Where to buy blank chassis ?

[GrimJosef]

Thanks to the forum I've sourced some big(ish) transformers for my valve amp project. I now need a chassis to sit them on. I'm thinking of steel (they're heavy) and maybe 17" x 10" x 3" (this is a 100W amp based on four KT66s, so it needs plenty of room).

Bluebell Audio sell such a thing http://www.bluebellaudio.com/enclosuressteel.htm but just as a cross-check I wondered if there were any other suppliers ? Ideally I'm looking for off-the-shelf stuff rather than custom-made as Christmas is coming and the wallet's getting thin ...

Cheers,

GJ

[Top Cap]

There are places in the UK for buying these, always at a price of course.
I did a quick google and found these two:-

http://www.ampmaker.com/index.asp

http://livinginthepast-audioweb.co.uk/xfrmrch.html

I find the cost of packaging always seems to eat up the budget, some of the really nice rack cases look reasonably priced until you realise that you have to add chassis, top and bottom covers etc and finish up paying over £150 for the complete item. Take for example my latest project, it cost £15 in components but £35 for decent looking enclosure for a total final cost of £50 plus of course the dreaded post & packing .
Les

[Herald1360]

Have you thought of simple fabrication? A flat sheet of whatever you fancy on four suitably mitred or just part of the flange cut off bits of angle stock is pretty easy to do......

Maybe a large diecast box? You get a base cover included that way!

A local sheet metal fabricator could fold something up- complete with all holes etc ready punched- for a price, if you produce a suitable drawing.

Chris

[John12868]

Try Bluebell Audio. They sell parts for DIY Amplifier construction.
/enclosuresalu.htm

Regards

John

[yesnaby]

Hello,

The engineering/physics department at Essex University were very suspicious of why I was using their metal folding machine back in the 1970s ....

Michael

[John12868]

Oooops! Should have read the original post. Sorry

[Ed_Dinning]

Hi Josef, You can make your chassis using car repair plate (galv steel) and it sprays up nicely. It is usually thin enough to fold in a vice.
Don't be put off by the metalwork as the material is low cost.
For larger holes a "cone-cut" works fine.

If you get into it big style it is worth investing in Q-Max chassis punches.

Have you tried any model engineers in your area, they could probably make up a chassis for you easily.

Ed

[dseymo1]

An old caravan will yield as much sheet aluminium as you are ever likely to need - perhaps a little on the light gauge side but easily reinforced in fabrication. You can cut it with tinsnips, fold it by hand between a couple of bits of Dexion, and pop-rivet joints.
Otherwise, discarded PC cases make very tidy enclosures and/ or chassis with minimal modification.

[yesnaby]

Hello,

This last post is interesting as when I made some aluminium chassis in the 1970s, one place that was always recommended for getting the sheets was caravan producing 'factories' (can't think of the proper term for this). Not sure whether they still use the same stuff, probably not.

Michael

[GrimJosef]

Thanks very much for the replies folks

Chris, Michael, Ed, dseymo1:
Once upon a time I would have been tempted to try making my own chassis. But then I did try, and that's when I learnt just how cack-handed I was (and still am). I could do it, but to end up with anything I'd be prepared to let anyone else see I'd have to spend way, way too long on it. And if I ever get this project finished it will be a bass guitar amp, so a) there is a risk that other people will see it and b) time not spent learning metalwork will be time spent learning the guitar (and if you think my metalwork is bad, you should hear my guitar playing ).

I should also point out that the ironwork really is heavy. The mains transformer weighs 9kg and the output tranny and choke add another 8Kg between them. Hence my preference for steel, and heavyish steel at that. And even then I think the whole thing is going to need some extra reinforcement. I fear this eliminates the PC case option, although this is otherwise a very neat idea and one I will definitely file away for future use. I also like the sound of a die-cast box. But I don't think I'll get one big enough. And even if I did, the slight taper that's needed to get them out of the die might make it difficult to attach a front panel squarely.

Les,
I had come across Ampmaker (and then forgot about them) but not Livinginthepast-Audioweb. Thanks for that. They are the sort of people I was looking for but their chassis are not, I think, as good as Bluebell's for my particular application. However I will re-visit Ampmaker because they do head cabinets too and I am also "challenged by" (= useless at) woodwork.

John (and I),
We know about Bluebell. They can sort me out for £11.22+VAT for the basic chassis. I would have gone straight to them (and I probably still will) but I was also interested in a cage. Unfortunately their cage is only 5.2" high which won't clear my mains transformer.

In summary it looks as though there aren't many suppliers in this field (maybe I'm not surprised) but there's at least one who can get close.

Thanks again,

Cheers,

GJ

[ScopeMonkey]

Originally Posted by yesnaby

Hello,

This last post is interesting as when I made some aluminium chassis in the 1970s, one place that was always recommended for getting the sheets was caravan producing 'factories' (can't think of the proper term for this). Not sure whether they still use the same stuff, probably not.

I needed a new top plate for a chassis a few years ago - something I could chassis punch easily, so aluminium was ideal.

A firm of window fabricators down the road, when asked if they had any offcuts, proceeded to cut me a plate the right size and I don't think they even charged anything. Might be worth a try if you can locate any facilities to do the relevant folding.

[Mike Phelan]

GJ
You could use angle for the corners if you aren't confident with bending sheet neatly. It won't take long if you use pop rivets to hold it all together.
You could even spray paint it if you sort the earthing out.

[John M0GLN]

What I have done in the past for projects involving big heavy transformers, chokes and capacitors is to mount these on a flat steel base, say 2 - 3 mm thick, this base then only requires fixing holes drilling in it, and to mount the other components on a much lighter aluminium sub chassis screwed to this base, its much easier to work with, punching out for the valve holders etc. In plan view just position everything as if it were on a single chassis and the wiring would be the same.

John

[Antlong]

Hello all,

I recently visited the Morgan car factory at Malvern; they have a lot of aluminium offcuts, quite thick, may well be worth contacting.

Regards Ant