Material

Is most of the aluminum hardware made from 6061 or 7075 .... Is most coming from sheet good or from solid blocks... I know stupid questions lol

Mostly 6061 because the cost of 7075 is considerably higher, at least at most of the remnant places I buy my materials at.

Far from stupid. Kind of depends on the part:

• Rudder brackets, machined engine mounts and skid fin brackets would most likely be block
• Skid fins, some tail mountings and rudders would most likely be sheet.

The biggest thing is to try to get your material to be fairly close to your finished part dimensions so you're not wasting a lot
Along with the cost of 7075 being higher, it can also be harder to machine than 6061 is, just due to it's being harder than the 6061. Some may not notice the difference while others will.

gooycheese said:

Is most of the aluminum hardware made from 6061 or 7075 .... Is most coming from sheet good or from solid blocks... I know stupid questions lol

Click to expand...

There is alot of 6061 aluminum that is extruded in the form of strips and tubing. MACS Products would buy mostly extrusion and very little plate and little sheet.

The reason I ask is I work where 6061 is really common... We have coils of the stuff... We run it thru levelers and make sheets... Pretty sure we have lotsa different gauges ... Gotta check an confirm... Stainless in huge amounts also.

6061 T6 is good for mounts, brackets and most general widgets. 7075 T6 is significantly stiffer compared to 6061T6 which makes it superior for slender parts like rudders and turn fins. It is more difficult to machine over 6061 T6 and for turns fins a little more care is necessary to bend as it will crack easier.

If you are making turnfins or rudders I would not recommend buying second hand material unless you know for sure its 7075 T6. Otherwise local supply houses can get it for you and there is always McMaster Carr.

I work for a company called "Olympic Steel"... We are what's considered specialty metal( meaning mainly aluminum and stainless). We also have 90 & 230 ton press breaks and a couple lasers... This 30/30 is one we use TruLaser 3030 / 3040. I gotta find out if I can get some stuff made... I know we don't have 7075...

2024 is also a good trade off between 6061 and 7075. Easier to machine than 7075, but stronger than 6061.

In my experience, speaking from 40 years in machining, it is important to pay attention to the numbers following the main alloy designation. 6061, 7075, etc designates the alloy. The principal difference between those two alloys is the addition of Zinc in the 7075 to toughen it. The numbers that follow indicate additional charactistics, like hardness, and how that was obtained. I won't try to explain all the things that are done, or all the possible combinations, but will focus on two common alloys, 6061-T6xxx and 7075 T3xxx. (the xxx is the added information that is not particularly relevant). In particular, 7075-T3xxx (usually specified as T3511), IS harder and tougher than 6061-T6xxx but not necessarily harder to machine. 7075 is much stiffer, so forming fins into curved parts requires about 30% more bend than 6061-T6 because of spring-back, and you cannot form sharp-corner bends without risking cracking. . 6061-T6, like 7075 T3 has been heat treated to strengthen it, but it bends more easily and you can form reasonably sharp bends without cracking it. Plain 6061 (also listed as 6061-T0) is very soft and bends rather easily. You can remove the heat treatment from T6 by heating it to a high temperature and quenching it, but I wouldn't recommend that. 6061 that has been softened WILL eventually partially re-harden by itself, but that can take a long time.. In machining, 6061-T6 will tend to form long, stringy chips and load up on endmills and in the flutes of drills because the chips tend to weld to themselves if not properly cleared with air and lubricating mist or flood coolant. 7075 forms what are called "micro-chips" which are actually harder than the parent material (due to work-hardening), and have far less tendency to weld together. A brush or air/mist-coolant is sufficient to carry them out of the cut and you have less loading of end millas or drills. I have come to appreciate the qualities of 7075-T3511 for a lot of parts, and the strength is quite a bit higher than any other aluminum. If it weren't much stronger, they wouldn't use it in places like fighter jets and other equipment. Titanium is stronger than any aluminum and holds up to high heat much better, but that stuff is perfectly awful to machine, not to mention, way more expensive. 7075 is about 30-50% more expensive than 6061. You can buy small pieces at inflated prices from McMaster-Carr, or OnlineMetals, and it is very difficult to find in surplus. Aluminum that comes in rolls and is unrolled and flattened may not be as hard as ordinary sheets.. It is a convenient format for transpostation and storage, where surface integrity is important. Sheets are easily scratched, rolls are not. Check for marking on the material for the "following" numbers and decode them (you can find hardness charts on-line). 6061-T3 is less hard than 6061-T6, 6061-T0 is very soft..

