My Printable 3D Crossbow Design

Discussion in 'Slingshot Crossbows' started by anthony, Oct 16, 2013.

  1. anthony

    anthony New Member

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    Hey All,

    Just for fun, I am attempting to create a crossbow that can be printed on a home 3d printer. I really do not mind if this does not work, I am only doing this for the fun of it. Just wondering what you guys think. I am planning on using thera band. In the future, I am hope to design a roller system to increase the power of the xbow. I will be using ABS plastic and only be using printable materials, excluding metal bolts/nuts/thera band. That is my challenge.

    ABS is flexible and strong. Not sure if it can stand the pressures of thera band, but that's the fun of this little experiment. I would like to keep the bow in my design. I understand that I probably do not need it for a slingshot xbow. But I would like to try and make it work. I do not want to use any wood or metal...

    Features:
    -Collapsible stock
    -Iron sight
    -Fore grip
    -Collapsible Bipod
    -Adjustable Rail system
    -Simple trigger mechanism
    -All parts are designed to be printed on a 8x8inch 3d printer bed.

    Just wondering what you guys think. I am probably going to have some questions for you guys as I go along. Hope you don't mind me bugging you... lol. BTW, I have only been cadding for about three months so I have a lot to learn yet. I am a very busy person, but will try to update this as I as have the time too. Version 1 of this design is completed. I have no expectations for version 1. This will be a test version only. My next step is to start printing. I hope to begin printing over the next few days. Once it is printed then I can try simple thera band tests and slowly increase the resistance. Hopefully I can improve my design and make an awesome crossbow.

    BTW, the crossbow is called TALC which stands for TActical printabLe Compact Crossbow.

    Cheers;
    Anthony

    Screenshot from 2013-10-16 22:14:59.jpg

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  2. CaptainBacon

    CaptainBacon Knowledgeable Man

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    ABS should be strong enough to handle this application. however the bow arms are a concern. Shorten the bow arms to be just short enough to allow for the theraband to not engage the side of the weapon when drawing and firing. They should only need to extend from the side by about 1" realistically. That removes a few parts to be printed, and makes the entire assembly more compact.
     

  3. kineticweaponry

    kineticweaponry Senior Member

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    That is a really awesome idea! i don't think that the school would let me use their 3d printer for it though haha:)
     
  4. Slagskimmer Mike

    Slagskimmer Mike thinks TBG smells better than roses

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    Welcome to the forum Anthony.

    This is a cool project, first one I've heard of too. Fitting each part in an 8X8 is a noble challenge, one that many can repeat when you have success. Unless you get ABS string (whatever you call it) really cheap it might save you some cash to do some of the parts out of wood on the first prototype.

    My designs always evolve in between drawing and reality, so I save my best materials for after a working proof of concept.

    I think the toolpath is the critical factor for strength. My experiences with ABS tells me also that it is up to the task.
    The orientation of how the stuff is printed changes the strength, but I'm just guessing.

    Keep us posted.
     
  5. BeMahoney

    BeMahoney Builder of things

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    Just guessing


    I think this bow could easily cost around 1500 to 1800 Dollars.-?
    Seems to me you will need to find a sponsor!- I suggest
    to give that ISS a little call :)- just in case the astronauts are
    not allowed to bring slingbows, but would like to be able to make
    some in case of some Zomlien-ATTACK!?

    Nice Project!, keep posting!

    Greetings,

    Be
     
  6. anthony

    anthony New Member

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    Thanks everyone for the support.

    Making the first prototype out of wood is a great idea. But not sometime that I can do right now. I am currently living in an apartment and do not have the right environment for it. The tenants next door would not appreciate drilling/sawing noises... lol. Plastic is not too expensive. I can get a ~2lbs roll of abs for about $25.00. Which is not too bad. I do have a couple extra rolls handy, so I should be good.

    Great idea. Shortening the bow arms to 1 inch. That will be my next plan...

    I was wondering if you guys could comment on the following. The draw length is about 13.77 inches if I shorten the bow arms to 1 inch. That length is measured from the top of the crossbow to back where the string hooks into the trigger. I plan on shooting bolts not steel balls. I am guessing the arrows will be around 16 to 18 inches in length. I plan on using theraband gold. I want to keep this design as compact as possible. I was wondering if you could comment on what dimensions should I cut the theraband. I believe JoergSprave cuts his band with a 3cm width. What should the length be? I am considering using the bullpup design used by JoergSprave with the rollers. Are there any concerns with these dimensions or is the draw length too short. I am trying to find a balance between compactness and performance.

    Who knows maybe this slingbow will save the earth from an alien attack... lol.

    Here are some images of demo parts that I printed. Just for fun... The beauty of 3d printing is that I can scale down the parts for testing purposes. Helps to save on plastic and time to print.... Cheers;

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  7. Tremoside

    Tremoside SINdustrial designer

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    Hi Anthony, Exciting project you have here! I'm really curious about the results. Keep it comin' !
     
  8. MountainStorm

    MountainStorm Termite

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    Really curious about how strong these parts will be. Thanks for the great photos.
     
  9. BeMahoney

    BeMahoney Builder of things

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    Hey Anthony!

    Great progress to be seen on those pics!-

    If I were you I would use
    Jörgs calculator. http://www.slingshotchannel.com/band_calc.html

    I´m still new here, but I think the band length would be around
    25% to 20% of the drawlength (maybe 3.25"?). Bandwidth depends on the weight of the bolts.

    What Jörg posted yesterday is pretty much what your project sounds
    to be if "forkwidth" is around three inches?..

    https://www.theslingshotforum.com/f5/brutally-short-25mm-steel-ball-crossbow-31322/#post235549

    One thing I see on the pics is then Thin trigger-disc.. To support a nice
    drawweight, I think this should be a lot more stable/thick..?

