Tapping aluminum

[Leatherneck]

Is it better to fine thread or course when tapping aluminum? Thank you.

[Ol'fogasaurus]

Is it better to fine thread or course when tapping aluminum? Thank you.

Depends on the AL.

https://www.thoughtco.com/aluminum-or-a ... oys-603707

This is a basic list of the alloys and the components in each alloy. Add to that there is the temper of each alloy going from -0 to -6 or -8 (I think -8 is the strongest alloy I worked designed to). An example might be 2024- T6 to which the part may be designed to be formed in a -0 condition then heat treated to a -T6 condition.

https://www.practicalmachinist.com/vb/c ... um-235446/

This might give you some additional thoughts on threading. Machining vs. tapping is very different as the threads are shaped differently.

https://www.eng-tips.com/viewthread.cfm?qid=39629

Another set of thoughts on AL.

http://www.shender4.com/thread_chart.htm

A thread tap chart.

I could go on I think but this might give you a basis for search.

Lee

[Leatherneck]

Ok, let’s say I know bumkiss about the alloy it’s something I found in the metal pile, what say you Lee? Just pick one.

[Ol'fogasaurus]

Do you know what the AL stock actually is? What is it going to be used for and if you have a choice of material what kind of loads do you expect it to be used for and how thick is it?

Lee

[Ol'fogasaurus]

Do you know where the stock came from or what it was used for? It is a hard question to answer.

Lee

[Ol'fogasaurus]

Without knowing a lot more: if it is a thick piece of stock/material and you are putting a big load on it then I would suggest that you go with less threads per inch. The threads would be stronger due to the thicker material in the threads.

Lee

[Leatherneck]

Yes will be thicker and more of a stand then support. Thanks Lee.

[sideshow]

I suggest matching the bolt threads, and use a common thread to the rest of the device. Fine thread while in theory generally isn't used as galls and crosses easier (harder to make well).

[Leatherneck]

Gotcha, I will use that “ keep it similar “ thought in the other. Looking through my 20 year can couldn’t find enough fine thread bolts in that size.

[GS guy]

I generally use coarse thread in AL, unless the material is thinner - like 1/8" or under. Also use 70-75% thread height drill sizing and a good cutting fluid for both drilling and tapping.
Jeff