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#1
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Steel or Aluminum
Thanks to all the RATs for previous advice on custom chassis size. I'd like
to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west |
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#2
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Stck to aluminum or other non-magnetic materials. Steel conducts hum into
circuitry like no tomorrow. -- Gregg "t3h g33k" http://geek.scorpiorising.ca *Ratings are for transistors, tubes have guidelines* |
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#3
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Aluminum doesn't rust and is easy to drill, but solder doesn't stick to
aluminum and chassis can be flimsey. Steel is tough and can be soldered onto, but can be difficult to drill (and can damage drill bits and wears out punches quicker) and can rust over time. Personally, I'd choose Al. C.W. |
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#4
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"west" Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, ** Nickel or chrome plated copper would be better than either. ............... Phil |
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#5
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"Gregg" wrote in message
news:ujkMd.46$Ox3.44@clgrps13... Stck to aluminum or other non-magnetic materials. Steel conducts hum into circuitry like no tomorrow. o0hh t3h n0e5s!!!!!!!!!11111oneone http://webpages.charter.net/dawill/I...tAU7_Front.jpg All depends on what you want. That's why buildings are made of steel and airplanes of aluminum. Aluminum tends to be soft and weak, but stiff (because you use a greater thickness), corrosion-resistant and easy to work. Steel is stronger, cheaper and all the other things that usually go with it (like solderability). Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#6
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Aluminium is lighter. This can be important too.
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#7
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schreef in bericht oups.com... Aluminum doesn't rust and is easy to drill, but solder doesn't stick to aluminum and chassis can be flimsey. Ever thought of copper ? |
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#8
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IMHO aluminum is too weak and it's not so easy to work 'cause it is too soft
and bends and sticks to the tools. Steel is too hard, particularly stainless... a guy here in Milan made a 6550 PP amp out of a large rectangular (reversed) oven pan, some 4-5 mm of AISI304. I suppose it's .. well .. robust. I'd say that copper is the best of all in terms of ease of machining: just remember to paint it with a protective transparent lacquer as soon as You finish polishing it with sandpaper, or it will get brown in a wink. A further advantage of a 3mm copper plate is that it IS definitely a ground reference, at least for a power amp. Ciao Fabio "west" ha scritto nel messaggio . .. Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west |
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#9
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"west" wrote in message . .. Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west Aluminium is cheap and easy to machine and work with .. Electrically, it's resistance, per unit, volume, is lower.... than steel ... Steel is stronger but is harder to work ... This is not a bridge, you're building .. If this is a DIY, build it at home, jobby ... go for aluminium .. I like 2mm thick Steel is ferrous ... iron .. magnetic ... Trannies sit on it .. magnetic fields ... not a good idea ... Stainless steel ? Looks attractive but will blunt every drill and hole punch you've got .. 2mm ALLLOOOOOMINUM ... go for it .. cheers jim .. |
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#10
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Understand Tim, but what would you use to make an amp?
west "Tim Williams" wrote in message ... "Gregg" wrote in message news:ujkMd.46$Ox3.44@clgrps13... Stck to aluminum or other non-magnetic materials. Steel conducts hum into circuitry like no tomorrow. o0hh t3h n0e5s!!!!!!!!!11111oneone http://webpages.charter.net/dawill/I...tAU7_Front.jpg All depends on what you want. That's why buildings are made of steel and airplanes of aluminum. Aluminum tends to be soft and weak, but stiff (because you use a greater thickness), corrosion-resistant and easy to work. Steel is stronger, cheaper and all the other things that usually go with it (like solderability). Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#11
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I did think of copper, but where can I buy sheets o copper?
