He said 40 tpi which is pretty tough, also if you have any "White Lead"
I use that (and it's probably 40 years old)on the super tough jobs mixed
with paraffin and talo.
-------- Original Message --------
Subject: [AR] Re: Tapping holes in SS 316
From: "Troy Prideaux" <GEORDI@xxxxxxxxxxxxxxxx>
Date: Tue, August 04, 2015 6:32 pm
To: <arocket@xxxxxxxxxxxxx>
We only use HSS for tapping our stainless so providing you take the necessary
precautions you should be ok. What size thread is it?
Troy
_____
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Robert Watzlavick
Sent: Wednesday, 5 August 2015 11:22 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Tapping holes in SS 316
I had seen the suggestion about Moly D - I think I have some Moly D grease
for the car. Not sure if that is the same thing or not.
The larger hole is a good idea - I don't need any strength to speak of for
this so I could go with 50% thread (0.096 vs. 0.089 drilled hole).
I found a bar of 316 in my scrap bin so I'll test it out. The HSS taps I was
planning on using are brand new so maybe I can get away with it.
-Bob
On 08/04/2015 07:14 PM, Michael Clive wrote:
Titianium taps, Moly D lube. (Molybdenum disulfide)
On Tue, Aug 4, 2015 at 5:06 PM, Troy Prideaux <GEORDI@xxxxxxxxxxxxxxxx> wrote:
316 isn't necessarily harder than 304 - I've often seen 304 grades that are
harder than 316 grades and vise versa so if you can tap into 304, the chances
are you can tap into 316.
If the valve body is a casting, the chances are it's actually not 316 but a
close variant with similar properties that can be identified as 316, but
could be a harder material than your true 316 stock material.
Tapping stainless in general: I generally drill the initial bore out wider
than normal to avoid tool breakage. When hand tapping, I'll rotate the tap a
revolution or so and then reverse half a rev or so to remove some of the
frictional stress on the tap and follow that process all the way to
completion. Use a good grade of tapping grease if possible or at least
cutting grease. Make sure your tap is aligned straight with the hole -
preferably start the tapping process in the same drill press position as the
drilling process if you used a drill press or fixed machine to drill the hole.
If machine tapping - tool life can be increased significantly by following
the suggested speeds and feeds that are practically difficult to achieve by
hand tapping.
Tapping small fine threads in hard stainless materials is hard especially by
hand.
Troy
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Robert Watzlavick
Sent: Wednesday, 5 August 2015 9:48 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Tapping holes in SS 316
I need to tap some #4-40 holes in an SS 316 valve body (Swagelok
SS-4P4T) for a bracket. I'd really like to avoid breaking the tap so
any tips? I usually use SS 304 and aluminum so I haven't worked much
with the harder stainless steels. The tap is HSS and I was just going
to use Tap Magic for the cutting fluid. If I have to, I can drill all
the way through the body and put a nut on the other side but I'd rather
use a threaded hole.
-Bob