bend yr own boxes 101

[duck_arse]

here is the bender I use to make my boxes, and the how I make them. you can use it to bend simple flat style, or the slope-front style as illustrated. the whole thing is made from, and uses, junk and recycle. you can waddle off to the hardware/metal shop and pay for the parts, or do your shopping on the footpath on the way during council clean-up. get it where you find it. if you have more than just a power drill, a hacksaw and a power jigsaw, look elsewhere, this isn't for you.



the very first step is cardboard. get the measures of a box you think you might like to make as a starting point. fold as many cardboard mock-ups as you like, the more the better. scale the measures up and down, change the proportions, get it so you think it looks right. make cardboard templates of the box profile and mark up where the parts will go; this will help with odd angles.

now cut/hack/gouge holes and fit the parts in your mock-up; make sure they fit. re/arrange them as you like, and make sure they fit. if you are using a sub-panel, you'll lose a lot of space straight off, so make sure everything fits. use the parts you are building with, not just something close, and I can't stress enough, make sure they fit. everything, including the circuit board WITH its components and standoffs, the battery, jacks and the footswitch, and all at the same time. if you're bending the box with 'returns', make sure the footswitch can be fitted into its hole without fouling the return. same goes for pots with long shafts on sub-panels.

as Mrs. Beetson once said "first you must your steel". I showed a bit to a man who knew once, and he said "0.9mm zinc anneal". this is about what to aim for, and you can best get it from (the u-shaped cover of) a mini-tower pc case of the 386/486/pentium era. go thinner or thicker, whatever you've got. (there used to be places that sold junked computer parts by weight: I don't know if they still exist.) cut the long sides from the top part. the right-angle flange from the back sides can be very handy, so cut it about 10~15mm in from the back.



cut yr slabs for bending. I always use felt tip pen to mark a wide line near, then measure and scribe a line through to the metal, leaving a line of contrast. cut close to the line, then clean up the edge with a file, taking the metal right to your scribed line, and sand to 400 grit on a bit of thick plate glass to ensure straight, to remove all file marks and burrs along the edge. this is now your reference edge, use it and a set square for your next couple of measures/scribes/cuts/sands, and you should end up with a decently square and clean rectangle of steel. cut at least three at a time, it's messy and time consuming.

now sit down with your slab, your box measures and a set square. pick a reference edge and felt tip/scribe all your bend lines to the metal from that edge. if this is your first attempt, expect to wreck it, so don't bother with marking or drilling holes. otherwise, you can mark/punch hole positions and at least drill pilot-holes before bending.



the bender. you will need:

a stable work surface (with a lipped top) - something you can lever against, a heavy bench is good, a black&decker workmate is the worst choice possible.

a brake - any straight bit of steel. I use some "dexion" racking/shelving angle (60mm x 40), you can buy some angle-iron from the steel angle place. hammer the edge as straight as you can get it against your chosen anvil, clean-up the edge w/ file and sand smooth/shiny.

a brake mount - I used plywood (200mm x 280), with the angle mounted flush to the front edge, backed by a length of 40x40 pine, with long wood screws through from under, and another bit square-to for bracing. the mount is fixed to your work surface with long bolts through to braces under (more dexion). you'll be levering against this, you want it well braced and rigid.

a work clamp - another block of wood (35mm x 60) and some bessy- or g-clamps. the dowels shown locate the work clamp and prevent it hitting the floor ever time you loose the clamps. the clamps clamp against the back of the brake backing block.

persuaders - auto panel beaters call them hammers, mallets, dollies, flippers, blocks. I use a small ball-peen hammer, a large rubber mallet, blocks of aluminium 150x50x90 as an anvil/straight edge/dead weight and 70x40x30 and a dolly/flipper, and blocks of wood as blocks of wood.


the bend



the start - put your slab of marked-up steel in the clamp and align the scribed bend line with the edge of the brake. this is where the squareness of your finished box starts, accuracy counts. align the top of the clamp block with the brake edge; this is where the goodness of your bend starts. tighten the g-clamps.