west "Ronald" wrote in message ... schreef in bericht oups.com... Aluminum doesn't rust and is easy to drill, but solder doesn't stick to aluminum and chassis can be flimsey. Ever thought of copper ? |
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#12
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Here's a whe
http://www.onlinemetals.com/merchant...owunits=inches Obviously it is sold at Tiffany's prices if You only need 1 sqft... Ciao Fabio "west" ha scritto nel messaggio ... I did think of copper, but where can I buy sheets o copper? west "Ronald" wrote in message ... schreef in bericht oups.com... Aluminum doesn't rust and is easy to drill, but solder doesn't stick to aluminum and chassis can be flimsey. Ever thought of copper ? |
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#13
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"Jim McDonald" wrote in message
... Aluminium is cheap and easy to machine and work with .. , , , , .... ... ... , .. , , ... .. ... .. ... .. ... ... .. ... .. cheers jim . Ackkkk. My comma, period and especially the blatant apostrophe, will never be the same. ~:-O Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#14
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"Fabio Berutti" wrote in message
... IMHO aluminum is too weak Which is why you use thicker pieces. And as a matter of fact, 7075-T6 is as strong as 1018 cold rolled (and 2.7 times stronger and stiffer by weight). and bends and sticks to the tools. They sell WD-40, y'know... it's not just for displacing water anymore! (No, it never was, and never will be, a spray lubricant!) Steel is too hard, particularly stainless... They also sell this new wonder metal known as High Speed Steel. a guy here in Milan made a 6550 PP amp out of a large rectangular (reversed) oven pan, some 4-5 mm of AISI304. I suppose it's ... well .. robust. Nice. I'd say that copper is the best of all in terms of ease of machining: Gack choke sputter!!! Pure copper is about the gummiest thing you can find. (They say razor sharp tooling and milk for cutting fluid is the best you can do.) Copper alloys like brass and bronze generally machine well, but are too "slippery" (hence their use in bearings) to cut with anything but the sharpest tools. just remember to paint it with a protective transparent lacquer as soon as You finish polishing it with sandpaper, or it will get brown in a wink. Or green, or blue. Unless you want that. In which case, toss it in your litterbox for a week.  A further advantage of a 3mm copper plate is that it IS definitely a ground reference, at least for a power amp. Not that using the chassis for grounding (unless done very carefully) is ever a good idea, of course. This I know from personal experience... Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#15
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"Fabio Berutti" wrote in message
... Here's a whe http://www.onlinemetals.com/merchant...owunits=inches Obviously it is sold at Tiffany's prices if You only need 1 sqft... It's also used for roofing and gutters, so you might check a local fancy-shamancy remodeling place in town. Don't know if it'll be thick enough though. Steel is very easy to copper plate, so if you just want the look, that would be a good cheap solution. Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#17
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west wrote:
Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west I made all my projects of aluminium. Mostly 1.5 to 2mm thick. Where it was too flimsy I used aluminium Ts or Ls or Us. Self threading screws or rivets to fasten them to the chassis. I made frontpanels from 5mm and even 10mm alu. Whished I could have machined them. I like to build modules on aluminium panels and then screw them together into a frame of alu Ls. Use Us for bigger frames. For smaller projects you can get alu profiles where alu sheets slide in. Almost no screws to open view. Also I hate to drill or punch holes into complex, hollow forms. It's easier with alu sheets instead. And when I mess up I lose just one sheet and not a whole chassis. I also like to work with brass and copper but never did chassis with those materials except for some small boxes which were used for RF-shielding. Steel chassis are more attractive for series production because one can point-weld and do sharper bends. Then galvanize the chassis for anti-corrosion. But this was always out of question for small projects. Nowadays even alu welding is not out of the question provided you can afford the appropiate welding machine. The hardest part was always to give the front panel a nice finish. Brushed alu is nice, brushed brass is nicer. But you need some contraption to make linear and parallel brush strokes. It just does not look right when made free handedly. I tried sandblowing alu and brass but it takes all shine away and looks dull. It is also very difficult to do evenly. But what looks nice is sandblowing and then brushing. With alu you need to keep the temperature down, otherwise the alu will smear and you get little ripples on the surface which spoil it all. That is why a rotary brush is not a good idea. Nowadays I just don't have the time do such jobs :-( . You might ask on the DIY metal works news groups. There are some savvy guys. Kind regards, Eike -- Lions go to absurd lengths to retain the posession of their skins. - Stewart Edward White 1913 |
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#18
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Sorry, I should have been more precise: when I speak about "machining" I
