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Thread: How do inventors build their prototypes

  1. #11
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    Quote Originally Posted by mixedgas View Post
    Start with a 7x10 mini-lathe and brass, plus the US Army Field Machining Handbooks. Skip the mini-mill, I own one, but rapidly upgraded to a full size Bridgeport Clone. DRO options are worth their weight in Gold on Mills and Lathes. However I do most of my measuring with a Mitutoyo 500-196-30 Caliper.

    View the Mini-Lathe as a kit of parts, they take some hand fitting to get to a .0005" precision over 6" of cut. That took me 48 hours of hand scraping the lathe ways. Do NOT go CNC on your first lathe, you will be endlessly frustrated if you do. Anyone who tells you to begin with CNC while learning the fundamentals of machine tools is doing you a disservice. Little Machine Shop is my preferred vendor for these. You'll need considerable tooling, a rule of thumb is that the tooling/spares/etc. for a machine tool will be at least the same as the cost of the tool when purchased used.

    Considering where you live, McMaster Carr corporation is your newest friend.... www.mcmaster.com

    Find: US Army, Fundamentals of Machine tools, too big to upload to PL.
    US Navy: Machinery Repairman Handbook
    US Navy NEETs (electronics self help)
    Book: The Art of Electronics, Horrowitz and Hill, Second Edition, NOT the Third.
    MIT Machine Shop Videos
    Book: Building Scientific Apparatus by Moore and Davis.
    Dan Gelbart's videos building prototypes in the shop on Youtube
    MrPete222 / Tubal Cain's machining videos on Youtube.
    Frank Hoose's mini-lathe.com (<<<<< THIS!)


    I can do more quick invention work on the lathe then I do on a Mill daily at the University. The Mill is far more important in the shop, but a beginner can get really, really, creative with a lathe with less chance of ruining the machine and far less expense. Learn on a "disposable" 7x10 or 7x12 with readily replacable parts. Yes, they are junk compared to Bridgeport or Clausing or old South Bend, but a well tuned 7x10 is an utterly amazing piece of junk when working with soft metals such as Aluminum or Brass.

    One of the niceties of machine shop tools is you can rapidly destroy your own machine until you learn where to place the cutting head before powering up. Hence my suggestion for a 7x10, replacement parts are cheap.

    Avoid Sherline, Taig, Prazi. and lathe/mill combo tools.. Sherline is a good starter for aluminum work, but you will rapidly replace it with a 7x10.

    I should warn you, establishing a shop is extremely expensive, and if your proficient with it, well, getting addicted to drugs is probably cheaper.. Makes Aviation with a light sport license look affordable if your not careful. (Not that I would endorse Drugs in any way)

    In the lower 48, a good used mill starts at 2,000$ plus another 1000$ in shipping and handling. Not to mention the need for a massive , very dry building, a really solid and level floor, and often three phase power or the need for a 3-7 HP phase converter. Cheap tabletop mills often suffer from deflection issues, even though they look strong, obtaining good results requires massive steel castings in most cases. Hence the full size mill if needed.

    In your case it may be easier to send milling out. Used Mills are tricky to buy, and the bugs/wear/old age issues do not show up until you use the machine for a while. I'm not sure I'd ever buy a used one again, but I sure as hell can not afford a new one. :-)

    Machine tools are made of a tough steel that rusts nearly instantly if not kept oiled. You can easily ruin your tools by neglecting them.

    Evaluate if you have the needed 3D thinking skills on a lathe, you'll know if you have the knack or not really quickly.
    abebooks.com is your friend.

    You can do some wicked stuff with just a Dremel tool, but that requires thinking and good hand/eye skills.

    Please see attached...

    Steve
    Thanks for the info. I have a mini-mill and mini-lathe. Bought them when they were only $399. They have gone up considerably since then!
    I'd probably skip the mini-lathe and go to something like a small Atlas or Clausing lathe if I did it again. The mini-mill has served me well, actually. A Bridgeport would be much to big and heavy for what I do.
    I'll check out the books you mentioned, too.

