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Thread: How to make a rectangular hole, smaller than 1", in aluminum sheet?

  1. Top | #11
    Administrator rrmccabe's Avatar
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    By the way Greenlee makes an actual punch for some things like this. Not sure if they will have it for a 15 pin but maybe you could find a used knockout punch for your connector.
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  3. Top | #12
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    Quote Originally Posted by rrmccabe View Post
    We will do what we can to help you come up with a solution. Even at hundreds per year drilling and filing would not be bad to get you started
    well thanks, but the drilling/filing method is not going to work for us.

    At the moment, the fret saw is looking like the best result for the lowest price (about $50). But still hoping for an affordable punch solution.

    cheers!

  4. Top | #13
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    Quote Originally Posted by rrmccabe View Post
    By the way Greenlee makes an actual punch for some things like this.
    YES! i'm aware of it. Starting at $200

    http://www.mcmaster.com/#knockout-punches/=psmwyq
    http://www.l-com.com/d-sub-punch-db1...e-greenlee-231

    Not sure if they will have it for a 15 pin but maybe you could find a used knockout punch for your connector.
    sadly, we cannot opt for used tools, since we need to equip all our team-members with a uniform toolset, with the ability to easily replace worn-out/broken tools.
    Last edited by johnyradio; 12-13-2013 at 04:59 PM.

  5. Top | #14
    Senior Member Kennyd's Avatar
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    Search "Roper Whitney" punches on eBay, they have many punches that may work, and the company has many dies in different shapes. I just bought a #8 with a stand for a good price.


    Also, you can get punches on eBay for cheaper then Grainger or McMaster: Greenlee 25 Pin D Subminiature Panel Punch RS232 | eBay

  6. Top | #15
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    many thanks, but these are out of our price-range. i found the exact punches i need, see links above. Starting at $200

  7. Top | #16
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    for multi use tools for what your doing you cannot beat a dremel tool, there are cutters for plastic and metal, there is the depth cutter guide attachment that could easily be adapted to follow a pattern, a punch for what your showing would need to be custom made and big $$, most of the methods available will create distortion problems in the finished piece as punching no matter how good still moves the material.
    If it were me Id get a die grinder and set it up like a vertical spindle sander
    Hi! Im Steve and Ive never had a iron deficiency

  8. Top | #17
    Senior Member mjncad's Avatar
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    Welcome to WA John.

    First let me say thank you for working to teach kids creative skills that will be useful later in life. I'd much rather see your approach to helping people succeed in life than Uncle Sugar's throw money at the problem that has failed. OK, so much for my editorializing.

    Watching your organization's video using sonotubes for speaker enclosures, and other repurposed items reminds me of Depression Era adults telling people of their youths where they scrounged whatever they could to make toys for themselves. That is how imagination and creativity are fostered. Although the Soapbox Derby cars of today bear no resemblance to their namesakes that were created from old wood soapboxes, scrap wood, discarded baby-buggy wheels, tin cans for headlights, etc.

    Unfortunately your per person budget really puts a crimp in your options. Anyway, please see my replies in red along with some links I hope you find helpful.


    Quote Originally Posted by johnyradio View Post
    Hello

    We are a non-profit electronics mentoring project for at-risk youths.

    We need an inexpensive, portable, quick method to cut, drill, or punch a clean, accurate, rectangular hole in 0.012 (30 gage) aluminum sheet.

    we are going into production, so we need something quick and consistent.

    We do everything by hand, and each builder is an independent craftsperson, so each builder needs their own personal toolset. So it can't be too expensive.

    We can only use hand-tools (electric or manual), or inexpensive benchtop or table tools (about $50 max, but $25 seems more reasonable to cut a hole in aluminum!). The method should lend itself to other size/shape holes. Modifying or repurposing off-the-shelf tools is fine, tho.

    Here's the piece. It's something like a gas pipe or chimney pipe cap from a plumbing supply company.



    The rectangle hole needed is approx 1/3" x 2/3", and it must fit the following part (JUST the trapezoidal section with little holes in it, not the entire part):



    As others have said, there are punches out there for D-sub connectors; but they will be quite expensive.

    I've found a few methods, need feedback/suggestions:

    • Buncha holes: The old "drill a bunch of holes in a row" method. Not accurate, not clean, not professional-looking. We could clean it up with a file, but too time-consuming, and still not very accurate.


    Agreed, this is only good for prototype or one-off projects where appearance is not critical.

    • Nibbler: Drill holes in the corners, then use a nibbler. Seems only slightly better than the above method. Concerned about curls/distortions and burrs in the metal. However, if someone knows a tool and technique that will give us consistent results, please share! Do nibblers give clean, straight tiny cuts, without curling or messy edges? One guy says "Nibblers are punches- they punch a series of overlapping round holes. They leave behind a pile of razor sharp miniature half moons that stick to shoe soles, flesh, socks, wood, pretty much everything. They do not cut straight lines very well. Freehand, you usually a get a slightly serrated looking edge. Used up against a clamped down fence, they are a bit better, but still not shear quality." If that's true, forget nibblers.
      Precision Hand Shear Sheet Metal Snips Nibbler Cutter Cutting Tool Cut Modify | eBay


    I've never used one; so I have no real comments as to how well they work.

