Ever break a tap?

[muskieken13]

If you're not already using it, a good cutting fluid can make a world of difference.
Note cutting fluid, not lubricating oil. Cutting fluid is designed to bring metals together, not keep them apart like lubricating oil

ok ,I'm GOING TO ADAMIT I KNOW NOTHING, I was drilling stainless steel pipe 3inch pipe 1/8 thick! ruined a lot of drill bits was using wd 40 on the drill bits./ also used transmission oil ... so when drilling should I cutting oil, what should i use next time I'm drilling metal.

 

[MTGreen]

ok ,I'm GOING TO ADAMIT I KNOW NOTHING, I was drilling stainless steel pipe 3inch pipe 1/8 thick! ruined a lot of drill bits was using wd 40 on the drill bits./ also used transmission oil ... so when drilling should I cutting oil, what should i use next time I'm drilling metal.

WD-40 is good for cutting/tapping aluminum only. Transmission oil is good as a penetrating oil (older red Type F best especially mixed 50:50 with acetone) -this is done frequently in 3rd world countries. There are a number of cutting fluids on the market -I use Mobilmet 766 for stainless, but I think that only comes in minimum gallon size. For small jobs Tap Magic or a similar competing product works fine. Check in the pipe threading section of the hardware store if you can't find anything in the tap/die section. Ace hardware even has a house brand cutting fluid and Napa auto parts stocks several products. There are also spray foam cutting fluid products that are nice as they stick to the tap and don't run off immediately.

 

[sandman2234]

ok ,I'm GOING TO ADAMIT I KNOW NOTHING, I was drilling stainless steel pipe 3inch pipe 1/8 thick! ruined a lot of drill bits was using wd 40 on the drill bits./ also used transmission oil ... so when drilling should I cutting oil, what should i use next time I'm drilling metal.

Stainless steel drilling and tapping is a whole different ball game, as with a single speed fluctuate it can work harden to become a serious problem!
Good luck,
David from jax

 

[LD1]

Stainless requires slow speed high pressure

 

[MTGreen]

ok ,I'm GOING TO ADAMIT I KNOW NOTHING, I was drilling stainless steel pipe 3inch pipe 1/8 thick! ruined a lot of drill bits was using wd 40 on the drill bits./ also used transmission oil ... so when drilling should I cutting oil, what should i use next time I'm drilling metal.

In addition to cutting fluid you should pay attention to drill bit speed. Basically, stainless requires slower speeds than steel and much slower speeds than aluminum. Heat is what kills drill bits. Your drill bit has to stay harder than the material you are drilling in order for it to cut, and if you heat it up hot enough it will effectively degrade the heat treatment/hardness of the drill bit which will in turn increase friction which further degrades the hardness and you have a snowball effect.

Slow speed and good cutting fluid is your friend here. If you are bringing up a steady steam of chips you don't run the drill faster. If you are not bringing up chips and you know your drill is sharp you need to put more pressure on the drill as stainless can work harden and narrow/eliminate the hardness gap between work and bit. Using a quality cobalt bit also is helpful. The larger your drill bit the slower you need to go.

If you want to go down a rabbit hole you can look up surface feet per minute (SFM) for the material you are working with and how that relates to drilling. Just keep in mind that the published SFM charts are for machine shops with rigid machine tools with flood coolant/lubrication where time=money and tool life is a secondary consideration. If you use these, I would suggest starting at 50-60% of listed SFM and go from there.

 

[sandman2234]

Stainless requires slow speed high pressure

And if you let off the pressure as you break thru the other side, it work hardens and you break the drill. However, if you aren't careful you will break it as you power thru! Danged if you do and danged if you don't!
David from jax

 

[panamaguy]

As a former tool and die maker don’t use a 4 flute tap whenever possible.
2 flute machine taps are much more robust.
#7 (.201) is the tap drill size.

From what I understand 2 flute is for aluminum. 4 flute for steel

 

[Beaver Cove Deere]

From what I understand 2 flute is for aluminum. 4 flute for steel

You’d be wrong. Bottoming taps were typically 3 or 4 flutes but I normally just ground off the lead as required on a 2.

 

[ArlyA]

Back to the OPs question. One must be super careful to not break taps, so occasionally breaking them is the nature of the beast. Tap oil is a plus, but not a guarantee you'll not break them. Tap oil are cheap so I use it all of them time for tapping or drilling.

 

[MTGreen]

From what I understand 2 flute is for aluminum. 4 flute for steel

That's generally true for end mills for the non-production type machine shop, don't think that necessarily applies to taps