it is important to have as much measures and scribble on your slab of metal as possible. different colours too. I was caught on the hop, and had nothing prepared, but the finished pics of one I did earlier show what I mean.



apply some wood - use a bock of wood (you will develop a favourite) which is at least as wide as the piece you are bending as a dead weight. hold it flat against the metal with the bottom edge against the clamp block, and apply some slight bending force to the top. you want to transfer this mass/pressure to the bend by giving a whack to the lower with the rubber mallet. if the metal twangs or slaps, you're not quite holding the wood right. you'll know it's right when you feel it. you want the metal to bend right the way across in one, not bend the left then the right: you'll end up with bulges. only bend 20~30 degree here.



apply some metal - get your even deader weight metal block. bending steel against aluminium means the Al will end up dinged, but what can I do? use steel if you have it. hold it flat against the metal like with the wood, and down against the clamp block. apply bending pressure at the block-top again, and again whack with your mallet low, letting the mass of the metal block do all the work. bend as far as you're going here.



tap it up - now you can use your smaller weights to flatten/correct/tidy the bend right the way across, against the edge of your brake. follow with the hammer if needed, or to release some stress. the epoxy paint will be dinged, flaking and lifted by now, but you'd expect that.



check yr bend - release the clamps and the clamp block, take out the slab and check your work. now is the time to put it on the anvil and use the flipper/small block to flatten the faces and square-up the bend, or check yr bend angle against your template. a good bend will show a nice straight line with a constant radius of curve and no bulges or flat spots.

considering I didn't tighten anything properly, this demo bend worked out quite well. it has no marked lines, so the accuracy of the bend is doubtful at best.

if you are doing a box with returns, bend the return first, then the upright face. when you turn the slab to do the opposite end, you will discover the limitations of this rig, ie the box top-panel has to be at least as long as your brake-edge to workbench under-edge. or mount the brake-mount on risers.

if you are doing the complex slope-front, leave that middle bend last. you'll have to bend that pretty much by hand with wood blocks and with the panel clamped across an aluminium channel or similar for your brake. creativity is needed here, as will be an anvil clean-up and your templates.



afterwards, measure all dimensions, compare/check how far your bend lines have moved, how your dimensions have changed and how good your bends turned out. flatten your flat faces with yr dolly/flipper. your marked lines will all move with bending, you'll need to account for this on your next bend. using your pane of glass as a flat reference, rest your bent metal on it, see if it sits flat. tip it on its side, see if it is square/true. use twisting/bashing to get the best flatnesses you can. now evaluate yr work, can I use this for a pedal?

but what about the baseplate and side panels? well, the baseplate is fairly easy, just measure and cut/file/sand a rectangle of steel to fit.



the side panels - did I mention all the woodwork needed earlier? use whatever clean, knot-free wood you have, jarrah, tassie oak, the old lounge, about 10~15mm thick, and mark the outline of the bent case on it. then route/circular saw to a bit more than half-depth around that line, then file/chisel/sand so the wooden cheeks fit inside the metal sleeve as it were, and provide support all the way around.



this u-shaped bend is a good example. shape to the metal/sand/finish your woods, then you can screw through the metal into the ledge, providing a box rigid enough for fuzz pedal work. I use plastic-thread screws from video cassettes; they are small headed and black, so they disappear easily.

I'm about to do a set of cheeks, I can add a how to do wood if requested. and a how to cover this mess, as well.

[GibsonGM]

GREAT write-up, Duck_Arse, and please do continue!  I'd be interested in how you approach wooden enclosures on a budget!

I've bent mental with a home-made 'break' like this for a long time, but have never tried to make my own boxes like this.  Think I might give it a try now!   An authentic-looking BMP is within reach using this method, for sure!   

Could you post a pic of a finished one of that style, so we can see how you dealt with going from the light Al to wood?
Thanks.

[duck_arse]

thanks, but do you really want me typing more? what do you mean by "light Al to wood?"

[Ice-9]

Nice tutorial duck_arse, I am wanting to make a chassis for an amp design in the new year, this is just the thing I was looking for. 

[jmasciswannabe]

Awesome post, thanks!

