Hand Tap or Drill Motor?

[Celestialsailor]

Originally Posted by HopCar

Mr. Thomas, my high school shop teacher would have smacked my butt with a big paddle if I had chucked up a tap in a drill. I'm sure he's long dead so I may try it.
Do you reverse the drill every so often to break the chip?

No...Test your drill to ensure you are in low speed and clutch it, so it will clutch out if you grab the chuck with a moderate grip. Use ample cutting oil of some sort all on the tap and a little on the hole if need be. Throttle the speed to start and allow the tap to find it's way. You will feel the tap straighten itself in the hole. When the tap feels free of cutting, release the variable speed trigger and while keeping the drill steady, find reverse. Gently throttle the tap out. (I'm assuming we are experimenting with an old mast section). I usually use a 2 or 3 flute HSS tap. Not usually a Home Depot one.
Next... go to the grave of your shop teacher and tell him we no longer fly Biplanes.

[GrahamHO]

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

I've tapped hundreds of holes by hand especially in stainless steel and aluminum. Best to use a tapered tap if the hole is not blind. A taper tap is easier to start.


A plug tap has only a slight taper and is more difficult to start but can go further into a blind hole. Then a bottoming tap has no taper and will go to the bottom of a blind hole. You can start with a taper tap and finish with a plug tap if you need to. But if your hole is open you can go right through with a taper tap and you won't need a plug tap.


Use a tap wrench. There are different sizes so choose one your tap will fit. It's not much good using a crescent spanner but it can be done in an emergency.


Put some cutting fluid on the tap and a little on the hole. Keep applying some as you go. Use a little pressure turning clockwise and once the tap starts to bite after about a turn, wind it back a half turn. Then another turn and wind it back a half turn. This is to clear the threads of the tap. Keep going like that until you are finished and then wind it back out and clean the work. If you simply wind around and around the tap can grab and can even break especially in stainless.


Stainless steel is one of the hardest metals to tap and brass is one of the easiest. You need a high speed steel tap for stainless. That refers to the metal they are made of not how fast you turn them. You can get away with a cheap tap for aluminium or brass or muck metal but HS taps are best.
There is of course proper engineering machinery for tapping holes. You might be able to carefully use a battery drill in softer metals, but you have more control with a hand tap. I only use hand taps.

I almost forgot. Make sure you drill the holes with the correct size tapping drill. You can look that up for your tap size. I'm mainly using metrics these days so I can't remember for 1/4"

[GrahamHO]

Originally Posted by Reefmagnet

I have to confess I've snapped bolts in the mast when screwing down cleats (that are thick and use long bolts) because my thread (well, drilled hole tbh) was cock-eyed slightly. With thinner material to pass bolts through, or larger hole to screw clearances this problem diminishes. If you need accuracy and don't have "boilermaker's eye" then a jig would be a great idea, I reckon.

If you want to make sure your hole is straight ( using a hand drill) get a cheap carpenters sliding square. Take the sliding rule out and use the groove in the square piece (where the rule was) as a guide. You can hold the drill against the groove and the square flat on the work. It doesn't matter if you scratch the square as you probably will. Once you have gone as far as you can, take the square away and the drill will keep going the way you started if you are careful. If the work is curved like a mast you will find it is flat in one direction. That's all the jig you need.

[GrahamHO]

Originally Posted by Delancey

Unfortunately it's hard for flesh to mimic a machine, which is what the pro's use. A tapping machine. Pro's don't tap by hand. Agreed with Happy's comments.

Would only add that the non-pro's best bet is a cordless drill with a clutch. Start out on the lower end and work your way up. Less chance of snappy snappy. Also, never hurts to practice on some scrap. Practice makes perfect!

If pros don't tap by hand, why do professional tool shops sell tap wrenches?
What is "unprofessional" about tapping by hand. Try tapping in 316 SS with a battery drill. You will be snapping taps.
Even if you have the proper machinery for tapping, you might not be able to get the work to it.

[GrahamHO]

Originally Posted by paulajayne

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

You'll need to explain it to me. I'm from New Zealand.

[Delancey]

Originally Posted by Delancey

Pro's don't tap by hand except occasionally. Especially ones who have developed carpal tunnel syndrome.

Here, I've amended my capricious comment. In the meantime there are a lot of moving parts in the attached diagram but not a single one that is straight and round called an AXIS.

FWIW, pop rivets! Not my favorite fastener in the world but they have their application. Installing mast hardware that is loaded in sheer is one of them.

Screw fun fact : while the use of screws such as the Archemidian screw existed since the time of Archemides, the use of the screw as a mechanical fastener was not invented until the sixteenth century when it was first used by armorers to fasten metal plates.

If you visit the Metropolitan Museum of Art and look at the collection of armor you will see the most amazingly beautiful hand-made screws which feature artfully embelished screw heads fit for a king. Many of the suits of armor in the collection were in fact just that, fit for kings.

[paulajayne]

Originally Posted by GrahamHO

You'll need to explain it to me. I'm from New Zealand.

LOL

Urban Dictionary: handjob

[HappyMdRSailor]

Wow, this got busy fast!

Originally Posted by jeepbluetj

In the event of breaking off a tap and the subsequent major boogering of the hole you were trying to tap, what do y'all think about nutserts?

You mean neuticles??? Are we referring back to the hand job here?

A nutsert btw has zero application on a boat, and hardly more off one...

Originally Posted by Blue Crab

How many of you would make a jig? This is dealing with the curvature of the mast per Brenda's comment.

Not a chance Crabby... It's going to muck things up unless you spend more time making your jig than drilling the holes in the mast... Use a nice tiny but sturdy bit for a pilot hole... like 1/8th... All you have to do is be aware of 90 both ways... Of course, we're assuming you want all fasteners @ 90... If you're using a curved spacer plate for a flat mount on a rather curved surface... We're getting into the tricky realm...

