Tap lessons please!

[ehatcher]

No, not that kind of tap..........this kind:


It occured to me today as I was tapping some parts for a new Pelican case rack that I know very little about the right way to tap.

What is the best way to keep the tap straight when hand tapping? (I got one crooked today and had to remake a part)

Should I be using a specific oil? (something other than the ten-year-old can of 3-in-1 in the pic)

I was taught that you advance the tap 1/4 turn, than back up one full turn to cut the chips off, I do this but I still sometimes get some gauling in the threads.

I have a chart that recomends what size number or letter drill to use, but I usualy wind up going larger because it gets too hard to twist the tap and I don't want to break the tap. Am I doing something wrong?

I usually buy Hanson taps at the hardware store - should I be looking at another brand?

What is the meaning of life? (figured if you knew all the other answers you might know that too)

If there is a thread here that already covers this, feel free to write a smart*ss remark (which will be graded) but at least give me the linky

Eric

[aardschok]

When I use taps, I usually have the part in a mill. I use the mill with a chuck head and a center point in it to steady/square the tap to the hole. (You might could try a drill press if you have one.)I dont start to counter turn untill after at least 1 full turn. With some metals, I use engine coolant (antifreeze) to help cut threads. There are specific oils for tapping. Check with an old fashion hardware store like Ace or Truevalue. Also, if any tooth of the tap is missing or chipped,...trash it.

As for the meaning of life..., I always thought that riding was it.

[Stagehand]

often you can make a small jig that will keep a tap straight. Mostly its your pilot hole that will determine straightness, because the tap will tend to center itself in the hole if your not too ham fisted. By a jig, I just mean a 1" or so thick block of material with an appropriately large hole to fit the drill bit for boring square, and clamped over the work.
Yeah, a drill press would be nice

I dont know what chart youre using, bit I'm led to believe its pretty specific as to what size hole to bore. I know to tap threads for an M10 helicoil you need to drill a 13/32" hole. Helps to know what all size thread gauge you want to end up with, and work backwards.

I've had good luck with white lithium for hand tapping. It catches the big chunks of waste metal and keeps them out of the way. When I was cutting male threads on black pipe, we used a lighter, fluid type-(not Lighter Fluid )- even just WD if nothing else to keep the metal cool.The curly-que's dont get in the way so much on the outside threads.
Female threads (interior) you got to take your time with Just like life.

Gauling happens from a less than really sharp, clean tap, I'm led to believe. It will tend to rip the softer metal. 1/4 ahead, 1 back is not a terrible approach, really. Its a hand feel thing, mostly. You know when its cutting nice, and you can feel right when it starts to bung. Also, the tap has to be harder metal than the piece. Most taps are pretty tough, but sometimes your piece is high carbon


I dont know from brands, really, I just buy the best I can afford.

Hope this helps.

[LoFlow]

I like WD 40 for tapping aluminum.

Tap Magic for all steels.

Cast iron I tap dry.

[Stagehand]

i dont hink ive ever done cast iron. that doesnt sound like fun.

[ehatcher]

I am taking notes here.....

Originally Posted by El Conquistador

You might could try a drill press if you have one

I have a drill press - how do I use it to tap? I tried it once, took out the bit I drilled with, chucked up the tap, then tried to run the tap in by turning the chuck by hand, did not have any "feel" that way, was not sure how much downward pressure to use either.

Originally Posted by Stagehand

often you can make a small jig that will keep a tap straight.

I like the jig idea - "plan B" if I can't make the drill press do it and it will work for parts that can't be jigged up in the drill press too.

Eric

[boxermoose]

lots of practice

Use goodsharp taps - if using hand taps use the appropriate cutting fluid - as said for Al use WD-40 or varsol, magic tap is OKfor steel but if you are doing stainless use a cutting fluid specificfor it

Cast iron is dry as mentioned - or you can use lard (really)

Hand taps - 1/4 to 1/3 turn, then backwards to break the chip. If you use amachine tap just keep on going

Carefull about bottoming out - if you are ina blind hole try to bet a startingtap and a bottoming tap

[cagiva549]

Buy a tapping fluid called Tap Magic , there is a different product for aluminum or iron . you will be amazed at the eaze of thread cutting with the right tap fluid . For hand taping the work needs to be secure , the vise is fine , slow and even with the tap handle , tap fluid on the threads , and taps break very easyly . If there are any chipped teeth on the tap throw it away and get a new one . SEYA

[CBR900RR]

Use an Engineer's square to square the tap.

Cutting fluid depends upon the metal. If it's aluminium, kerosene is recommended. For cast iron, no lubricant is required as the graphite in the cast iron acts as a lubricant. For mild steel, engine oil will suffice.

[gsweave]

Start the threads with a starting tap and follow with the plug tap to finish the job. Use the bottoming tap finisher when the threads need to go all the way to the bottom of a blind hole.

Taps are very brittle and easily broken, use caution and patience when threading a hole.

1/4 turn back an 1/8th to clear chips lots of light oil your choice, this will produce clean sharp threads.

