4 replies to this topic

[chuffed]

I'm looking to make my own rear beam, of a similar design of some others on the market.

I have had the idea to use a long billet of aluminium, machined down with all the correct holes drilled in. then, where the radius arm brackets attach just tap into the billet and use stainless steel bolts.

 

However, will the threads in the aluminium be strong enough with the forces felt through them? if for example the beam is inch and a half thick the threads could be and inch long, if not longer. would they simply pull out?

 

The beam will be lightened between the mounts with holes.

 

Thanks

[Tamworthbay]

There is no simple answer, the main issue is what grade of aluminium? The most common at metal suppliers are 2014/2015 and 6082 (usually in T2 or T6 form). Then there are a massive range of types for specific applications with a wide range of properties. It may be possible to find one to suit but it would be a lot easier to design it with appropriate steel fittings in it.

[tomgale]

instinctively I'd be wary, I've always been told to avoid designing threads in aluminium (better to use long bolts to washers and nuts on the other side) as aluminium is quite soft. that being said, some of the more exotic alloys (think 7000 series etc used in aircraft) might be better, but very expensive. Generally I've always thought it better practice not to put threads in big parts, as a stripped thread during assembly or maintenance can render it scrap, with standard fastners a stripped thread is a minor inconvenience rather than a catastrophe.      

[morganb3]

If you are using Aluminium in a welded structure, 6082 T6 with 4043A filler is the best. For threads I would be wary, As much depth as you can get and use a helicoil insert to spread the load.

 

I wouldn't do it personally for such a high load application.

[Fast Ivan]

to many variables to give an informed answer, this would need to be designed and stressed out before any metal was cut