Aluminium generator locker lid

[blackrose]

To clarify, that's an aluminium lid, not an aluminium generator!

 

I'm making a locker for my generator. (I've been through all the safety & BSS issues so let's not take this thread down that route). The frame is made from 2" angle and I was thinking of making the lid from 6mm thick aluminium sheet which isn't cheap. The lid would be split into 3 parts with the central part hinged and resting on the two outer sheets so that the generator can be refuelled.

 

 

My question is would the 6mm thick aluminium sheets (Grade 6082T6 / H30TF) bend where they are unsupported across the 45cm width if someone sat or stood on the locker? (i.e. the sheets are only supported around the perimeter of the frame). Or should I put some supports across the frame and use thinner gauge aluminium sheet?

Edited September 14, 2013 by blackrose

[Robbo]

Will you be running the generator in the box? If so then thick dense wood would be better to cut the sound down.

[blackrose]

Will you be running the generator in the box? If so then thick dense wood would be better to cut the sound down.

 

It's an open locker made from angle so that air can get in but the rain can't. The open sides vent overboard and the onboard facing sides will be solid. So the sound will come out anyway, but I'm not concerned about noise. It's a very quiet generator - much quieter than my engine. I just need to know how strong 6mm aluminium is before I order it.

Edited September 14, 2013 by blackrose

[bottle]

It will bend depending on how much weight is put on it, so buy 6mm and support it.

 

 

Have I stated the bl####ng obvious.

[blackrose]

If I'm going to support it then I wouldn't use 6mm aluminium for the lid - I'd probably use 4mm. I've run out of angle so I was trying to avoid ordering more of that as well. I just thought I might be able to get away without supports if I used 6mm for the lid.

Edited September 14, 2013 by blackrose

[Sir Nibble]

I think you will have no problem with someone standing on a 6mm ali sheet supported at only 450mm separation. Until of course a really fat bugger decides to tap dance on it!

[blackrose]

I think you will have no problem with someone standing on a 6mm ali sheet supported at only 450mm separation. Until of course a really fat bugger decides to tap dance on it!

 

Yes, it would depend on the weight of the person standing on it. I think I'll give it a go. If it looks too weak then I can always retrofit some supports underneath.

[Barry]

If you need to support the lid but don't want to buy more angle, could you make some bearers out of wood?

[bottle]

My answer was a bit tongue in cheek but it will distort a little no matter how thick it is, aluminium stretches and stays stretched, the problem will manifest itself in the hinges.

[onionbargee]

To clarify, that's an aluminium lid, not an aluminium generator!

 

I'm making a locker for my generator. (I've been through all the safety & BSS issues so let's not take this thread down that route). The frame is made from 2" angle and I was thinking of making the lid from 6mm thick aluminium sheet which isn't cheap. The lid would be split into 3 parts with the central part hinged and resting on the two outer sheets so that the generator can be refuelled.

 

 

My question is would the 6mm thick aluminium sheets (Grade 6082T6 / H30TF) bend where they are unsupported across the 45cm width if someone sat or stood on the locker? (i.e. the sheets are only supported around the perimeter of the frame). Or should I put some supports across the frame and use thinner gauge aluminium sheet?

6mm Al is so over the top my jaw just hit the floor !

 

I'm guessing £150 a sq / M ?

 

ideally you would use 2mm and weld in angle frames to stiffen it. Think of a aircraft, strong but light.

 

I had a 2mm Al lid folded for a 6 kva Diesel geny for £20 by my local sheet metal firm a few months ago .

Edited September 14, 2013 by onionbargee

[blackrose]

If you need to support the lid but don't want to buy more angle, could you make some bearers out of wood?

 

That's another posibility, yes.

My answer was a bit tongue in cheek but it will distort a little no matter how thick it is, aluminium stretches and stays stretched, the problem will manifest itself in the hinges.

 

I've made things out of aluminium before and never had that sort of distortion problem.

6mm Al is so over the top my jaw just hit the floor !

 

I'm guessing £150 a sq / M ?

 

ideally you would use 2mm and weld in angle frames to stiffen it. Think of a aircraft, strong but light.

 

I had a 2mm Al lid folded for a 6 kva Diesel geny for £20 by my local sheet metal firm a few months ago .

 

I don't think 2mm would be strong enough for someone to sit on without bending between the supports unless I put a lot of frames in. Mechanical strength is multi-dimensional and I'm not sure if aircraft are generally subject point loading on their fuselage.

 

And I don't weld so what's it going to cost to bring in a welder? I've bolted the frame together with 10mm x 20mm stainless dome-headed coachbolts and stainless security nuts. The whole frame is actually made of 50mm x 4.8mm equal aluminium angle so that it won't corrode and because I hate working with steel. So I either buy more aluminium angle or I buy thick aluminium sheet that won't need supporting. Swings and roundabouts...

 

Edit: I've ended up ordering 4mm sheet and some more aluminium angle which worked out cheaper than 6mm sheet alone. I should have enough sheet left over to do the inboard side of the locker too.

Edited September 14, 2013 by blackrose

[smileypete]

You're gonna run a genny in a locker? Hmmm....

 

BSS issues aren't a problem really just take it out while the BSS is being done. Doesn't mean it's at all safe or workable of course.

 

All that aside, how about making a 1 piece lid with framing, then a separate slightly raised hinged flap for whatever.

 

Personally though nothing can be guaranteed safety wise, I'd see if the genny can take an external fuel tank that can then be kept in a separate suitable locker. Also a powerful ignition protected bilge blower would help stop heat, petrol fumes, or exhaust fumes accumulating.

 

cheers, Pete.

~smpt~

Edited September 14, 2013 by smileypete

[blackrose]

You're gonna run a genny in a locker? Hmmm....

