CLINK! Broke (another) tap. Wisdom?

[HoosierBuddy]

So...last night I was finishing up a project to make a decorative part out of aluminum for my car. It involved 4 10-24 threads in aluminum for 3/4" long screws.

I drilled all 4 holes all the way through the aluminum 5/32" (that's about .007 oversized actually, as the tap said to use a smaller #25 bit which I don't have).

I used a can of that foamy threading oil on everything and started in with the tap. I made it until the tap was just coming out of the bottom of the aluminum before it hung up and I snapped it.

I must really **** at tapping. I bet I break a tap in 1 out of 10 cases I try to thread anything.

Any hits out there or tricks to help my average?

Phil

 

[G1GRANDEUR]

did you back out tap 1/2 or 1/4 turn every full turn?

 

[Thunderbisciut]

Tap could have been crooked, could have been putting too much pressure on the side, could be cheap taps, etc.

I usually do 1/4 turn tighten, 1/2 turn loosen over and over again till it's through.

 

[HoosierBuddy]

Once it got down in the aluminum I did....say after about 5 turns in.

Worst part is I had about an hour in the part with the broken tap in it...sawing it and milling it to shape. Even if I get the tap out, I can't use it because it'd show...and I'll never get the tap out without damaging the aluminum.

Phil

 

[ChevyEFI]

SKang's post +1

Back it all the way out and clean cuttings out a few times too.

Much fewer breaks that way.

 

[454ragtop]

First off, you need a good sharp HSS tap, then you need something to hold it square to the work. This types of fixture http://www.ebay.com/itm/FLX-50340-M...135?pt=LH_DefaultDomain_0&hash=item27ce55c94f works excellent, although that one is way over priced, just one I found quick. If you don't have a fixture, drill a hole that the tap will just slide through in a scrap of wood or alum., in a drill press and use that to hold the tap square. Should be a very easy tapping job in aluminium.
HTH, Jim

 

[N.I.]

Where you using a taper tap?

If so then either your taps are rubbish or you weren't square to the work piece.

 

[mark40sw]

I agree with what other have said above.
HSS taps are many times better than high carbon. I don't like cutting threads with high carbon, especially smaller threads- the taps are just too brittle.

There is cutting fluid made just for aluminum.
http://www.tapmagic.com/TMaluminum.htm

"Gun taps" or spiral point taps make thread cutting easier on through holes.
http://www.icscuttingtools.com/catalog/page_216.pdf

 

[Steinmetz]

Don't bend the tap while twisting. Use a tap guide if you have one.

 

[03protege]

1. Make sure you are near perfectly square with the hole you are tapping.
2. Always back out frequently, I have learned a pretty good feel for when it needs clearing. When in doubt sometimes I have completely removed the tap and blown the threads out.
3. I switched from the foamy oil to standard motor oil I like it better.

I also bought an upgraded ratcheting tap handle and I have had much better success ever since doing so. It came from Harbor Freight.

 

[woody 73]

Woody Tip:

Next time you go to the Food store pick up some Crisco Lard in a small can; darn good stuff be sure and coat your taps, slather them up and go to town as they say.

 

[Alchymist]

All the above, +

 

[Gert]

Perhaps of use:

 

[Zrexxer]

So...last night I was finishing up a project to make a decorative part out of aluminum for my car. It involved 4 10-24 threads in aluminum for 3/4" long screws.

Were you actually trying to tap 3/4" deep for a #10 screw? If so you're starting to put a lot of torsion on a small diameter tap when you get that deep.

Try counterboring the holes from the back so you're only having to tap 1/4" deep, or 1/2" deep, and you'll save a lot of tap breakage.

 

[bullnerd]

And most important...DONT use 10-24 taps! Like 6-32 they have the worst thread depth to minor diameter ratio.

10-32 gun tap, put it in a cordless drill, lube it, (there are different lubes for aluminum) all the way in-all the way out in one shot.Especially if its a through hole.If blind, it will still work but you will have to pull the chip string out.

 

[bsaint]

I use forming taps on aluminum.

 

[454ragtop]

And most important...DONT use 10-24 taps! Like 6-32 they have the worst thread depth to minor diameter ratio.

10-32 gun tap, put it in a cordless drill, lube it, (there are different lubes for aluminum) all the way in-all the way out in one shot.Especially if its a through hole.If blind, it will still work but you will have to pull the chip string out.

I usually prefer a coarse thread in aluminum, less likely to strip out. With proper setup, it really shouldn't be a big deal.
Jim

 

[454ragtop]

Here's a more reasonably priced tap guide http://www.ebay.com/itm/SELF-ALIGN-...220?pt=LH_DefaultDomain_0&hash=item4cf564d3bc I knew that first one was way overpriced. These work very well, loaned mine out a couple times. and they were amazed.
Jim

 

[bsaint]

Seriously this is what you need.

http://www.amazon.com/dp/B007BTPRCO/?tag=atomicindus08-20

 

[PT Doc]

To reiterate, use hss only, good fluid and be square to your work and you won't have problems.

