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Discussion Starter · #1 ·
After seeing Joerg’s legolas designs I decided to design a legolas myself. The kinds of bow Joerg designed around are expensive in my country so I found the cheapest bow I could afford and built a legolas magazine for it. That worked really well and the design is a success I'm my opinion. The bow I use is a Man Kung Cb30. Here is a picture of that design:
Wood Wire Electric blue Rectangle Cable


Once I had completed that design I really wanted to get away from having to buy a bow. So I started to design a 3d printable compound bow for my legolas mag. My complete bow and legolas magazine can be made cheaper than the cheapest compound bow I can buy in my country. Here is a picture of that design:

Gas Machine Drill Tool Drilling


The bow uses pvc electrical conduit for limbs and aluminium tube for the barrel. It is meant to be a self defence weapon for people who can't own a gun or don't want to own a gun. The bolts weigh 270 grain. I am comfortable that a gut shot from this, with a broadhead will take the fight out of most men.

The barrel is replaceable so the bow can be used as a compound bow with standard arrows too (although I have not tried this) .

Purple Gas Machine Electric blue Engineering
Automotive tire Bicycle handlebar Gas Bumper Automotive wheel system
Camera accessory Toy Machine Gas Metal
Automotive tire Camera accessory Audio equipment Cameras & optics Line
Audio equipment Automotive tire Vehicle Gas Bicycle part


The bow can be fired vertically or horizontally as is the user's preference. There are 3 cam profiles on each cam. One profile is for the bolt sting, another for the cam syncing and yet another for latex tubes which offer additional energy to the bow.

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If you have questions I will be happy to answer them if possible.
 

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Hi, nice design!
Im wondering that printed pvc can withstand reasonable forces.
Waht is the strength of the printed plastic? (normal to printinglayers)
 

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Discussion Starter · #3 ·
Hi, nice design!
Im wondering that printed pvc can withstand reasonable forces.
Waht is the strength of the printed plastic? (normal to printinglayers)
HI Marcus,
Thanks for the compliment.

The limbs are white pvc tube and are not printed.

Printed parts are not as strong as moulded parts. When I started I didn't think it was possible to build but I'm very impressed with what the 3d prints can handle. I am testing the bow to see when and why parts fail and then redesigning to make the necessary changes so it's a work in progress. I've just made the riser stronger. (busy printing it)
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It's been printing for 20 hours now and has about 10 hours to go.
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Do you have a 3d printer?
 

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No I dont have one, but from time to time I think about buying one.
I expect once you have it you'll may use it more often.
But as mentioned ,... the biggest backdraw -> The parts are usually very weak (my experience so far with parts from friends)
Specially for the moving parts on the bow the strength/weight ratio really matters.
 

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Discussion Starter · #5 ·
Strength of the parts has a lot to do with how you print them. You will be surprised by how strong they can be. There are guys who have printed semi auto 9mm uzi type guns with pla that last 1000's of rounds.

 

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Discussion Starter · #7 ·
Thanks for the suggestion. After heat treating the PLA its holding up very well. I will go for carbon fiber if the riser suffers creep deformation over time. So far so good.
 

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Very nice work.
I print pistol crossbow parts and have found that for bigger body pieces, carbon fiber filament works well. But CF filaments are typically ABS with some percentage of carbon fiber added and can vary a lot in how well they print, layer bond and in strength. I have started using instead polycarbonite filament and the layers fuse tight, it prints well at 165C nozzle/105C bed and is super strong. I printed a trigger mechanism - trigger and trigger cam - from polycarbonite and have hundreds of shots on it and its still perfect, including the contact surface between trigger and cam. The bow has a measured pull of 68lbs., so a lot of force on those small parts.
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Discussion Starter · #9 ·
Very nice work.
I print pistol crossbow parts and have found that for bigger body pieces, carbon fiber filament works well. But CF filaments are typically ABS with some percentage of carbon fiber added and can vary a lot in how well they print, layer bond and in strength. I have started using instead polycarbonite filament and the layers fuse tight, it prints well at 165C nozzle/105C bed and is super strong. I printed a trigger mechanism - trigger and trigger cam - from polycarbonite and have hundreds of shots on it and its still perfect, including the contact surface between trigger and cam. The bow has a measured pull of 68lbs., so a lot of force on those small parts.
View attachment 42631
Do you mean 265 C on the polycarb filement?

I'm printing on a pla printer I printed with a S500 Creality so I couldn't print those temperatures.

Do you have an enclosed machine? If not, how do you cope with the warping?
 

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Do you mean 265 C on the polycarb filement?

I'm printing on a pla printer I printed with a S500 Creality so I couldn't print those temperatures.

Do you have an enclosed machine? If not, how do you cope with the warping?
Sorry, yes, it's 265C. Printed on a kit printer - FolgerTech FT5. Using a Volcano extruder and the enclosure temp runs roughly between 55 to 65C.
I think thr polycarb would print well at 260. Not sure about the enclosure temp but I see no sign at all of warp at 55C. A cardboard box around the printer would likely get you there.
 

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simple start to use Esun PLA + l,h : 0,1-0,16 ,100% inf ,225 C ,forget PC,carbon etc, very very expensive filaments for nothing extra
 
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