mean using the (mostly hand) tools I have (like most hobbysts): drill, cup saw, conic drill bits to enlarge holes, jigsaw, files of any kind, grinder... I never used a puncher. I usually make even the trapezoid holes for mains plugs starting from a drill hole and working it out to shape with a file: it's an hobby, after all, and the more time consuming, the better. I did not mean that copper is a good material to be worked with industrial tools, but I suppose this was not the scope of the thread... I happen to have some friends working in some big factories, producing pressure vessels and heat exchange equipments for refineries, but I never managed to get access to the tubesheet drilling machine to "speed up" my hobby. As per the ground reference: I did it in 2 or 3 units, welding the "grounds" of the circuits to the points of the strips that were in turn bolted to the frame plate. I do not understand why a bus wire should be a better "zero" (ie. lower internal resistance) than a 3 mm thick plate, 12" wide by 16" deep. (Obviously the abovementioned units were all power amps, I never did this with phono stages..) Ciao Fabio "Tim Williams" ha scritto nel messaggio ... "Fabio Berutti" wrote in message ... IMHO aluminum is too weak Which is why you use thicker pieces. And as a matter of fact, 7075-T6 is as strong as 1018 cold rolled (and 2.7 times stronger and stiffer by weight). and bends and sticks to the tools. They sell WD-40, y'know... it's not just for displacing water anymore! (No, it never was, and never will be, a spray lubricant!) Steel is too hard, particularly stainless... They also sell this new wonder metal known as High Speed Steel. a guy here in Milan made a 6550 PP amp out of a large rectangular (reversed) oven pan, some 4-5 mm of AISI304. I suppose it's .. well .. robust. Nice. I'd say that copper is the best of all in terms of ease of machining: Gack choke sputter!!! Pure copper is about the gummiest thing you can find. (They say razor sharp tooling and milk for cutting fluid is the best you can do.) Copper alloys like brass and bronze generally machine well, but are too "slippery" (hence their use in bearings) to cut with anything but the sharpest tools. just remember to paint it with a protective transparent lacquer as soon as You finish polishing it with sandpaper, or it will get brown in a wink. Or green, or blue. Unless you want that. In which case, toss it in your litterbox for a week. A further advantage of a 3mm copper plate is that it IS definitely a ground reference, at least for a power amp. Not that using the chassis for grounding (unless done very carefully) is ever a good idea, of course. This I know from personal experience... Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#19
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Phil Allison wrote: "west" Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, ** Nickel or chrome plated copper would be better than either. Its interesting you should say this. I recall a pair of EAR509 models with chromed chassis. What mess they both looked after 15 years. Peeling chrome, wrinkles, spots..... One of them had caught on fire inside and burned out its power tranny. ( I found the fuse value was 6 amps instead of 3 amps ), and the heat made that chassis all the worse. Dynaco ST70 also looks shabby after time, McIntosh..... Unless you get a real good chrome job done, its pita. I have a pile of chassis ready for new amps. these were all made by a professional metal worker with some huge automatic stamping machines. There are perforated steel coves, bottom plates, transfomer brackets, everything looks like its was made where Quad gets their stuff done. Its all 2mm thick steel, and the range of powder coating available from the same place is impressive I also have a pile of steel pots for all the transformers, and these are beautifully welded and ground at the corners like all the chassis and cages. Its not just the material that matters, its work that is put into making it look made well, strong, and smooth to touch, so that its impossible to cut a finger anywhere. Steel is a fine material for tube amp chassis because it don't bend when an amp is dropped. There is no bother with magnetics. I never use the chassis for the 0V rail; this is always a separate path and it is connected to the chassis at one point only with a 5 watt 15 ohm R The chassis is connected to the earth directly. Hum never is a problem. I have done 300 watt amps by sawing a 75mm x 40 mm rectangular steel tube in half length wise to make a channel size in 3 mm steel I couldn't find. I arc welded and ground it round at the corners. Then I made the chassis top in 2 mm AL, and had it anodised. Lots of careful drilling, counter sinking, sanding was done, and one has to keep a very keen eye out for avoiding scratches in the metal one uses. I have also used brass channel, with steel tray and box for the PS, and an AL top for the tubes. I might consider chrome, but the prep work has to be ever so good. It can be a rugged finish which lasts well compared to paint. Tube amps are heavy, and the slightest bump against something takes the paint off. But powder coat is not bad. The work the locals here do looks like the best stove enamel finish you could ever find. But that silver look of chrome looks cheap and nasty to me although other dudes think its very nice. I just spray paint some gear, and that's good enough for a one off where somebody wants a black item. Patrick Turner. .............. Phil |
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#20
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On Thu, 03 Feb 2005 03:54:05 +0000, west wrote:
Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west My personal preference is aluminium for one-off chassis and steel for multiple orders. Ali is easy to work if you keep to 1.6mm or, at most, 2mm thickness. It is possible to bend it with minimal tooling (providing you keep the lengths and thickness down and arn't too fussy about the end result). Ali's natural finish isn't too bad for prototypes and you can get suitable primers to allow it to be painted. It doesn't rust anyway! Steel is much harder to work in a home workshop (bending can be *really* difficult as you need a serious amount of pressure) but, providing you want a few items doing, it can work out much cheaper for a local sheet metal firm to use. You don't really need 2mm steel unless you have really heavy ironwork to support. Steel is also generally easier to get a good finish on too - it needs it though to prevent rust! -- Mick (no M$ software on here... :-) ) Web: http://www.nascom.info Web: http://projectedsound.tk |
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#21
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Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west I'll probably get something wrong here but... From the technical standpoint, the non-ferrous metal (aluminum) works better to shield the components from stray (leakage) magnetic fields from the power transformer and other sources. It is also less prone to induced currents in the chassis itself from leakage fields. |
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#22
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"Jon Yaeger" wrote in message
... 1) I don't know of an easy way to join and seal copper without using solder or brazing material, which destroys the "virgin copper" look. If you are painting it with an opaque finish, then no problem. Try phos copper - low melting point while keeping the appearance. Or weld (TIG needs a few amps per thousandth thickness due to the conductivity), or just make your joints tight. Theoretically you could also use a brass braze and use acid to burn the zinc out of the surface, leaving it coppery. 2) Copper is fairly reactive and unless protected can corrode in certain environments in conjunction with dissimilar metals (e.g. steel) Actually, copper happens to be one of the noble metals - in fact steel provides galvanic protection, to the dismay of some old radio chassis which were copper plated (possibly for solderability?). (Frankenhouse is one rusting example of this action; all the copper remaining is still pink. Most of the surface is rough with rust spots crunching though.) Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#23
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Definitely aluminum, steel is much too difficult to work and heavy too.
If you need to add more strength to a chassis, then BRACE the underside with some heavy duty aluminum angle stock, available at most hardware stores. Use lots of metal screws to secure it and run it (or them) the length of the chassis. If your clever with your layout you can even bolt the transformers directly to them. John "west" wrote in message . .. Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west |
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#24
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"Fabio Berutti" wrote in
: IMHO aluminum is too weak and it's not so easy to work 'cause it is too soft and bends and sticks to the tools. Steel is too hard, particularly stainless... a guy here in Milan made a 6550 PP amp out of a large rectangular (reversed) oven pan, some 4-5 mm of AISI304. I suppose it's .. well .. robust. I'd say that copper is the best of all in terms of ease of machining: just remember to paint it with a protective transparent lacquer as soon as You finish polishing it with sandpaper, or it will get brown in a wink. A further advantage of a 3mm copper plate is that it IS definitely a ground reference, at least for a power amp. Ciao Fabio Aluminium comes in a number of different grades. Some varieties (like the type used to some cheap sheet ali) indeed are weak and are nasty to machine (kinda like cheese). Extrusions tend to be made of better stuff (though it would pay to check with your supplier as to what you are getting - there is a 4 digit number that applies to ali which defines its characteristics). I love it for chassis making!. You can anodise it all sorts of nice colours. http://homepages.kcbbs.gen.nz/moby/6A3.jpg M |
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#25
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As per the ground reference: I did it in 2 or 3 units, welding the "grounds" of the circuits to the points of the strips that were in turn bolted to the frame plate. I do not understand why a bus wire should be a better "zero" (ie. lower internal resistance) than a 3 mm thick plate, 12" wide by 16" deep. (Obviously the abovementioned units were all power amps, I never did this with phono stages..) I would avoid passing heavy currents thru the chassis, like heater currents (could create some hum as some "grounds" would have some 60Hz voltage developed on it due to the chassis resistance (low, but not zero). I usually do "star" grounds where things like the ground return of the power transformer, negative side of filter caps, and cathode resistors for the output tubes meet. It's much easier to manage current flow paths with separate wires than trying to predict the paths currents would take thru a chassis. Some production amps did use the chassis, but that's after an iteration or two in the lab by experienced people. And they probably did star the high currents and used the chassis for small currents. |
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#26
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Can you send me some pixs of your chassis with the dimensions? Maybe we can
