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tapping oil...are they all the same?

F

fehdxl

Well Known Member
I'm working on installing the iflyrv10.com flush door handles and have run into a bit of an issue. So my question to the group is, does it matter type of oil I'm using while tapping the threads? I was using some generic 3-in-1 oil thinking it didn't matter...but now I'm not so sure.

So the rest of the story is that one of the tasks due to the flush handles is to tap the C-1014 door handle spur gear for set screws instead of a roll pin. My first issue is that it dulled tap #1 to the point where the threads weren't deep enough for the set screw to go in. So I bought taps #2 and #3, and after one, what I thought was good hole, I snapped #2 tap in the second hole. Turns out, that also on that gear, I drilled #21 which is correct for a 10-32 tap, but it must have been too stressful since the gear cracked at both holes.

Then on the second gear, I drilled both holes to #19 and things looked promising right up to the point where tap #3 snapped in the first hole. BTW, there is no drilling into a tap--it's hard stuff. So for those keeping track, now I have one dull tap and two broken taps; I've had better days.

So now that I've managed to mess up $74.60 ($37 bux for one gear!) worth of parts (ouch) I want to avoid this again next time. Thanks for any help you can suggest!

-Jim
 
Relton Rapid Tap

I use Relton Rapid Tap on hard and ferrous metals.
http://www.relton.com/cutfluid2003.html

A good tap from an industrial supply house should cut unhardened steel easily. Make sure the tap drill is the correct size (consult any tap drill chart or Machinery's Handbook). Make sure the tap is aligned with the hole (don't laugh, it happens). If you have drilled the hole in a drill press, leave the part in the drill press vice, remove the tap drill, insert the tap in the chuck, lower the tap to the hole and with a slight amount of down pressure on the tap, rotate the chuck BY HAND to get it started. Then remove the tap from the chuck and use the tap wrench. Advance the tap 1/2 turn, then rotate backwards about 3/4 turn to break the chip. Repeat until the tap hole depth is adequate.
 
The oil definitely matters. Even cutting oil differs; the guy who does my machining managed to get his hands on what may be a lifetime supply of gun-barrel oil (I forget exactly what it's called) that he swears by and after watching him mill my gear legs for the cotter pin holes, I can see why. I use dark cutting oil for most of the hand work I do. Even so, it is still pretty easy to break a tap if you are not careful. For steel, I usually only go 1/4 turn before backing the tap to break chips and try to flush them out fairly often. Don't turn the tap until it gets difficult; that puts too much stress on both the tap and the work. And another way I see people breaking taps is by using only one side of the handle, which offsets the force on the tap, making it lean, bind, and ultimately break.
 
The new tap magic is very good. That is what we use in our tool and die shop. Just note the old formula could not be used on aluminum as it would make smoke and eat the aluminum. All the new stuff says right on the packaging that it works for aluminum and steel. The only way you would get the old formula is to find some laying around in someone's work shop. If you can find a 2 flute spiral point tap instead of a 4 flute plug tap you will have much better luck. Always back the tap out a little every 1/2 turn or so to break the chip or the tap will lock up in the hole and break when you try to back it out. Hope this helps.
 
Unless your running a production shop, any compatible oil will do the trick. Yes, there are differences, but your not machine tapping dozens, hundreds, or thousands of holes. Your tapping by hand in mild steel or aluminum.
The important thing is to use lubrication. The type is not that critical for your task.
 
I have some cutting oil from Snap-On that I use for drilling and tapping. Smells nasty and sulfury, but it is thick enough to stick and defy gravity when needed.
 
Well my new gears, oil and tap arrived this week. All I have to say is that it was effortless! Lesson learned...use quality taps, especially in hard metal.

Here's a picture... the bottom tap is the cheap one (note the rounded over teeth), the top the one from McMaster-Carr.



Thanks for the help!

-Jim
 
Tip for the Day

Just a note on drilling and tapping for set screws on the gears. You would not normally ever put the set screws opposite each other as that will suspend the gear from 2 small points . Common practice is to put the second screw at 90 degrees from the first screw so the screws push the ID of the gear into the OD of the shaft giving much more contact area.
 
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