[GibsonGM]

thanks, but do you really want me typing more? what do you mean by "light Al to wood?"

Just a pic of one fully assembled, if you have one.  Might be cool to see the final product.  Al. to wood, just meant that you're finishing off with wooden sides.

[wildebelor]

Man this is so great! Thanks again for the write up!!!! 

[tubegeek]

duck_arse for King! Long Live duck_arse!

[Mustachio]

Really cool methods and reuse of materials duck! Thanks for the write up!

I love those recessed push button switches! I've been designing something to recess my pots.

[PRR]

Wear Gloves!!

Yes, I handle fresh-cut steel without gloves. Sometimes I don't bleed all over the shop. But a cut steel edge can slice to the bone.



In the US, Home Depot has large light steel:

MD Building Products 1 ft. x 1 ft. 16-Gauge Steel Weldable Sheet   
Model # 56038  $10.98
0.06 in  (about 1.5mm)
   
Master Flow 24 in. x 36 in. Galvanized Steel Flat Sheet   
Model # GFS24X361P  $9.34 / each
0.012 in (about 0.3mm)

Both tend to be in stock. You may need a clerk to find it for you.

The 0.06" (1.5mm) will be wicked-hard to bend with improvised brake.

The 0.012" (0.3mm) is pretty flimsy. Cuts easy, bends easy. Probably not good for a box more than a few inches wide, or a box you will STOMP.

The idea to cut-up a 486 PC is excellent. A PC case needs no strength but adequate stiffness. They use a low-low-cost steel because thickness adds stiffness. And they buy it the softest possible hardness so their punches don't wear out. This is pretty much what you want.

Thickness (T) can go by panel width (W). If the W/T ratio is 10 the part will be SUPER strong. Truck frame. W/T of 1,000 is whippy, car hood without the inside stiffeners. W/T of 100 to 200 is a place to start for low-load panels without internal bracing. The Duck's 0.9mm stuff could go 90mm to 180mm, 3.5" to 7" wide panel. (When used in a PC as a 16" 400mm panel there's often added stiffening.)

Then H-D's thin-stuff can go 2 or 3 inches, the 0.06" stuff is good for 6 or 12 inches. You of course "can" make a small box with thick metal, but it is more cost and particularly more WORK, especially to get tight bends on a ShopMate.

I just had a brain-burp. Find a car-geek. Get some burned heads from a Chevy V-8. And some long bolts with nuts. Clamp the heads together, slack, insert sheet, align, tighten, align, tighten. You can beat that thing with the Ford BFH (20 pound sledge) and it won't cry. (Iron Chevy heads are a glut on the local market, because it is cheaper to buy new ones than refurbish the old ones. If your area is different, find any two same-pattern heads in *iron*. Alloy won't take a good beating. Post-1994 Hondas are right out.)

[duck_arse]

geeze, dumb luck, look where it got me. thanks people, you are too kind.

yes to gloves, but "make sure they fit". I've got to stop saying that. I wear suede and canves gardening gloves, and anything that keeps Al dust off your fingers has to be good.

if you can find pc cases that are rivitted instead of spot welded, you can drill all the rivets out, and it's fun to hammer out the remain of the mandrill with a centre punch, and your pile of junk shaped steel is much smaller and easier to hide in the garage.

the reason I say make sure etc is because of those bloody push buttons. they are huge space takers. them and 3 piece sub-panels. gahh.

I haven't quite gotten to a "complete" box on this bender just yet, but I'll be doing a set of wood panels in the next week or so, so I'll do a write-up on the router-bench-guide thing as well. mmmmm, photos of wood ...... there are some wood cheek examples of mine in the photos pages, if you're too impatient.

