Help tapping small threads, please

[DJP]

My post #38, right hand picture shows the chip ejecting style of tap in action. These taps are preferred in blind holes so chips don't go down into the hole cellar, bung up the tap & risk breakage. I've also heard you are not supposed to reverse these to break the chip like conventional taps & that makes sense. Blind holes shouldn't be substantially deep anyway. What I have done just to be safe on certain holes is wound the tap out completely, give it an air blow & then proceed in again. Personally I find the good quality taps of this style to work excellent. When you have a through hole, forward ejecting taps have an exit for chips to drop out. Or at least theoretically that's how its supposed to work.LOL

I have compressed air in my shop to support the other side which is dedicated to auto repair. I use the air to run power tools and the dry off Varsol soaked parts for cleaning, however I have an aversion to using compressed air to clean chips off my machines or tools. This may be off topic but I have to mention the danger to your eyes when tiny metal chips fly in unexpected directions.

 

[john_reese]

I have compressed air in my shop to support the other side which is dedicated to auto repair. I use the air to run power tools and the dry off Varsol soaked parts for cleaning, however I have an aversion to using compressed air to clean chips off my machines or tools. This may be off topic but I have to mention the danger to your eyes when tiny metal chips fly in unexpected directions.

That is why I keep a big Shop Vac around.

 

[petertha]

Point taken. Nobody said anything about blasting chips & tools with air. I don't agree with that either. You have a regulator. Set it on very low. Mine is probably less than an aerosol can electronics cleaner. I position the nozzle over the hole & put a rag over the work. The chips go into the rag, not into the air. Safety first boys & girls.

 

[john_reese]

I admit to using air occasionally to clear chips from small holes. About the same procedure you follow, Peter

 

[RonW]

Happy New Year to all. I am surprised that through all of this no one has mentioned using a first, second and bottoming tap in sequence with small taps. I regularly use #4 and #6 taps in aluminum, (sorry about the American spelling) and seldom have a problem. I buy good HSS taps from Spaenaur in Kitchener, Ontario and they have seldom let me down. For the most part a second cut tap will fit the bill if cost is a factor but for blind holes the full set works best. For cutting lube I use tallow for steel and a tapping fluid for aluminum. Brass is done dry. Ron

 

[Dubi]

Happy New Year to all. I am surprised that through all of this no one has mentioned using a first, second and bottoming tap in sequence with small taps. I regularly use #4 and #6 taps in aluminum, (sorry about the American spelling) and seldom have a problem. I buy good HSS taps from Spaenaur in Kitchener, Ontario and they have seldom let me down. For the most part a second cut tap will fit the bill if cost is a factor but for blind holes the full set works best. For cutting lube I use tallow for steel and a tapping fluid for aluminum. Brass is done dry. Ron

Happy New Year. Interesting post. In our shop we will use Tapmatic (both types) and will tap Brass dry as you stated. However, in one case we had some very expensive special underwater switches which had 5/16 whit bushings but they would not fit into the machined housings.

We made a special jig to run a die down the threads, they stuck and twisted so I ordered that the technician put a drop of paraffin on the bushing. The die ran down beautifully. I still do not know why the die stuck as it did.

 

[olympic]

While reading this thread I just realized that "small taps" seems to mean #4 or #6 to many people here. However, there are much smaller taps in use (#2,#0, etc.). Does anyone have advice on removing broken very small taps?

I seem to use 2-56 and 0-80 a lot, but I have never broken one, not even in that nasty aluminum; that being said, I think that it's just a matter of time....

Oh. I did break a 000-120 tap once, but that's because I knocked the delicate (and expensive) little thing off the bench onto the floor. Ouch!

 

[Gene Pizzoli]

While reading this thread I just realized that "small taps" seems to mean #4 or #6 to many people here. However, there are much smaller taps in use (#2,#0, etc.). Does anyone have advice on removing broken very small taps?

I seem to use 2-56 and 0-80 a lot, but I have never broken one, not even in that nasty aluminum; that being said, I think that it's just a matter of time....

Oh. I did break a 000-120 tap once, but that's because I knocked the delicate (and expensive) little thing off the bench onto the floor. Ouch!