Show us a pic, or a super spectacular Crabby drawing...

Originally Posted by a64pilot

Way back when I was drag racing KZ-900's once you got the motor making lots of power, the engine case halves would pull apart as the bolts would literally be pulled form the aluminum case halves, drilling them out and installing helicoils stopped that.
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Oh man... I forgot how many cases I Helicoiled! It was just plain smarter to do it before there was a problem...

Originally Posted by HopCar

Mr. Thomas, my high school shop teacher would have smacked my butt with a big paddle if I had chucked up a tap in a drill. I'm sure he's long dead so I may try it.
Do you reverse the drill every so often to break the chip?

Depends on what it is... Thin aluminum < 1/8" you can usually blast straight thru... Thicker aluminum and all else, it's just like hand tapping feel wise... Go in as much as the material will allow... sometimes a couple turns in, sometimes 1/2 turn... and reverse to break. I usually go out the same as I went in... Lather, rinse, repeat until she's done...

Backing all the way out, air blasting the hole and the tool, and relubing always helps...

[S/V Alchemy]

Originally Posted by HappyMdRSailor

Wassup Crabby my man!

Oh ... for sure you can tap with a motor... With a bunch of caveats:

1. Depends on what your tapping... Soft Al on the easy side of the spectrum, Hard SS on the other...

2. If this is your first foray into it... 1/4 should be the tiniest you try... 6/8/10/12 are easier to snap...

2A.... The most important learning step is to keep the lateral movement of your drill motor to ... well, none..... Or snappy-snappy

3. Have a DECENT motor... Ace Skill ain't the way to go here... Power&chuck= suck.... Nor is overkill... A Porter Cable 1/2" is going to have TOO much torque and run on.. (past where you want to stop=broken tap) Dewalt is perfecto...

4. Sharp tooling and lotsa lube

5. You won't bugger it.... small trigger pull until she gets resistance, about 1-2 turns, reverse 1/4 turn, forward-reverse-forward-reverse... You can back all the way out and clean your tap/relube after you have a few turns in...

Easy peasy really... 8 predrilled holes in 1/4" Al plate = 3 minutes

You're getting some good advice here, but I would suggest that tapping with a motor would be best done with a drill press (or the sort of setup that allows you to use a power drill as a press) and a momentary foot switch to keep the speed really low. Taps are pricy and easy to screw up, so the advantage to doing it by hand (slow, but with full control) is better unless you have precision work to accomplish multiple times and want to use a bit stop or other means to tap accurately.

So the "right answer" depends on a lot of variables, plus your own "touch".

[Cheechako]

Originally Posted by a64pilot

A few have brought up the difference in a machine vs hand tap, but to me using a drill to tap is just wrong, like using a hammer to install screws, yep it's fast, you can get done in a hurry, but it's just wrong.
But many, many machine shops and almost all manufacturing use machines to tap, so it is possible and obviously if the right feed and speed and tool is used it works well, but so far as going to my tap set that I have had since I was 16 and chucking one in a rechargeable drill? No way.


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Actually it's very common. Machine tools often use a "Tapping Head". This device forgives the problem between feed and speed. Once a tap bites in, it will move at a given feed with every revolution.
Tapping with a drill is easy and quick and actually has advantage over hand tapping. Hand tapping you rock the tap while you twist with your hand movement, with a drill motor you don't rock the tap. Of course you must have good dexterity and control. In thin aluminum, rocking while hand taping can lose you a thread when you may only have 3 threads.

I was taught to use a 2 flute tap in softer metals like aluminum (CLears out the chips better) 4 flute taps are for steel etc and are often "bottom" taps. (to tap near to the bottom of the hole.)

[Cheechako]

Originally Posted by GrahamHO

If pros don't tap by hand, why do professional tool shops sell tap wrenches?
What is "unprofessional" about tapping by hand. Try tapping in 316 SS with a battery drill. You will be snapping taps.
Even if you have the proper machinery for tapping, you might not be able to get the work to it.

Nothing unprofessional about hand tapping. Pros do tap by hand, and do tap by machine. Every situation is different. I have hired and fired many machinists, tool makers and millwrights in my career.

[Cadence]

Originally Posted by Celestialsailor

No...Test your drill to ensure you are in low speed and clutch it, so it will clutch out if you grab the chuck with a moderate grip. Use ample cutting oil of some sort all on the tap and a little on the hole if need be. Throttle the speed to start and allow the tap to find it's way. You will feel the tap straighten itself in the hole. When the tap feels free of cutting, release the variable speed trigger and while keeping the drill steady, find reverse. Gently throttle the tap out. (I'm assuming we are experimenting with an old mast section). I usually use a 2 or 3 flute HSS tap. Not usually a Home Depot one.
Next... go to the grave of your shop teacher and tell him we no longer fly Biplanes.

I found that funny. One if mine in HS had been a barnstormer.

[jkindredpdx]

Originally Posted by hellosailor

...
To a Colonial, "paraffin" is the white wax used in canning and candle making.

Or a clear fuel that I put in my lamps...

[GrahamHO]

Originally Posted by Celestialsailor

Next... go to the grave of your shop teacher and tell him we no longer fly Biplanes.

You never heard of a Pitts Special? Arguably the top performing aerobatic plane. Not including jets that is.

[jacaranda]

Having spent considerable time and effort involved with drilling and tapping in all sizes in varied materials by varied methods,
unless you have access to precision machinery guaranteeing alignment ,drill by hand drill and always always tap by hand using proper lubricant, specially on alum to prevent binding . If you are in a hurry use a machine tap (by hand) rather than the typical 3 handset

Brendan