[duck_arse]

look closely at your pc cover while you plan your cuts. as someone once said

the right-angle flange from the back sides can be very handy, so cut it about 10~15mm in from the back.

and who are we to disagree? if your cover has a narrow flange along the back edge, I'd have that for a square and true bend every day, good enough for where you need it. and does it have a shallow-lipped front edge? can you think of a way to use this as a battery hatch? many manufacturers have used a lip-and-screw cover. plan your other uses before you chop your slabs, you'll get better mileage.





there is more stuff there. the good people at the Marantz company used to produce equipment with champagne anodised panels. so, you've pulled the knobs (very nice), pots and switches, cut up and bent the baseplate, now have a look at the front panel. the extrusion is again square enough, and thick enough for 3mm tapping. as shown in my pink orange detail (part 2), you can have your knobs match your internal brackets. now that's classy. and I've got a harman/kardon amp inside ......




showing from left to right - maple (I think) from a lounge, (weathered blond) jarrah from somewhere, pink jarrah from the council sports shed and a fence paling.

you may find you have a nice plank of wood 22mm thick, but you only need it 12mm for your cheeks. so, if you're like me, you spend days rigging circular saw jigs so you can cut along its length to a somewhat constant thinner thickness, and you end up with a thinner plank and a thinner still plank, which would appear useless. but if you have a box you want to wood-up, a u-over/u-under style box with some unsightly rivet heads and overhanging lips, cut the thinner slice to shape, maybe drill some jack holes, dress/sand, oil/polish, and now you've got some dress panels. you get more wood.

there are some among us, Kipper, who have been heard making disparaging comments about australian timbers, but I won't name them here. not only are our hardwoods some of the hardest known, but, as shown in the inset above, so are our grubs. I cleaned out the borer hole in that middle front piece, and it is shown with a 7.0mm drill poked through. can't be an easy life eating jarrah .....



those of you who've thrown out your video cassettes already, skip this part. for the rest, look at the stuff inside. you get - the metal leaf spring, just what you need to poke into clipped plastic cases as you take them apart - plastic pillars, what can't you do with them? - a split spring-steel bush thing - have you ever needed to bush a knob, or extend a pot shaft? - a solid-brass bushing, looks like another standoff, and will match the plastic pillar - some hair springs, suspension for your wighat - the front door, flat black plastic strip, with the bonus of 2 three way corner pieces, good for something.

and of course, the screws. to me, these seem to be the exact thing for holding wooden cheeks: the diameter seems right; the coarse plastic thread is a boon; they are not only black, but have an easy to hide pan head; the quality seems many times better than anything comparable in the hardware shop. I did some hardwood head-snapping tests and only managed to break one screw. pilot holes are easy to drill, right?

if we have any engineering adults about who could do a BOTE* force/stress analysis for the screws and wood as used here, and could tell me if adequate or needing upgrade, I would be very grateful. and any engineering pointers for a pinning method/best placement for the part 1 type enclosures would help me immensely.
*back of the envelope. a drink coaster/napkin will serve the purpose, but not the acronym.


the next time you are near the hardware store/shop, go inside, looking for nothing. walk up and down all the aisles, look at everything, pick stuff up, poke around shelves, fiddle with things you can't identify, heft stuff for weight, allow no-one to help you. it's surprising the way things suddenly seem perfect for something they weren't meant to do.

as prr noted, wear gloves doing things w/ metal. anyone who's ever worked on the innards of a pc knows that EVERY internal cut/punched surface of the case will have one razor edge. there are no exceptions here, you can even cut yourself on the covers of cd/floppy drives.

and when you've finished the working session, and you are leaving the work area, get into the habit of dropping the riggers/work/gardening gloves you've just taken off right on top of whatever it is in the middle of your work bench. then when you come back the next day, you can't even make a start until you have picked up the gloves, and you may as well put them on while you're holding them. the more often you wear the gloves, the less reasons you'll find for taking them off.


that's another 2 cents well spent. and yes, part 2 will follow, as you would expect. any comments/questions/pms/corrections/engineering/money happily accepted. receipts issued on request.

[petey twofinger]

really cool , thank you for sharing all this , it must have taken a little bit . thanks !!

[Harry]

the next time you are near the hardware store/shop, go inside, looking for nothing. walk up and down all the aisles, look at everything, pick stuff up, poke around shelves, fiddle with things you can't identify, heft stuff for weight, allow no-one to help you. it's surprising the way things suddenly seem perfect for something they weren't meant to do.

I love this advice.

Thanks for the ideas D.A.

