This article is in response to the drifting topic "A few Technical PSU Questions", which turned towards sheet metal. I think a new, more visible thread is in order for this topic. So here's a starting contribution...

Tin Snips for Cutting Metal, and Making Holes In Things

...including computers. So you want better airflow, real fan grilles, ducts, etc., maybe even a window. It's time to get cutting. This article is a detailed introduction to basic sheet metal cutting, in aid to fixing all those details that make our computers quiet. I wrote this article because a whole lot of people who want quiet computers aren't big-time case modders, and never really wanted to be. But we end up fixing and tweaking out of necessity. If we're lucky it even get's fun.

You might look into this mess and think "I'm only gonna do this once and I will never use the tools again." But you have a really neato idea and it just has to get tried. Find a friend with tools, or hire someone. If it's to hire, look for smaller heating companies or sheet metal shops. Find a place where you can work it out with someone in the shop. Most little things, like cutting holes or making simple brackets, are so easy that a cool metalworker will do them in a flash, and you can avoid nasties like 1 hour minimum shop charges. They might not even charge for metal if it's in their scrap pile, and there's always lots of good scrap. Best is to find someone who wants to do the job because it's interesting. They will be cheaper and do better work.

If you decide you want to dive in then... below you will find way too many gory details, and full blow-by-blow how-to's and why-for's. After that, a gentle nudge into the world of basic sheet metal work and what it can do for you. If you think any of that will help you on your way, then steel yourself and read on...

Dremels, the ever present. I admire and appreciate the one-tool versatility of dremel cutting, and have no argument with the many excellent results. Dremels have good strengths for modding: they can cut a line across/through an existing corner, drill-grind-polish, and do touchups. And they work in almost any material. I do however dread the notion of using them much for most sheet metal cutting. They are just slow.

I recently spent two years working in a sheet metal shop. There are lots of fancy big special tools (makes you drool), but the most basic hand tools still do most of the work. My favorite way to cut metal is with Red+Green tin snips (yes you need both). With a little practice you can work honest miracles in mere minutes. Oddly, computer people just never seem to use tin snips, as though they don't exist. I don't get it, since they are my first choice.

Tin snips cut anything from aluminium to stainless steel, from tinfoil to 32 guage (very thin like PSU's) up to 16 guage (thick like a credit card). Thinner is generally easier. Way too thin (tinfoil), very hard (stainless) and very thick (20-16 guage), can all get more challenging, but can still be done very well. Everything in between those extremes is just plain spiffy

I have seen 'nibbler' or 'nibble notcher' tools, and they do some neat things. Some modders even seem to have heard of them! A nibbler is: maybe cheaper than 2 pairs of tin snips (but for a quality one?); definitely slower; and probably more versatile concerning very small square holes (depending on your skill). They probably compliment more than replace tin snips. Nibblers are popular, but I haven't used a pair yet. Many of my tips below would apply well to them too. Especially: buy a good one if you intend to actually use it, and keep it sharp.

General Tips for Cutting Sheet Metal

0. Sheet metal is damn sharp, fresh cut edges are bloody sharper! Be aware and move slowly to avoid getting cut. Rushing around sheet metal always gives you cuts. They are seldom fatal but always messy.

1. You want (need?) high quality tin snips. They are the most important sheet metal tool. They must be sharp. NEVER CUT STEEL WIRES WITH THEM! Avoid cheap combo sets if at all possible. Wiss is the brand for any sheet metal pro I've ever met. You only need Red/right and Green/left snips, the Yellow/middle is almost never used (didn't even buy 'em in our shop). I suspect the combo sets are an industry subsidized conspiracy: has all the fancy colors, con's you into thinking you own the tool, then discourages you 'till you hire a pro Live with the cheap ones if you must, but treat them really extra nice.

2. You need a sharp scribe / awl. A nail or screw seldom cuts the mustard, they are too soft. The scribe / awl is a very handy tool for it's own sake anyways. Lee Valley Scratch Awl is the best I've seen. Quality - hard steel - is a must for an awl to outlast it's cost.

3. Measure twice, cut once! Measure twice, cut once!

3b. 2/3 of the job is in the measuring and layout. I measure on 1/16" rules, but my marks are within about 1/64" or less by eye. Have fun with metric. Accurate layout is the hardest but most important part of the job.

