Using a lathe to turn Aluminium

[hamster]

Hi all,

I want to make some tapered aluminium legs for a coffee table I am making. They will be about 450mm long and taper from a 55mm diameter at the top to about 30mm at the base. I was planning to use solid aluminium barstock (round).

How would I go about turning these? It may be a stupid question, but would it be possible to turn them on a woodworkers lathe or do you need a special metalworkers lathe to do this? As Triton don't make a lathe I have zero understanding of this arcane aspect of woodworking <grin>.

Any ideas where I might get this done at a reasonable price - I rang GW Engineering in Melbourne but they quoted me $200 for each leg!

Marcus

[RETIRED]

Gooday.

Aluminium can be turned on a wood lathe but you have to know what you are doing. It is more scraping than cutting.

$200/leg is a rip off by engineering standards. $200 for the 4 is realistic. Would cost that much too turn them on a wood lathe as well.



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Ian () Robertson
"We do good turns every day"

[Dave in Cairns]

Marcus, that's a fair bit of meat you want to take off and this may sound a bit bizzare but I can assure you it works. When I was shipwrighting , it was fairly common practice to plane aluminium with a power plane. No special cutters , just the tungsten blades used for timber. Taking cuts of around 1mm , you can take most off most of the waste and complete the taper on the lathe.

[This message has been edited by Dave in Cairns (edited 28 February 2001).]

[hamster]

OK, another (related) question...

I want to cut the 50mm barstock at an angle so that the legs of the table splay out slightly. I have a mitre box and of course lots of wood cutting blades but what would I use to accurately cut the aluminium?

I had assumed that a wood working blade (either circular or manual) would not be usable in Aluminium but now I am not so sure. I have a good quality hacksaw but no way of accurately making the cut.

Marcus

[Dave in Cairns]

Marcus, If you are going to attach the legs with a thread into a T-nut or similar , the top of the leg will need to be square. Usually the underside of the table is rebated at the angle to receive the leg. Once turned , the foot will able to be bevelled with a file. Tungsten blades work well with aluminium , but for a table saw or drop saw , you'll need a blade with 80 + teeth.

[hamster]

Hi Guys,

I was planning on welding a 3mm thick, 100mm square aluminium plate to the top of the legs that I would then screw though into the table top.

Dave, I'll have a look and see if I can get a suitable blade for my Triton, although I'm a bit nervous about how accurately I can cut an angled piece of round barstock, even with the protractor. I keep having visions of the stock rotating as it cuts and me ending up with an expensive pointy stick!

[Jeff]

There are mitre boxes with hacksaws, and rigging up a hacksaw to a wood cutting mitre box is pretty easy too. If you have a power mitre use a fibre metal cutting blade as for a power circular handsaw. They are typically smaller but not to worry. Do make the cuts smoothly and try not to let the blade get up too much speed. WEAR PROTECTIVE GEAR. I have cut a lot of metal in both of these ways. I also suggest you clamp the piece before starting any cutting. For the actual turning you can take a tip from a metal lathe and put a handle on it. Remember to rotate your stock very slowly and if you can find a way to lubricate the cutting action with thread cutting oil or similar it will be much easier. Put a pan under your work and perhaps have an assistant drip the oil on as you go, you won't want to start and stop and you will need both hands to hold the cutter. Good luck.

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"Turning wood into treasures"

[Glen Bridger]

Hi Hamster,
$200 per leg sounds a bit steep to me too. I reckon that they didn't want the job. Here my suggestion. Look in the Yellowpages and find a supplier for the alloy bar then, if it's a reasonable price find a machine shop that will do the turning.
If this works out in your budget, then get the supplier to cut the bar stock at the correct mitre angle.
They will more than likely cut it with a "cold saw" which will give you a perfect cut.
It won't be cheap, even using commerial grade alloy.
Metals are best turned in metal lathes, its much safer.

Glen