do some business, if they're for sale. Cordially, west "Patrick Turner" wrote in message ... Phil Allison wrote: "west" Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, ** Nickel or chrome plated copper would be better than either. Its interesting you should say this. I recall a pair of EAR509 models with chromed chassis. What mess they both looked after 15 years. Peeling chrome, wrinkles, spots..... One of them had caught on fire inside and burned out its power tranny. ( I found the fuse value was 6 amps instead of 3 amps ), and the heat made that chassis all the worse. Dynaco ST70 also looks shabby after time, McIntosh..... Unless you get a real good chrome job done, its pita. I have a pile of chassis ready for new amps. these were all made by a professional metal worker with some huge automatic stamping machines. There are perforated steel coves, bottom plates, transfomer brackets, everything looks like its was made where Quad gets their stuff done. Its all 2mm thick steel, and the range of powder coating available from the same place is impressive I also have a pile of steel pots for all the transformers, and these are beautifully welded and ground at the corners like all the chassis and cages. Its not just the material that matters, its work that is put into making it look made well, strong, and smooth to touch, so that its impossible to cut a finger anywhere. Steel is a fine material for tube amp chassis because it don't bend when an amp is dropped. There is no bother with magnetics. I never use the chassis for the 0V rail; this is always a separate path and it is connected to the chassis at one point only with a 5 watt 15 ohm R The chassis is connected to the earth directly. Hum never is a problem. I have done 300 watt amps by sawing a 75mm x 40 mm rectangular steel tube in half length wise to make a channel size in 3 mm steel I couldn't find. I arc welded and ground it round at the corners. Then I made the chassis top in 2 mm AL, and had it anodised. Lots of careful drilling, counter sinking, sanding was done, and one has to keep a very keen eye out for avoiding scratches in the metal one uses. I have also used brass channel, with steel tray and box for the PS, and an AL top for the tubes. I might consider chrome, but the prep work has to be ever so good. It can be a rugged finish which lasts well compared to paint. Tube amps are heavy, and the slightest bump against something takes the paint off. But powder coat is not bad. The work the locals here do looks like the best stove enamel finish you could ever find. But that silver look of chrome looks cheap and nasty to me although other dudes think its very nice. I just spray paint some gear, and that's good enough for a one off where somebody wants a black item. Patrick Turner. .............. Phil |
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#27
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Tim,
You should go in the chassis/metal business. Sorely needed and I bet you would be very successful. west "Tim Williams" wrote in message ... "Fabio Berutti" wrote in message ... IMHO aluminum is too weak Which is why you use thicker pieces. And as a matter of fact, 7075-T6 is as strong as 1018 cold rolled (and 2.7 times stronger and stiffer by weight). and bends and sticks to the tools. They sell WD-40, y'know... it's not just for displacing water anymore! (No, it never was, and never will be, a spray lubricant!) Steel is too hard, particularly stainless... They also sell this new wonder metal known as High Speed Steel. a guy here in Milan made a 6550 PP amp out of a large rectangular (reversed) oven pan, some 4-5 mm of AISI304. I suppose it's .. well .. robust. Nice. I'd say that copper is the best of all in terms of ease of machining: Gack choke sputter!!! Pure copper is about the gummiest thing you can find. (They say razor sharp tooling and milk for cutting fluid is the best you can do.) Copper alloys like brass and bronze generally machine well, but are too "slippery" (hence their use in bearings) to cut with anything but the sharpest tools. just remember to paint it with a protective transparent lacquer as soon as You finish polishing it with sandpaper, or it will get brown in a wink. Or green, or blue. Unless you want that. In which case, toss it in your litterbox for a week. A further advantage of a 3mm copper plate is that it IS definitely a ground reference, at least for a power amp. Not that using the chassis for grounding (unless done very carefully) is ever a good idea, of course. This I know from personal experience... Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#28
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Tim Williams wrote: "Jon Yaeger" wrote in message ... 1) I don't know of an easy way to join and seal copper without using solder or brazing material, which destroys the "virgin copper" look. If you are painting it with an opaque finish, then no problem. Try phos copper - low melting point while keeping the appearance. Or weld (TIG needs a few amps per thousandth thickness due to the conductivity), or just make your joints tight. Theoretically you could also use a brass braze and use acid to burn the zinc out of the surface, leaving it coppery. 2) Copper is fairly reactive and unless protected can corrode in certain environments in conjunction with dissimilar metals (e.g. steel) Actually, copper happens to be one of the noble metals The others being silver & gold. But copper turns green in the right conditions Yecch!!! Cheers, John Stewart - in fact steel provides galvanic protection, Didn't they use that on frogs legs in the lab? JLS to the dismay of some old radio chassis which were copper plated (possibly for solderability?). (Frankenhouse is one rusting example of this action; all the copper remaining is still pink. Most of the surface is rough with rust spots crunching though.) Tim -- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
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#29
