Anodised aluminium rods - threading?

[FestitaMakool]

Hi,

Wonder if there is someone who can tell me how to successfully thread anodised solid aluminium rods..?

Here’s what I’ve learned: (8mm rods and M8 tool in 1.0 and 1.2 threads, not that it matters a lot, but)

I’ve done 1/4, 1/2 and full turns, putting a lot of downwards weight (rod being vertical) and chucked the rod in my drill, pressing on the back of the drill firmly at low speed (crawling..) with the thread tool in my vies.

Best result has been two threads, and then it strips the two threads when going further.
Is it the anodising that’s making too much resistance?

I’ve kind of caved in now and bought me a black steel rod  [oops]

Thanks,
Stig

 

[RustE]

Anodizing is a surface treatment, and usually the last step in a manufacturing process. Cutting threads on a rod that was already anodized will expose raw aluminum.

What were you using as a cutting fluid for the tap?

 

[FestitaMakool]

I used regular machine oil, nothing special.
I’ve noticed some using some sort of grease though.

I know anodising is just at the very top of the surface, and when clamped in my chuck it left marks.
Oh, I did also taper the start, one quite short and regular to what one see on bolts, and I did one very long and low tapering sanding on a disc sander. Still, same result. The short taper (1-2 mm in) did get a slightly better result.

 

[mwolczko]

Did the aluminum clog the threads of the die?  If so, you’ll have to clean it all off.
I’ve had success threading Al by hand, turning a quarter turn, and then backing up the same amount to break off chips and clear the die.  I don’t push down once the thread is established.  Don’t know how much difference the anodizing makes. You could remove most of it by spinning the rod against an abrasive.
Also, what’s the size of the rod relative to the size of the threads, measured at the peak?  Having the rod slightly smaller helps with chip clearance (say, 85% of the way from the troughs to the peaks).

 

[Cheese]

Hey Festita...aluminum is rather gummy and can grab the tap or the die. For threading aluminum I'll usually start with a LARGER diameter pilot hole or a slightly SMALLER rod diameter. You'll still get good useable threads but it makes the task a lot easier and lessens the risk of breaking a tap.

First thing is to measure the OD of the rod. Per Machinery's Handbook, the max OD for an external M8 x 1.25 is 7.972 mm, while a M8 x 1 is 7.974 mm. I'd probably reduce the diameter of the rod by an additional .010" or so.

For working aluminum I use Alum-Tap, Tap Magic Aluminum or regular isopropyl alcohol. Heavy, thick fluids don't work as well because they retain the aluminum chips. Be careful with the IPA as it is flammable.

Follow mwolczko's method, just a quarter turn at a time. [smile]
http://www.tapfree.com/alumtap.htmlhttp://www.tapmagic.com/product/2/tap-magic-aluminum

 

[Svar]

I've threaded anodized aluminum. Did not have any problem. Anodizing makes no difference for threading. Better make sure you die and rod are properly matched.

 

[Crazyraceguy]

The main thing with aluminum is the variability of the alloy. The lowest grades are very soft and gummy and that makes them difficult to machine. Higher/harder types are much better for that. They also polish better too.
Don't use oil for any kind of aluminum cutting/machining though. Oil makes it worse. There are specific aluminum cutting/tapping fluids that  do a great job.

 

[Steve1]

I’ve had success threading Al by hand, turning a quarter turn, and then backing up the same amount to break off chips and clear the die. 

I agree.  I think the problem is technique, rather than the anodizing.  Aluminum is soft --- should thread easy.

 

[rst]

Usual problems with tapping is either excessive pressure starting or not enough.  Too much and the threads will strip each other, too little just tapers the ends.

 

[greg mann]

It appears you are using a bottoming die if I understand your reference to 1 or 1.2 threads. You need a die with a longer thread chamfer. You mentioned tapering the end of the shaft to help get started which tells me your instincts are right. The problem is the die is trying to form a full thread within one turn of the die and that is too hard to accomplish. The thread should be fully formed after about three turns. Your tool is designed to finish off a thread close to a shoulder after a different die with a longer thread chamfer has already cut most of the thread.

In reference to taps they sometimes call them starter taps and bottoming taps. You need a starting die. If you can find one you will see the difference.

