5 ms·

After 4 days 6 hours it did 36,720 iterations. After 10 days it failed on 37,112 iterations. It takes 10 seconds per iteration. My calculations say it would h

After 4 days 6 hours it did 36,720 iterations. After 10 days it failed on 37,112 iterations. It takes 10 seconds per iteration. My calculations say it would have failed after 4 days and 7 hours. I wonder what happened to the other 5 and a half days. Very cool experiment. It's this type of testing that makes me feel reassured in mechanical engineering. It's about reassuring that a car air bag will work after years of inactivity, or a car seat belt buckle will not break under pressure in a collision. The only way to know is to test, test, test.

tnorthcutt 14y ago
After 4 days 6 hours it did 36,720 iterations. After 10 days it failed on 37,112 iterations. I noticed that inconsistency as well.
acrooks 14y ago
I think the 10 day figure included the time it took to build the machine.
pcantin 14y ago
I'm the guy that built it: During the tests, I had to guess the current count based on the estimate that one full iteration was about 10 seconds. This was not a good estimate and it made me overshot the actual number. When the test was finally over I was able to see on the SD-card the final 'real' total of 37,112. I'm making a new video explaining some of this.
- officialjunk 14y ago
  Honest question: do you think it matters that the bricks are attached with a radial motion rather than linear? From my personal usage, I tend to press all areas down at the same time rather than one side fully contacting before the other. I would imagine the wear is different between these two cases.
  - pcantin 14y ago
    You're right and this is why I intend to build a better rig. More answers in this new vid I just uploaded: http://www.youtube.com/watch?v=VLt8HkIOAuY http://www.youtube.com/watch?v=VLt8HkIOAuY
    - fryguy 14y ago
      Do you think you could perhaps make it faster by doing computer vision and making the mechanism go up-down only and not waiting for the sensor, and then checking the photo while it moves?
      - pcantin 14y ago
        The sensor was not the slowest element, it was the servos combined with the design. For the next build I plan to use a big step-motor rotating in continuous mode and transfer the rotation motion into a linear one like steam powered machines do.
    - gvb 14y ago
      I like your plan of testing LEGO bricks[1] from different eras, but I would recommend you use the same rotary mechanism for all the tests. If you change the mechanism to a linear one, you won't be able to compare with confidence the first (rotary) test with any follow-on linear actuator tests. OTOH, if you repeat the (rotary) 70's era test with the linear actuator, that would be interesting estimate of whether a rotary actuation is better or worse for the brick longevity. Of course, you will still have a sample size of one, so your confidence interval will be meaningless. I can see this turning into a lifelong obsession... ;-) [1] http://aboutus.lego.com/en-us/legal-notice/fair-play/ http://aboutus.lego.com/en-us/legal-notice/fair-play/
      - pcantin 14y ago
        Once I have a new test machine that his much faster I will indeed retest all the eras (with multiple tests per era). Of course this time I plan to build a real sound proofing system around it. This last machine was really annoying.
- Crake 14y ago
  Congratulations, sir. I just about lost my shit laughing when I saw the arduino in the first picture. Good work, it's really cool seeing people doing interesting projects like this. The maximum number of lego presses is something I might never have thought of (I'm a k'nex person!), but I'm really happy to now know.

tnorthcutt 14y ago

After 4 days 6 hours it did 36,720 iterations. After 10 days it failed on 37,112 iterations. I noticed that inconsistency as well.

acrooks 14y ago

I think the 10 day figure included the time it took to build the machine.

pcantin 14y ago

I'm the guy that built it: During the tests, I had to guess the current count based on the estimate that one full iteration was about 10 seconds. This was not a good estimate and it made me overshot the actual number. When the test was finally over I was able to see on the SD-card the final 'real' total of 37,112. I'm making a new video explaining some of this.

officialjunk 14y ago
Honest question: do you think it matters that the bricks are attached with a radial motion rather than linear? From my personal usage, I tend to press all areas down at the same time rather than one side fully contacting before the other. I would imagine the wear is different between these two cases.
- pcantin 14y ago
  You're right and this is why I intend to build a better rig. More answers in this new vid I just uploaded: http://www.youtube.com/watch?v=VLt8HkIOAuY http://www.youtube.com/watch?v=VLt8HkIOAuY
  - fryguy 14y ago
    Do you think you could perhaps make it faster by doing computer vision and making the mechanism go up-down only and not waiting for the sensor, and then checking the photo while it moves?
    - pcantin 14y ago
      The sensor was not the slowest element, it was the servos combined with the design. For the next build I plan to use a big step-motor rotating in continuous mode and transfer the rotation motion into a linear one like steam powered machines do.
  - gvb 14y ago
    I like your plan of testing LEGO bricks[1] from different eras, but I would recommend you use the same rotary mechanism for all the tests. If you change the mechanism to a linear one, you won't be able to compare with confidence the first (rotary) test with any follow-on linear actuator tests. OTOH, if you repeat the (rotary) 70's era test with the linear actuator, that would be interesting estimate of whether a rotary actuation is better or worse for the brick longevity. Of course, you will still have a sample size of one, so your confidence interval will be meaningless. I can see this turning into a lifelong obsession... ;-) [1] http://aboutus.lego.com/en-us/legal-notice/fair-play/ http://aboutus.lego.com/en-us/legal-notice/fair-play/
    - pcantin 14y ago
      Once I have a new test machine that his much faster I will indeed retest all the eras (with multiple tests per era). Of course this time I plan to build a real sound proofing system around it. This last machine was really annoying.
Crake 14y ago
Congratulations, sir. I just about lost my shit laughing when I saw the arduino in the first picture. Good work, it's really cool seeing people doing interesting projects like this. The maximum number of lego presses is something I might never have thought of (I'm a k'nex person!), but I'm really happy to now know.