Tool Making

Discussion in 'Techniques' started by KC3KNM, Jul 12, 2018.

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  1. Jul 12, 2018 #1

    KC3KNM

    KC3KNM

    KC3KNM

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    If this is the wrong forum, please report this post to be moved.

    Does anyone else enjoy making tools? Between saving money, killing boredom and tailoring something to a specific purpose I find myself doing this pretty often. I think it'd be a neat idea to try to compile some different scratch built tools or building aids that we can draw ideas from, I know that I've come across some neat stuff in the past that sparked an idea for something of my own. I'd like to share my most recent build, hopefully you guys can take something of worth away from it.

    I just finished a small rotary tumbler to assist in making black powder and eventually mixing other propellants. I threw this together using things I had lying around the workshop. The body is a plastic coffee can, which works well, but runs slightly out of round. I may try a similarly sized tin can, but with the low RPMs I'll be using it at the plastic should be fine. The motor is from an old cordless drill and is controlled by a cheap PWM controller I had left over after I installed a brushless spindle in my desktop mill. It's getting power from a PC power supply that I use to power my chargers, so the entire power setup didn't cost me anything. I'm using a few rubber bands as a belt which, admittedly, is a little janky but they've held up to about 12 hours of run time so far. I may 3D print one from some ninjaflex if they become a problem.

    The rails are PVC coated with plastidip and have bearings pressed into them which ride on 1/4 steel rods anchored into the 3D printed mounts. They run pretty true and the plastidip grabs the rubber bands around the can really well. The base was laser cut from a sheet of acrylic I had lying around, but I plan to move towards something else as it's a little too flexible and brittle for my tastes but for now it works. The motor mount and frame pieces were laser cut from a clipboard (it appears to be some type of particle board), which worked out surprisingly well. It's very stiff and flatter than the light ply I was originally planning on using. Cheaper, too!

    Out of pocket the whole project ended up costing around 5$, I had to grab some screws and bits to tie it all together.

    IMG_0943[1].JPG
    Here's a quick video of it in action. In the video I've got 4oz of powder in it, and even at higher RPMs it's stable, albeit a bit loud.



    If anyone has some homemade building aids to share, I'd love to see them. Thanks!
     
  2. Jul 12, 2018 #2

    cherokeej

    cherokeej

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    This isn't the thread I thought it was going to be. I have to "tool up" for almost every job on the lathe.

    Cute tumbler you've made there. Cobble together what you have on hand, and make it work. Darn right.

    Personally, I would be very hesitant to use a tin can for milling energetic materials. Tin cans aren't tin. They're steel.
     
  3. Jul 12, 2018 #3

    KC3KNM

    KC3KNM

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    I grew up in my Dad’s machine shop and worked as a machinist for a few years. Didn’t have too much experience with turning things, but I’ve built my fair share of flycutters and broaches.

    Yeah, that’s mainly why I went with the plastic. I’m not ball milling anything currently (I powder the components separately before using the tumbler), but might in the future. So it’s really just a mixer in it’s current capacity, but I’ve got some lead media balls I can use when I get there.
     
  4. Jul 12, 2018 #4

    Steve Shannon

    Steve Shannon

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    When you do tumble materials together including the oxidizer and fuel, do so with the tumbler at the far end of a very long extension cord like this:
     
  5. Jul 13, 2018 #5

    KC3KNM

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    I’ve only been using it with some potassium nitrate powder I had to make sure it ran well. I was planning on mixing actual propellant/BP back behind the garage, but the extension cord idea seems much safer. It hadn’t crossed my mind, thanks!
     
  6. Jul 13, 2018 #6

    OverTheTop

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    I don't have a big backyard, so can I put it in the neighbors place?

    I was watching this vid and a guy I work with saw it. Conversation ambled to thermite, then copper thermite that I might use to augment some igniters in the future and he mentioned stuff called MTV. Interesting mix, but it has too much kick for our normal use (and is ESD and friction sensitive :eek:) but might be an interesting read:
    https://en.wikipedia.org/wiki/Magnesium/Teflon/Viton
    Don't try this at home!
     
  7. Jul 13, 2018 #7

    Steve Shannon

    Steve Shannon

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    I think the person to ask is your neighbor and your insurance company since it’s his property you’d be risking.
    Unless you have the space to do things safely, some things just shouldn’t be done.
     
  8. Jul 13, 2018 #8

    heada

    heada

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    Also, use non-sparking media. For BP, I have some ceramic stones I use. https://www.mcmaster.com/#4918A151 For harder things I use brass balls. For anything questionable, I mill them separately and then screen mix them together. Regardless, distance is a must. I have mine set up on the far side of my shed, about 120 feet away from my house and 300 feet away from anyone else.
     
