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by GrabCAD
Last crawled date: 2 years, 6 months ago


static load test of 226 lbs!!! CONFIRMED! (3:20)

testing the lever (5:36)

static load test of 250LBS!! UNOFFICIAL, critical failure (11:30)

damage assessment (13:20)


I'm considering this design finished for now, I've uploaded all the files.
In summary, the design intent behind this clamp design was to have something SIMPLE, STRONG and ROBUST and to explore a means to increase the holding force of the clamp. I didn't want to use a screw thread to apply torque as I wanted something that could be quickly clamped on and off. I also wanted to exploit the fact that you can use infill with the 3DP process to keep the overall weight down, but still have descent structural integrity. It's a beefy design yes, but that doesn't mean it weighs a lot, only 89grams.

***A note on support material. Since the ISS printer can't handle support material, this design uses a VERY small amount of support material INTEGRATED IN THE DESIGN ITSELF so there's no need to generate support material. The support material is easily removed by hand, not tools are required.

As for the Aesthetics, knowing the end purpose of the clamp was for the space industry, I wanted to keep the surface simple and clean, free of logos and unneeded pocketing where dust and bacteria can collect. Also, the need for pocketing wasn't necessary as you can adjust the weight through infill with 3DP. All the models I printed and tested used only 30% infill!!!! With this particular design, I was able to hold a static load of 150lbs, with room to spare.

I respected the rules on radiused edges and tried to apply them as closely as possible to this specific model.

Anyway, I feel I was very successful in achieving this goal with this design, and I learned a lot in the process, like how to orient 3DP parts for maximum strength, due to weaker layer bonds from the 3DP process.

I tested the clamp using a 150lbs static weight running perpendicular to the rail without failure, I estimate I could have increased it to over 160-170lbs. I tested with 78lbs static weight running along the handrail before the my test rig started to slip, the clamp held in place. The video's of these specific load testing experiments are posted below.

The main file to print is:

This file has only been oriented for printing with slic3r/Pronterface software, it HAS NOT been repaired or resized, it should be good to go for printing as it sits, but each machine is different and sometimes the scale needs to be reset. If so, just down convert to mm from inches or vice versa. The print settings are listed on the picture in my gallery showing the green print. All other file formats are attached and can be modified and fresh STL files can be created from them.

*The pin hinges can be printing separately, and if needed, higher infill can be used on just the pins for added strength.

I'd like to Thank NASA, GrabCad and the community for giving me an excuse to waste some plastic on my new 3D printer! :P

There are tons of great designs, good luck to everyone, don't forget to have fun and ALWAYS where you safety glasses!

Check out my research progress below, starting from 2-14-2015 up to now. It will give you a good idea about all the iterations and troubleshooting I had to go through to lead up to this final design.

With that, I leave you with this famous quote from our old friend, Spock, which I think sums this whole experience up.

"Once you have eliminated the impossible, whatever remains, however improbable, must be the truth".

**All models were printed with the Lulzbot Taz4 and Lulzbot mini 3d printers!


**Training for Zero-G :P



The prints finished, the one on the Lulzbot mini printer stopped midway so it had to be scrapped. I was able to assemble the clamp and do some weight testing...incredibly, I got up to 150lbs of static weight on the clamp!!!! with room to spare, that's my full weight! supported by the clamp without breaking. I considered that a static load test, BUT I actually tried to lift the bucket of weights slightly and let it drop a bit to add a little extra force on the clamp and it held. I'm sure it could probably take up to 160-175lbs, if not more! Incredible!

here's some video:

testing the clamp action:

static load test, 140lbs, I added 10lbs later.


Finished doing the CAD on the full scale model this weekend, they're being printed right now! Should have working prototypes tomorrow. I had issues with slic3r, didn't seem to like my .stl.

short video (about 3 hrs into 7hr print):

**2-14-2015 Evening..
Code name: Strong man

It's times like this that are a testament to how important it is to have a 3D printer if you're a designer. I went from doing this custom design in CAD, many unknowns, completely uncharted territory, to having a proof of concept a few hours later, thanks to my Lulzbot Taz4...

I just tested the latch mechanism and it works SOOOOO WELL! I was really surprised I nailed it on the first print. Similar to a boot self locking boot buckle, the lever arm pulls the latch hook pivot in an arch, therefore it's overtight at the apex, once it's passed the apex of the arch, it automatically wants to pull itself down the rest of the way so it's self locking, and makes it hard to flip open accidentally. I'm in love with this design....it's a beautiful thing, just a matter of perfecting it now. This is going to be VERY COOL! Can't wait to polish and print up the final test version!!!!


** 2-14-2015 WIP!

Learning from my previous designs, and figuring out that hinge pins printed in the horizontal direction were extremely robust opened the door to trying a latching system to increase the holding force of the clamp. It's inspired the buckles on my dirt bike boots. Not sure if I will have time to finish. Prototyping and test printing now...

My original clamp design:


If I were to choose between these two designs, although this design is a little more complex and the print time is longer, I think it's overall strength and improved holding force outweighs those factors, so I would favor this design.