 

BSS issues aren't a problem really just take it out while the BSS is being done. Doesn't mean it's at all safe or workable of course.

 

All that aside, how about making a 1 piece lid with framing, then a separate slightly raised hinged flap for whatever.

 

Personally though nothing can be guaranteed safety wise, I'd see if the genny can take an external fuel tank that can then be kept in a separate suitable locker. Also a powerful ignition protected bilge blower would help stop heat, petrol fumes, or exhaust fumes accumulating.

 

cheers, Pete.

~smpt~

 

I am making a 1 piece lid with a hole and a flap.

 

There will be no heat build up, accumulating fumes or exhaust. The locker is made from 2" angle spaced by about 4" horizontally, apart from one solid side and the lid, so it's basically out in the open air. I'll post a picture once it's finished.

Edited September 14, 2013 by blackrose

[blackrose]

This is it. I've just got to put one more length of angle across the top long edge under the handrail to stop the rain getting in, make the lid, the front side and the sheet over the half side next to the control pedestal.

 

It's all bolted together with 10mm x 20mm stainless coachbolts and security nuts - but I haven't tightened them up and snapped them off yet. It's bolted through the deck with the same bolts but secured with ordinary nuts so I should be able to remove the whole thing in one piece if I want to (I think!) Anyway, I can't ever see why I'd need to remove it. It's not going to corrode and I'll just paint around it.

 

The generator is on wheels so it can be rolled in and out for servicing. I'm just figuring out how to make the front side/door.

 

Edited September 16, 2013 by blackrose

[Captain Fizz]

Sorry, but it is going to corrode. Stainless and aluminium don't like each other.

[blackrose]

Sorry, but it is going to corrode. Stainless and aluminium don't like each other.

 

I disagree.

 

I've had this conversation before with a woman in a chandlers who also thought that she knew what she was talking about. She shook her head at me muttering "dissimilar metals!" saying that brass and steel didn't like each other and the steel would corrode.

 

This may be true if you put them in contact underwater, but in the air there isn't a problem. Dissimilar metals behave galvanically if they are immersed in an electrolyte. Without the electrolyte they don't react and are perfectly happy together. Any rainwater that gets between the aluminium and stainless won't stay there very long.

 

Anyway, I've made something from aluminium and stainless screws before which has been left outside for many years and I've never had a problem. So how do you account for the fact that it didn't corrode?

Edited September 16, 2013 by blackrose

[staffiepower]

Hi Blackrose.

I think you made the right choice going for the 4mm ali , iv'e made a few aluminium fuel tanks for racing cars and recently my own series 1 landy,

and find making them out of 3mm, and obviously fully welding all the seems a good construction i certainly wouldn't go less.

as for the fear of corrosion between the stainless fixings and the ali construction i wouldn't worry about that, mild steel and ali combination

would be a bit of a concern as any old landy fan would tell you but stainless fixings and ali has been used in bridge guards for years without

problem.hope this helps regards neil.

[blackrose]

Hi Blackrose.

I think you made the right choice going for the 4mm ali , iv'e made a few aluminium fuel tanks for racing cars and recently my own series 1 landy,

and find making them out of 3mm, and obviously fully welding all the seems a good construction i certainly wouldn't go less.

as for the fear of corrosion between the stainless fixings and the ali construction i wouldn't worry about that, mild steel and ali combination

would be a bit of a concern as any old landy fan would tell you but stainless fixings and ali has been used in bridge guards for years without

problem.hope this helps regards neil.

 

Thanks Neil.

 

I think Onion was right that 6mm was over the top, but only from a financial perspective. If money was no object I'd have a big barge made out of aluminium!

 

Mike

[blackrose]

Here are a couple of pictures of the finished locker. I've just got to hinge the flap for the fuel tank. The generator will be locked with a couple of motorbike chains to the steel, one of which will stretch across the front from the vertical rail to a padlock located inside the control pedestal. It's not impregnable but it's a decent deterrent. It's all bolted together with security nuts apart from the front which can be removed in one piece for generator servicing. (The chain will prevent the front from being removed by unauthorised persons!)

 

It took a bit of thinking about to design it into that space, keep the generator secure, provide adequate ventilation, stop the rain getting in and have all controls accessible. I've got some primer for aluminium so eventually it will be painted. It wasn't that difficult to make and it's rock solid (I've stood on it). For a DIYer with limited skills I'm quite pleased with the result. All it took was an angle grinder, a drill and a socket set.

 

 

Exhaust end

Edited October 3, 2013 by blackrose

[Timleech]

I'm currently trying to repair an old Lucas marine parallel motion windscreen wiper, it's made largely of aluminium with stainless fastenings, it's been in a real marine environment (ie salty) for all its life which I'm guessing is probably at least 40 years.

There is some serious local corrosion of the ali in a couple of areas, but not especially around the stainless fastenings, most of it is fine, and there has been no real problem getting the fastenings undone.

I don't think Blackrose needs to worry on that score.

 

Tim

[blackrose]

I'm currently trying to repair an old Lucas marine parallel motion windscreen wiper, it's made largely of aluminium with stainless fastenings, it's been in a real marine environment (ie salty) for all its life which I'm guessing is probably at least 40 years.

There is some serious local corrosion of the ali in a couple of areas, but not especially around the stainless fastenings, most of it is fine, and there has been no real problem getting the fastenings undone.

I don't think Blackrose needs to worry on that score.

 

Tim

 

Yes, I think aluminium can corrode in salt water environments, but my understanding is that apart from salty exposure ali can only corrode on the very surface and then it stops because the surface corrosion layer then prevents any further corrosion. Anyway, it will be painted at some point - not just yet though - I've got other stuff to do.

 

Mike

Edited October 3, 2013 by blackrose