Tapping fluid vs oil

[mjm46@bellsouth.net]

Not being a machinist, a lot of these things are a mystery to me. I've been tapping threads since I was a boy. My dad taught me to put some oil on the tap to help the thing cut and clear the chips. Oil was always a loosely generic term, I've used about everything from "3 in 1" to Rem Oil to 30 wt motor oil. They all seem to work just fine in all the holes I've tapped.

Without getting technical (I'm confused enough already) have I been doing something wrong all these years? What's the difference?

[flehto]

When I was tool and diemaking, most of the tapping was done in the drillpress and tapping fluid was used because of the higher speed and the tool steels used. At home , machine oil is used. { 3 in !}.....Fred

[Hungry Horse]

 Was taught to use tapping fluid in a shop that made custom radius rigid electrical elbows. I found that tapping fluid, seemed to work better, and run cooler. I use it on all my machine work now. The one I use the most is Rapid-tap.

                  Hungry Horse

[Steve-In]

Oil is a lube, cutting fluid (oil) has additives that carry away some of the heat generated by the cutting tool.  Watch for a tool show and go there and pick up some free samples.    Cutting fluid would probably be of more benefit on your drilling operations.  Heat generated by your drill can cause local surface hardening causing your taps to fail.

[T*O*F]

It depends on the material that is being tapped.  For our purposes either tapping fluid or oil is fine.  I got some aluminum plate from a friend who works at a place where they make joint replacements.  We were using it to make hanging targets for our woodswalk.  The stuff defied tapping and after breaking 3 taps, I went with thru-bolts instead.  Even with Tap Magic, gun oil, automotive oil, etc the blasted thing would go a couple of threads, then gall and seize.  I have no idea what its composition is, but a roundball barely leaves an indent in it.

[WadePatton]

unless you are pushing the limits of the lubricant, then really nothing.  tapping by hand is hardly going to do that.

industrial applications require as much heat removal as lubrication-but the better the lubrication, the less heat is generated.  

heat is the enemy, spawned by friction.  friction is a function of the amount of material being removed, the speed of removal and pressure applied.  heat accelerates dulling of the cutting edges and can work harden the materials.  the former being the main thing you want to avoid.

my point is don't over think it for small-scale, low speed applications.  just use something.  steel is quite forgiving.  titanium and aluminum and other "exotics" may require more consideration, but i don't see them as period correct.  

i like to use something that doesn't stink to high heaven...

[tallbear]

I picked up a good tip on here a while back.I got a tube of boelube.http://www.mscdirect.com/product/61232534.Since I tap through the wood for my tang and lock bolts this stuff works great without any chance of contaminating the wood with oil.One tube should last a lifetime.

Mitch Yates

[Acer Saccharum]

Cutting/Tapping fluids usually have extreme pressure lubricants in the formula, such as sulphur or molybdenumdisulphide. Motor oil does not.

I use Rapid Tap, which no longer has trichloroethane in it, which worked like a dream, but was very bad cancer risk.

[billd]

On a muzzleloader I tap dry except the bolt that goes thru the lock bolster.  There's only two other holes and they are thin wall.  So as to not contaminate the wood I start the bolster tap dry about 2 or 3 turns then take the lock out of the gun and finish tapping it on the bench with oil. 

Bill

[cunninmp]

Micah,
Acer has pretty much hit the nail on the head. But there is much more to then that.
All things being equal, a cutting/tapping fluid will produce a much better thread. If you could
look at the surface finish of completed threads you would find a smoother surface finish
on threads produced with a fluid meant for that purpose. A very smooth cut thread will be
stronger then a rough cut one.
But also the size of the tap matters a lot. If you look at an 8-32 tap, it should have a GH
number after it. The most common would be a 8-32 NC GH3. The 3 after the GH means the
tap is .0015 over the Pitch Diameter. A GH1 would be .0005, a GH2 .001. A GH5 is .0025.
Years ago I had to test 8-32 threads in 5/32 CRS. The purpose was to find out if cutting fluid
had a influence on the integrity of the thread. I tapped 10 holes for each fluid. Then an inch
pounds torque wrench was used to see what it took to strip the female threads. All tapping was
done with a Procurnier Tapping Head and a GH3 tap. Fluids were Kerosene, Motor Oil, Tap-Magic and
Moly-D. Also used a brand of water soluble cutting fluid which was used on our CNC machines.
The taps were changed out after they ran the 10 holes.
Well the force to strip was the worst with Kerosene and Motor Oil. Next was the water soluble.
The best was the Tap-Magic and Moly-D. Moly-D having a slight edge over the Tap-Magic.
So how much better, statistically between 25 to 30% better.
So if I were to tap a hole in a lock plate I'd use a high quality tap, and a high quality tapping
fluid. Simple as that.
Mike C.
 

[billd]

All this is good info for someone in a machine shop or production environment.  We're talking about the home builder trying to hold a lock in place.  The original builders used hand made taps and bolts out of inferior steel to what we have today.,  A little drop of bear grease or possum oil is all it takes.  Lard too.   Probably a drop of spit was used in a pinch.

