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Mechanical Testing Experiment

Discussion in 'Projects' started by Printed Solid, Jun 16, 2013.

  1. Printed Solid

    Printed Solid Volunteer Admin
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    Thread started for discussion of an experiment to evaluate several factors on the mechanical characteristics of 3D printed parts.
     
  2. Mike Kelly

    Mike Kelly Volunteer

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    I'm very interested in the results of this. What sort of experiments do you have planned?
     
  3. Printed Solid

    Printed Solid Volunteer Admin
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    Initial plan was around evaluating different vapor polishing processes and parameters controlled against the non-vapor polished version. I haven't had time to really think about it since the thread was started. I'm envisioning a pretty massive designed experiment.
     
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  4. Mike Kelly

    Mike Kelly Volunteer

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    Good idea. I'd also like to see some experiments of different tension/compression/shear/adhesion stress tests done on different printing configurations.
     
  5. Leon Grossman

    Leon Grossman Active Member

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    I've found that parts can delaminate relatively easily if they aren't treated in a vapor bath. I've resorted to putting all of my load bearing parts in a vapor bath before using them.
     
  6. Printed Solid

    Printed Solid Volunteer Admin
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  7. Leon Grossman

    Leon Grossman Active Member

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    Just an acetone vapor bath. Nothing terribly fancy.
     
  8. JDM_

    JDM_ New Member

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    What equipment do you use for you vapor bath? glass jar on the heated bed or something else... I saw someone online use a vegetable steamer/frier....
     
  9. Leon Grossman

    Leon Grossman Active Member

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    Right now, I'm using a crock pot liner on a standalone electric burner. I keep the acetone from escaping by putting a ziplock bag of ice on top of the lid. It's remarkably effective.

    I'm going to get one of those friers as soon as I get a chance to track one down. My solution works fine but the thermal mass of the crock pot liner means that it takes a while to heat up and, more importantly cool back down after I'm done.
     
  10. JDM_

    JDM_ New Member

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    Interesting method. Could you snap a pic of that next time so I can understand what your doing better?
     
  11. Leon Grossman

    Leon Grossman Active Member

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    I finally got around to doing some more vapor polishing. Of important note is the fact that the filament I used this time is total junk. It was from Online Filament Store. I had great results with them and the purple I have. I had to print at half speed to get a mostly good print out of this filament and you can still see some cracking at the top of the good one.

    Left 80mm/sec, Right 40mm/sec
    2013-07-31 18.26.10.jpg

    I took the lid off to show the acetone boiling. The deep fryer means you don't need to hack together silly platforms made out of thin aluminum like I've done here...
    2013-07-31 18.40.16.jpg

    If you're not doing silly things like taking the lid off, the ice keeps the acetone in the container and keeps it from escaping. You can also put your nose right up to the pot and you can't smell the acetone.
    2013-07-31 18.32.24.jpg

    Here's the final result. Normally, the end result looks almost injection molded but this silver has something about it that just doesn't quite look right.
    2013-07-31 19.44.44.jpg
     
  12. Leon Grossman

    Leon Grossman Active Member

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    Before and after acetone quantities.
    2013-07-31 18.32.43.jpg 2013-07-31 19.43.02.jpg
     
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  13. Harry

    Harry Team ROBO 3D
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    Wow Leon! I need to do some vapor polishing! haha.
    Do you think if I did it in a kitchen pot on the heatbed of my printer that would work/be good?
     
  14. Leon Grossman

    Leon Grossman Active Member

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    Acetone boils at 56C so, technically, it's possible. Where you may get into trouble is if the thermal mass of your container is so large that it takes forever to heat. That's why I use the electric burner instead of the crock pot heating element. It just took too long to heat up.
     
  15. Harry

    Harry Team ROBO 3D
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    Could I do it on my stove?
     
  16. Printed Solid

    Printed Solid Volunteer Admin
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    @Harry: just suck it up and buy the $30 presto fryer :p . IMO, this should be done outside anyways.
    @Leon: Love the ice and retaining the acetone. Any issues with condensation on the lid dripping down onto the part? I do mine in a fryer outside. In the winter, I would get condensation on the screw that holds the handle to the lid that would drip onto the part.
     
  17. Leon Grossman

    Leon Grossman Active Member

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    If it's electric stove, yes. Though I still think the deep fryer solution I haven't bothered to buy yet is probably superior.

    If it's a gas stove, it's unlikely to kill you but you'll look funny without eyelashes the first time you decide to look inside to see how it's doing.
     
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  18. Leon Grossman

    Leon Grossman Active Member

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    The type of stuff I print is not high detail, so it isn't damaged by a bit of excess acetone. That said, I haven't noticed any significant problems with dripping and I pretty much am deliberately creating condensate to prevent escaping acetone.

    Before I used the ice, I was having so much escape that I boiled all the acetone out once and then wound up charring the part I was trying to polish. It was... interesting.
     
  19. Printed Solid

    Printed Solid Volunteer Admin
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    We kind of got sidetracked with the vapor polishing, but I'd like to get back to the experiment.

    I thought I had access to an Instron, but turns out I do not. Does anyone have access to a tensile tester, Instron or whatever. Something to get load and elongation at a controlled pull rate. If you have an extensometer, that's always a nice bonus, but probably not necessary for the purpose of this experiment. I'd prefer to keep the shipment in the US but beggars can't be choosers.

    I have some PLA and PLA/PHA dogbones I would like to test right away. I'll also run some ABS, vapor polished ABS, and MEK treated PLA as well. 2 Samples of each piece.

    Any takers?
     
  20. keraynopoylos

    keraynopoylos New Member

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    Sorry to go off-topic again but, aren't you worried a deep fryer might get the temp too high and become potentially dangerous?

    When using the heat bed Harry, what temperature do you set it on?

    I guess we don't want the container to be sealed in order to keep the pressure at normal levels. If so, wouldn't a very small hole on the lid take care of the problem? I don't suppose you would lose too much acetone through it...(?)

    Finally, how long does the process usually take?
     

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