No Luck Tapping

[BigSki]

This is the ONLY stuff we use in aerospace for tapping in aluminum, it's was formulated by Boeing.

[kamikazekalle]

Be sure not to use a bottoming tap, made for finalizing treads in blind holes. It will not "bite" good at the opening of the hole, and will destroy material without treading. I seen people struggle bad with tapping then using the wrong tap.

The bottom one in the following picture is a bottoming tap:

[Crawling Calvin]

One other thing that is good to know is fine pitch threads [M3... 10-32] and so on aren't very strong in aluminum. M4, 10-24, and more "coarse thread" screws have more ability to bite the material and are less likely to strip out. Screw thread inserts maybe a good idea also if you plan to thread something in and out a lot. They are harder than the base material and there are a ton of kits available for them. Just follow the directions and your good

I have a custom clamping plate for when I make chassis tapped to M3x.5 in T6-6061 aluminum and the plate is just about 3/8" thick. I make sure that my screws go in at least 3/16" into the plate to make sure they don't rip the first few threads out and thus kill a chassis when I am machining.

[tom@vp]

dayam, everthing a man needs to know to make mil-spec threads, dont forget the get thread go/nogo gage, and to measure your minor pitch when your done !

[Charlie-III]

Ummm....while there are quite a few great thoughts here, I have to say, "it could be better".

1-Use the correct drill to make the hole.
2-Drill the hole as close to 90* to what needs to be tapped.
3-Make sure you "break the chips" as you tap (more to follow).
4-Use a correct lube for the tap.
5-(maybe should be closer to #1??) tap AT LEAST 1 screw/bolt diameter for hard materials (like steel) or 2 diameters for softer diameters (copper/aluminum/plastic/etc.)

While the "drill guides" & "lubes" are nice to bring up, items above are really required.

Doing a "tapping guide" is nice, it's not normally needed.
When using a #1 or 2 tap, you can "feel" when it goes "on center". These taps have a lead-in taper, this allows it to "self center" when getting started.
As to breaking chips, if you have a 3 flute (or groove) tap, spin the tap in 2-3 turns when starting, then, back it off ~1/2 turn (this breaks the chips off)....if using a 4 flute tap, spin it backwards at least 1/3 turn. Once the tap is part way in, do 1 to 1.5 turns in before doing the reverse twist to break the chips.

The 2 main reasons for breaking taps is:
1-Bending the tap too far
2-Clogging the flutes with chips

With practice, you can "free-hand" tapping with no issues.

Considering I've tapped 10's of 1000's of holes in multiple materials, I think I know "just a bit" about tapping.

BTW, when tapping plastic, water can be an acceptable lube.

Any questions....just ask.

[CREEPERBOB]

Your the man with the answers charles , as a maintainence man for many a year ,tapping , or threading of any type is a learned art not a givin' one.

[Charlie-III]

Originally Posted by CREEPERBOB

Your the man with the answers charles , as a maintainence man for many a year ,tapping , or threading of any type is a learned art not a givin' one.

Thanks, 20+ years as a maintenance/facilities person, 3 years as a "machinist" plus 40+ years doing all sorts of automotive/motorcycle/RC/etc work....you learn what is, "Really needed" vs. what is "nice".

Not slamming anyone, just saying.

Now, I'm teaching my son (asw27x) the same simple things.

[Dynamic Concepts]

Originally Posted by CREEPERBOB

.............tapping , or threading of any type is a learned art not a givin' one.

Yes, and that is why a tap guide is a simple, yet useful tool for a novice or pro alike, depending on application......

[KMS]

I do sum free hand tapping after drilling my hole's with my milling machine ,For tapping fluid I use ,,TAP MAGIC ,, found at www.wttools.com I drill and tap my 4-40 thread holes with tap magic the stuff is great ,,,,Kms

[Getrag]

Charlie mentioned:

"The 2 main reasons for breaking taps is:
1-Bending the tap too far
2-Clogging the flutes with chips"

But Clogging the flutes doesn't mean much to a lot of people.
What he is saying is that the grooves that run all the way up and down the tap are meant to hold the material that gets cut away. With out lube, and even with lube they fill up and it gets hard to turn the tap and your tap can break.

What I do, and I tap mostly by hand and if I don't feel lazy I'll get up to get lube, but if you don't lube you need to this for sure:
For every 1 turn of the tap, back it out half a turn or so, you'll feel it loosen up and get easier to tap.

If the hole is deep you need to back the tap out all the way and brush off the tap and blow in the hole whatever you want to clear out the cut material. Then start tapping again.

This will really help.

EDIT: Whoops... sorry Charlie I just noticed I missed a paragraph where you explain this... haha oh well its important to do.

[Mackspower]

Originally Posted by tom@vp

what size are you tapping, is it a roll tap or cut tap.

need correct drill size, start with one size smaller, then redrill with correct size drill, keep drill very straight or perpendicular to the work face.,

same with tapping, keep tap very straight, i dont what tools you have but if you can drill a hole in a block of wood or aluminum the size of the outter diameter of the tap do it, then use that for a tap guide.

Great advice for keeping the tap straight! My eyeball/elbow calibration has a heckuva time keeping the darned thing in line with the work. Thanks!

[STJ7780]

Originally Posted by sumquak

as far as cutting oil, WD-40 is the best cutting oil for aluminum, the only thing it's good for, imo.

x2
WD40 is the best commonly available cutting and tapping fluid for aluminum. As for tapping, a tap guide is great but you already have one and didn't even know it. Your drill press. Clamp your piece to the drill press table, drill the correct size hole, remove the bit and install the tap. DO NOT turn the drill on but rather turn it by hand while applying light downward pressure to the tap. After the tap has made a few turns, use the chuck key to release the drill chuck from the tap without removing the tap from the aluminum. Now it has started enough to continue with the tap handle. Good luck
Steve

[Charlie-III]

Originally Posted by Getrag

EDIT: Whoops... sorry Charlie I just noticed I missed a paragraph where you explain this... haha oh well its important to do.

No worries, it won't hurt to have it covered twice.

[Johnsinski]

A couple of tips:

1. Press down (lightly) at the start to help prevent the tap from coming back out pulling the top threads out.

2. If you can't use a tap guide, during the beginning of tapping, rotate the work piece (or your point of view) about 90 degrees to visually check that you are going in at the same angle as the hole (90 degrees to the surface). You can adjust the early threading without screwing them up too bad.

3. 3mm is kind of tough for the inexperience, 4mm should not be too bad. Use good taps, I've seen brand new cheap 3mm taps that are bent, that makes it even more of a challenge for beginners.