    • Metal snips or metal shears, ditto above.


    I'd rather use a nibbler than tin-snips; plus I doubt you'll find a pair of snips capable of doing something that small.

    • Metal file: I don't mind a quick file to smooth sharp edges, but to cut the whole hole with a file is too time-consuming and labor-intensive, and not accurate.


    Fortunately aluminum is soft and easy to file; but you'll need jeweler's files from a hobby shop or jeweler's supply store due to the thin sheet metal in your projects. Regular sized files are too big, clumsy, and coarse for your kind of work. Jeweler's files come in numerous shapes, and I have a couple of sets. Please see this link.

    Search Results - Micro-Mark

    • Arbor punch press. This seems promising. My idea is to get a standard 1/3" square punch, and then punch two holes side-by-side, to get my desired 1/3" x 2/3" rectangle-- but that could produce a crooked rectangle if the squares are not lined up. Does thin aluminum really need a 1/2 ton or more of pressure?
      1 2 Ton Arbor Press | eBay


    As others have said, these are better suited for pressing bearings, etc. As for the amount of pressure, you'd be surprised at how much pressure is needed for punching/stamping sheet metal. Look at how thin the sheet metal is on modern cars; yet their stamping machines output hundreds of tons of pressure or more.

    • Hammer: I understand the punch and die used on the punching machines can be used by hand, with a hammer, without the machine. Anyone have experience with that?


    Nope, I haven't.

    • Hand-punching tool. I'm very interested in this method, as it seems simple, quick, and consistent. But have not yet found a hand-punch with square punches. Anyone? Do these things hold any size punch, from any manufacturer, like a drill can hold any size bit? Trick-tools tells me "all square sizes will be $173 each."
      Grizzly.com
      XX Hand Punch, Roper Whitney Sheet Metal Punch


    I have no idea if the punches and dies are a standard configuration that are interchangeable like holesaws are; but I doubt it. Assuming you could find a D-sub punch, I think the cost will be out of reach.



    Same comments for the hand punch.

    • Dremel or similar tool?


    Actually I think this will be your best bet. What I would look into is Dremel's plunge router attachment, then make a jig/template of the D-sub cutout, and just trace around the template. A proper router bit should cut through the aluminum like butter.

    335-01 Plunge Router Attachment / Model: 335-01

    This Dremel attachment is probably cheaper, and might work using the same jig/template idea to trace around.

    565 Multipurpose Cutting Kit / Model: 565

    • Square punches for wood. Wood these work on 30 gage aluminum? The retailer says "These Punches are hardened to RC48 which should be harder than your aluminum so yes it should work. The question will be the durability and how long it will stand up and it will probably need more frequent sharpening than using this on wood as it was intended."
      Square Hole Punches - Lee Valley Tools


    The punches are hard enough; but the cutting edges are optimized for wood, and will quickly be destroyed.

    • Screw-down: Not invented? I've heard of a punch that you just tighten until it punches thru, but have not found any. i imagine drilling a small round hole in my aluminum sheet, then fitting two small separate hardwares on either side of the sheet, screwed to each other through the small round hole. They are some kind of punch and die. Then, tighten them down, and out pops the square hole in my sheet. Does this exist? If not, let's invent it!
      Q Max Square Sheet Metal Punch 19mm | eBay


    The cost of inventing something like this will add up very quickly, and the concept probably works; but is too slow for mainstream industry to use, hence the reason you haven't found them to be commonplace.

    • Straight-line punch? Something like a chisel. With a hammer, cut each side of the square hole. Seems promising, yet risk of inaccuracy.


    Cold chisels are used for metal working; but not for the kind of work you'll be doing. Wood chisels; though hard enough will fail quickly.

    • Big round punches + corner punch: Round punches a very inexpensive, so punch 3 large 1/3" holes next to each other, overlapping. The corners would be round, so maybe a corner punch could help
      Search Results - Micro-Mark


    Too many steps and too inconsistent without a jig/template to guide the punches. Any kind of punch made for leather, paper, etc is the wrong type as they use cutting edges that need a consistent edge.



    Jeweler's saws are wonderful tools and should be part of the communal tool kit for prototypes. However; they are slow; but will cut aluminum with ease. You'll need plenty of very fine tooth blades, which break easily. In my teenage model-making days, I cut plastic, metal (aluminum, brass, some thin mild steel), and wood with a jeweler's saw. And as you say, they are only as accurate as the user.

    Search Results - Micro-Mark




    • Something else?



    Many thanks!

    John Weiss, Director
    Bayview BOOM Mentoring Project
    bayviewboom.org
    415-68-WHEEL

    We teach teens in the hood how to build boomboxes. This is a violence-reduction program, and much more. Check out this fun 2-minute video of some of our participants:
    I've moved on to mature greener pastures free of the NSA.

