Tapping -- How to's and How not to's....

[sparky961]

What's the logic in this? Maybe it stays liquid in a really small hole but for any "normal" size it will have evaporated long before having the chance to be helpful. ...............

Have you have tried it ?

Don't need to.  There are enough chemicals I inhale that are "necessary" to cause me to avoid using them unnecessarily.

[Mike E.]

Ok, fair enough.

[ieezitin]

Roll form taps.. do a great job the pilot size's are different but are available on the net.... you need a little more power to form your thread but break less if not at all.. most people don't know about roll-form taps which means e-bay sellers sell them cheap.  do your own research they are great.

Anthony. 

[Lew_Merrick_PE]

Here's a paper I put together on sizing pilot holes for tapping.

[howsitwork?]

cheers for the paper to read

I must admit trying roll form taps for aluminium and they work well but I was very concerned about the force I had to use at first. They do seem significantly stronger though.

Count me in for spiral taps, oh the joy of watching the swarf come out ! Cost a bit more but much more satisfying to use especially in the smaller metric sizes. Not got any imperial ones yet.....

I stick to paraffin mixed with neat cutting oil but have also found WD40 works well for ali. Anyone tried milk - seriously one guy I know swears by it!