    Anyway: your energy is impressive, and I am really curious what the finished
    bow will look like!

    Thanks for sharing!

    Greetings and best regards,

    Be
     
  10. Tilia

    Tilia Junior Member

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    technology can be freaking awesome :cool:

    ill have to follow this threat
     
  11. anthony

    anthony New Member

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    Hey Everyone,

    Again thanks for the positive feedback. I am considering re-designing the full body of the crossbow, Most of the changes will be to re-enforce the body, since it will be under a lot of stress. One of my ideas is to use threaded rod in the body of the xbow (for safety reasons only). The threaded rod will be placed length wise in the body. The body is under great compressional force, the threaded rod will help to re-enforce the plastic. Another bonus is you won't need as much plastic in the body. The body can be printed with less infill (More hollow inside). If you don't want to use the rod idea, you can just print the body with higher infill. It will be up to the user. All other parts will remain the same.

    Thanks BeMahoney for your help. I'll differently look into that calculator. I want to put a little more thought into the roller system and dimensions of my draw length... The trigger disc in the above picture is a little old. I printed it a few weeks ago. I just posted those images just to give you guys a sample of what can be done. I have already improved some of the parts... rails, handles, trigger... etc.

    Best regards to everyone.
     
  12. anthony

    anthony New Member

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    Updates.....

    -Made the handle a little longer. For those who have larger hands...
    -The rails now follow the MIL-STD-1913 spec. Before I just set the rails to some random size. Now you can possibly use your gun rail accessories on the bow. See image showing a fore grip attached to my rail.

    Cheers;

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  13. anthony

    anthony New Member

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    I am sure most people here recognize this design... lol. This is just a fast mock up of where I am going. I am still playing with the dimensions, plus the design also must be printable while remaining strong. Using the rollers we should be able to get ~20 or 21 inch draw length. Which is a great upgrade. I placed a hole through the body for a 5/16 threaded rod. I am hoping the rod will give the body extra strength. If you guys have any thoughts or ideas let me know.

    Cheers;

    Screenshot from 2013-10-20 20:40:33.jpg

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  14. CaptainBacon

    CaptainBacon Knowledgeable Man

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    You'll need to lower the rollers so that when the bands are attached, the string will have downward pressure on the arrow guide. As it looks now, you may end up with a gap, rendering your guide useless.

    It's looking good so far, and I'm really excited to see where you take this next.
     
  15. anthony

    anthony New Member

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    Thanks. Yes the rollers do need to be lowered a bit.

    Right now I am just playing with some design ideas. I was thinking about since I am using a steel rod for support in the body. We could split the body into smaller printable pieces. So currently the body is 16 inches long and has to be printed into two 8 inch pieces. I am just wondering if we could split the 8 inch pieces into two four inch interlocking modules. The strength will come from the rod, but the body will be easier to print. So the advantages of this idea include:

    -Faster to print a smaller module, especially if your prints start to fail.
    -The modules will just repeat the same pattern, so you can make the body as long as you wish. Want a 24 inch draw, print anther 4 inch module and slide it onto the steel rod.
    -This will make the crossbow easier to print on smaller bed sizes. I believe the cube has a bed size of 5.5x5.5 inch. So in theory you can print the 4 inch body modules on the cube.

    Cheers;
     
  16. CaptainBacon

    CaptainBacon Knowledgeable Man

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    Why even print the body portion when you could use widely available aluminum stock from big box hardware stores. A couple aluminum square tubes would create your arrow guide and be more than strong enough. All you have to do with your design is create your stock/trigger block/firing mechanism and your fork pieces, and create a couple slots for the metal to sit into.

    I would save the design work and printing for the parts that are harder to fabricate otherwise. Anybody can buy a couple pieces of metal, and customize the draw length in that regard without having to print more pieces and possibly fail. Think of it like a "Crossbow kit, just add the body" ordeal.
     
  17. anthony

    anthony New Member

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    Hey,

    Thanks for the feedback. I do think this is a great idea. I just uploaded some of my files to thingiverse. Located here: http://www.thingiverse.com/thing:169596. I am not in a position right now to do any wood/metal work on the design. My original goal is to make this design as printable as possible. I understand metal/wood are better materials for such a design and printed handles/stocks are a great bonus. For now, I would like to make a printable body. Just for the fun of it nothing more. I am releasing the files with the intention that I will make the crossbow to fit my goals, but if someone would like to modify the parts or use them in their own project now they can. The parts are now GPL. Therefore the use of these parts are open to the user. Right now, I don't want to make a universal crossbow kit. Just my printable crossbow. Hope you can understand.

    Cheers;
     
  18. CaptainBacon

    CaptainBacon Knowledgeable Man

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    Absolutely. I was just thinking about whatever made it easier for you design wise. I like the idea of being able to just completely fabricate this with 3d printing.

    As I said before, I'm liking this idea and want to see the finished build.
     
  19. anthony

    anthony New Member

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    I still believe your idea is great and hope others will use the parts in their designs. It's really a great idea, someone makes a wooden crossbow but can substitute a few 3d printed parts into their design. Makes total sense.

    Don't worry I do intend on completing this. Even if its total junk. I just enjoy the challenge of creating things like this. If for some reason that I don't post any updates for awhile. It's just that I am busy at the moment.

    Please CaptainBacon post any comments you wish. I really enjoy reading everyone's comments and suggestions. That's what makes this a fun hobby.
     
  20. anthony

    anthony New Member

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    Here are some quick pics of my stand. I believe it is also called a bipod. The stand will connect to the rails and the top can rotate like a hinge. The body portion of the stand did not print really well. One of the legs warped.... It was my fault for not cleaning the glass printer bed properly... lol. But it is still functional as in the pics. I may print another one in the future.

    Cheers;

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