tapping technique question

[BTL-A4]

I have a Craftsman tap and die set made in China. I break small taps, usually #10 on down. I use 3-in-1 oil for lube, drill the right size, or closest available size (usually bigger) hole, rotate the tap once, back it out about halfway, rotate once, back it out, etc.
The smaller bits tend to flex a lot. I'm holes tapping aluminum that are often half or more as deep as the tap.
What am I doing wrong?

 

[The Cobbler]

cheap taps

 

[HotWire]

Use a tapping block to keep your tap concentric with the hole. Also make sure to clear chips and use aluminum tapping fluid. Aluminum is ‘gummy’.

You can make a tap block yourself or buy them.

First one to pop up on google.

BIG GATOR TOOLS 2 Tap Guides for Hand Tapping https://www.amazon.com/dp/B00137FMJS/?tag=atomicindus08-20

Sent from my iPhone using Garage Journal

 

[4xdog]

I was taught to tap/drill aluminum with mineral spirits, not a cutting oil. I’m sure the folks here know much more about this than I...

 

[darkzero]

Get better taps, good HSS ones, not cheap carbon, China HSS, or hardware store grade powdered metal taps. You'll be amazed how much better good quality taps perform. Also 3n1 oil is not a cutting fluid. For aluminum WD-40 will work better.

 

[WoodsTruck]

On small holes, I only turn the tap 10-20° then back it up to hear the curl pop, then repeat. Slow, but I quit breaking taps that way. I also printed a cap for my tap so I can push with the center of my palm and turn with the fingers. This helps keeping direct pressure when starting the threads and keeps me from wobbling.

 

[larry_g]

The tap must be straight into the hole.
Champher the top of the hole before tapping.
Use the correct thread cutting lube for the material your tapping.
Make sure your tap is for threading and not restoring threads.
Know the percentage of thread depth your after.
Use a proper tap handle that applies only rotational force to the tap and NO sideways force.

For tap drill/percentage of thread go here, https://www.guhring.com/media/documents/tech/Charts/CutTapDrill.pdf

You'd be wise to spend some time on the above site studying what else may be involved in threading and the different taps available.

lg
no neat sig line

 

[matt_i]

If you have a drill press (milling machine even better) you have the perfect jig for starting the tap. Chuck on the OD of the tap and twist it into the work.

If you buy "gun", "spiral point", or "thru hole" taps these have 1 less flute and thus more meat at the core. It also curls the chip ahead of the point so the flutes don't jam nearly as easily. Can be used in a blind hole but must pick out the curl at the end.

 

[MBfreak]

+1 on post 4.
I use denaturated alcohol when drilling, turning, tapping aluminium.
It is very cheap and available everywhere, and works perfect.
I am sure that vodka would work just as well.

I am also lucky to have a large amount of top quality taps and dies made by Swedish companies SKF and CEJ. All surfaces are polished. Threading a M2 bottom hole is easy.

Ola

 

[Doug Arthurs]

wd-40 having kerosene in it makes a good alum tapping fluid. Like others have said no cheap taps.

 

[turbowoodworker]

TapMagic makes a fluid specific for Al.

 

[snyder]

TapMagic makes a fluid specific for Al.

I second this.

 

[zmotorsports]

Like others have said, tap quality is first and foremost. Most cast taps are not actually made for creating new threads, they are made to chase existing threads so a good HSS thread cutting set is best.

Secondly a tap guide of some sort to keep the tap perfectly perpendicular to the work and square with the hole will help a lot and lastly a good quality tapping fluid for aluminum. I've used TapMagic's aluminum thread cutting fluid as well as moly thread cutting fluid and those are my two "go-to's" when cutting threads.

 

[BuffettFan]

TapMagic makes a fluid specific for Al.

Third for Tap Magic. It just works.

2nd for a tapping block if you're freehand tapping, not in a drill press or mill.
If you do have one of those available and it fits your particular circumstances, it is a great way to get started straight.

2nd for getting rid of the Chinese taps. There is nothing more expensive than a cheap tap.

Keep the chips cleaned out! As has been mentioned, back up the tap to break the chip, but also blow them out of the hole and then use more Tap Magic.

Good Luck!

 

[kazlx]

Don't use ****** taps. And use a tap guide. WD-40 works fine in aluminum. Tap Magic if you want to spend money. Use a spiral point tap if you're doing through holes, way easier. Also drilling the holes to 65% thread instead of 75% like most guides will make it noticeably easier and reduce the holding power of the thread a very negligible amount.

 

[Lwel9226]

Don't use ****** taps. And use a tap guide. WD-40 works fine in aluminum. Tap Magic if you want to spend money. Use a spiral point tap if you're doing through holes, way easier. Also drilling the holes to 65% thread instead of 75% like most guides will make it noticeably easier and reduce the holding power of the thread a very negligible amount.

