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Question on order for tapping thread

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smckerrell

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Hi all

Newbie here, thank you for adding me.

I’ve just bought and had delivered three M4 taps to make a thread in some mild steel—the three are supposed to be used in order—is there an easy way for me to tell which one to use first, second and third please?


The only difference I can visually see is a slight difference in each in where the thread begins proper—so hoping that might be useful?

All help much appreciated

Simon
 

Bod

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1st tap has least threads, and most taper.
2nd tap has small amount of taper.
3rd tap has no taper, and full threads.
If the metal is not too thick the maybe only the first two are needed.
The third is for threading blind holes almost to the bottom.

Bod
 

redhunter350

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Simon, Bod is correct but just do you know there are also sets of “serial” taps. These ere much the same except the taper and second taps are a smaller diameter thus cutting progressively deeper threads and the third or plug tap must be used for the final thread. Don’t forget to use a suitable cutting lubricant !
John
 

Dalboy

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Also to add to the order of the taps and most important is drilling the correct hole for the size of tap and keeping it square to the hole otherwise it may become harder to tap the deeper you go. Normally ends up breaking a top. Turn tape 1/4 turn in then reverse to start with as a beginner
 

hawkeyefxr

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As a rule of thumb only turn the tap about a quarter of a turn when cutting the thread, you then back it off anticlockwise then carry on. If it feels sticky reduce this to an eight of a turn and back off.
 

chaoticbob

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The OP has probably tapped his holes by now, but assuming the taps in his set are standard ISO 529 taper, 2nd and bottoming rather than the serial taps John describes, it might be worth saying that there is no requirement to use the taps in order. The only difference between them is the chamfered lead - typically 1-2 threads for bottoming, 3-5 for 2nd and 7-10 for taper. If you have a way (eg drill press or lathe) of holding the tap square to the work it's perfectly OK to use a bottoming tap from the outset - I have threaded several hundreds of holes both through and blind this way. The only use I have found for taper and 2nd taps is when tapping freehand where it's next to impossible to start a thread true with a bottoming tap.
Serial taps can be identified by the bands on the shank - one band for the first, two for the second and none for the third.
Bob.
 

John Hall

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And when using small sized taps like this, it’s really easy to snap them if tooooo much pressure us used, gently does it, don’t try and force them round especially in hard steel etc. It is better to start with the first/ taper tap as this will start cutting without much force and enlarge the thread gradually…Make sure you use the correct tapping drill, and try and buy good quality taps and dies like Presto, Dormer, Goliath etc…and use cutting/tapping fluid..
 
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