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Gilbert Bates wrote: Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west I'll probably get something wrong here but... From the technical standpoint, the non-ferrous metal (aluminum) works better to shield the components from stray (leakage) magnetic fields from the power transformer and other sources. It is also less prone to induced currents in the chassis itself from leakage fields. Turns out that it the other way round. Easy for one to test this concept. All you need is any common power transformer which you first of all carefully hook up to the local AC power source. You will also need an output transformer. You can detect the stray field set up near the power transformer with the output transformer, preferrably unshielded if you have one. The voltage resulting can be observed on the high impedance winding of the OPT with an oscilloscope or if you haven't got one, a set of headphones will do. Sometimes there is so much coupling you will hear the AC hum on a loudspeaker connected to the OPT output winding. Once you are set up & receiving the AC hum you can do lots of interesting experiments to determine the shielding properties of various materials brought between the pair of transformers. Another test to try is the orientation of the transformer pair with respect to each other. If they are to be side by side on the chassis the core orientations should be mutually perpendicular to get maximum rejection of power frequency hum set up by the stray field from the power transformer. Cheers, John Stewart |
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#30
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west wrote:
Thanks to all the RATs for previous advice on custom chassis size. I'd like to ask if given heavy enough gauge ... which is better for constructing an amp ... steel or aluminum? Do they each have their own merits? Thanks. Cordially, west Aluminum can be "hand-machined", if you have a Dremel and buy some smaller steel bits--the ones they sell for "wood and plastic use only"? I found recently that those work pretty well on 6061-T6 aluminum, but you must work very slowly cutting just a bit at a time and keep a firm grip on the Dremel or it will chatter and chew up your workpiece. You could use quarter-inch-thick Aluminum sheet and slowly, carefully mill out even the big tube base holes, I'd bet. ....Welding aluminum is difficult but welding sheet of any metal is difficult, so plan on either screwing the sides together using angles or welding a frame, and screwing the sides onto that. ----- Stainless steel looks nice but it is expensive and it is a bitch to cut, a bitch to drill and a bitch to weld. It really is not a home-DIY sort of material for most fabricating. ...Aluminum is easy to cut but comparatively difficult to weld. REGULAR Steel is difficult to cut but much easier to weld. ~~~~~~ |
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#31
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On Thu, 03 Feb 2005 18:11:42 -0600, DougC wrote:
Aluminum can be "hand-machined", if you have a Dremel and buy some smaller steel bits--the ones they sell for "wood and plastic use only"? I found recently that those work pretty well on 6061-T6 aluminum, but you must work very slowly cutting just a bit at a time and keep a firm grip on the Dremel or it will chatter and chew up your workpiece. You could use quarter-inch-thick Aluminum sheet and slowly, carefully mill out even the big tube base holes, I'd bet. .... My father used to machine 1/4 inch aluminum with a router. He'd make a wooden template for the router, and take his time, but get beautiful results. I've always been too afraid to try it, myself. Sescom will do punched lightweight aluminum chassis to order, and can anodize them afterwards. They're beautiful, but you'll need to build an internal framework of various angle stock to bear the weight of transformers and such, and to carry the load to the sides past the flimsy (for tube amps) corners. Maybe worth the trouble and cost for some projects. Once you've seen a punched panel anodized through the holes you may fall in love with flimsy chassis. Or maybe not. Good fortune, Chris Hornbeck |
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#32
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"Chris Hornbeck" Sescom will do punched lightweight aluminum chassis to order, and can anodize them afterwards. They're beautiful, but you'll need to build an internal framework of various angle stock to bear the weight of transformers and such, and to carry the load to the sides past the flimsy (for tube amps) corners. Maybe worth the trouble and cost for some projects. Once you've seen a punched panel anodized through the holes you may fall in love with flimsy chassis. Or maybe not. ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. ............... Phil |
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#33
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Hi West ,
Over here in the Netherlands it's no problem ..... http://www.ae-europe.nl/toebehoren.htm Ok , about 50 euro for 50 x 50 cm isn't cheap , but ...... Ronald . "west" schreef in bericht ... I did think of copper, but where can I buy sheets o copper? west "Ronald" wrote in message ... schreef in bericht oups.com... Aluminum doesn't rust and is easy to drill, but solder doesn't stick to aluminum and chassis can be flimsey. Ever thought of copper ? |
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#34
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Behold, Tim Williams scribed on tube chassis:
snippage Steel is stronger, cheaper and all the other things that usually go with it (like solderability). Exactly! Steel can encourage the "ground it anywhere" technique - what we want to try and avoid :-o -- Gregg "t3h g33k" http://geek.scorpiorising.ca *Ratings are for transistors, tubes have guidelines* |