4. Use a metal ruler and scribe to mark out your cut lines. Use a compass with a point for round shapes. You can cut within less than 1/64", if you mark that accurately. A scribe line is shiny and very precise, and it actually guides the blades a wee bit, allowing shockingly accurate and neat work. If you can support the metal on a hard surface, use the awl to 'punch' the corner points first. You don't need to go right through the metal, but do put a good little dent there. These punchmarks help placing the ruler when marking lines, and stop the snips cutting when you get to a corner. If you want more visible lines then colour beside your scribed lines with a Sharpie felt pen. Always scribe your cut lines unless you're freehanding. Always.

5. Cut square to the metal. If you don't hold the snips straight up and down, you won't get a square edge. Take your time, be precise. It's still the fastest way you can do this job by hand.

6. Red vs. Green: Use Red when the metal you are keeping is to the Right side of the line. Use Green when the keep is on the Left of the line. The kept metal stays flat. The cuttings curl upwards and away from the line. Right handers use the Red by default, left handers use the green, it's easier that way to see the line you're cutting. But you switch back and forth freely as needed or desired. Tight spots will often make the choice for you too, that's one of the reasons you need both sides.

6. File your work lightly. Use a fine mill-file: good ones ($) are harder and sharper. Stroke it mostly along the cut edge, not across. You can get nearly machine precision touch-ups with a little patience and a sharp file (not that rusty/shiny toothed thing from the lawnmower shed ). Because you have a good file you don't have to push hard. Or use a Dremel tool

...now how about those holes...

So much for the basics. Now on to the job. A new fan hole. A new window hole. Maybe as an air port for a duct or muffler box you're adding on (build that too!). Tin snips will cut holes down to about 3/4" in lighter metal, maybe 1 1/2" in heavy stuff. The problem is this: flat metal; no hole; need hole x by x, or x around. Easy strategy:

1. Measure Measure and mark and measure your hole and measure.

2. Punch a hole near the center. This is where you will start your cut from. You might need to support the workpeice on a damageable wood backing to prevent it from bending, like for a thin PSU cover or a flat side cover panel. I use my Lee Valley awl, just drive it right through. You could use a hammer and nail, drill a hole, shoot it with a gun.... If it's a small hole (nail, awl) you need to warp the metal a bit so that one side of the hole is bent up and one side is bent down. This gives you a raised lip to start cutting from. I do this with the awl by just pushing it over sideways before I pull it out of the metal. A bigger hole, say 3/8" drilled, is big enough to start your cut from flat.

3a. Fun: Cut outwards in a spiral. Freehand. This step is what lets you cut a hole without bending the the metal left outside the finished hole. You'll be amazed. You can start from even a wee hole, and spiral outwards with your cut. The metal will get a bit bent near the cut at first, that's ok, by the outside of the spiral you can get your flat cut easily. By cutting a spiral, you let the waste metal from hole spiral up and away from the snip's blades, as it needs to do. You can stop any time and cut off the emerging waste spiral to get it out of your way, at your convenience.

3b. Strategy: Spiral out in 2 or 3 or more rings, leaving the last 1/4". By spiralling outwards in say 1" to 2" swaths you can now cut up to the last 1/4" from the finished hole. The width of your swath is actually limited by the guage. The waste swath needs to keep curling up and out, without a big struggle. Cut too wide for the guage and it gets hard to curl away, so cut a narrower swath. On square holes just leave the corners rounded for now, they get squared out later. But leave that last 1/8" to 1/4" in for now. You are not trying to finish the hole here, just get it opened up to make the final cut really easy.

4. Now cut the finished hole very carefully. The last 1/4" strip always spirals out of the way very easily, so it's easy to stay right bang-on line. On straight lines you can feel the line, and ride it with the blades.

4a. For square holes you angle in very gently and sidel up to each line, then follow it to the far corner. That cuts out most of each side, right up to its far corner. To cut the other end of each side, and finish the corners, you change snips from Red to Green or vice versa. Start cutting up against each side where it's already cut straight, easing into the remainder. Cut back along the side to the corners that are still left. When you hit each end the corner bit will fall out and you are done, with a nice clean flat hole every time.