[Ice-9]

Wear Gloves!!

Yes, I handle fresh-cut steel without gloves. Sometimes I don't bleed all over the shop. But a cut steel edge can slice to the bone.

Yes, I have even seen Kevlar safety gloves sliced through by steel sheet.

[tubegeek]

Yes, I have even seen Kevlar safety gloves sliced through by steel sheet.

Ay caramba!

[Gus]

I would also use eye protection

[duck_arse]

bend yr own 2 - different bender, different boxes - more bending


I was asked recently if the left pictured box could be bent with the junk brake bender. I said no, problems with accuracy and repeatability (a worthy opponent). I am an idiot; not only can I bend these, I have been bending them, only in a different form. and I've shown you the bender, and you didn't pick-up on it, either.



the "tuva" and the pink squeezer (shown above, right) are single u-shaped bends with wooden side-cheeks. they have a recessed angle bracket at each end under, (detail, above) which attaches the baseplate, flush as you like in the groove shown. the cheek-holding screws passing through the panel also pass through these brackets, as do the jacks, pulling the whole thing together with a minimum of fixings. those of you with a dremel or similar tool will have no problems with cutting the recesses needed to flush fit the brackets with the woods.

there is nothing to stop you from turning the bend 90 degrees, for either side-entry or wood-mounting jacks, and you can wood-mount/side-entry at the same time if you so desire, no rotation needed. you can even use a perspex light-plate bottom thing, or invert the whole mess, perspex now on top, and bang in some swirly leds for a "freakout vortex" type affair.

the u-over/u-under style is simply a u-bend bent on a separate jig and sized to fit inside another u-bend. you don't need any wood, but you will need some brackets or Aluminium bars to drill/tap/rivet, and hold the whole mess from flying apart. we'll see in part four.



as in part one, start with cardboard mock-ups. I make an open-bottomed box of the size, and then cut an aperture where the pots/switches will go. cut some squares larger than the new hole, and put your positioning holes in the loose squares to swap in/out quickly. this is where you make sure everything fits. allow for the wood thickness. and battery. with a card to blank the hole, the mt box makes a good all-in-one-spot thing for the panel parts while building.

cardboard templates are a must if you intend to wedge, as I will for this demo bend. take note of the way the angle shifts parts clearances relative to the parts on the upright panels. draw it all on your template to check it all fits.

mark everything with dimensions as you go, then when you have decided, collect them all onto one sheet of drawings. make all your north-south top-panel measures from the panel-middle reference, and your jack measures from that panel-end. this is a good way to beat the vagaries of the bends themselves.

if you are wedging your bend, offset the panel-middle mark, simple as that.



mark up your blank plank. find and scribe the middle of the plank, on both sides. mark your hole centres on the inside of your panel, don't forget to reverse your drawing, and nothing but the panel middle on what will be the outside.

the pale green lines on the plank shown were the straight/square reference edges when cutting, they now jamb against yr straight edge while you set-square yr scribings. the red line is the panel middle, but the magenta line is the offset reference for all our top measures because we are wedging this bend.

shown at right is a bit of video cassette front-flap, with a few measured holes drilled. this slides along the edge as shown for those repetitious east-west scribings that so vex us. it could have been more robust if I'd used the marantz front panel, and could have been used for pot-markings if I'd thought to make it longer. you don't need to make that mistake. mark the holes with their distance-to-edge.

the plank shown has a blizzard of markings, all meaningless because I don't have anything in mind for this bend, yet. they are illustrative only. with this in mind, I have only drilled pilots for the thru-panel screws and the jacks, as they are the most difficult. in your case, drill all your pilot holes; full-size holes may produce some unwanted problems in the finished bend.


the u-bender is much simpler than the junk brake, to build and use well, and has better repeatability. you can bend wide or narrow of one size, toe-to-jax on the same jig, but there is no real reason not to make 3 or 4 jigs. this bender will do wedges as easily, simply by offsetting your panel-middle mark towards the toe. you can then correct yr angles using your cardboard templates.

