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Thread: Sheet metal flatness / availability

  1. #11

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    Mar 2020
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    Re: Sheet metal flatness / availability

    Great book. One of my engineering professors in college gave me a copy. Everyone involved in manufacturing should read it.

  2. #12
    Drew Wiley
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    Sep 2008
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    Re: Sheet metal flatness / availability

    Ha, Randy, something you said brought back a memory and made me chuckle. A job I held for five or six years in my 20's was at a store catering to auto dealership mechanics, machinists, etc, with a huge selection of specialized bolts plus Starrett precision tools. Precision ground straightedges were ordered on demand, took at least six months to get, and at that time, all of Starrett's billing, communication, internal paperwork, etc was literally hand written. Those straightedges had to be made of a special kind of steel which was not stainless. After a particular individual waited six months for one, which required a substantial prepayment in those days, when he inspected it he complained of the oily feel and wasn't amused by the oily paper it was wrapped in. Once he got back to his facility (in this salt air climate, near the Bay itself), he promptly removed all the oil with solvent, and placed the straightedge in a closet. When he actually needed to use it another six months later, it was so rusted and edge-pitted that it was useless. He might as well have bought a 50 cent yardstick instead.

  3. #13

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    Feb 2009
    Location
    Chicago, IL
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    176

    Re: Sheet metal flatness / availability

    Peter,

    It sounds like you need more precision than the following will provide, but for general usage where I need aluminum sheet of about .020” to .030” thickness, I simply use aluminum cookie baking sheets. They are flat, not expensive, and come in larger sizes than sheet stock from a hobby store.

  4. #14
    ic-racer's Avatar
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    Feb 2007
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    6,359

    Re: Sheet metal flatness / availability

    The Starrett catalog. I got a Starrett catalog at a used book sale in 1973. I was fascinated with all that stuff; I wanted to be a designer in Jr High.

  5. #15

    Join Date
    Dec 2012
    Location
    Northumberland, UK
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    Re: Sheet metal flatness / availability

    Quote Originally Posted by r_a_feldman View Post
    Peter,

    It sounds like you need more precision than the following will provide, but for general usage where I need aluminum sheet of about .020” to .030” thickness, I simply use aluminum cookie baking sheets. They are flat, not expensive, and come in larger sizes than sheet stock from a hobby store.
    That's a great idea for general purpose thin sheet. Often non-stick as well...

    There must be lots of things that could re-purposed... Kick sheets, finger plates (for doors)?

  6. #16

    Join Date
    Nov 2017
    Posts
    582

    Re: Sheet metal flatness / availability

    I'm just a very amateur making steam models. Aluminium is not really my favorite to work with. The typical extruded bar you find in diy stores is a pain to turn or mill (even to file). It has a tendency to "flow" instead of chip when you work it. It clogs your tools and sticks to it like glue. Often a very rough surface as a result.

    The harder grades alu are easier to machine. Look for something like Si1 or with Mg in it. With a sharp tool (Co ones if you have them) and a suitable cutting oil when drilling. There are some alloys (with Zn and Pb) made for CNC automated machining that should be better but getting your hand on them as an amateur is another issue. If you need something that has from the start a nice surface and good planarity you could try to get your hands on Planoxal. A rather hard alu that machines well. It is claimed to be flat in a couple tenths of a mm/m. But the thinnest is 8mm.

    Sheet metal isn't much fun to do in a home workshop. Shears are large and the small ones not worth their money. It is often hard to clamp without distorting it, larger than your machine can handle etc. And finding a place that want to sell you a small piece can be hard (I haven't found any willing to sell copper sheet smaller than 1 mē). So I have most of it laser cut to my drawings. Look for a company near to you that is willing to do that. It also means you do not need to keep several sheets of different thickness in stock.

    Overall I prefer steel to work with. Also easier to paint when everything is done. For some small (round) pieces brass or bronze, those can also be soldered or brazed. But like alu a pain to paint. And drilling bronze can be rather stressfull as it has a tendency to grab your drill and pull it in your workpiece.

    As you are in the UK, for small sizes of non-ferro I used Mallard Metals Packs before Brexit but it looks as if they closed for good. Plastics, in case you need them I used directplastics, they are also very helpful if you ask them something. But again, with Brexit I don't know if that will be interesting anymore. They have a very large selection and sell you small pieces.
    Expert in non-working solutions.

  7. #17
    Drew Wiley
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    Sep 2008
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    Re: Sheet metal flatness / availability

    Ice racer - I've got a better Starrett catalog than you have, due to its much better prices (1905). Have one from the 1920's too. Some of the product numbers haven't changed from the 1880's; and if you order a new ruler for a combination square that old, it will fit precisely unless the head has rusted.

  8. #18

    Join Date
    Dec 2012
    Location
    Northumberland, UK
    Posts
    268

    Re: Sheet metal flatness / availability

    Havoc - many thanks for the guidance on materials based on your own experience, that's invaluable to a metal working 'newbie' like me.

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