Hand Tap or Drill Motor?

[hellosailor]

Whichever way you go, practice on a piece of scrap metal first. See just what you're getting into. If the metal isn't welded onto your boat, taking it to a machine shop may be quite reasonable as an option. Quality taps, or a tap set, aren't so cheap.


Keeping the hole plumb vertical also counts, so if you have a drill guide that helps ensure that, use it. If not, think about getting one.


And you might be surprised at how far aluminum "chaff" can float out from the hole. Eye protection is strongly recommended to make sure it can't easily get into your eyes when a drill is involved.

[paulajayne]

Aluminum - paraffin is the lubricant for tapping / drilling.

[Blue Crab]

Originally Posted by paulajayne

Does not " A hand job" mean the same in the States as it does in the UK?

I believe it does. Pip pip, cheerrio!

[hellosailor]

To a Brit, paraffin is the name for what we Colonials call Kerosene. (Which was once a brand name trademark, apparently.)
To a Colonial, "paraffin" is the white wax used in canning and candle making.

[roverhi]

Tried using a drill but broke a couple of taps and gave up. Took more time to remove the broken taps than it would've taken to do it by hand.

What would make tappimg way easier is a RATCHETING tap handle. Seems like a no brainer tool that someone would make but haven't seen such an animal. Have problems with my wrists and turning the tap handle then repositioning and rotating hand to turn it again gets painful. Not having to reposition your hand and just twist it back and forth seems the ideal solution.

[mramoo]

I've been a maintance mechanic for 45yrs and I still tap holes by hand. If you snap the tap off in the hole, your in for ten times more work.

[paulajayne]

So use Kerosene for your hand job but stay away from naked flames --- See what I did there...

[oleman]

Tapping is an ART that many people never fully develop and attempting power tapping with a hand drill makes it worse.
Aluminum is also NOT an easy to tap material because it doesn't cut well and has a tendency to gall. Stainless steel is equally bad.
multiple holes that have a relationship with each other should be done with a jig especially if the base material is not easy to get to.
One of the most important parts of tapping is starting the tap 90 degrees to the base material. Based on circumstances a jig could be required.
Taps come in various diameters so all 1/4 taps don't make the same finished diameters.
You need the proper tap with very sharp cutters, very hard taps are for machine tapping because they break easily if driven off angle.
Carbon steel taps have no real world application. Select high speed steel for hand tapping, cobalt and carbide will just get you in trouble with breakage.
REMOVING A BROKEN TAP FROM ALUMINUM can become just about impossible. There are tap extractors but in my early years I quickly learned that tapping can be job where you get no easy second chance.
It could be worth your time to have a jig fabricated with a milling machine at a machine shop to set the pitch and angles of the job.
With proper tooling, knowledge and set-up you should have an acceptable outcome.
Good luck with your project.

[skipmac]

I once worked for a company that built a very expensive machine that was mounted on a custom trailer. Involved drilling and tapping dozens of holes from 1/4" to 3/4". While I was there production ramped up and they tried tapping the holes with power drills but were breaking 50% or more. Called their tool and die supplier to complain and he explained we needed a different type of tap for power. He brought us a couple boxes of power taps and problem solved.

I forget exactly what the difference was but you could hold them side by side and it was very obvious. If I recall the cutting edges started smaller so the initial bite in the hole was shallower.

Anyway, the point being, stick with a hand tap unless you are very, very slow and very, very careful or get the right tap for power. Broken taps are a HUGE pain to remove. The only thing I've found to remove one (other than a machine shop) is a diamond or carbide cutter bit.

[Cadence]

Originally Posted by Blue Crab

My own very limited experience has been to use the proper drill bit and tap the holes by hand.

My buddy, the expert, uses taps in his drill motor. Bingo he's finished but it seems risky when you don't want to bugger up.

What's the pro way? I need (8) 1/4" holes for fine thread machine screws.

Thanks

Tap them by hand. If you trust him, have him do them. I wouldn't unless I had seen his ability many times.

What material are you taping?

[Cadence]

Originally Posted by mramoo

I've been a maintance mechanic for 45yrs and I still tap holes by hand. If you snap the tap off in the hole, your in for ten times more work.

Hard to drill them and easy-out them.

[model 10]

Originally Posted by mramoo

I've been a maintance mechanic for 45yrs and I still tap holes by hand. If you snap the tap off in the hole, your in for ten times more work.

Yep. If you want to use a drill motor use it to clean up the threads after you have taped the hole by hand. Of course if you have 800 holes just accept you will have few problems using power tools.

[TKDSailor]

The way most taps break is when the tap is bent; i.e. does not remain perpendicular to the surface being tapped (sometimes via torque, but rarely). They are extremely brittle and can not take a side force (we have broken them by dropping them on the floor). At our machine shop, we use 4 methods- hand, drill, CNC machine, and tapping machine. When we hand or drill tap, we use a 1" thick piece of aluminum with a hole slightly larger than the tap size, and press it against the part being tapped so that the tap stays vertical. We seldom break taps.

On the mast, you are tapping a curve, so this becomes a bit tricky. I, myself, would mount it in a drill, use some cutting fluid, and drill those suckers... but I have probably tapped 10,000 holes before. The drill guide would still be able to help you, though- you just have to drill the hole in the 1" aluminum piece on a drill press so that THAT hole is perpendicular to the other surface. Here is a pic of the drill guide we use for different size taps. Best of luck and smooth sailing!

[weavis]

A hand job will give a satisfactory outcome.

[Cheechako]

Do it by hand unless you are doing many holes. If you have good "touch", with a hand held (slow) drill it's pretty easy though.
It's an art; if you bottom the tap it will break off. just tap the drill trigger quickly and you are done. Use coarse threads in aluminum.