Thank you for all the info... I will get more details on exactly what we have at work.

I've found that run of the mill 6061 has gotten "gummier" over the years and therefore crappy to machine, I use 7075 on almost everything now.

Except where titanium is even better yet.

pitboy said:

2024 is also a good trade off between 6061 and 7075. Easier to machine than 7075, but stronger than 6061.

Click to expand...

2024 is also quite a bit more expensive than 6061.

Terry Keeley said:

I've found that run of the mill 6061 has gotten "gummier" over the years and therefore crappy to machine, I use 7075 on almost everything now.

Except where titanium is even better yet.

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Terry,

There is a difference between "extruded" and "cold finished", as well. Even though both are spec'd to "T6" the cold finished material is much "crisper" than the extruded, and is much nicer to machine.

I prefer to machine 7075, other than the stress relief warping that often occurs when machining large cross sections away. But, anticipate this, leaving some material for final clean-up, and this isn't an issue.

I got over my fear of titanium a long time ago. It really isn't that bad to machine, once you realize that you can't force it to cut like aluminum, like a lot of people try and suggest. Slow spindle speeds, with heavy roughing passes, and it just washes away.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

Hi Gentl,

Has anyone experience with forged aluminium?
Is there maybe any source for this kind of material?
(for example to Conrod, I made some before from used original airplane propeller)

https://www.as3performance.co.uk/yamaha-yz-80-85-1994-2020-forged-aluminium-gear-change-lever/
Thanks

From what I am told we don't have large amounts of t6 6061... .190

We don't have 7075 or 2024... So guess I don't got a source for much...

You can make most of your mounting hardware from 6061 aluminum angle

gooycheese said:

From what I am told we don't have large amounts of t6 6061... .190

We don't have 7075 or 2024... So guess I don't got a source for much...

Click to expand...

McMaster Carr a great source

Brad Christy said:

Terry,

There is a difference between "extruded" and "cold finished", as well. Even though both are spec'd to "T6" the cold finished material is much "crisper" than the extruded, and is much nicer to machine.

I prefer to machine 7075, other than the stress relief warping that often occurs when machining large cross sections away. But, anticipate this, leaving some material for final clean-up, and this isn't an issue.

I got over my fear of titanium a long time ago. It really isn't that bad to machine, once you realize that you can't force it to cut like aluminum, like a lot of people try and suggest. Slow spindle speeds, with heavy roughing passes, and it just washes away.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

Click to expand...

I have learned that Titanium cuts exactly the same as 7075T6 aluminum, but at 15% of the feed and speed.

Steve,

So..... Not even remotely the same....? If you mean that the cutting tools rotate and the material disappears, then, yes. Outside of that...." Ummm, no.

When I was regularly making Ti connecting rods, I had been using the same Hanita carbide roughing end mill for almost a decade to rough them out. Then I would use a carbide finish end mill to finish them. For the 7075 connecting rods, I would use the same carbide end mill for both roughing and finishing. If I had used the same speed and feed numbers for the Ti as I did for the 7075, I would have gone through a bunch of cutting tools. A bunch.

I remember starting a new job. It was some time after I had been making my Ti rods for a while. Right away, they gave me a Ti job, since I'd told them I'd machined a lot of it. The supervisor I was working under gave me that crap about "I cuts just like aluminum", and insisted I set my speeds and feeds as such. After smoking a handful of cutting tools, and not getting much done, I reverted back to numbers I knew would work. I completed the job without even damaging the remaining cutting tools.

I have heard this myth that "Ti cuts just like aluminum" many times, and it just isn't the case. Unless you just like tossing junk carbide over your shoulder.....

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

Brad, you obviously didn’t understand what I said. I said titanium cuts exactly the same as 7075 aluminum, but at 15% of the feed and speed.

If you run 3000 RPM cutting 7075, you’ll run 450 cutting titanium. If you feel 30 IPM cutting 7075, you’ll feed 4.5 cutting titanium. At least that’s the way I’ve been doing it in my Tormach, and it seems to work just fine.