The one time builder doesn't have to go out and buy special tapping fluids.   Use a quality non Chinese tap and not carbon steel.  Make sure your hole is the correct size, start it straight and take your time with the tap.  It will be fine.


Bill

[Acer Saccharum]

You can drill the hole in a drill press, then change to a tap. Turn the drill press chuck by HAND, do not use power. Run the tap in a couple of turns, and that will ensure the tap is straight with the hole. Then you can take it out, and finish tapping by hand.

[Bob Roller]

One more thing,countersink the hole to be apped the depth of one thread on each side.
It makes for a much neater looking job.

Bob Roller

[Acer Saccharum]

A quality tap, and good oil, and the tap will last for hundreds of holes. As Bill D sez: the right size hole is crucial.

[ironwolf]

  On most tap/drill charts, the drill size given is for 75% thread engagement and one must compensate accordingly.

  KW

[Bob Roller]

I always go one size under the chart on the drill bit.Those of us on the forum
that have a lot of shop experience have a lot of experience to offer to those
who have little or none. I sometimes wonder if ANY math is being taught in school
and are none of these youngsters being taught how to SEEK information??
Different materials require different methods. 12L14 and 1144 require different
treatment when being worked than 0-1 or 4150 or Half Hard which I worked with
when working in a shop that catered to the coal mines here in WVa.Dead soft materials
don't do well in the hostile environments of deep mines. Certainly not home workshop
doings.

Bob Roller

[Mark Elliott]

I had used a quart can of dark sulfur bearing cutting oil for years to tap and drill and lubricate my lathe tools.   When I started to run low,  I couldn't find that at my usual industrial supply vendor.   So,  I bought a gallon of tapping fluid that I think is more for cooling high speed work than tapping.   It is very light and clear and it doesn't work nearly as well as the old stuff that looks like particularly dirty motor oil.  Does anyone know where I can get that old dark sulfur stuff?

[wilkie]

According to my nearly 100 year old Greenfield tap and die set instructions plenty of lard oil should be used.  Since I try to be saving with my tools and materials I have used bacon grease for many years when drilling, tapping, and hacksawing.  You would be supprise how much longer a high speed or high carbon hacksaw blade will last if bacon grease is used instead of cutting dry.

[mjm46@bellsouth.net]

Thanks guys. I never even thought about machine tapping. The little T-handle works fine for me.

[Dphariss]

A quality tap, and good oil, and the tap will last for hundreds of holes. As Bill D sez: the right size hole is crucial.

And the right tap for the application, not terribly important here since most of our tapping is carbon steel of some sort or another.
The LUBE is CRITICAL if re-tapping holes in hardened parts.
For most uses even lard oil will work well and has for a very long time.
I use Castrol's moly bearing tapping fluid. But I also tap stainless. At my usage level a pint will last a LONG time.

Dan

[flehto]

To expand on Acer's post asre starting a tap....I turn on the power and shutoff and while the spindle is idling, engage the hole and after a few turns, the spindle stops and the tap is un-chucked and the rest of the tapping is done on the bench. Good and fast way to ensure that the tap is inline w/ the hole......Fred

[Acer Saccharum]

I use spiral point gun taps for almost every application. These are two flute, and the leading edges are ground so that the chips are pushed forward of the tap. They are far stronger than a four flute hand tap. The hand taps I use when I want to tap the threads close to the bottom of a blind hole. But I start the tapping with a gun tap, and tap as far as I can with it, then switch to the bottoming hand tap.

[Dphariss]

I had used a quart can of dark sulfur bearing cutting oil for years to tap and drill and lubricate my lathe tools.   When I started to run low,  I couldn't find that at my usual industrial supply vendor.   So,  I bought a gallon of tapping fluid that I think is more for cooling high speed work than tapping.   It is very light and clear and it doesn't work nearly as well as the old stuff that looks like particularly dirty motor oil.  Does anyone know where I can get that old dark sulfur stuff?

Look for Castrol Moly Dee tapping fluid. Its dark and ugly and made for tapping.
Check MSCdirect.com
http://www.mscdirect.com/product/45730595
Its not cheap though at about 45 bucks a pint at MSC.

Dan

[ironwolf]

  The sulfur bearing oil that Mark Elliot referenced is Dark Thread Cutting Oil, used mostly in powered pipe threading machines.   I know that Ridgid makes it,  and there are generic versions as well.

  Happy tapping to all,  Kevin

[FL-Flintlock]

  The sulfur bearing oil that Mark Elliot referenced is Dark Thread Cutting Oil, used mostly in powered pipe threading machines.   I know that Ridgid makes it,  and there are generic versions as well.

  Happy tapping to all,  Kevin

Rectorseal & Relton are the top two brands followed by Rigid & Morris.  LPS Tapmatic paste is handy for tapping blind holes.