4b. For round holes just cut the last ring out very carefully. Ease into the edge at a very gentle angle. That last little strip peels out in a nice spiral.

4c. For small holes. You probably want to cut these as the last, careful, step of your spiral, because there just isn't always enough metal to leave that last 1/4" strip. Still, you might try for a last 1/16". The metal outside the finished hole will often get a bit bent, but you can flatten it afterwards. For smallish holes in thick metal, the whole spiral thing might just not work well. You probably need to drill the starting hole, and warp it. From there I usually just make a ratchety mess (chop hack chop), leaving the last 1/32" to 1/64" inside the line. That way you can hammer the work flat, and file out out the hole cleanly up to the line using a round file. Small holes can be done, and they go quickly enough, even if they are fiddely. Of course a hole-punch set would be lovely.

5. File and flatten as needed. Well it should have been perfect, but a bit of filing and a few hammer taps will fix almost any remaining flaws. The trick to flattening sheet metal is to put a heavy flat peice of metal behind it, and tap it gently with a hammer. We used a 2" round by 4" long chunk of steel, very nice. You just work around your cuts, giving gentle taps till it's all flat. With care the results look almost like they came out of a machine.

Well, after all those details I'm sure it's clear as mud. Try it out, play with some scraps from a sheet metal shop. Sheet metal is easy stuff to work with a little practice.

Afterward: fun in the metal shop:

I had lots of fun at my sheet metal job, and I found out how great sheet metal is. I've done lots of wood, steel, plastic and composites, and fabric, but sheet metal is still my favorite material. It's so clean, quick, strong, formable, and versatile: it's almost as useful as duct tape. Once you get used to it, you find that you just whip up all kinds of little holders, brackets, covers, connectors, braces, boxes... it's just amazing. It quickly replaces lot's of other quick-fix or home-brew solutions with something easier and better, and often 'right' instead of 'improvised'.

You don't need much to use sheet metal at home. The tools mentioned above are almost all you need to make practically anything. A few other handy tools are some pliers, a drill, a pop-rivet tool, and maybe a vice for doing small easy bending jobs. There are cool little $20 bender jaws that fit in a vice too, and do a better job than a naked vice. So, that's what you need to make most all of the little things you could want to make from sheet metal.

There is only one last thing that opens up all the possibilities, and it's the hardest thing: long bends or folds can't be done well by hand, not even over a good edge. If you can live with just bending a narrow edge on not-too-heavy sheet, ask a sheet metal shop to make you a folding bar: up to 2' long, double sided for two widths, maybe 1/4" and 1/2", or anything up to 1". They would probably want $50 to $75 for one, but it will do an awful lot and not take up any space. Better would be a small break (or bender), and I have seen them > 24" for $150'ish, but that's for a cheapy. Still, you could probably even make good custom cases with care and cleverness, and that's something most people wouldn't even dream of for a mere $250 total worth of tools. The best thing is a real box break, but that's big, heavy, and >$500 or way more: you would have to have some serious ambitions in mind, and you should just go hang out at a real sheet metal shop.

At the metal shop we put in furnaces, made up all the ducts, and did just about every odd thingy a sheet metal shop does. Having all the big tools to play with off hours was really fun. I made up some custom Hi-Rise covers for a trio of very slim MSI desktop book-PC's, so we could add extra HD's and normal CDRW's. They were regular, inverted-U type desktop covers, but with extra panels hanging down in front and back to cover the new hight. They were done in heavy 18 guage, which made them fairly difficult to cut but very strong. The light 30 guage internal drive cages and brackets were much easier, if a tad flimsy. Fun projects, lots of possibilities.

I hope you have got something out of all this, or maybe even enjoyed yourself.

Happy computing, Crisspy.

Well done, Crisspy!!!!

MikeC,
Yank this post and make it part of the main site!!

Queue

yeah nice post crisppy write it up as a full tutorial and see if we can't get the site /. 'd again, but where's the angle grinders??? they're cheap as and handy for cutting holes and stuff.... my nibbling tool has done most of my modding in my case so far.

Well done Crisspy!

