Thread: Milling Aluminium - A Question

I have not milled much aluminium and before I venture too far into the unknown I thought it would be pertinent to ask whether a block of aluminium will distort if most of it is hollowed out.

The block has been cut from some 65mm thick plate and my intention is to use it to make a switch enclosure for the tool and cutter grinder. I have a pair of Allen-Bradley switches that I would use to switch the power to the two VFDs required for grinder's motors. The original switchgear would be used to switch the VFDs' output.

While cast enclosures are cheap and readily available, they aren't deep or wide enough for my liking. The enclosure I wish to make would be the same width as that on the Hercus, 165mm. Wide enough for the switches and a pair of indicator lamps.

So my question is do I need a stiffening web across the middle of the box if the wall thickness along the long sides is about 5mm? I intend cutting all the way through the block.

BT

DSC_6171 (Large).jpg DSC_6172 (Large).jpg DSC_6173 (Large).jpg

DSC_6177 (Large).jpg

Depends what the material is, and importantly the temper.
If the material is a scrapyard "no spec", it's a case of sucking it and seeing. If it is, for example, 6061 T651, then no problems. Where I used to spend my 9 to 5 they used to machine bigger deeper boxes than you are proposing, with wall thickness' down to 1.00mm out of that material. The "T651" means that the material has been stress relieved, quoting from"Aluminum standards and data" (yes it's 'mercan)

"T*51 Applies to plate and rolled or cold-finished rod or bar, .........."

Hope this helps.
cheers
Bill

Originally Posted by wakeup111

Depends what the material is, and importantly the temper.
If the material is a scrapyard "no spec", it's a case of sucking it and seeing. If it is, for example, 6061 T651, then no problems. Where I used to spend my 9 to 5 they used to machine bigger deeper boxes than you are proposing, with wall thickness' down to 1.00mm out of that material. The "T651" means that the material has been stress relieved, quoting from"Aluminum standards and data" (yes it's 'mercan)

"T*51 Applies to plate and rolled or cold-finished rod or bar, .........."

Hope this helps.
cheers
Bill

Thank you Bill,

I hadn't thought to ask what it was when I bought it. I rang Robert Cameron, the supplier Robert Cameron and was informed that it is marine grade 5083 H116 temper. The bloke I spoke to reckoned there shouldn't be a problem with distortion but shouldn't isn't wont so I guess it will be suck and see. I might have problems with the machining though!http://www.atlassteels.com.au/docume...v_Oct_2013.pdf

Bob

Hi BT,

I like the idea of custom switch enclosures. They always add that custom touch.

I'd leave a rib in the middle to provide a bit of extra support for the front panel as much as anything else. Are you going to recess the switches?

Sorry I can't help on the distortion question, I'd just go ahead and do it.

Ray

Hi Bob,
Do any of these suit your job?

IME distortion won't be a problem. You will get away without the internal brace but you may need to support the long sides to stop them flexing when you are getting down to finished size.

Hi Bob,
My suggestion would be to have the stiffening web in the design it will ensure no distortion and not require any side support when milling. I would also clamp your block on a couple of sacrificial pieces one each end, drill a series of large through holes in the block to allow swarf and coolant to escape, recutting your swarf is not a good idea.
Bob

Originally Posted by rodm

Hi Bob,
Do any of these suit your job?

Hello Young Rod,

Before purchasing the block I visited Jaycar and bought an enclosure measuring 115 x 95 x 55 ( Altronics have one slightly smaller ) but it looked out of proportion when positioned against the Hercus' enclosure. Hopefully the carved out block will look the part.

Bob.

Ray, Bob and Bob,

I will leave a web. I'm of two minds about cutting all the way through the block or stopping about 5mm from the back. To cut all the way through would require a long cutter and those I have are around 25mm in diameter. The largish corner radius might impinge of switch space but it's only might at this stage. I'd use a vacuum cleaner to remove the swarf.

I hadn't considered recessing the switches because the originals are simply surface mounted. No point making life more difficult than it needs to be.

Bob.