Looking for opinions on taps. I thought that as light a hobby as we have any tap would do, I'm finding that not to be the case. I break a Kadee tap about once a month, then I tried Dubro which promptly broke on it's first use tapping *plastic*.
Taps - what brand is best?
thx Greg
You can buy good taps from a number of sources. However, the thing you may really need to do is use a slightly larger tap drill. If you get 75 % threads, they are about 90 % the strength of 100% threads. Used to have a sklled machinist tell me this often until I finally took his advice.
You should also consider using a lubricant in tapping metals; Ivory soap works well, as does beeswax.
Brian
Greg,
For small diameter taps, try using a pin chuck to hold them rather than the standard type of tap wrench. This limits the torque you can apply to the tap and gives you a better feel for the tough spots where the tap is in danger of breaking.
Also, if you've got a bench drill press, hold the pin chuck lightly in the drill chuck so that it can rotate in the chuck jaws. Put the work piece on the drill table and tap the hole by turnignthe pin chuck. This means that the tap enters the hole sqeare, and it cannot wobble of the square which can also cause it to break.
Jim.
You could buy "Dorman", they make about 3 styles, but at about $40+ Oz$ (~$28US) each, I declined. Fortunately I found my Kadee 2-56 tap but the smaller size has vanished. Alan in beautiful Golden Bay, Western Oz, South 32.25.42, East 115.45.44 GMT+8 VK6 YAB ICQ 6581610 to reply, change oz to au in address
I have a set of taps and dies from Morris, and they have lasted a long time.
When you tap a hole, it's important to turn the tap backwards a half turn every turn or so to clear the chips out. I bet this has more to do with breaking taps than the brand name of the tap...
Jeff Sc. Machinist, Ga.
There's a lot of different design taps out there as well as different materials that they get made from. I tend to prefer the 3 flute taps as they seem to be stronger, especially in the smaller sizes. Several notes of worth: Always lubricate the tapping process. Even cheap oil will work a lot better than trying them dry. Always turn the tap squarely into the hole as this means that the tap isn't going to be trying to carve out the side of the hole at the far end of the hole. Always frequently back the tap up a bit to clear the chips and, if you are doing a deep hole (more than 6 threads) back the tap all the way out and clean it to insure that the chips don't jam in the hole. Don't just drive the tap into the hole or you will break them with great regularity. Tapping is a process that produces chips of small size that can jam in the slots and rapidly increase the force on the tap till it just shears from the forces. Do things right and you should be able to use a single tap for many years.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
I've used K&S for several years, and the only one I broke was one I dropped with the handle attached. The tap is cut from a larger billet, leaving a sturdy shaft
On Tue, 22 Jul 2003 21:42:24 UTC, "Bob May" wrote: 2000
A good way to do this is to chuck the tap in the drill press and make sure the work piece is set up properly. Turn the chuck by hand and you will get a nice straight job. Of course back the tap out frequently.
A lot of the best taps are made by little industries nobody ever heard of ... often on special contract to other industries and the military/aerospace firms.
As for GOOD taps, check out any full machinist's supply catalog ... MSC, J&L, etc. Be prepared to spend money. One really GOOD (depending on what you want it for) 4-40 tap may cost perhaps $60.00. Let's not talk GOOD taps.
For model railroad usage any decent High-Speed Steel (HSS) straight flute 'plug' length tap will do nicely. Cost is in the $2.00 - $3.00 range, each. For 'through' holes the 'spiral point' ('gun') style is especially nice, and less prone to clogging and breakage. Cost is about the same. To tap to the bottom of blind hole you'll also need a 'bottoming tap' ... cost is about the same. sometimes a decent used highewr quality tap may be better than a new cheap one.
For a well rounded set you'd thus need three of each size, as listed above. Sizes you'll likely need for model railroad use, in approximate order of usefulness include: 2-56, 0-80, 1-72, 4-40, and 6-32. Thus five sizes and three taps in each ... 15 taps total. You can buy them as you need them. Many never need more than the 'plug' taps.
There are MANY, MANY other sizes and types. Most sizes are not likely needed by model railroaders, and many are specialized types of taps (different thread pitches, thread forms, shanks, tapers, lengths, 'thread forming' taps, etc.). There are also a similar bunch of 'metric' sizes (that's every bit as big a 'swamp', just a different one).
As for breakage, the harder the tap the more easily it can be broken. Often the good ones break easier than the cheap ones ... IF ABUSED. Consider them to be made of glass. It's hard to break a tap by just threading holes. Taps usually break from being twisted SIDEWAYS (bent), not from over-torquing. They can also jam in the hole if the flutes fill with chips. The tap usually needs to be reverse rotated a fraction of a turn every couple turns forward, to 'break' the chips (except with 'gun' taps). At the first sign of binding, back the tap out, clean the chips from the flutes, and try again. If it's not going properly, determine WHY. Something's WRONG.
Most tapping, especially in metal, requires the use of some form of lubricant/cutting fluid. Such fluids include oil, wax, water, kerosene, milk (yes), lard, and whole bunch of commercial fluids. Different materials require different fluids. Yes, sometimes it can be done dry, even with good success, but that's rarely the best choice in metals.
One of my lab assistants, a student, just completed hand tapping 400 plus 5/16-18 holes in 3/8 steel plate. He never broke the tap, but did wear it out ... one broken tooth, and now quite dull. Such taps are even then useful, for cleaning out rusted nuts and such.
Dan Mitchell ==========
Greg Forestieri wrote:
Good advice. The 'standard' thread is defined as a 75% one. That's the thread you get when using a common 'tap drill' for the hole. 100% threads are hardly ever needed or specified (not even possible, really ... 99% maybe). In hard materials, those that are hard to tap anyway, often a less than 75% thread (larger hole) is still satisfactory, and much easier on the tap.
Dan Mitchell ==========
"R.A. & G.D. Whit>
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