Articulated Folding Knife
Please refer to my Maker World site for 3D printed parts download ...
https://makerworld.com/en/models/1784...
DESCRIPTION
The attraction of this knife design is in the way the parts in the handle move as the knife blade opens and closes. The actions include blade locking and a sprung release to close it; the knife also looks cool. My design makes this knife 3D printable to be used as a prop, ONLY!
NOTE: Whilst the knife has a blunt edge, the blade has a point that can be harmful if used carelessly.
PARTS LIST
I managed to find the nut and bolt and spring that I designed with amongst my spare parts, so could build my design straight away. If you need some or all of the parts I used, I make reference to the Bambu Lab shop equivalent parts. Alternative supplier parts can be used, too.
• Custom 3D printed parts - 5 pieces
• Compression spring: 0.5mm x 6mm x 15mm (approx.) (BB014)
• Counter-sunk screw M3 x 12mm (AA087) and M3 nut (AB005)
• 1.7mm printer filament for pins: 13mm x 2
TOOLS
• Screw driver / Allen key
• Needle file / drill bits for 2mm and 3mm holes.
• Sharp blade
• Loctite screw lock.
ASSEMBLY
• Cut required pins from a roll of 3D filament using a sharp knife. PLA will work fine.
• Check holes on parts.
Unfortunately, the 3D printed parts can be made in different brands and plastics. The result is holes (in particular) of varying accuracy. Easily fixed with a combination of a round needle file and a drill bit.
• Assemble the two arms parts onto the butt part. Note the hole alignment slots.
• Locate spring into position on base.
• Position butt into position, surrounding the spring and insert first pin.
• Position blade and insert nut and bolt. Blade should move easily.
• Secure the two arms to the blade with the second pin.
• Test the blade movement and position locking.
Should snap into the open position and lock.
Blade should fully return into the handle when closed.
• Apply Loctite to the nut and bolt. Care not to get any Loctite on the plastic.
• Done.
THANK YOU
I hope that you can find this print useful, too. If so, you can support my work by buying me a coffee …
https://buymeacoffee.com/dansoussi
Remember to leave a comment, perhaps a like to keep me enthused to make more.
PRINTING INFORMATION
My print is made in 1.75mm Bambu Lab PLA Silk Silver filament on a Bambu Lab H2D printer. Print supports are not required.
A couple of notes. The knife blade is angled on one side. To get a smooth print result, I used Bambu Studio’s “Variable layer height” for part of the blade. Bambu Lab PLA Silk is extremely brittle, so easily cracks with stress. If it didn’t look good, I wouldn’t be using it!
Both the print profile and the individual STL files are included for download.
Q&A
Q: I made the holes for the pins too wide. Have I ruined the part?
A: A simple fix is the use a pair of pliers and squeeze one end of the pin, enough so flattens, but widens, too. It should now securely fit into a hole.
Q: Blade is not snapping into position. Why?
A: Possible reasons for not snapping into position includes:
Nut and bolt are too tight. Loosen a little and try again.
To ensure good tension in the mechanics, the compression spring needs to have the right characteristics. That is, 12-17mm long, and around 0.4mm thick. Weak spring tension can be fixed by stretching the string length a small amount, then, try again.
Note that too high a spring tension will likely crack the printed part.
Q: What happens if I press too hard on the blade?
A: Remember that this is a prop. Under stress, parts of the knife will likely break. Just enjoy the articulated mechanics of the knife. The knife has no functional use as a knife!