  9. Top | #18
    Senior Member mjncad's Avatar
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    Quote Originally Posted by johnyradio View Post
    aren't those arbor presses intended for punch and die?
    Quote Originally Posted by justsomeguy View Post
    what you are really looking for is a press with the appropriate size template and a punch out made up though, then you can just quickly punch out the exact size you need and have it the exact same every time, very little burs or filling needed..but that is starting to get pretty pricy going that way...
    Quote Originally Posted by rrmccabe View Post
    I really dont think there is any sub $100 tool you can buy that will do "quick and consistent" production work. You are going to have to compromise and do a little extra work.
    Quote Originally Posted by johnyradio View Post
    i wonder if there some similar machine designed for punching.
    The closest thing you're going to find is an "ironworker;" but these machines are expensive (many thousands of dollars), and the tooling (punches and dies) are very expensive as well (hundreds of dollars). Since ironworkers are used more for heavier metal fabrication, I doubt there are D-sub dies for them, and if there are, they are considered specialty items raising the cost even further.

    Punches meant for leather and paper work by cutting the material in a manner similar to a knife. The kind of punches you want consist of a punch (male) that fits into a close fitting die (female) that are made from hardened tool steel. The material being punched is the weak link, and brute force creates the cut and pushes the slug out the bottom.

    Quote Originally Posted by Kennyd View Post
    Search "Roper Whitney" punches on eBay, they have many punches that may work, and the company has many dies in different shapes. I just bought a #8 with a stand for a good price.


    Also, you can get punches on eBay for cheaper then Grainger or McMaster: Greenlee 25 Pin D Subminiature Panel Punch RS232 | eBay
    What Kenny found is your best bet; but you'll have to follow RMcCabe's advice and compromise on your tooling and/or workflow. You could have the kids rotate on the jobs to teach them different things. One day have a kid punch out sheet metal, another day he cuts sonotubes to length, another day he decorates/paints the tubes, another day he does final assembly, and another day he does quality control testing.

    McMaster-Carr is my favorite store; but they are expensive. If I can something cheaper somewhere else I will; but if I need something and no one else has it, they are my go to source.
    I've moved on to mature greener pastures free of the NSA.

  10. Top | #19
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    Quote Originally Posted by mjncad View Post
    Welcome to WA John.
    thanks, mjncad.

    First let me say thank you for working to teach kids creative skills that will be useful later in life. I'd much rather see your approach to helping people succeed in life than Uncle Sugar's throw money at the problem that has failed. OK, so much for my editorializing.
    i really appreciate your encouragement, you get it! and i don't mind your editorializing (until people get annoyed, because it's a metalwork not political forum I know social workers in the ghetto who agree with you (tho i think Uncle should support this type of work).

    Watching your organization's video using sonotubes for speaker enclosures, and other repurposed items reminds me of Depression Era adults telling people of their youths where they scrounged whatever they could to make toys for themselves. That is how imagination and creativity are fostered.
    sir, thanks for taking the time. Yes, repurposing whatever's at hand is part of the philosophy, because it's about ingenuity, and it's greener-- trying to counter the buy-discard-buy-discard mentality.

    My Depression era/WWII Dad made sure i grew up knowing how to use tools. Just trying to pass it along. A lot of these kids don't know tools. But they love learning it, i have a waiting list of kids waiting to work with us. They get it too. They go crazy for this project. People think kids in the hood don't want to learn, but they do-- maybe schools are out of touch?

    Although the Soapbox Derby cars of today bear no resemblance to their namesakes that were created from old wood soapboxes, scrap wood, discarded baby-buggy wheels, tin cans for headlights, etc.
    that's very interesting, because i started the project a couple yrs ago with the goal of doing exactly that! We got a small grant (from burning man) to do a parade of Derbies and artbikes. It's still the long-term goal, but i discovered the hood needs more making/building activity first. So that's our current focus.

    What I would look into is Dremel's plunge router attachment, then make a jig/template of the D-sub cutout, and just trace around the template. A proper router bit should cut through the aluminum like butter.
    335-01 Plunge Router Attachment / Model: 335-01
    This Dremel attachment is probably cheaper, and might work using the same jig/template idea to trace around.
    565 Multipurpose Cutting Kit / Model: 565
    Thank you for that, it's going on my list of options to investigate.

    You could have the kids rotate on the jobs to teach them different things. One day have a kid punch out sheet metal, another day he cuts sonotubes to length, another day he decorates/paints the tubes, another day he does final assembly, and another day he does quality control testing.
    While the assembly-line approach is likely more efficient, I'm going for the 'independent craftsperson' model. For a couple reasons: i want the youths to learn and master all steps and skills, and not just be a factory cog. And also, i'm just nostalgic about the old-school master scenario, which goes against the grain of today's impersonal factory model.
    Last edited by johnyradio; 12-14-2013 at 02:08 AM.
    mjncad likes this.

  11. Top | #20
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    Quote Originally Posted by Coffee? View Post
    for multi use tools for what your doing you cannot beat a dremel tool, there are cutters for plastic and metal, there is the depth cutter guide attachment that could easily be adapted to follow a pattern, a punch for what your showing would need to be custom made and big $$, most of the methods available will create distortion problems in the finished piece as punching no matter how good still moves the material.
    If it were me Id get a die grinder and set it up like a vertical spindle sander
    Many thanks! added to the list of options to consider.


 
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