Tapping

Re: Tapping

Fred in NC

>Raymond, I am not an expert on tapping. I had the same results the first time I attempted it. Taps, I find, are kind of brittle. Box store taps are not the best quality either.

First of all, the hole needs to be the correct size. For 1/4-20 NC the drill is a #7, or you can use a 13/64" (.2010 ").

Next, you need lubrication while tapping. There are special cutting oils for this, but I found that Lard or Crisco works very well. Put some on the tap.

Box store taps are the tapered kind. When you start cutting it will be easy until you get past the tapered part of the tap. Then you will start feeling the resistance. At this point you need to start clearing the chips as you tap. What you do is screw in the tap about 1/2 turn, and back off a turn or so. Then repeat until the tap goes through. For deeper holes you might need to back off even more, and clear the lubricant/chips out, and put more lard on it.

Hope this helps.

Re: Tapping

Carol Reed, Strawberry, AZ

>One more tip I found helpful.

Slightly chamfer the hole with a countersink bit on both sides. It helps get the tapped hole perpendicular to the surface of the metal and leaves a much better finished hole.

I use cutting oil. It is easier to clean up than lard and it isn't all that expensive.

Re: Tapping

Jack Stevenson

>Make sure you ain't messing with drill steel. That stuff eats taps. BTDT

An old hand at this said 4047 steel is good for this type of thing, but I'm now way over my pay grade in even bringing up this strange number.

Lard, crisco, or cutting oil works wonders, but getting Greenlee taps and dies is a move in the right direction.

I just bought a set of Ti coated drill set from HF for around 50 bucks. It goes from 1/4 on up to 1"-8! I've used it twice and it hits the sweet spot each time. It loves lubing, though.

Jack

Re: Tapping

Bruce in N.B. Canada

>Raymond one thing I might add to Fred's post and that is good quality taps usually come in a set of three... taper tap, plug tap and bottoming tap. A taper tap is tapered in order to make it easier to start but then if the hole that you are threading is a blind hole you will not be able to cut threads to the bottom of the hole and for this you would have to use a plug tap (little less taper) or bottoming tap(very little taper) depending on how far you plan on cutting threads. Yes taps are very hard and brittle if you break one they are a real pain to get out as ordinary high speed or carbide drills will usually not cut them. If a carbide drill bit is able to drill a hole in a tap then I would have to say that it is a poor quality tap and probably only good in soft non ferrous metal. Butterfield (brand name)make a good quality tap. Dont't forget to make sure you have the proper size hole for the particular thread pitch and diameter, many taps have the preferred drill size etched into the body of the tap. They are not usually fractional sizes either but letter or number sizes. After you get the tap started and cutting threads, back the tap up counterclockwise quarter of a turn for every half or three quarter turn that you go clockwise. Its best to use a little cutting oil, lube oil will work if you don't have any cutting oil, you might have to remove the tap to clean the chips of metal out depending if it is a blind or through hole. Try not to force the tap or you will end up breaking it... hope this helps.

Good luck

Bruce in Saint John, N.B.

Re: Tapping

Roger Smith

>Raymond, First there are several different styles of taps. Mostly they have to do with the amount of taper on the end. You would want a starter tap (it has a long taper on the end).

Next, most taps are broken because of a side pull on the top of the tap. It takes very little effort to break a tap using an adjustable wrench. The tap-wrench is a tap-saver because it places the torque straight up and down the tap without any side loading.

Others have already mentioned the importance of using a lubricant. I hope this helps.

roger

Re: Tapping

Raymond Overman in SC

>Thanks for all the answers. The tap that I purchased was a through tap and came with a drill bit. I think my problem may have been that I placed to much pressure sideways in my effort to force the tap through. Anyway, my second attempt will be a little more informed. Hopefully I won't have to have a third.

Thanks again!

Re: Tapping

Russ Fairfield

>Did anyone mention that the tap should be screwed in with a rocking motion? Take a little bite, back it 1/2 a turn to clear the chips, and then take another little bite. Takes longer than screwing it straight through, but you won't break a tap.

Re: Tapping

Ron in Drums PA

>Beautiful!

huh?

Raymond Overman in SC

>

Too many windows open at once? Hee Hee MUWHAAHAA

Jay in TX

>

A most obvious problem has been missed.

Al Crandall

>I have tapped thousands of holes and guided a fair share of apprentices through this task. When hand tapping most newbies find it very difficult to keep the tap on the same centerline as the hole. If you start a tap crooked, no amount of finessing will let you finish the job without breaking the tap unless you are only putting a couple of threads into a thin piece of steel. My preferred method to insure a straight tapped hole is to start the tap with the drill chuck in the drill press. Turn the chuck by hand until you have cut a thread or two, and then take the tap out of the chuck and finish by hand. If the job doesn't lend itself to being done in a press, you can improve your odds by drilling a hole the same size as your tap into a board and placing the board over the hole you want to tap. The board will keep the tap perpendicular to the work long enough to allow a couple of threads to be started, afterwhich it can be removed and the remainder of hole can be hand tapped.

Opps!

Ron in Drums PA

>Jay figured that one right.

Re: A most obvious problem has been missed.

John Lucas

>I do the same as AL with the drill press but I find that backing the tap up CCW every quarter of a turn seems to be the most important. This breaks up the chips and helps them clear. I make my own lubricant out of kerosene and oil mixed 50/50.

One other thing....

TD

>The recommended hole size is for maximum thread depth which is used on thin metal. For thicker metal go to a size larger drill. If you can get 4 full threads then you only need about 75% thread depth. By thread depth I mean from the peak of the thread to the valley. Another tip for thicker metal is to drill a stepped hole. To do this drill your standard hole and then go up a size or two and drill down about 1/4th the depth. Never look up while tapping, keep your eyes on the tap. If you rock the tap it will likely break.

TD

Re: A most obvious problem has been missed.

Leo Van Der Loo

>Ray I agree with Al, I also have tapped many many holes and yes broken some taps, the most important part of tapping after the right size hole is to get the tap started straight in the hole, if possible, drill the hole in the drill press and do NOT take the drilled piece out, put the tap into the chuck and start the tapping by turning the chuck by hand as Al said, or use the drill press pulley to turn and get the tap started straight, then loosen the chuck and take the part with the tap still in to your vice and continue tapping, use a tapping wrench ( the ones with the 2 arms ) , feel how your tap gets twisted as you cut the tread, back off some and lube, then cut some more etc. Just take your time, don't force it.

Have fun and take care

Leo V

Tapping Guide *LINK*

Fred in NC

>Very useful little device. Sold by machinist's suppliers. Info and pics at the link.


Inexpensive Tapping Guide

Re: Tapping Tips

Don Orr

>What a great thread (pun intended). So many excellent tips and tecniques simply by asking. Now if I can remember them when I need to tap something. Wait! this computer thing is connected to a printer...

Thanks to all for the continued generosity of knowledge and experience. As Dom G. said-"what a great resource!"

Re: Tapping

Kurt Aebi

>You can also use a bar of soap for the tapping lube!