Cutting or punching square holes in steel sheet?

I need to make some square ( approx. 50*100 mm ) and round ( approx. 75mm diameter ) holes in either 2 mm steel or 3 mm aluminum sheet.. I can cut the round holes using a holesaw ( bimetal body, carbide tipped ) in the drillpress, but how do I cut the square holes with a good result?
I have a drillpress ( cheap one ), but I am willing to invest some money ( not a fortune though ) in the proper tools if needed.. A CNC mill would be nice, but not quite within the budget .-)
Any suggestions will be appreciated
/peter ( another one of those weird scandinavians )

That stuff is often best done with a punch. Then there is also the drilling out of the hole and filing to size. This is only done on a onesy type thing tho. I think that Greenlee has a 1/2" square punch but am not sure.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

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OK.. I can get a limited selection of the Greenlee stuff over here, but 1/2" is way too small, and I dont think it would work too well if I try to make overlapping holes ( to get the size right) with a punch ?
The excact dimensions of the square hole I need is 45*108 mm ( 1 mm oversize os OK )
Another punch-question: I am about to order some Greenlee punches for the smaller holes I need to make, but from the litterature I can get on the Greenlee Slugbuster series I cant see if they come with the needed drawbolt or not... Does anyone know?
/peter

I don't know what will be included, it's probably best to confirm that with your supplier. There are thrust bearings available for the drawbolt to rotate on, and these are great for punching with a wrench/ratchet/socket by hand. The plain bolt will get tedious for numerous holes done by hand. Another thing to check on would be the head size of the drawbolt.. they have some square heads that you might not have a socket for, so you might want to be sure to get the hex head drawbolts in a size that your tools will fit.
WB ..............
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This
1/2"
oversize
drawbolt

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What might help is knowing how many holes you need - one, two, dozens, hundred, thousands.....
John Martin

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hundred,
30-50 for now... But I may need to make more of these panels later..
/peter

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use the 1/2" square greenlee for the corners and mill out the rest

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Yes.. See.. thats the problem.. I dont have access to a mill at the moment :-(
/peter

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Peter, For the square holes, while it would be a PITA, you can make a layout, drill the corners (larger diameter than a blade is wide), then cut the entire square out with an electric saber saw (jig saw?). Certainly not the best way to go, but it does work. Be certain to match the blade to the job at hand if this becomes your choice. Drilling the corners allows for the blade to make the 90 degree turn, if that isn't obvious to you. This would be relatively easy with aluminum, not so great in steel.
I agree, if you can get a Greenlee punch that would work, that's the best of all worlds, even if you have access to a mill. The only thing better would be a large punch in a proper press. A mill would not address the sharp corner I assume you desire. .
Harold

You may find a specific puch at mcmaster carr http://www.mcmaster.com/ for the bigger hole - something like an LCD window puch or you can have it custom made - then you need the hydraulic press to run it - but be prepared to pay a lot of money - you may be better off producing your panel/faceplate in a drawing / cad program and farming the work out to someone with a laser/water jet cutter or if you don't mind a little cleanup a CNC plasma cutter - for 50 to 100 or so it would be way cheaper than a big punch/die. If your product starts to move and you need more then you might want to consider spending the money for the equipment. The other option is to do it by hand (small square puch the corners then cut the rest) but given that you have other holes to make and of various sizes - you would be better off hiring it out - the added advantage is that you can be spot on with placement & accuracy everytime.
I hate hiring out myself, but when I have produced face panels and such this has been far more economical (and time saving) than the the Do It Yourself approach
Good Luck
Tom
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Answering my own post but... go to http://www.mcmaster.com/ and look at page 2124 of the catalog (DIN punches) the 45mm (1.77in) is no problem but they only go to 92mm (3.626in) and the price is US$549 - and then you still need the hydraulic press - like I said - farm it out
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75mm
tipped )
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be

Hey Peter,
You left out a bit of important information. How many, and how accurate in size and location shape? Would a nibbler do?
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXX
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Well I dont need it a 100% perfect fit, but I do need to be able to mount DIN rail GFCI and fuseblocks thru the holes, while keeping a good appearance, so I am thinking up to 1 mm oversize will be OK..
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You tell me :-)... Sheet is either 2mm steel or 3 mm aluminum..
/peter

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46X92mm
not
exactly
The 46*92 mm punch is the closest thing yet, but I need the width to be 108 mm ( I posted the excact dimensions somehwere in this thread )..
That hydraulic punch driver.. any clue on cost ?.... Would it be possible to use one of those cheap hydraulic press thingies like this one? http://www.biltema.dk/products/productimage.asp?iItemId 854 ( can get this one for about 150$ wich I find cheap )... It is rated for 5 tons..
Square vs Rectangular :Just shows that I shouldnt post messages in a foreign language when I got up at 4 am and worked for 12 hours :-)
/peter

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    I don't think that it would work well -- without a *lot* of special fixturing first being applied.
    The hydraulic drivers for the chassis punches -- only my belief, as I have never had my hands on one, so others can fill in corrections at will -- has a hollow piston on a cylinder at the end of a hose. The base of the cylinder rests against the top of the die. A bolt is placed though the hole in the piston, through a hole drilled or punched in the sheet metal, and then threaded into the punch. (Hm ... this is for round punches only. Keyed ones, and rectangular or square punches have a screw with a keyed shape which goes through the die and the punch, and (for the sizes which I have used), have a nut to draw the punch down into the die (and through the sheet metal). Some more complex ones have three drawscrews which go through the die and thread into the punch. (An example of this is the one for the DB-25 connector mounting cutout.)
    There needs to be some way to assure that the punch and die are in proper alignment. Your hydraulic press won't do that by itself. Neither will a single draw screw -- unless there are some guide pins to either side of the screw to maintain alignment.
    Anyway -- the hollow piston hydraulic slave cylinder is powered by a hand-operated pump, or an electric one -- capable of 10,000 PSI (sorry -- I don't know how many Pascals that would be -- not used to Metric units of pressure yet.) Enerpac is one of the makers of such pumps, and may be the maker for the Greenlee sets, for all I know.) I believe that the cylinders in question can develop 10 tons of force from 10,000 PSI of hydraulic pressure.
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    Well ... "square" also can be used to mean "at right angles", so "square" here distinguished it from round or a parallelogram or trapezoid, so you can claim one of those meanings. :-)
    Enjoy,         DoN.

I don't know where you are, but you might be able to design and have made locally a punch set to use in a cheap hydraulic press. My thoughts on a design would be a punch of the right size with two holes for alignment. And a die with two rods that align the punch. The rods would be in the area being punched out. You could put the punch on the material and get it aligned, then use it as a drill guide to drill the alignment holes. If I were doing it, I would have the alignment rods attached to a plate and the plate attached to the bottom of the die with a couple of dowel pins and a couple of screws. After punching several holes, you could unscrew the screws holding the rods and push the scrap on through the die.
Please note that I have never made such a thing, so there might be a bunch of problems that I did not consider.
Dan
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I don't know if it's a practical solution or not but you can drill square holes with your drill press. See:
http://upper.us.edu/faculty/smith/reuleaux.htm
for details.
Martin