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Welded aluminium switchbox

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kenking-King Design29/01/2019 12:54:30
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301 forum posts
868 photos

A client, who'd previously ordered Mosquito U/C legs, contacted me again to ask if I could make an aluminium box to carry nine light switches, for mounting on the dashboard of his Land Rover. Although not aeronautical, this, my first experience of this aluminium welding process, may be of interest to fellow aeromodellers, and it worked so well I would encourage them to try it. I know it is well established, and others probably use it regularly, but there may be some such as myself for whom joining aluminium sections has been problematical.

For this job I was sent a cardboard mockup, with some switches and the basic dimensions required, seen here alongside the finished box

Start and finish !

The box is 205mm long, 65mm on the face, and approximately 50mm deep. The endview shows one acute angled bend, and one slightly obtuse.

Basic folded box

I used 2mm sheet for rigidity, but struggled to produce truly round 12 mm holes without severe burring. In the end I made a punch & die set, a la Q-max style, using silver steel, appropriately hardened, and that did the job niicely.

Nine hole row

Endplates are also 2mm sheet, and after some trials (and tribulations) with some soldering processes (It may be that my sheet has a high silicon content or something) I settled on Alu-weld, which worked very well indeed. An internal view displays the very neat weld fillets, as produced.

Internal view

I welded over the joins again on the outside, having established in trials that nothing would fall apart, and then dressed the fillet down to the surface, which shows solid metal. I haven't yet sectioned through a trial joint, but anticipate that penetration must be pretty well complete.

Endplate welded in

The finished box is extremely strong, and I'm well pleased with the result. I must state that I have no connection with Alu-weld, apart from being a satisfied customer.

Finally, a view of a switch in the guarded position .......

A  mounted switch

and the unguarded, ready for toggling.

Ready to toggle

Thanks for viewing, and I hope you find welding this way solves some problems for you.

SONNY MONKS29/01/2019 13:16:37
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269 forum posts

compliments on the fabrication work,very tidy indeed,i take it you have vast experience?

Former Member29/01/2019 14:49:39
724 forum posts

[This posting has been removed]

kenking-King Design29/01/2019 18:39:57
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301 forum posts
868 photos

Sonny, thanks for your kind words. I would hesitate to claim vast experience, but I have been around a long time, and one can't help but pick things up on the way. My first time with this process though, and I'm glad I found it (with the help of earlier posters).

Supertigrefan, I just followed the printed instructions, but in case you've not got them proceed as follows :-

Thoroughly clean the surfaces to be joined. After degreasing either file or rub with wet & dry paper. For my endplate joints I cleaned both components on the edges and a strip about 3 or 4mm wide on the faces. Heat was applied with a common type of gas cylinder torch, to the aluminium only, occasionally removing the flame and drawing a welding rod along the join to test the temp. Do not heat the rod directly. Once the rod melts draw it along the joint to lay down a small fillet. You may have to reheat a little to make up heat losses as you proceed. With the fillet molten agitate through it with a piece of stainless steel wire (or stainless screwdriver, it says in the text) scraping gently along the parent metal pieces under the fillet. This encourages the rod and parent metal to combine, forming a new alloy, and also means that some of the parent is absorbed into it, so there IS some penetration. When I filed and sanded off the raised external fillet I found solid metal throughout (see photo).

Hope this helps,

Ken

Bruce Collinson29/01/2019 19:11:40
576 forum posts

So in terms it’s brazing? I had a quick surf over lunch and found a lot of trade names Alu-Weld but not the product. I suspect lots of us will be checking this out. Where from.?

BTC

Former Member29/01/2019 19:24:53
724 forum posts

[This posting has been removed]

Stephen Smith 1429/01/2019 20:59:41
244 forum posts

Why not just tig it? If your doing fabrication I don't know how you manage without one.

Former Member29/01/2019 21:22:59
724 forum posts

[This posting has been removed]

onetenor30/01/2019 06:02:46
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1901 forum posts

I first used aluminium solder back in 57/8 when i crashed my heavy combat wing. This broke the nose off my Javelin engine.. I brass wire brushed the area round the joint then with the crank in place heated it on mum's stove and applied the stick which ran round the joint fairly well. Filed it a but to even off. Then to ensure airtightness smeared Araldite thinly round the area. The result wasn't too bad and the engine runs well today.I can't recall the brand now but it was new back then. However check out this page.

P.S. I still have some of the original rods but can't get to them just now to tell what they are.

onetenor30/01/2019 06:02:47
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1901 forum posts

I first used aluminium solder back in 57/8 when i crashed my heavy combat wing. This broke the nose off my Javelin engine.. I brass wire brushed the area round the joint then with the crank in place heated it on mum's stove and applied the stick which ran round the joint fairly well. Filed it a but to even off. Then to ensure airtightness smeared Araldite thinly round the area. The result wasn't too bad and the engine runs well today.I can't recall the brand now but it was new back then. However check out this page.

P.S. I still have some of the original rods but can't get to them just now to tell what they are. Maybe Lumiweld

Edited By onetenor on 30/01/2019 06:12:33

kenking-King Design30/01/2019 08:15:45
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301 forum posts
868 photos

Supposed to be driving from East to West Scotland today, Wed. 30th, so checking road conditions. If I don't go, or when I get back, I'll trudge over to my shed, check supplier details and post them here.

kenking-King Design03/02/2019 16:44:28
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301 forum posts
868 photos

This took a bit longer than expected, sorry! The supplier of the welding/brazing rod I used is Techno-weld. Find them at www.techno-weld.co.uk or enquiries@techno-weld.co.uk

I have an additional supplier with a similar product called HTS2000. He is Christopher Drew, Deats Ltd., Chy Vean,Higher Tredegar Rd., St. Ives, Cornwall TR 262 AU or at drewstoolshop@gmail.com

Usual disclaimer, but I'm sure either outfit will help you achive similarly satisfactory results.

Regards,

Ken

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