  9. Jul 13, 2018 #9

    Steve Shannon

    Steve Shannon

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    You’ve got brass balls? Sorry, I couldn’t help it.

    In post #3, the OP said he has lead ones to use when he starts making BP.
     
  10. Jul 14, 2018 #10

    KC3KNM

    KC3KNM

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    I've read that lead media can contaminate what you're milling, so I'm definitely open to something else. I've been browsing a lot of the fireworks forums and have been seeing a ton of different opinions on this.

    https://www.skylighter.com/blogs/fireworks-information/ball-milling-media

    I've also seen mention of certain ceramics sparking (in that link and other places), so maybe brass may be the best idea? I'm definitely holding off on milling anything (together, that is) until I'm more educated here. As you've mentioned, milling separately and then mixing after milled seems to be a good technique, and will likely be what I end up going with. Thanks for the input!
     
  11. Jul 14, 2018 #11

    Steve Shannon

    Steve Shannon

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    One other thing: when milling separates, use different containers. Several years ago one of our members used the same coffee grinder to grind all of his separates. It’s been long enough ago that I’ve forgotten details, but the way I remember it when he ground fuel the residual oxidizer combined with the fuel and he got burned quite badly. His son posted sort of a lessons learned post on Rocketry Planet as a cautionary tale for others who might be tempted to do the same. Those mistakes are the ones those of us without experience are apt to repeat.
     
  12. Jul 14, 2018 #12

    OverTheTop

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    I actually mentioned using the neighbor's yard as a joke ;). I should have used the [joke] emoji.
     
  13. Jul 14, 2018 #13

    KC3KNM

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    Great point, luckily I've got quite a few of these coffee cans laying around! I also have multiple coffee grinders that I use for different materials, so I've been careful in that regard. I appreciate the info, I'm definitely in the learning phase here, so I'm trying to take in as much as I can to mitigate any risks I'm going to face. Thanks!
     
  14. Jul 14, 2018 #14

    Steve Shannon

    Steve Shannon

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    I suspected it was a joke. I nearly said “Sure, tell him I said it was okay.”
     
  15. Jul 14, 2018 #15

    heada

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    I don't blade mill (coffee grinder) but if you do, you must have 1 for fuels and 1 for oxidizers. Never shall you cross use them. I ball mill everything and fully wash the jar and media between types. Ceramic is only used for bp so that never gets washed. Brass balls aren't cheap compared to low carbon steel balls or ceramic but they're worth it. And as Steve said, you can claim to have brass balls.
     
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  16. Jul 15, 2018 #16

    prfesser

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    Part 1 of a complete Gingery lathe build:



    Now THAT'S toolmaking!

    Best -- Terry
     
  17. Jul 15, 2018 #17

    KC3KNM

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    Wow! That’s awesome! I’ll have to check out more of his videos, never come across his channel before.

    I’ve got a friend who is really into casting and has a pretty nice setup. We’ve played around with the lost wax method using 3D printed wax parts. The wax filament is definitely one of the oddest filaments I’ve used so far.
     
  18. Jul 16, 2018 #18

    sooner.boomer

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    Lost wax casting was one of the first manufacturing methods. You can even set up a master mold and make wax copies from it. The ultimate is machinable wax that can be cut/milled/drilled/etc. with great accuracy because of its hardness, then use in a mold because it has a (fairly) low melting point. I've made a bit of jewelry and odd decorative bits with lost wax casting.
     
  19. Jul 16, 2018 #19

    OverTheTop

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  20. Jul 16, 2018 #20

    KC3KNM

    KC3KNM

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    I’ve been looking at an SLA printer for my next machine. Any experience with them? Their high temp and tough resigns look awesome, though it’s a little expensive.

    It was a blast playing with it. I’ve been looking into getting some machinable wax for my little mill to play with in the future. Definitely something I want to explore further.
     
  21. Jul 16, 2018 #21

    OverTheTop

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    We have a Formlabs 2 at work. Gives really good results, depending on which resin you print. Resin is not entirely cheap, but for fast prototyping it is great. The trays have a finite life (depends on use) and the resin has a shelf life after the bottle is opened.

    I don't think I would buy one for myself unless I had plenty of money or very keen on using it. YMMV. But then again I have access to it and it does do nice prints!
    DSC07042resize.JPG BulkheadInAirframe.JPG

    Some of my SLA printed parts used here: https://forum.ausrocketry.com/viewtopic.php?f=56&t=5324&start=15
     
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  22. Jul 16, 2018 #22

    KC3KNM

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    That’s some fantastic work!

    The Formlabs 2 is a little more affordable in the US, but still not cheap by any means. I do a lot of printing, so I might be able to justify it down the road. There has been a few hobby grade SLA printers coming out recently, but they don’t appear to be quite as nice (though much cheaper).
     

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