Drill charts will provide proper hole diameter for particular tap. Use em follow them. Normally two sizes below tap size.

Alum, will want to gum up, use lots of oil, unscrew tap and clean often.

I would not use a machine of any type unless it was a tool steel, even then I still would try hand tap first.
I take that back we do use a machine for 3" stainless pipe threads.


Patience is the key let the tap do the work. the squareness of your hole will determine proper threading angle or lack of it


Three types of taps.

Starting
Plug taps
Finishing or bottom taps.


Meaning of life? Always pay it forward. It will get back to you in time.

[Kraftsman 73]

Starter or hand taps: These are ground on a taper, that being it takes about 6 to 7 full revolutions before you have a full depth thread. These are the easiest to start straight by hand.

Plug tap: These are ground with a shallower taper, only takes 3 full revolutions before you have a full depth thread. These are the most common taps sold.

Bottoming tap: These are ground so it only takes 1 1/2 revolutions before you have a full depth thread. As the name implies, used to produce threads all the way down the drilled hole.

Look for taps made of H.S.S. High Speed Steel. Superior to high carbon taps.
Good source of taps: www.travers.com www.mscdirect.com

I have the shank from a broken tap that I ground to a point. Note on larger taps the end is counter-sinked. I drill the work piece with the drill press. Then I remove drill bit and chuck up my ground broken tap. I place the tap in the drilled hole and lower the chuck until my custom tap holder mates with the counter sinked end. This stabilizes the tap while I turn with a tap wrench. Tap goes in nice and straight. I will try to get some photos of this setup.
At work I have access to a Bridgeport milling/drilling machine. If the tap is not too large, I will just chuck up the tap and tap with the machine. But please keep in mind, I have drilled and tapped thousands and thousands of holes using this method. Broke a few taps when I was learning my trade. Today I will still tap by hand when the tap is too big for the machine.

Tapping aluminum seems easy. Remember, aluminum is "gummy". Aluminum likes to stick to cutting edge of tap (also true with drills during drilling operations). Good lubrication is the key to tapping aluminum. Lots and lots of lube. Tap Magic offers a fluid formulated for aluminum tapping.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=20887770

Advanced tapping info. A spiral flute tap is great for tapping blind holes.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=20887571
A spiral point tap is great for tapping through holes.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=20887643

More info can be found here:
http://en.wikipedia.org/wiki/Taps_and_dies
and here:
http://www.sheldonbrown.com/tooltips/taps.html

Hope this helps! Good Luck!

Regards,
Kraftsman 73

[Will LC8]

Originally Posted by ehatcher

I am taking notes here.....



I have a drill press - how do I use it to tap? I tried it once, took out the bit I drilled with, chucked up the tap, then tried to run the tap in by turning the chuck by hand, did not have any "feel" that way, was not sure how much downward pressure to use either.



I like the jig idea - "plan B" if I can't make the drill press do it and it will work for parts that can't be jigged up in the drill press too.

Eric

Eric they make a tapping jig that is sorta like a little drill press with a tap handle. You can find them on ebay every now and then for cheap from people who don't know what they are.

If you want to use some starting taps I have a bunch of three piece tap sets (starting,plug and bottoming) in coarse standard sizes to 1/2". I can bring the size you need next weekend. If your using metric your out of luck as all I have is a standard tap set for metric.

Will

[aardschok]

Originally Posted by ehatcher

I am taking notes here.....



chucked up the tap, then tried to run the tap in by turning the chuck by hand,

Eric

Don't put the tap in the chuck, just use the chuck head as a center to the back of the tap driver. (Here, I'm using a counter sink as a center)

then just start the first two full turns that way.

Both hands should only be use if needed to steady the tap, never to drive it.

[ehatcher]

Originally Posted by El Conquistador

Don't put the tap in the chuck, just use the chuck head as a center to the back of the tap driver. Both hands should only be use if needed to steady the tap, never to drive it.

That looks like it should solve a lot of the problems I have run into. I am going to venture that if I do it this way the plug taps (using the right terms here now...) will work fine.

Originally Posted by willf650

If you want to use some starting taps I have a bunch of three piece tap sets (starting,plug and bottoming) in coarse standard sizes to 1/2". I can bring the size you need next weekend. If your using metric your out of luck as all I have is a standard tap set for metric

Thanks, I have taps, but we are going to talk about that tubing bender you have, I need crash bars and a rear rack.......

Eric

[GreaseMonkey]

Well you haven't lived until you've broken a tap off in a blind hole!

All the advice about using a tapping fixture or a drill press is well worth paying attention.

If you are tapping more than 1 or 2 holes a year, you really owe it to yourself to but a small can of tapping/cutting fluid.

I prefer "Tap Magic" as mentioned earlier by someone else. You'll need 2 different cans, tap magic aluminum and tap magic EP-extra which does everything except for AL.

If you are feeling adventurous, pick up an old machining textbook and read how to sharpen taps. It is not only a valuable skill to have as you can get extra life out of your tools, but being able to grind bottoming taps is quite handy to have when working with plastics.