 

[Slupie]

I dislike tapping aluminum, it is soft and likes to gum up the tap. Use proper cutting fluid for Al, like other posters said
1. Drill your holes square first
2. be parallel to the hole with your tap, use a tapping guide
3. cutting fluid, cutting fluid and then more of it
4. for every turn in back the tap out 1/4 to 1/2 turn, if you feel a lot of resistance back out the tap blow out the tap and the hole and repeat

 

[Outlawmws]

What kind of aluminum was it? if its not a free machining aluminum you re going to have troubles and f the taps are not sharp even more trouble.
and on many o f the other comments on depth keeping it straight etc....

 

[Hammer1963]

Tapping Aluminum is not difficult. I would suggest using a Tap block until you are comfortable with tapping. As stated above, break the chip often. A common mistake is the use of general purpose cutting oil. A 50/50 mixture of Kerosene and Lard based cutting oil works good for Aluminum.

A #10 thread only requires 9/32" depth of threads for maimum pull strength, so there's no need to tap to extreme depths. Maximum strength is 1 1/2 x the diameter of the O/D of the thread.

 

[flippin]

I dislike tapping aluminium, it is soft and likes to gum up the tap. Use proper cutting fluid for Al, like other posters said

Agreed, though soft, aluminium is a pain to tap because of how gummy it gets. Most machinists I work with prefer to tap steel despite being harder because the material chips away from the tap threads. The material clinging to the tap is your worst enemy.

However working with aluminium boats, I am forever tapping and have broken my fair share of taps. As mentioned already being square, using the right cutting compound (I like the Walter aluminium paste) and clearing the shavings all the time is critical. I also switched to spiral taps and though expensive they are much better. Lastly given that your f%#!ed if you break a tap (removal is near impossible) I use the air gun a lot to clear the chips especially in blind holes.

Good luck.

 

[cyato]

Hey Guys,

First time posting here... At the risk of offending any knowledgeable or "proper" machinists on here, screw tapping by hand! When I had my first tapping experience 17 years ago, I had to hand tap (no tapping jig) a couple dozen 10-24 holes in 1/2" aluminum plate. It took me all day long and I was super nervous and I did break one tap. On a subsequent project that I outsourced to another vendor, we had a situation where they had to drill and tap almost 200 10-24 holes in 1/4" aluminum plate. They left that job until the day before the deadline, and I was freaking out because I thought that the job wouldn't be finished. That was the day I was introduced to 2 flute spiral point "gun" taps. (We buy ours from McMaster. Check out p/n 2523A448.) They tapped those holes in less than 30 minutes with a cordless drill, a 10-24 "gun" tap and A-9 lubricant. I was blown away. I immediately came back to LA and bought some and have never tapped by hand since. Unfortunately almost all tap and die sets that are out there come with four flute hand taps which break pretty easily, so you have to buy gun taps separately. While small gun taps (like 4-40 or 3mm) can still break easily, I rarely break 8-32 or larger taps as long as it's not some weird situation. It takes a little practice getting used to tapping with a drill, but as long as you're not jerking the drill around when switching from forward to reverse, it's pretty hard for me to break a tap on a through hole. I've used this technique in 3/4" aluminum, 1/2" mild steel, all sorts of plastics and other metals. I'm not saying that i never break taps, but its a very rare occurance.
Hope this gets some of you to try it out and not dread tapping like I used to.

Good luck!

 

[cyato]

Just wanted add one more thing since we're on the subject of tapping...

Tap sockets are very useful for many situations where the tee handle that comes with tap and die sets would not work. They have 1/4" or 3/8" socket recesses on the back side and allow tapping (or re-threading) using ratchets and extensions for hard to reach areas. They are one of my (many) "must have" tools...

Here's a link for them on Amazon.
http://www.amazon.com/dp/B0002SRFOE/?tag=atomicindus08-20

They're made by Lisle and I've never seen them made by any others...

 

[acdc73]

Just wanted add one more thing since we're on the subject of tapping...

Tap sockets are very useful for many situations where the tee handle that comes with tap and die sets would not work. They have 1/4" or 3/8" socket recesses on the back side and allow tapping (or re-threading) using ratchets and extensions for hard to reach areas. They are one of my (many) "must have" tools...

Here's a link for them on Amazon.
http://www.amazon.com/dp/B0002SRFOE/?tag=atomicindus08-20

They're made by Lisle and I've never seen them made by any others...

I have a similar set, and I use them along with a stubby ratchet nearly everytime I have to tap someting.


right size tap drill and proper cutting oil for type of material is critical.

 

[acdc73]

BTW TapMagic cutting oil works well, the old "toxic" formula was the best.

