# 7075 vs 6061



## Brass_Machine (May 7, 2008)

Is it just me or does 7075 machine so much more beautiful than 6061?? I just tapped 24 holes. 12 of which were in 6061 and 12 in 7075. It took me 3 times as long to tap the 6061 than the 7075.

I think from now on I will use 7075 whenever I can.

Eric


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## BobWarfield (May 7, 2008)

Well now how the heck can you make space age carbon fiber framistats without some of that there aircraft alu-min-i-um?  ;D

Cheers,

BW


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## zeusrekning (May 8, 2008)

I have to second Bob's comment.  
IMHO the tougher grades machine better because they are less gummy. We have done armor plates for the military (5000 grade material of some sort IIRC) and it machined alot better than we had planned. On thing on the 7075 is when it comes to polishing. On the RC parts we used to make, the low end ones were 6061 and the high end 7075. The 7075 would polish up OK but compared to the 6061 it had a lot less shine. Apparently the copper in 7075 keeps it form shining up as well.

Now Eric how about some titanium? I mean, come on those bike need to be lite. 
Tim


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## GailInNM (May 8, 2008)

I mostly use 3 aluminum alloys. 6061-T6, 2024-T5 and 7075-T6. Each has particular advantages.

6061 is the most available in almost any shape. It is also the least expensive. It is easy to anodize with consistent colors, even in a crude home anodizing set up. It can be easily welded.

2024 is much higher strength. It costs about 80 percent more than 6061. Machines very nice as it had a very crisp chip. The high copper content makes it harder to anodize and is difficult to weld. Yield and ultimate strength much higher than 6061. 

7075 is the highest strength common alum alloy. Yield and ultimate strengths almost double of 6061. The strength falls off at elevated temperatures so is not a good choice for high performance pistons in model engines. Machines very nice, similar to 2024. More difficult to anodize than 6061, but not as difficult as 2024. Not good for welding. Cost is about double of 6061.

None of the three are really happy about being formed or bent. Other alloys are much better for this, but don't machine well. 

For a brief overview of these alloys, go to:
http://www.onlinemetals.com/aluminumguide.cfm

Gail in NM,USA


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## Brass_Machine (May 8, 2008)

zeusrekning  said:
			
		

> I have to second Bob's comment.
> IMHO the tougher grades machine better because they are less gummy. We have done armor plates for the military (5000 grade material of some sort IIRC) and it machined alot better than we had planned. On thing on the 7075 is when it comes to polishing. On the RC parts we used to make, the low end ones were 6061 and the high end 7075. The 7075 would polish up OK but compared to the 6061 it had a lot less shine. Apparently the copper in 7075 keeps it form shining up as well.
> 
> Now Eric how about some titanium? I mean, come on those bike need to be lite.
> Tim



I want to use titanium, I have a bunch of stuff in mind. Have never machined it before... I heard it was tough on the tooling?

My kickstands are still very light. Stock GSXR kickstand is 18.6oz mine 7.4oz ;D I would say that is pretty good.

Eric


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## zeusrekning (May 8, 2008)

My dad had a Deco screw machine catch fire running titanium skull pins. It used oil for cutting fluid and the titanium gets hot. IIRC low spindle speeds and high feeds. Some tough stuff.
Tim


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## Brass_Machine (May 8, 2008)

GailInNM  said:
			
		

> I mostly use 3 aluminum alloys. 6061-T6, 2024-T5 and 7075-T6. Each has particular advantages.
> 
> ...
> For a brief overview of these alloys, go to:
> ...



Gail,

That is some great information. I have never thought to use 2024. I usually use 6061 (the cost isn't as bad) and 7075. 

Thanks
Eric


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## Brass_Machine (May 8, 2008)

BobWarfield  said:
			
		

> Well now how the heck can you make space age carbon fiber framistats without some of that there aircraft alu-min-i-um?  ;D
> 
> Cheers,
> 
> BW



 :big:

That cracked me up! :big:

Eric


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## jack404 (Sep 27, 2008)

GailInNM  said:
			
		

> I mostly use 3 aluminum alloys. 6061-T6, 2024-T5 and 7075-T6. Each has particular advantages.
> 
> 6061 is the most available in almost any shape. It is also the least expensive. It is easy to anodize with consistent colors, even in a crude home anodizing set up. It can be easily welded.
> 
> ...



This is a great answer and mirrors my own experience precisely

( was wondering if i was a bit touched in the head when someone told me they all machine the same way)

Thank you !!

Jack


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## Mainer (Jan 2, 2009)

In my limited experience...
Titanium can be machined with wicked sharp HSS. You'll probably want to use coolant, as machining it generates an astounding amount of heat compared to machining steel.


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## Peter Neill (Jan 2, 2009)

In the UK, the Aluminium of choice is usually 6082 T6 (H30 or HE30 TF in old money).
A bit stronger/harder than 6061, machines and taps beautifully, anodises lovely, and used for anything you want.

Some years ago we had a fantastic alloy from Alcoa called QC7 which was probably around 30% stronger/harder again then 7075. It was produced as tooling plate for injection mould tools, machined superbly, but using similar parameters as mild steel. Don't know what happened to it as I haven't seen or heard of it for a few years now.

Peter


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## scoop (Jan 2, 2009)

I have some offcuts from airbus wing spars and stringers that I collected over the years that I machined them for a living.Don't really know much about the spec of it but it cuts beautifully and polishes up well.Cuts tight to drills and taps which is good as it holds sizes accurately especially when reaming.Will be sad when I run out of it.
 Love cutting titanium,hss is ok just run spindles slow and try not to let tools dwell or rub as thats when you lose the edges off the tools.Drills will cut tight on titanium so I prefer to use oil on them to avoid built up edges.Always seem to get a good finish on titanium and the colour of it contrasts well with steel if you mix the materials on a project.

  best regards Steve C


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## georgeseal (Jan 2, 2009)

Ask Steve (cedge)
He knows exactly what grade of Aluminium every peice that he uses. :big: :big:


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