  2. #12
    Join Date
    Dec 2018
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    Quote Originally Posted by VDX View Post
    ... what are the building dimensions and rigidity specs you're looking for?

    When active with "microtech" +15 years ago, I've modified some Isel-CNC-mills for higher rigidity and resolution - did some "high-tech" and precision stuff with them too ... PEEK, aluminium, brass, (steel-sheets) with accuracies down to 2-3 microns in smaller parts

    Actually I'm using an Isel MiniFlat prototype (with servos instead of steppers) for my laser-worx and an Isel EP1090 for milling - attached images of the MiniFlat and EP1090 together and the EP1090 with a "car-PC"-controller alone ...

    Viktor
    My friend helping me upgrade is using an ESS-B smooth stepper with break out board and motor control circuits for each motor. The smooth stepped allows you to plug right into the eithenet port on your computer and use Mach 3/4. It still uses a dewalt router so it would be nice to upgrade to something that has automatic speed control but that’s big money.

    The machine is being raised up and made more ridged and the cheap bands replaced with screw drives.

    As long as I can easily convert solid works to Mach 4 and this thing can cut aluminum without a bunch of problems this should be an awesome tool to have.

    I will have to google your references when I get home to my real computer.

  3. #13
    Join Date
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    ... for "automatic speed control" - without a bunch of money - look into GRBL.

    My machines run with free/OS 3D-printing-softwares+firmwares like Pronterface (modified it for my needs to "gieCAPS") + Marlin4Due ... or with Editask10 (CS, 3-axes-license around 200€, I have a developer-license with 32-axes capabilities) ... or with Remote (CS too, but free download from Isel service) ... or BeamConstruct (CS too, but free download from HAlaser).

    All of them (but BeamConstruct) have multiaxes-lookahead with acceleration whats driving the CNC-mills with up to 100mm/s (or my beltdriven machines with up to 800mm/s) ... BeamConstruct is primary meant for galvo-scanners, so "instant" speeds (without acceleration) for galvos with up to 50m/s or for belt-driven XY-plotters with up to 100mm/s ...

    Viktor
    Aufruf zum Projekt "Müll-freie Meere" - https://reprap.org/forum/list.php?426
    Call for the project "garbage-free seas" - https://reprap.org/forum/list.php?425

  4. #14
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    Oh man, you had to mention the dremel tool didn't you!

    I've made tons of things out of scrap sheet metal and a pack of oxide cutting wheels over the years. I remember when I first discovered the fiberglass-reinforced cut-off wheels though... Those are *so* much more durable than the regular ones. In the early days I would break two or three wheels just trying to cut out a slot for a DB-25 connector! (That was before I realized you could buy a punch for that...)

    As for cutting glass, I've had decent results using the same oxide wheels. You have to go really slow and let the heat dissipate so the glass doesn't crack though. I don't think I ever had to cut all the way through; usually once I had a deep groove cut I could just split the glass along the groove and it would be fine. I made a bunch of bounce mirrors that way. (Some were from really thick mirror stock, like 3/8 inch thick, which took forever to cut.)

    Adam

  5. #15
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    ... for breaking mirrors (thickness up to 5mm) I'm using the carbide bits from a broken circular saw blade ... cut them from the blade with a welding laser

    Viktor
    Aufruf zum Projekt "Müll-freie Meere" - https://reprap.org/forum/list.php?426
    Call for the project "garbage-free seas" - https://reprap.org/forum/list.php?425

  6. #16
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    One comment only because I've spoken to a few folks here that didn't already know this, for sheet aluminum too thick for shears you can cut it on a tablesaw provided you have a carbide tipped blade and take multiple shallow cuts. Be very careful because it's not a forgiving material to cut, just err on the side of shallow cuts moving quickly over deep cuts moving slowly so that your blade is actively cutting, not rubbing. Sure it's not as ideal as a waterjet or mill, but you can do a lot with sheet aluminum and a tablesaw.