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#35
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Phil Allison wrote:
"Chris Hornbeck" Sescom will do punched lightweight aluminum chassis to order, and can anodize them afterwards. They're beautiful, but you'll need to build an internal framework of various angle stock to bear the weight of transformers and such, and to carry the load to the sides past the flimsy (for tube amps) corners. Maybe worth the trouble and cost for some projects. Once you've seen a punched panel anodized through the holes you may fall in love with flimsy chassis. Or maybe not. ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. .............. Phil One of the summer jobs I had while still in high school was running the anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of 1943 were all anodized in a large tank of Chromic Acid. The whole thing was powered by a motor /generator set up. When first turned on the DC current to the bath was very high but as time progressed the voltage had to be increased to maintain the current. Eventually the wing tank was finished & lifted out for rinsing in water, then dried. As Phil has noted, anodizing results in a very thick layer of high resistance on the surface of the Aluminum (Aluminium). That was my summer in 1949 while my pals were carrying bricks & cutting grass. Cheers, John Stewart |
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#36
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in article , John Stewart at
wrote on 2/4/05 8:44 AM: Phil Allison wrote: "Chris Hornbeck" Sescom will do punched lightweight aluminum chassis to order, and can anodize them afterwards. They're beautiful, but you'll need to build an internal framework of various angle stock to bear the weight of transformers and such, and to carry the load to the sides past the flimsy (for tube amps) corners. Maybe worth the trouble and cost for some projects. Once you've seen a punched panel anodized through the holes you may fall in love with flimsy chassis. Or maybe not. ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. .............. Phil One of the summer jobs I had while still in high school was running the anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of 1943 were all anodized in a large tank of Chromic Acid. The whole thing was powered by a motor /generator set up. When first turned on the DC current to the bath was very high but as time progressed the voltage had to be increased to maintain the current. Eventually the wing tank was finished & lifted out for rinsing in water, then dried. As Phil has noted, anodizing results in a very thick layer of high resistance on the surface of the Aluminum (Aluminium). That was my summer in 1949 while my pals were carrying bricks & cutting grass. Cheers, John Stewart Isn't hexavalent chromium an incredible carcinogen? Jon |
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#37
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"John Stewart" Phil Allison wrote: ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. One of the summer jobs I had while still in high school was running the anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of 1943 were all anodized in a large tank of Chromic Acid. The whole thing was powered by a motor /generator set up. When first turned on the DC current to the bath was very high but as time progressed the voltage had to be increased to maintain the current. Eventually the wing tank was finished & lifted out for rinsing in water, then dried. As Phil has noted, anodizing results in a very thick layer of high resistance on the surface of the Aluminum (Aluminium). ** That is one hell of a coincidence JS !!!! One of my customers, here to pick up his EV 'Entertainer' yesterday, was telling me how he worked at Hawker DeHavilland's facility at Bankstown in Sydney - on Vampires !!! The front fuselage was made of plywood and covered in fabric - which as a lad he painted with many coats of silver paint to help make it look like alloy !! ................ Phil |
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#38
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Phil Allison wrote:
"John Stewart" Phil Allison wrote: ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. One of the summer jobs I had while still in high school was running the anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of 1943 were all anodized in a large tank of Chromic Acid. The whole thing was powered by a motor /generator set up. When first turned on the DC current to the bath was very high but as time progressed the voltage had to be increased to maintain the current. Eventually the wing tank was finished & lifted out for rinsing in water, then dried. As Phil has noted, anodizing results in a very thick layer of high resistance on the surface of the Aluminum (Aluminium). ** That is one hell of a coincidence JS !!!! One of my customers, here to pick up his EV 'Entertainer' yesterday, was telling me how he worked at Hawker DeHavilland's facility at Bankstown in Sydney - on Vampires !!! The front fuselage was made of plywood and covered in fabric - which as a lad he painted with many coats of silver paint to help make it look like alloy !! ............... Phil Tried to send you a photo at your posted email address of a Vampire aircraft acting like a huge blowtorch, but no luck. So I have posted it at ABSE & ABPR where I hope you are able to copy. Attached message follows. Cheers, JLS ---------------------------------------------------------------------------- Phil- Here is a photo you could show your customer. These aircraft would often start in this fashion after failing to start on one or two of the initial tries. Unburned fuel would settle in the engine & we would have to as a group tip the tailplane down to the ground. Then most but not all of the fuel would run out on the ground. What remained on ignition often resulted in a huge blow torch, so I had a camera at the ready this time. This photo was taken at Chatham AFB in New Bruswick in the summer of 1951. Cheers, John |