I think we now have the longest post ever!

TerryW

I have never read such a good explanation on how to use M1's , M2's and M3's.


-Bri

And because of crisspy's post, I've cut 3 perfect 120mm holes in one of my cases. This has saved me a bundle of money, because I was thinking about getting an expensive Greenlee punch. No need to now. Those Wiss tin snips are something else.

My goodness I feel like snipping something. I wonder if I could snip something on my Laptop.

Great tutorial crisppy. If my new case ever gets here, your post is going to be invaluable.

I'm confused by the different types and sizes of tin snips. What are "aviation" snips? Will they work well on most case steel? How long of a handle would I need?

does the "offset" type of Wiss snips have an advantage when cutting 120mm fan holes?

Hi everyone. Here's what I know about tin snips, what kind, etc.:

What you want is very specifically Wiss RED M-1R & GREEN M-2R snips. These are very high quality tin snips, and they are offset (just the right amount) to allow you to appoach a cut from whatever side you need, or cut around corners. The blades are extremely hard molybdenum steel, which thinks nothing of cutting normal steel daily for years on end (including 18 guage, 16 in a pinch), and can even cut stainless steel up to fairly heavy guages (extreme punishment). The YELLOW M-3R snips are totally unneccessary: I never even saw/used a pair in the sheet metal shop where I worked for two years, and I can assure you that there is nothing you can't do with just the RED & GREEN pair. If you find a sane retailer, you will pay a sane price, say under $15 per snip, total under $30. Here's a sane retailer on line for example, found by Googling wiss tin snips:

Tools-Plus has Wiss M-1R & Wiss M-2R.

DO NOT BUY CHEAP GENERIC COMBO SETS !!! They will get dull quickly, and the pivots are often sloppy so they bind up. They are just a big waste of money. Heed this warning, from Cases & Damping: 120mm knockout punch tool here on SPCR:


PS... the Malco snips also sold at Tools-Plus look like good quality too. I don't see why they would be any worse than Wiss, except that they cost $8 more per each. The point is quality, and I can personally vouch for Wiss as an industry standard brand of outstanding quality.

PPS... as for handle lengths, the Wiss M-1R & M-2R are just right. I don't know why they call them 'aviation' snips either, they would be better called 'funace guy' snips AFAIC.

Thanks for the specifics. My local Home Depot has the Wiss M-1R and M-2R for $15 each. They even come with a leather belt holder.

crisspy, I just thought I'd share some close ups of my first hole:

Showoff!

Just found this wonderful thread, crisspy. THANK YOU!

One question. I already own Wiss M-6R and M-7R "Metalmaster Snips." How do these differ from the M-1R and M-2R you recommended, and are they equally suitable? It looks like the shape of the head is somewhat different, but it's not clear to me what this means in terms of usage.

Anyway, thanks!

Very nice crisspy. That is a whole plethora of information.

also what do you think abotu adjustable whole saws that fit on electric screw drivers?

Excellent article on tinsnips, I consider myself a tool freak, and even I learned considerable from it...

A few other tools and tips that I've learned over time, not necessarily from case modding, but from general working on similiar sorts of things. I would class a lot of these in the fairly advanced tool class, probably not worth buying for a single project, but good if doing more than that.

First off, if you are doing power tools, a good set of hearing protectors is a must... Ditto eye protection. Watch out for floppy clothes, long hair, jewelry, etc. A tool with enough power to mod your case easily will mod your body even more easily if you let it!

Useful tools:
An air compressor is a wonderful thing... Get the biggest you can manage, as it increases your options for adding more tools later. I have a 20 Gallon, 3.5hp unit which works but is on the small side. Better are the 5-7.5 hp units with a bigger tank. My unit works, but requires me to pause frequently to let the air pressure build back up.
You can fill a shop with air tools to do all sorts of things, but the ones I find most useful for case work are the following.
1. Air cutoff wheel (Whizzie wheel) a more powerful version of the abrasive cuttoff disks Dremel fans are fond of. Best on straight cuts or large curves. Uses 3" disks that are much less fragile than the ones in a Dremel.
2. Die grinder - Again larger version of Dremel, good in the right places. I also have a mini die grinder that is about the size of a fat ball point pen, uses 1/8" Dremel type bits for the same types of work. I find it easier to use than an electric Dremel.