  7. #17
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    I cut my aluminum (up to an inch thick) with a bandsaw.
    And my plexi and my polycarbonate, pretty much anything non-ferrous.
    Not glass, though. Glass cutter for that.

    HTH...M
    Runs with Lasers

  8. #18
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    I actually took Adam's advice above regarding the use of a table saw to cut aluminum. I was seriously freaked out the first time I tried it, but it really is quite easy as long as you don't go too fast. I was able to cut 1/4 inch thick aluminum plate with zero issues.

    I still use a jig-saw for small work with aluminum, but if I need to trim a large aluminum baseplate for a projector my first choice is the table saw. It works great!

    Unfortunately, my early success with aluminum gave me the idea to try it with thin gauge sheet steel. That was a mistake. Don't *EVER* try to cut steel with a table saw, even if you have a carbide-tipped blade! It's really dangerous and you're likely to get impaled. I'm just lucky I didn't hurt myself. But I did ruin a $50 blade in about 3 minutes... (And holy hell was it loud!)

    Pro tip: If the metal you're trying to cut is glowing orange at the point where the saw meets the metal, you're doing something wrong!

    Adam

  9. #19
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    Default More cutting remarks

    I cut 1/4" (and thicker) aluminum with my bandsaw all the time. Quoting from the Lumia sticky:

    https://www.northerntool.com/shop/to...1386_200481386 (note updated URL)

    Ideal for cutting up aluminum for motor and lens mounts, base plates, etc. Note that you want to set it for the slowest speed and you need to keep the wheels clean of aluminum debris. These aren’t really designed for metal work, but if you use a 14tpi blade and keep ‘em clean, they work a treat.
    I've been using mine for 7+ years now, on my 4th blade. I use a 1/4" blade, don't remember the tpi, maybe 14 (not in my shop now, email me if you need this info.)

    You really need a properly aligned fence for this. Lots of tips on Youtube for tweaking saws to proper use.

    Also, if you are cutting really thick Al, lube the blade with a wax stick and go slow.

    For cutting long pieces and pipe, I use a miter saw with a 100tpi blade.
    I have a fancy blade on my table saw, but would be terrified to use it with metal.
    To cut glass, get a cheap tile saw and an expensive blade - Black Widow diamond jobbie.

    HTH...Mike
    Runs with Lasers

  10. #20
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    Sep 2014
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    Colorado USA
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    Quote Originally Posted by clickamouse View Post
    I cut 1/4" (and thicker) aluminum with my bandsaw all the time. Quoting from the Lumia sticky:

    https://www.northerntool.com/shop/to...1386_200481386 (note updated URL)

    Ideal for cutting up aluminum for motor and lens mounts, base plates, etc. Note that you want to set it for the slowest speed and you need to keep the wheels clean of aluminum debris. These aren’t really designed for metal work, but if you use a 14tpi blade and keep ‘em clean, they work a treat.
    I've been using mine for 7+ years now, on my 4th blade. I use a 1/4" blade, don't remember the tpi, maybe 14 (not in my shop now, email me if you need this info.)

    You really need a properly aligned fence for this. Lots of tips on Youtube for tweaking saws to proper use.

    Also, if you are cutting really thick Al, lube the blade with a wax stick and go slow.

    For cutting long pieces and pipe, I use a miter saw with a 100tpi blade.
    I have a fancy blade on my table saw, but would be terrified to use it with metal.
    To cut glass, get a cheap tile saw and an expensive blade - Black Widow diamond jobbie.

    HTH...Mike
    I've found Ivory soap is a good dry lube for cutting aluminum on a table or radial arm saw. (edit) More explanation is required so I am referring to a solid bar of Ivory soap, not the liquid variety.
    Last edited by lasermaster1977; 01-23-2019 at 08:59.
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