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#39
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Phil Allison wrote:
"John Stewart" Phil Allison wrote: ** Beware - anodised aluminium is an INSULATOR !!! Any areas to be used for grounding will need to be SCRAPED bare first - a real PITA. One of the summer jobs I had while still in high school was running the anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of 1943 were all anodized in a large tank of Chromic Acid. The whole thing was powered by a motor /generator set up. When first turned on the DC current to the bath was very high but as time progressed the voltage had to be increased to maintain the current. Eventually the wing tank was finished & lifted out for rinsing in water, then dried. As Phil has noted, anodizing results in a very thick layer of high resistance on the surface of the Aluminum (Aluminium). ** That is one hell of a coincidence JS !!!! One of my customers, here to pick up his EV 'Entertainer' yesterday, was telling me how he worked at Hawker DeHavilland's facility at Bankstown in Sydney - on Vampires !!! The front fuselage was made of plywood and covered in fabric - which as a lad he painted with many coats of silver paint to help make it look like alloy !! ............... Phil The nose of the aircraft contained a DF (Direction Finding radio) which was considered a piece of super-mega-secret apparatus in the beginning. There was an explosive charge in the nose that would destroy the radio should the aircraft crash in enemy territory. By the time we were working on these aircraft several radios had been destroyed by a simple hard landing of the aircraft. Imagine how surprised the pilot was when the nose of his aircraft would explode on landing. One of the jobs specified in the maintenance contract at DeHavilland Canada was the removal of this nasty little gadget. The triggering device was a one inch diameter steel ball that would fly forward when you hit the deck to hard. That closed the contacts & the charge would explode. The steel ball looked like a giant ball bearing. These balls also looked like the balls in a pin-ball machine. I took some with me to a local restaurant where the owner had a pin-ball set up to make money. The owners son often played the pin-ball & would push it around the floor trying to get the balls going where he wanted them. I waited a couple of minutes & dropped a few of my steel balls on the floor under the pin-ball machine, then told the kid he had busted his father's machine. He picked up the balls from the floor & desperately tried to find a hole on the underside where he could fit them back in, but no luck!! Cheers, John Stewart |
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#40
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west wrote: Can you send me some pixs of your chassis with the dimensions? Maybe we can do some business, if they're for sale. Cordially, west I have a dozen or more monobloc chassis of two sizes to suit my future production. At this point they are not for sale because to get the good price from the automated metal worker I had to order several grand's worth of chassis. If I sell some off in small numbers, I am selling my livelihood off way to cheap without value adding by fitting out the amp with some decent parts. Better you get a metal worker near you to make you up a chassis or two, or three, if there is to be a pre-amp, and then do all the hole cutting yourself. There are bolt up type hole cutters to do all the tube sockets etc. Don't be afraid of 2mm steel; its good because you can tap if for machine screws, and its very rugged. For one off the best thing if you don't fancy bending thick metal is to source some Al or Fe channel, mitre 4 peices tother very neatly by filing the saw cuts, then drill and bolt angles into each corner internally, and use silicon with the bolts, or machine screws with C/S heads. Just add Al or Fe flat sheet for the top and bottom, and all this svaes having to bend up metal at home. I have done a lot of home bending. Best way without a press is to make a block of wood or plywood exactly the internal size of the chassis, and then cramp the sheet cut to size on the bench and bend the sheet around the block to ensure the bends are parallel and square. You need good wood working tools to make the wood formers. The problem with home bending is that it always looks like the work of an amateur unless you put all the time and effort in with the tools, and you have a workshop. The problem with wanting just 3 chassis from a metal worker is that he also has to make just a small run, and the guy working with a gullitine and bender can do a good job, if you go to the right bloke, and I suggest someone who makes stainless steel kitchen sings, and benches; I have had guys like this make brass plate chassis in an hour, including mig welding the corners and polishing it up to a professional standard. The last one for a stereo 5050 integrated amp cost me about today's aud$200, worth it for something that will last a long time. But often they are not interested in small jobs when they are making squillions from commercial kitchen fit outs, and they make you wait for-ever if they accept the job. But usually there is someone who makes metal articles near you someplace, and a chassis is dead easy, really. Talk to the guys, visit them at their workplace, take a sample....... Patrick Turner. |
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