Materials

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I had the following materials available: ABS, PLA, PLA-HT (or HT-PLA), IGUS (the one that is hard to read)

2 more players entered the game but outside of the contest as they are a bit special (see further down)

I first thought of comparing 0.2 against 0.1 layer height also but even after spending a lot of time with grinding of the 0.2 mm layer items I could not make them move smoothly.

My opinion: you would need to skale down piston or piston-base to make it work or maybe you could solve it with fine tuning the printing parameters

Test Maschine

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In order to compare the different materials I built a small test machine and used the same hacked HS 805BB servo and switched the pistons for the same weight's.

To control the up-down movement I used the poti attached to the axis (it's even a standard InMoov pot holder used for the omoplate, thanks Gaƫl)

Controlling the Servo

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Apologies to the Arduino and MRL geeks - I used a Pololu controller to run the tests

The Test Script

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Sorry, could not find an option to rotate the pic - but its only a few instructions to make repeatable movements up and down and got to a rest position at the end with the controllers script options.

The No Load Test

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To see how much power the servo eats to move I ran each piston up-down without every load.

Unfortunately I do not own a logging power measuring device so results are from what I observed on my power supply. I can limit the power with it so I used it also to see the power needed for an initial move from a standing position.

All tests have been run with 6V (no, no, I did not want to see any smoke, have seen that expensive experiment already ...)

The Items To Lift

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Some of you might know I live in Switzerland and the first best heavy item I found have been my ski boots! 2.5 kg each

As none of the pistons had any problem with a single boot I added the other one - 5kg, just a bit more power usage but no sweat for the test.

The Heavier Item

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The next bigger item was a filled beer case. It weighs 10 kg in total and felt heavy on my arm. Looking at my little test machine I did not feel very safe with the heavy load. The string should be good for 70-90 kg but having that case in the air on the tiny string made be add a book post below it. But it worked like a charm and lifted up with all pistons like nothing.

Results (or why you clicked this)

Despite the work I invested results are rather unspectacular. PLA-HT was the winner but with a rather small heading. This might also be due to a smoother surface of piston or piston-base in my configuration.

More or less all the materials performed the same and GREAT - go for printable IGUS only if you hate sticky fingers because it does not need lubrication.

Surprises

None of the loads caused a slow down of the movements. The pololu controller slowes down motion for the target positions and with all loads the total up-movement was always 4 seconds.

The amps used for the different weights + 2.5 kg - 0.9 A + 5 kg - 1.2 A + 10 kg - 2 A

Outsider 1 - Ball Bearing Piston Base

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My own invention 1) I made a piston with 90 degree windings. I thought this would make it easier to flatten out the surfaces

2) I created a piston base with ball bearings (rather tricky but worked out fine)

3) However, the combination did not really work out. I gave up as I could not really get a smooth movement and I also had the impression that the full load on the 4 ball bearings might be too much - anyway - gave me something to do???

Outsider 2 - A Professional IGUS Spindle

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Whowwww, what a look. And it slides on itself down and has no hysteresys for direction change! Don't request an example - you'll get addicted!

This is only a give away example from IGUS and not made for heavy loads. Anyway, I tried it with the ski boot.

IGUS for Skiers

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I have printed out a socket for the spindle and ran the ski boot test - performed slightly ahead of the others but not a leap in performance.

Conclusion

The piston design is very well made (who doubted it?)

Use any material and make sure you either grind it as good a you can or - what I did with moving parts - use a repeated motion with abrasive milk added to the part. Then clean and grease it well (unless you use IGUS) and your set.

I hope you enjoyed - as always - comments make me light up :-)

Regards

juerg

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