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Originally Posted by OzEclipse
Leo,
Unless you want to make large numbers of these tubes, making your own is probably a case of diminishing return if not more expensive.
The mass produced ones have extra tube thickness on the end piece for the locking thread, a brass compression ring and internally threaded to act as baffling and reduce internal reflections and they are black anodised. I suspect the cost of the black anodising is probably almost as much as buying the extension tubes.
Have a roam around Ali Express, EBay, Amazon etc and see if you can find a finished piece that you can modify if you need something shorter.
The other option is to check scrap metal merchants or scrap bins of an engineering works. If you're lucky, they'll sell you stuff retrieved from the scrap bin at scrap weight cost or just give it to you.
Joe
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Thanks Joe!
As it is it's just a practice to get some machining in, I have the lathe, still as new with minimal use. Many of the commercial units I have do not have the ridging internally to reduce reflections though my little 35mm GSO does, it's simply a thin threaded section, I can do that it's only time which really means nothing on a pension. It's more about a precise length I need for a camera and 5 times powermate. It's not something made as one unit though I could mix and match to get the length I need but I'll machine one. Too many joints introduces slop and misalignment.
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We don't have any engineering shops locally, Capral have the size I want and I've contacted them to see if they'll give me a smaller section. Like most materials I buy, even if I did buy a 6 metre length I'd eventually use it for something, I do a lot of weird projects.
The anodising itself is cheap, basic kitchen ingredients to do it including black food dye. I'm not sure on the end result (and will look into the proper chemicals), last time I did anodising I worked at an electroplating place in Carnarvon St Silverwater where I ran the zinc and anodising tanks, AH, Westwood Winters, Wow, I even remembered the companies name (eventually). That was early to mid 80's WOW, I'm getting old.
Hmm, they are still in business, sadly the old owner will be long deceased (Merve Westwood) so I won't push my luck on getting some cheap work done there.
We no longer have any local engineering shops or I'd have scored an off cut of 60mm solid alloy. I have some 125mm 7075 and some 40mm 7075 but I'm not wasting the 125mm, I have a job for it, the 40mm I've misplaced, probably laying in the corner of my little garden shed or maybe under the crate with the new milling machine in, I had to roll the crate up a ramp and in the door somehow.
My friend used to give me most of my materials free before he shut down ( I had the option to go in and take almost anything I wanted when he shut down but I couldn't bring myself to do that to a friend (I always do his and his wife's business computers free, he's a good friend and has helped me out a lot)) He wouldn't accept cash for materials he'd paid a fortune for and I do not like ripping anyone off, let alone people I consider friends (a conscience can't be removed, not alcohol and not surgery (I don't drink now for over 30 years)).
If I had the lathe capacity I'd look into friction welding 50mm inside 60mm with 5mm wall, it's just spinning one up at a suitable speed, my Chinese lathe won't do that or I highly doubt it would. It would be a lot of time with trial and error and I doubt I'd succeed. I could try and fuse it with my plasma cutter but I think I'd blow more away than I'd fuse.
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The grade of aluminium matters as well. You will want it suitable for machining as well.
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Doug I'm reasonably familiar with the grades and believe 6060/6061 is fine with good corrosion resistance, machinability and weldability, not that I'm setting up my TIG, I can't even see to use it. I'm OK on the MIG or arc but TIG is what I excelled at 25+ years ago, not now.