If you haven't broken a small tap yet you're in for a humbling experience. Most taps are broken due to misalignment or failure to relieve the chips by backing off. You can counter this to some extent by a drilling a small pilot hole in a piece of scrap equal to the diameter of the tap body. Other wise, In my experience, use a hollow mill and replace it with a bushing. However if you believe in miracles you can pray a lot. Regards, Gene

 

[Roger Pry]

Thanks Olympic and Pizzoli these examples are the sizes I'm looking at.... I intend to try to build some test pieces on the order of a large pocket watch. Some holes will be in positions where setting up in a machine(mill etc) is not my intent. This testing is for skill honing. earlier I mentioned the Archimedes drill( I purchased a micro version on ebay) because I wanted to experiment an need alignment, down force and twisting action all at the same time. I've worked using 4-40 to 2 1/4" screws/bolts in industrial situations and now in retirement want to go smaller instead of bigger.

 

[rad1945]

With 55 years as a practicing Mechanical Engineer; using taps of all forms and sizes from 0.5o mm up to 150mm diameter. I have found the best solution has always been Goliath Threading products in conjunction with "Tap Magic" fluid.
Both of these products seem to be available just about everywhere.
If they are not available in your local store, they are through Amazon.

To remove a broken tap I normally go for a spark eroder.
Another item freely available from Amazon. The swearing you will provide trying to get out that first tap by the means will surely be paid from the life long service you will get from that eroder of your life time.

 

[neilw20]

Use taper, intermediate then plug tap.
I just use the intermediate, and then plug tap for blind holes.
I resharpen the intermediate as a gun tap, or just buy one. They are often called spiral point.
Reduces cutting load considerably. Tiny diamond disk on dremmel is easy to do the gun relief. (at least for me).
Disadvantage.. Chip goes ahead of tap, making blind holes a bit of a fiddle clearing spiral swarf.
https://www.ktstooling.com/images/F...d_Pic/5301TC_PHO_4C/5301TC_PHO_4C_Enlarge.jpg

ALWAYS use Tap magic or similar. Not just ordinary oil. The high sulfur stuff the plumbers use on their big pipe dies is ideal.
NEVER do it dry. Reverse often. Candlewax quite often ok on alumin(i)um
I often do down to 1 mm. Bit fiddly to sharpen... haha.
I set part in vice.
Drill correct size hole. Next size up for steel, often.
I have a pin I put in the drill chuck, with a rubber grommet on it.
Pin fits nicely into end of tap wrench.
With the rubber grommet drive, as soon as the tap goes in a bit, the pressure on rubber gets less, and then less torque.
Reversing out is not as forgiving.
It is VERY important to stay concentric and NO BENDING loads off line.
Last time I broke a tap, was when I dropped it on the concrete.

 

[hula-hula_guy]

My experiences with tapping aluminum ( and all non ferrous materials ) and I have 25+ years - use WD-40, it's a light runny solution that will follow the tap down the hole - not scrap off at the hole opening and lubricate only the exposed part of the tap like heavy tap oils. For all ferrous materials I like using tapping wax sticks, they melt at very low temps so the stuck wax to the tap will start to flow lower in the tapped hole as the tapping process starts to generate a small amount of heat.

As other have stated and probably the most important thing to take away from here is buy a good tap from a good industrial supplier. I have a good supplier who recently I needed to buy a 0-80 spiral point 2 flute tap for $7.00 bucks. And to compare I can get a very common 3/8-16 tap in a hard grade ( for tapping A2, D2, M2 tool steels ) for $12.00. I do have my own machine shop and we do get shop prices, so anticipate these quoted prices to be about 20% more, still very obtainable prices. Talk the the guys at the industrial supplier, tell them what you are doing and your experience level, they have resources far beyond what any of us truly know to help you out.

A good tap for the correct application should last 800-1000 holes easily, I have seen it with my own eyes. Ask for an old catalog, read through it and learn what tools are available to you - for instance, you will learn several companies taps are colour coding their taps - blue line for cast iron, yellow line for general purpose, green line for non ferrous, red line for stainless, black line for hardened materials. Prices between all those grades vary less than 10%. So buying for the correct application is not that expensive.

Above all, practice, take your time tapping, and truly focus when tapping - feel, sight, sound - these are all the factors for a successful tapped hole. As another person stated using your mill or drill press to start the tap, helps you get the feel for things and get a nice true straight start on your tap, then finish by hand will a good quality T handle for small taps say up to 3/8, and a regular tap handle for larger sizes.

HAPPY TAPPING!