I very strongly recommend you cut/square/measure/mark 3 or 4 planks at a time. it takes me forever to do the cutting, but the bends take literally 5 minutes. after all the setup time, you'll be left standing wondering what to do next if you only do one bend.



the bender as shown is just a block of wood 90mm x 45mm. the bending edges, which we will refer to as jaws from here on in, are heavy steel angle bracket 34mm x 13 x 2.0. a straight guide edge is mounted square, such that it stands proud of the jaws. as shown, the bend produces a top-panel of 93mm internal measure.

the block can be as long and as heavy/dense as you like. you can stack or cut to the wide you want, drill through and long bolt it to your workbench, over a bench leg to provide all the inertia needed, but with space under for clamps. make sure you have clear down either side of the jig to at least the length the bends will overhang.

the jaws shown are the cad passivated (!) remains of a telephone exchange test-panel, and have an ideal radius of bend. cut something similar (extruded Aluminium angle will be fine) to as wide as your widest planned panel, file/sand a radius if needed, and screw it to your chosen bending block with long countersunk wood screws. your finished bends parallelness depend on your relative squaring of both the edges of your block and jaws.

the (inside) length of panel toe-to-jax now becomes the distance across the faces of the two jaws, but you've already planned for that so it's not a problem. the guide edge should be sanded flat on glass, as it affects the accuracy of your finished bends. measure as best you can the middle point between the jaw faces, and mark this point on the guide plate; it is really the only reference you need.

the clamping block can be any hardwood block that will cover your intended top panel; chamfer the edges if you wish, and cut a viewing notch where it matches the middle of the guide plate. the blue tape shown is to help stop plank slippage.




above is shown our demo plank on the bender. all you need do is jamb your reference edge (again) against the guide plate, align the panel-middle reference to the guide middle, and clamp. if your clamp-handles are banging against each other underneath, you're doing it just right. bessey, g or quick, it doesn't matter. tight them up good, and check you're still aligned. you can use a vernier to measure from plank ends to jaw distance if you like. the centre-line method and your aligning accuracy makes this step unnecessary.



now get your favourite block of wood and a rubber/wooden/copper-and-hide mallet. hold the bashing block flat against the plank as shown (your hand won't look as good) with some down-bending pressure, and give a flat "thump". the aim is to bend all the way across the same amount each bash, so you end up with a straight and flat bend. if it doesn't twang or clank, you're going ok. turn your block and continue the bend until it is almost square, again as shown. then do the other side, the same way. I did, you weren't looking.

if you are doing a flat top, you can continue the bashing until the ends are square, you might as well. if doing a wedge, you'll need to hand-bend to your template soon.


that is your bend finished. take off the clamps and clamping block, and lift out your bend. get your pane of glass, and check for square/twist. the demo bend is shown straight out of the jig, and is as flat and square as I could possibly have wanted. the bends are straight and un-bulged. what more could you ask for?





and now you'll want to check against your template. a wedge will have a less than- and a greater than- 90 degree bend, so we do that now. hold the jax face flat against the glass, and lean on the top panel until it matches your template angle, less than 90. now hang the whole bent over the bench edge on the toe inner face, and pull/lever against it until you have your greater than angle correct (not "right"). you can also use the bending jig for this. the cardboard template will illustrate how consistent your bends are, and how parallel.

check again for twist and square on the glass. you can do some minor corrections just by twisting if needed, or put some sandpaper and get medieval on your glass. sorry. you really shouldn't need any corrections if your references were good and alignments square to start with.

shown are two bends from the one jig, neither of which I have plans for; more cluttering junk on my bench. and how long has the whole process taken, ten minutes?

so that's the end of part two. part three precedes, and in part four I'll cover those pesky wooden planks I'm always talking about and the pesky mounting brackets and and bottom plate. part five will be covering-up the whole mess and part six ..........

requests to please stop typing/comments/questions/corrections/engineerings/etc please and welcome.

[Kipper4]

Nice work Duck-Arse
watching and learning. Your giving me ideas.
Thanks

[GibsonGM]

Thanks again, Duck Arse - instructive as always, and getting me very interested in breaking out my clamps!!  I have some angle iron stock and hardwood - have to make me up a jig like this!