Electric drills:
Most versatile is a 3/8" variable speed reversible. If you are going to be using big hole saws, a 1/2" variable speed is helpful. I prefer corded drills as they have bigger cojones than a cordless. Regular drills are pretty easy. Hole Saws, watch what you buy. Many hole saws are suitable for wood and plastic only, especially the inexpensive ones. You might get away with using them on a thin aluminum case, and possibly even get one or two holes out of one itn a thin case if you use lots of cutting oil, but don't count on it. Look for the better brands, such as Milwaukee, Blue-Mol, Greenlee, etc. and specific package labeling saying they will work on metal.

DO NOT attempt to use one of those adjustable saws with a single cutter bit on an arm UNLESS you have it in a DRILL PRESS and the workpeice is solidly clamped! Using one of these bits in a hand dirill is an accident waiting to happen! What typically happens is the bit grabs on something and stops turning. The drill is still on though, so something else has to turn, whether it be the drill ripping out of your hands, the workpeice spinning around, or you getting tossed across the room (or more than one of the above) If you are very lucky, embarrassed is all you get, but more typically the workpeice gets damaged, and you often do as well. (ask me how I know this...)

Reciprocating Saw (Sawzall): Massive overkill for case modding, but one of the ultimate weapons of dissasembly... I use it to cut the copper for my watercooling blocks.

Drill press: Good for drilling holes, not essential in most cases, but can make life easier. DO NOT attempt to use a Drill Press as a cheap substitute for a milling machine - the quill bearings aren't designed to handle side loads and will fail rapidly. More significantly is that many (most?) drill presses use a tapered chuck mount, which rapidly comes unstuck when side loaded.

Milling machine: Very expensive, don't waste money on a cheap imported job, you'll regret it. (I do) If you check with your local used machinery site you may be able to get a second hand Bridgeport (the Cadillac of mills) for less than a new import... Don't even consider a mill that has anything other than an R-8 taper in the mill head unless you want to experience headaches and sticker shock any time you need to get tooling.... Not real good for case modding, but good for making waterblocks...

Gooserider

Dunno about those: bought some Bergen one's from Ebay (German make I believe). Used them on my case rear to make the fan hole larger and they were pants, like my case had just been mauled.



http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2334262716

Hope this Wiss ones are better, but for that price (and to get rid of my disillusionment), I'm tempted to my a Dremel (I know they are slow) or some wrist crunchers (a.k.a. nibblers) [/img]

I've also got a couple of decades of metal working experience so I'll chime in with my thoughts.

- Wiss make the best snips. There are a few different styles and tip materials. Home Depot sells two different styles with the steel tips and they work fine. More expensive stainless tips do not make nicer cuts but last longer. I would suggest that a single pair of red handle snips are all that is required for *most* jobs (for a right handed person, that is).
- Straight cut, non-seraded, snips make nicer straight cuts cuts than the seraded snips but are quire pricey.
- Wear leather work gloves. At the very least, wear a glove on your left hand when you cut with your right (and vice-versa).
- A decent quality bi-metal hole saw will cut a cleaner hole than can be made with snips.


-- Tom

Thank you for these 2 points, very useful info.
What are your opinions on nibblers ? I hate to spend 20 pounds plus on tin snips after the last ones savaged my case (thank fully an old Duron)

Snips will give you the best control if you can cut the material easily with them. It's very difficult to follow a line perfectly with a nibbler. Even if you can follow the line perfectly, a nibbler punches little holes (that's how it cuts) so the edge will not be smooth... not even compared to the serated snips.

I was in the HVAC industry so we didn't need to make anything look pretty. When I cut a panel for a car or make something dressy, I always use Bull-Dog snips. They are expensive but they make a really nice cut.

If the snips won't cut the material easily, you're better off with a nibbler. The snips will just bend the edges and you'll nick the jaws which will cause further damage to your project. I think you'll find that the Wiss snips that Crisspy is recommending will cut far better than cheap hardware store generic snips so I wouldn't be too quick to assume that you need a nibbler. If it's 20 gauge or less, you're probably best with the snips.


