any merchant should have Re-lion, and its great for tapping anything.

Steve

On Thu, 15 Jun 2006 15:13:15 +0100, Steve Taylor wrote
(in article <[email protected]>):

> rads wrote:
>
>> Stainless work hardens really easily. Once you start drilling keep
>> going and don'y allow drill to rub and build up temperature. Keep
>> drills really sharp and use cutting lubricants as above to keep
>> temperatures down.
>
> Using a seconds tap rather than a taper tap helps too.
>
> Steve

Good advice. I'd add that it's important to use a sharp drill and don't be
afraid to be brutal with the feed rate. As soon as the drill stops cutting
and starts rubbing you'll be in trouble so it's important to keep the swaf
coming out at a steady rate.

Lubrication is good but coolant is more important and water based cutting
fluids cool better than oil based ones because the specific heat capacity is
higher. If you haven't got any 'suds' then soapy water is better than
nothing. Use lots - you''re taking away the heat, not using it as a
lubricant.

You'll also find that A4 stainless (316) is more difficult to cut and work
hardens much more quickly than A2 (304), If you don't need the added chloride
resistance of A4, stick with the cheaper and softer grade.

Nick.

On or around Thu, 15 Jun 2006 21:25:52 +0100, Nick Williams
<[email protected]> enlightened us thusly:

>On Thu, 15 Jun 2006 15:13:15 +0100, Steve Taylor wrote
>(in article <[email protected]>):
>
>> rads wrote:
>>
>>> Stainless work hardens really easily. Once you start drilling keep
>>> going and don'y allow drill to rub and build up temperature. Keep
>>> drills really sharp and use cutting lubricants as above to keep
>>> temperatures down.
>>
>> Using a seconds tap rather than a taper tap helps too.
>>
>> Steve
>
>Good advice. I'd add that it's important to use a sharp drill and don't be
>afraid to be brutal with the feed rate. As soon as the drill stops cutting
>and starts rubbing you'll be in trouble so it's important to keep the swaf
>coming out at a steady rate.

Mind, I don't intend to be too brutal with a 4.2mm drill; good recipe for
broken bits of drill stuck in the job. Started with a centre drill to make
sure it was centred, and that cut OK - it was the elcheapo 4mm one that
wasn't playing ball.

>Lubrication is good but coolant is more important and water based cutting
>fluids cool better than oil based ones because the specific heat capacity is
>higher. If you haven't got any 'suds' then soapy water is better than
>nothing. Use lots - you''re taking away the heat, not using it as a
>lubricant.

I've got general purpose soluble cutting oil which seems OK for most things.
>
>You'll also find that A4 stainless (316) is more difficult to cut and work
>hardens much more quickly than A2 (304), If you don't need the added chloride
>resistance of A4, stick with the cheaper and softer grade.

not got the option at the moment, those bolts are the only ones I have which
are the right size for the job. I'll probably see if I can get A2 next
time.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Confidence: Before important work meetings, boost your confidence by
reading a few pages from "The Tibetan Book of the Dead"
from the Little Book of Complete B***ocks by Alistair Beaton.