NO HARBOR FRIGHT TAPS...
one of my machinist books tells me that in steel, a 53% thread will break the bolt before it will strip -- in most cases...

LynnW

 

[nutjob]

Here are some of the tools I use. See here for the hand tapper.

https://www.flexbar.com/collections/machine-tool-accessories/products/hand-tapper-reamer-complete-set



Kevin

 

[gearhead1]

Like others mentioned, look at the %threads. If it's not in a high strength application, go a tiny bit bigger on the tap drill diameter. That will not be tapping the threads quite as deep. Not depth of the hole, but depth of the thread into the part.

 

[BTL-A4]

Thanks to all. I probably should have mentioned that I was using a tap guide in a milling machine.

I borrowed some decent taps (old US made ones) and some Tap Magic. I also only turned the tap a half turn then a quarter back to clear the chips. I proceeded like this until complete. Night and Day! No flex in the tap at all, either.
I used a 7/64" (0.109") drill bit instead of a #36 (0.107") because I don't have numbered drill bits. I figured the bigger size was ok. I did this originally as well, so that wasn't the issue before.

It seems the tap and my technique was the problem.

 

[bullnerd]

6-32?

Whoever invented the 6-32 should drop dead. Worst thread to root ratio of any screw.

I use a small knurled handle to hold small taps. Its about 1" in Dia. and about an inch and a half long, round aluminum handle. Tap is held in with a set screw. Much more "feel" and less leverage over the tap, especially small ones like 0-80/2-56 etc.

 

[larry_g]

Thanks to all. I probably should have mentioned that I was using a tap guide in a milling machine.

I borrowed some decent taps (old US made ones) and some Tap Magic. I also only turned the tap a half turn then a quarter back to clear the chips. I proceeded like this until complete. Night and Day! No flex in the tap at all, either.
I used a 7/64" (0.109") drill bit instead of a #36 (0.107") because I don't have numbered drill bits. I figured the bigger size was ok. I did this originally as well, so that wasn't the issue before.

It seems the tap and my technique was the problem.

If you follow the link I posted above you would KNOW what to expect and if it is an OK guess.

lg
no neat sig line

 

[FANTM58]

I was taught and have had good luck with the old 1/4 in and 3/8 back..
It’s slow but you need to clean the cut material out regularly..

 

[MFolks]

Tapping guides; https://www.amazon.com/dp/B00137FMJS/?tag=atomicindus08-20

 

[Jack84]

Am I the only one that occasionally taps with a cordless drill?


Sent from my iPhone using Garage Journal

 

[bullnerd]

Am I the only one that occasionally taps with a cordless drill?


Sent from my iPhone using Garage Journal

Nope. Done hundreds, maybe more, of threaded holes with an old makita cordless with a bubble level glued to the top.

Down to 4-40.

 

[kazlx]

Same here. I have a little m12 driver that I use all the time just for that.

 

[The Cobbler]

Am I the only one that occasionally taps with a cordless drill?

Ive never tapped a new hole with a cordless, but in the early 90's I had a project where I had to clean the threads on about 3,000 5/16 nuts that were each welded to a bracket .
used my Milwaukee 12v cordless .

 

[Lassen Forge]

Don't laugh, but I've always used olive oil for cutting and machining aluminum. (Didn't matter if it was extra virgin or, um, not virgin ) An old machinist passed that along, and it has yet to fail me.

Also second on the quality taps... cheaper is way not better...

 

[Mr. T]

Well, if you’re doing this on a mill... have you ever noticed that a lot of tap handles have a hole at the top with a pretty large countersink? What I do is lock the table, start my hole with a center drill, finish the hole with my drill bit, put the center drill back in the chuck, then with the tap in the handle bring the quill down so that the tip of the center drill is resting inside that countersunk hole in the back of the tap handle. It helps to put a little piece of something (paper, scrubby pad, whatever) between the two to reduce friction. Then apply a small amount of downward pressure with the quill (not running) while you start the tap. This keeps your tap aligned with the hole. Once you are cutting real threads the quill pressure can be removed.

I’m sure there is a better thing to use than the center drill but it’s right there and I’m kinda lazy.

Either way this is about the best way to “hand” tap something that I’ve found.

Also, yeah, use good taps. The only down side is that they are harder to remove when you break one off. Because we’ve all done that.

 

[Kevin54]

Never use 4 flute taps for the small size. 2 flute only up until 5/16" then it will change to three flute.

 

[JJohns3WG]

When I start on a threading project I buy three taps that way they will never break. If you just have one it will always break halfway through the project at 5 o'clock on Sunday.

 

[bullnerd]

When I start on a threading project I buy three taps that way they will never break. If you just have one it will always break halfway through the project at 5 o'clock on Sunday.