-- Tom

I have to chime in too....

I followed the advice and bought the Wiss tin snips --- fabulous tools. I cut the grills out of my 3700amb case just like Ralf did. It was easy enough even for a non-mechanically inclined individual like me. Slapped some c-strip molding around it and it looked like a professional had been at work. I then decided it was time to do my original computer from Gateway. This time around I did even better. Made excellent circular grills. This site rocks -- crisspy and others that provide this kind of input -- thank you.

Btw, here in the US, one can walk into a Sears department store and find all 3 Wiss snips that crisspy mentions. Just head over to the hardware section. You will see the "generic three" and the Wiss brand. I advise going with the Wiss

I just cut out the rear 120mm grill on my SLK3700AMB case like Ralf and Wedge did but I used the Yellow M3 Wiss tin snips because that's what my dad had. I used a jigsaw and the tin snips on the middle part of the grill to try them both out and I went with the snips. It turned out really well. The only second thoughts are that maybe it would have been smoother if I had used red handled snips, I don't know, but it really looks nice with the rubber molding around it! Also, the snips are a little big for a job like this, they cut really nicely but I don't think I could have used them to cut a much smaller hole, you can't get the thing in there enough to have the blades level with the metal.

>, the snips are a little big for a job like this, they cut really nicely but I don't think I could have used them to cut a much smaller
> hole, you can't get the thing in there enough to have the blades level with the metal.

It would have been easier with red or green handle snips. Also, there are offset jaw snips that make it easy to cut extremely small circles.

Yes, definitely would have been easier with the red or green, but I'm glad to hear you got it done MikeK.

Can't you use a dremel to cut out the hole as well? I have the M1's but it would seem a bit hard to use it to cut the case with.

Yes, I dremeled out a stamped fan grille yesterday. I have never used snips, but a nice dremel kit is certainly handy to have. I am not sure which would be more efficient for this particular task.. the dremel is a little noisy and results in a lot of fine metal dust.

There are some really neat attachments you can get for the dremel as well:

I tried three fan hole shapes for rear fan (80mm Panaflo L1A):
- First time, square hole. I asked Dad to just snip the lattice work out. This left a square hole, while this was better for airflow it was clear that there was room for improvement.
- Second time, round hole. I drew an 80mm round hole and he cut that. Better yes, but still seemed like it would restrict some airflow.
- Third time, I used a Vantec Fan Vibration Kit gasket as a template and he cut that out. This shape is square with rounded corners. I'm satisfied clearly zero airflow restriction now. Notice that this is the same shape that is used by Seasonic Super Silencer 400W (SS-400AGX) rear fan space.



More pictures here of cutting and soldering.

Lilla

i just cut the grills out in my antec 3700amb..used a jigsaw and a power file...the end result is suprisingly good

Lilla,

I just finished looking at the pictures of your project - very impressive, especially the extremely slick power supply cooling channel and those incredibly professional fan mounting holes! I hope you do something nice for your Dad - like changing the oil in his car or making him cookies, or something...

Everyone should follow the link to check out Lilla's project!

I have to say, this is the first time I have ever seen grommeted hard drive mounts in a PC that make any sense to me - or seem like they will really work! When I bought a floppy and CDR/W drive from Directron, they had a "quiet" option to get drive mounting "grommets". I had no idea how they would work, but I coughed up the shekels - may did I get ripped. When they got here, they were just rubber (or neoprene, or whatever) washers - like the ones you home made out of tubing. Further, I had no idea what to do with them that would do any good!

I couldn't put them between the drive and the drive cage - no room. Even if I did, the screw head would just pass the vibration to the drive cage. I could have put the out side the drive cage (screw goes through washer first, then drive cage, then in to drive), but then the drive simply passes the vibrations directly into the cage. Even if I used two sets per drive and managed to get one inside and one out, the screw would still pass vibration to the drive cage where it pass through the drive cage.

You said that you used these home made washers to mount optical and floppy drives. How do you use them that they do any good?

I am going to look at my hard drive cage and see if I can modify to accept REAL grommets and use shoulder screws - this I understand! I'd love to think I could get some value out of those funky - and way expensive - rubber washers - help please?