 

[Steinmetz]

Here's a more reasonably priced tap guide http://www.ebay.com/itm/SELF-ALIGN-...220?pt=LH_DefaultDomain_0&hash=item4cf564d3bc I knew that first one was way overpriced. These work very well, loaned mine out a couple times. and they were amazed.
Jim

That's a good device. I use one. It reduces flexure on the tap and allows you to squarely approach the hole.

 

[Steinmetz]

Hey Guys,

First time posting here... At the risk of offending any knowledgeable or "proper" machinists on here, screw tapping by hand! When I had my first tapping experience 17 years ago, I had to hand tap (no tapping jig) a couple dozen 10-24 holes in 1/2" aluminum plate. It took me all day long and I was super nervous and I did break one tap. On a subsequent project that I outsourced to another vendor, we had a situation where they had to drill and tap almost 200 10-24 holes in 1/4" aluminum plate. They left that job until the day before the deadline, and I was freaking out because I thought that the job wouldn't be finished. That was the day I was introduced to 2 flute spiral point "gun" taps. (We buy ours from McMaster. Check out p/n 2523A448.) They tapped those holes in less than 30 minutes with a cordless drill, a 10-24 "gun" tap and A-9 lubricant. I was blown away. I immediately came back to LA and bought some and have never tapped by hand since. Unfortunately almost all tap and die sets that are out there come with four flute hand taps which break pretty easily, so you have to buy gun taps separately. While small gun taps (like 4-40 or 3mm) can still break easily, I rarely break 8-32 or larger taps as long as it's not some weird situation. It takes a little practice getting used to tapping with a drill, but as long as you're not jerking the drill around when switching from forward to reverse, it's pretty hard for me to break a tap on a through hole. I've used this technique in 3/4" aluminum, 1/2" mild steel, all sorts of plastics and other metals. I'm not saying that i never break taps, but its a very rare occurance.
Hope this gets some of you to try it out and not dread tapping like I used to.

Good luck!

Years ago, I used a tapping head on a drill press for high volume work (I worked in a machine shop before college). It worked fine, and I never broke taps. A-9 is also a good tapping fluid.

 

[larry_g]

I would have to ask the OP, Are you using a proper tap handle or turning the tap with a crescent wrench? Side force on a tap leads to lots of breakage. I'll also ask are you using dime store taps or dull ones?

lg
no enat sig line

 

[cyato]

Made a quick vid to show how quick tapping can be.

Never timed how long it takes to tap a hole until today, but I tapped 8 holes in one minute. Not bad considering the tap is pretty old! And the mild steel and 6061 aluminum weren't much different in terms of resistance to tapping...

 

[cheechi]

Try these

 

[flippin]

Made a quick vid to show how quick tapping can be.

Never timed how long it takes to tap a hole until today, but I tapped 8 holes in one minute. Not bad considering the tap is pretty old! And the mild steel and 6061 aluminum weren't much different in terms of resistance to tapping...

Awesome video Chris, thanks for sharing and taking the time!!! Btw which brand of spiral tap was that?

 

[Addrock]

I don't think I saw anything on thread percentage. Simply increasing your tap drill size is a way to decrease tap breakage. I have tapped thousands of holes many of those using cut taps in aluminum. Tap magic, yes, as well as tap blocks. Make one if you don't have one.

 

[JeffDM]

Aluminum tapping isn't that hard if you take your time to start right. Much of this was already given, but here it is anyway: I only use forming taps on aluminum if I can help it, failing that, machine taps, spiral point for through holes, spiral flute for blind holes. I only see "hand tap" style taps as a last resort, and there not good for aluminum. I usually figure any tool used on aluminum should not have been used on any variant of steel. It's worth buying a couple forming taps for an aluminum project. There are no chips, no need to constantly back out. Using a guide is good if you can't hold it straight and square. Taps are often intolerant of flexing, especially the tiny taps.

I also use Tap Magic Xtra-thick if I'm concerned and with small threads, it's the best tapping lubricant I've seen, especially with forming taps. A tiny dot on the tip of the threads is good for 2 to 4 holes.

 

[cyato]

Awesome video Chris, thanks for sharing and taking the time!!! Btw which brand of spiral tap was that?

Good question, but I'm not sure. We order all of our taps from McMaster, and they always are top level quality. Sometimes different sizes are from different manufacturers. Now that you bring it up, I'll keep an eye out for what brands they are.

 

[HoosierBuddy]

Thanks for all the great replies guys.

I remade my aluminum piece and got the tapping done. Your reward for helping me is getting to see a picture of the finished assembly.

Aluminum compressor cover for Sanden A/C compressor on my mustang.

Phil

 

[454ragtop]

Looks good. Curious, is the cover itself made from the cover to a GM Quad 4? I've had one hanging around for years, waiting for me to repurpose it.
Jim

 

[HoosierBuddy]

Looks good. Curious, is the cover itself made from the cover to a GM Quad 4? I've had one hanging around for years, waiting for me to repurpose it.
Jim

No. I milled it out of 1/4" 6061 aluminum plate....but your idea might work. You need about 5" square for the top.

Phil