 

[FestitaMakool]

Work in progress  [big grin]
Really, thanks a lot guys! Cheese and mwolczko, you’re right. After reading your replies I had a second look, and the OD had to be reduced. As you said Cheese, theres enough meat to grab on to, especially in my case where there is no need for holding force. I put the rod in the drill press and sanded off ca. 0,5mm off of the OD. Rod is 7,83mm and I sanded down to 7,33..
I did use the die the right way, at least 9 out of 10 times haha. I just did it backwards.. sooo..
The die is correctly M8 1,25.

I searched for som “cooling lube” but, no - Isopropanol has been removed from most paint and hardware shops.. As one clerk said: It was one of those things that worked, therefore they banned it haha [big grin] I’ll search through my stuff to see if there’s some forgotten canisters somewhere.

I’ll continue tonight, but here’s going forward on this test:
- Seems I’ll have my aluminium arms for the drill press after all  [smile]
[attachimg=1]

 

[Cheese]

Good for you...success is always a gratifying feeling.

FWIW...I can purchase IPA at the grocery store in the health/medical section or at the local pharmacy. I put it in a squirt bottle so a pint of the stuff goes a long way.

[attachimg=1]

 

[greg mann]

Hey, [member=44099]Cheese[/member], I didn’t know India Pale Ale would work for threading aluminum!!

 

[FestitaMakool]

Brilliant Cheese! Off course, tha Pharmasia!
Monday I will..

But honestly, a pint of IPA.. frighteningly good stuff, but I need to stay away, the engraver, with his delicate hammer and chisel pay me a visit the following morning even after a half.. [blink]
- Do you think the straw will do the trick?

 

[Cheese]

Hey, [member=44099]Cheese[/member], I didn’t know India Pale Ale would work for threading aluminum!!

[big grin]  Ya [member=22]greg mann[/member]  IPA in a plastic bottle for the aluminum and IPA in a brown glass bottle for me.  [cool]

 

[FestitaMakool]

These came out very nice. After battling the aluminium rods, tapping the wheel (I’d guess it’s magnesium) was a breeze in comparison.

I didn’t find any “real” handles that would suit, but these wooden balls did actually very good, very comfy to hold, and perfect when turning. I might keep the temporary..

Original:
[attachimg=1]

Keeping original, but with a better twist:
[attachimg=2]

Close up from behind - the meat in the wheel is actually thicker than visible here.
They didn’t need thread lock to sit properly, so the handles can be detached if I needed.
[attachimg=3]

 

[mike_aa]

[member=71478]FestitaMakool[/member]

Nice job! It now has a Mid Century Modern vibe to it!

Thanks!  Mike A.

 

[FestitaMakool]

[member=30413]mike_aa[/member]

Thanks a lot! And it’s going to be a joy using it soon, as I’ll be adding a wide table and fence.
Smooth untreated wooden handles are just so nice in the hand, and the aluminium rods feels much better than steel.

 

[Cheese]

That's a pretty slick little drill press Festita...laser, variable speed, only 22#, LED lighting, that'd be perfect for mobile situations. I'd imagine your modification makes the drill press a lot easier to use. Using just the wheel to drill steel or aluminum would get old in a hurry.  [smile]  A couple of questions:

How's the keyless chuck? It looks like it's made from steel & plastic.  [huh]

Can the clamp be swung out of the way around the column so that a large hole saw can be used?

 

[Michael Kellough]

That's a pretty slick little drill press Festita...laser, variable speed, only 22#, LED lighting, that'd be perfect for mobile situations. I'd imagine your modification makes the drill press a lot easier to use. Using just the wheel to drill steel or aluminum would get old in a hurry.  [smile]  A couple of questions:

How's the keyless chuck? It looks like it's made from steel & plastic.  [huh]

Can the clamp be swung out of the way around the column so that a large hole saw can be used?

I wanted one a few years ago for portable precise work (in particular on top of a large workpiece as can be done with Shaper Origin) but as far as I know it still isn’t available here. Ended up buying a DUSS drill stand and Metabo drill with locking variable speed trigger. I wish there was a cordless drill with locking vertical trigger, and 43mm collar.