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Is this printable?

Posted by noobdude 
Is this printable?
July 18, 2018 04:38PM
I'm new to 3d printing and yet have no idea on what is possible. Thus I started learning FreeCAD and modeled something which I hope might be printable. It's basically a clamping collet you slide a thin rope through and then fix it by tightening the screw.
Difficulties I see:
- Precision: Threads with 2mm pitch and 1.5mm groove depth
- Material: Clamps that must be bendable, but not break
- Ruggedness: Could it withstand a minor human stampede?
- Precision: On one end there's a pocket for a magnetic ring to be glued in. Is that feasible?

Even though this model is quite simple it's too big to attach. So feel free to download it from bitbucket: SpeedbarLock.FCStd
Re: Is this printable?
July 19, 2018 01:34AM
It could be done with a small nozzle and good part cooling.
IDK freeCAD, but it would be nice to design it parametrical, so you can adapt some tolerances to your needs.
IMHO, the part could be improved for it's intended purpose, too:
The slots in the thread could be longer to avoid breaking.
Both parts could have a different shape to make tightening ( by hand? ) easier. Think of a wingnut-shape or hex.
Re: Is this printable?
July 20, 2018 02:08PM
Thank you for your opinion!
In fact FreeCAD is parametrical and I have put some basic parameters like the length of the slots and the thickness of the bendable parts into a spread sheet.
I like the idea of adding aids for tightening by hand. But I preferred simple structures over wingnut-shaped extensions because this device is intended for use in the context of paragliding. Any extension that 'invites' a string to entangle might cause lethal accidents.
I designed the clearance between the two to 0.3 mm. Is that of suitable magnitude?

Edited 2 time(s). Last edit at 07/20/2018 02:11PM by noobdude.
open | download - Spannzange.stl (178.8 KB)
open | download - Deckel.stl (143 KB)
Re: Is this printable?
July 21, 2018 02:26AM
I was a paraglider ten years ago, mainly flying around " Wasserkuppe/ Rhön " smileys with beer

The clearance you've set may work, but you'll have to print it to know for sure.
Re: Is this printable?
December 18, 2018 12:21PM
I wouldn't risk it. If printed upright as shown in the pic you'll be stressing the part perpendicular to the layer lines (i.e. the rope tension tries to pull layers apart). That's the weakest orientation for 3D printed parts.

That said, dimensionally it should be about on the limit of what's possible with a 0.2mm or 0.25mm nozzle.

Material-wise, PLA would be too brittle and suffers from creep. So either the collets will snap off the first time you tighten them, or they will bend and loosen over time. PETG may fare a lot better. I don't have any experience with ABS so I can't tell you (fumes are too smelly for my setup!).
Re: Is this printable?
December 19, 2018 04:47AM
Could be a good candidate for a semi flexible filament like tpc 65. Inter layer strength is excellent, no different from stressess in any other direction. I don't know what the holding forces are though, so you'll have to experiment.

Kind regards

NFAN CoreXY printer:
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