We've got some parts that are tapped for a 2-56 thread. The material is 8620 and it is 1/8 thick. After breaking a dozen or so I thought I'd see what y'all have in the way of wisdom as far as these little nightmare taps are concerned. I'm assuming a 2 flute would be best. and wonder if there is some tapping fluids that are especially effective with tiny taps. What about running undersize taps thru first? Rosco
I've found that Kroil works with the small taps. Tried it out of desperation when I had an 0-80 get stuck one time and I knew that any force in either direction would break it. It loosened right up. I use it all the time now.
WHat are you holding the taps with? If you are using a standard tap wrench, stop.
Your best bet is to mount a small electronics knob on the shank of the tap so you can handle it with two fingers. You can break a tap that size by simply hanging a tap wrench cantelievered out with the cutting end.
First, be sure that you're drilling the right hole diameter. If you're undersized, you;ll break taps faster than with larger taps as the actual hole diameter is, percentagewise, a lot larger than you really want to do. You should be using a #33 drill for a 2-56 tap. If you can afford the issue of a larger hole, a #32 can be done but there won't be as much thread depth with that drill. Next, use a goodly amount of lubrication to insure that the tap is not siezing in the hole. The use of a Tapmatic or other clutch system will help to make sure that the tap won't break as quickly. If you're going by hand, use the hole on the backside of the tap to hold the tap from tilting to the side as this breaks taps real fast. Back off frequently so that the chips get knocked loose. A spiral gun tap will allow you to avoid this problem also. I consider a 2-56 to be a large tap, I've got 000-120 taps that I use so you can see that there's a long way to go for getting small! Taps on your size can be power tapped but you do have to be a bit careful, especially with some of the harder steels.
-- Why do penguins walk so far to get to their nesting grounds?
Trichlor-containing tapping fluid is best if you can get hold of any. I'm hoarding a can I bought before it disappeared for just such occasions. Last time I recall using it was for an 0-80 tap in some particularly gummy stainless.
I do some miniature tapping for optical instrumentation, and what I've found is that the *thread-forming* taps are way way easier to use than conventional thread-cutting taps in the miniature domain. Part of this is the larger cross-section, and the lack of chips is a huge advantage.
I make a little knurled hollow shaft with a setscrew to hold them, and twist them in by hand, with the work on the milling machine and the top of the holder held loosely in alignment with the work by an upside down drill bit in the chuck chuck above. Also you can get by with oversized holes since at these sizes you are likely not bolting down stuff on the edge of the force envelope. Others have suggestions for lubricants.
Note that you need a different size tap drill for thread forming versus thread cutting. The formula is in _Machinery's Handbook_.
The good stuff is 1,1,1 Trichloroethane (TCA). It was used in Tap-Ease, Energine cleaner and other household items. It was banned around 1990. IBM techs knew it as Gold Can (
), and used it by the gallons for general cleaning. Trichloroethylene (TCE) is not the same stuff and is still available at my local hardware store. I don't have any of the latter, so I can't compare it to the stash of TCA I misery use for tough jobs. Paid a dollar for a gallon of it at a swap meet a while back...Paul
Excerpt from Wikipedia
"For most of its history, trichloroethylene has been widely used as a degreaser for metal parts. In the late 1950s, the demand for trichloroethylene as a degreaser began to decline in favor of the less toxic
1,1,1-trichloroethane. Another problem with trichloroethylene is that it's just too good a solvent in many mechanical applications, as it easily will strip many paints almost instantly and dissolves some plastics. However,
1,1,1-trichloroethane production has been phased out in most of the world under the terms of the Montreal Protocol, and as a result trichloroethylene has experienced a resurgence in use."
Hmm, I thought the IBM stuff was TCE, but I see from the can picture that I was wrong. Didn't it also come in a blueish can with a white plastic squirt top? Besides using it on machines I used it more than once to clean my hands. So far I haven't melted with cancer or such. If I ever did, it would be hard to figure out what to blame because of all the nasty and now illegal stuff I have been near or involved with.
Is that (the gold can picture) your page? I couldn't find anything else above it on the domain.
==================================== warning --- MAS [male answer syndrome] reply
It is my impression that it is the cooling effect of the highly volatile TCE. Back before it was regulated/banned I used carbon tetrachloride for both tapping and turning. Worked wonderfully well, but OSHA/EPA would have cow today.
The chlorine in both compounds may also have some affect by preventing the bonding to the aluminum to the tap.
I will second the suggestion to use the thread forming/rolling/ chipless taps. Be sure to use the suggested tap drill as this is larger than the suggested tap drill for conventional taps.
Are you machine tapping or hand tapping? If hand tapping what sort of tap guide or block are you using? The suggestion to use a radio knob in place of a tap wrench on small taps is a very good one. Using a thread forming tap, with a guide and knob, possibly with carbon tet [if you can find any] should eliminate any tap breakage. If you do use carbon tet, avoid breathing the fumes or getting it on your skin.
As a practical matter, if you have female employees, it may work better if you have them do the tapping, as they tend to be considerably less "ham handed" and inclined to force things than the typical male.
Unka George (George McDuffee)
...and at the end of the fight is a tombstone white with the name of the late deceased, and the epitaph drear: ?A Fool lies here, who tried to hustle the East.?
Rudyard Kipling The Naulahka, ch. 5, heading (1892).
holding the tip with. Ans. a tap handle because of the awkward position of the hole and there being very little room to get any thing in there. I was going to suggest champhering both sides of the hole. Its the owner who is doing this(a woman) and I'm as usual giving advice. I'm wondering about these roll taps and if they are sutiable in all materials or just those which will let the metal flow. All of my experience with them is when i ran an edm years ago and would have to burn out broken roll taps. "I make a little knurled hollow shaft with a setscrew to hold them," This sound like soemthing to try Thanks Rosco
I do a lot of tapping with very small taps, such as 0-80, 00-96, and even smaller. Admitedly, mostly in brass, but the issue is the same. I hold the taps in small pin vises. The smallest that can take the tap. Also, very slowly. Never more than a half-turn without backing out.
If you can't get the old Tap-Magic, use the heavy dark sulfurized cutting oil or lard oil. Either of the last will work for most applications in steel. For really hard stuff I have a can of Brownell's Do-Drill, used for tapping holes in the harder gun receivers. MSC had lard oil at one time, I bought a couple of cans at the local warehouse. A quart can lasts me a long time. Was labeled "Buttrcutt" or something similar. Some of the "green" cutting fluids have lard oil in them, mostly not as good as the straight stuff. I have some waxy stuff in a stick I got from MSC, too, it's great for blind holes, just fill them up and the cuttings extrude out with the wax. Not quite as good as lard oil for hard stuff, though.
For taps, 2-flute ones are good for the small sizes, you really need a guide or bushing for doing this stuff. I have the smallest Starrett dogbone tap wrench that I use for the small guys, a #174, a T-handle isn't sensitive enough.
I talked with the woman who was tapping these holes and she said she was breaking taps untill she started holding the tap handle right at the tap. Sounds like this idea of a small diameter knurled knob is a great idea. Will also try making a guide and getting some of the recomended cutting fluid. I ordered form MSC some roll taps and we'll give that a try. Rosco