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3D print a Scribbler battery cover? Files attached — Parallax Forums

3D print a Scribbler battery cover? Files attached

Hi All,

We get occasional requests for replacement Scribbler battery hatch covers. Since the Scribbler molded parts are made in a set, we don't have a ready source of spares, and 3D printing came to mind as a possible solution. Ken obtained an .stl file for the battery cover, and I'm posting it here. I'm curious how well this might work - is it flexible enough for the latch? Do the hinge tabs print thin enough to fit? Do variations in material and printer resolution call for slight adjustments?

If anyone with a 3D printer and a Scribbler gives this a try, I'd love to hear what you used and how it turns out. Any vintage Scribbler will serve — the compartment changed with S3 but the cover did not — and there are still Scribbler 1's and 2s serving in classrooms.

Thanks!

-Stephanie Lindsay

Comments

  • ercoerco Posts: 20,244
    Hopefully this works well enough for most people. Results will vary by 3D printer and material used. Those tabs will be fragile!

    Another alternative for Parallax is to have an injection mold made. That's a simple part, so a 2-part mold will work, no slides. Soft tooling (aluminum) is relatively cheap & fast, sufficient for low-volume molding. Molded parts (especially those thin tabs) would be much stronger than any 3D printer could make. And since it's strictly a functional, nearly hidden part on the robot's soft underbelly(!), people are apt to be less picky about finish & color match. Not necessary to polish the mold (the cutter-mark finish is fine, just like Arlo's chassis) and just pay a vendor to mold a big batch in most any color (black is cheapest, because it's full of regrind).

    A second, even cheaper alternative is to make a silicone mold off an existing door and cast it in Ciba or another resin. Perfect finish and stronger than the original ABS part. I know a dozen guys who can do that for you. There are several Ebay vendors who make tidy profits by casting battery doors for old robot toys such as red venom repros: https://www.ebay.com/itm/AHI-1977-LOST-IN-SPACE-ROBOT-BATTERY-COVER/372154137570

    In fact, just send those guys a battery cover and they'll make & sell them on Ebay, problem solved.
  • Thanks for the input Erco! I hadn't thought of the eBay solution, that's an interesting one.
  • JonnyMacJonnyMac Posts: 8,912
    edited 2017-12-06 23:19
    Ken obtained an .stl file for the battery cover...
    I did that for him -- in case there are troubles, these are the steps that I followed.

    1) Downloaded and installed trial version trial version of Creo (don't do this unless you want calls from their sales department)
    2) Exported door from Creo as STEP file (attached)
    3) Imported STEP into FreeCAD, exported from FreeCad as STL
    4) Opened in MakerBot software to ensure bottom surface is at Z = 0 (screen shot is from this software)

    I don't have a printer big enough to print the door. It should be clear by the steps that mechanical things are not my strong suit -- still, I muddle along and get things done. I'm also going to checkout Eric's eBay link.
  • Much appreciated, JonnyMac! (Including the warning about Creo's sales folk).
  • ercoerco Posts: 20,244
    I put in a request to a friend with a nice Mojo printer. Will advise.
  • ercoerco Posts: 20,244
    Sorry, this little project got lost in the holiday shuffle. Just got the door from my friend today and it definitely needs some tweaks. My part was printed on a Mojo printer in beautiful white ABS. I don't think a PLA door would work nearly as well. Long story short: clips are perfect. Tabs each need a chamfer. Overall length & width too big, reduce each by 1 mm. First photo shows a "wedgie" with the too-wide door wedged in. Video walkthrough follows. Ken or Stephanie, happy to send you this part if you like.

    wedgie.jpg

    taper%20tabs.jpg

    width.jpg

    clips%20are%20good%21.jpg



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  • WhitWhit Posts: 4,191
    Nice full report erco!

    May have to try this...
  • RaymanRayman Posts: 13,797
    I was just playing with the Win10 3D Builder...
    It opens the STL fine and can order it printed from iMaterialize in polyimide for looks like ~$21 or so with shipping.

    Anyway, I measure the length at 111.90 mm and width at about 56.30 mm. Thickness is 2 mm.

    Sometimes the extrusion printer parts come out not exactly the right size.

    This might come out better on an SLA printer... But, it's thick enough that extrusion printer can work...
  • RaymanRayman Posts: 13,797
    edited 2018-01-25 19:13
    Printed with Formlabs Form2 SLA printer (just for fun, I don't actually have a scribbler).
    Came out looking great! Measure 112.0 mm for the length and 56.5 mm for width, so should be perfect fit.
    The latches seem springy enough to work.

    Anybody want to try it?
  • RaymanRayman Posts: 13,797
    Shoot, can't add images to post after the fact...
    Here they are:
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  • ercoerco Posts: 20,244
    Looks nice! Send it to Steph (OP) to try!
  • RaymanRayman Posts: 13,797
    Steph said it was a hair too big!
    We're ~ 1 mm too big in both dimensions... Sounds like it broke when forcing it in...
    She measured the actual door and it's ~1/2 mm smaller than the STL file says...

    But, I've made some new ones to try. This time scaled to 99%.

    There are two clear ones. One is just scaled, the other has some extra thickness added to the bent part of the hinge, where it seems to break.
    The gray ones are printed with Makerbot with "Tough PLA" at a 90 degree angle. I was surprised it worked at 90 degrees, but this should make the hinge very tough to break.
    The black one is printed in Nylon at 20 degree angle. Nylon is super strong. I don't think it can break, but it's a bit warped and the hinges aren't perfect.

    I'm trying the black one again with rinse away support material to see if that makes it better...

    Anyway, I'll mail these to Steph and hope one of them works without breaking...


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  • WhitWhit Posts: 4,191
    Nice work Rayman!
  • RaymanRayman Posts: 13,797
    edited 2018-03-13 17:59
    It took a few tries, but I think we found a version that works!
    Steph said the last ones I sent her worked and passed drop test when some foam was added to keep batteries from rattling around.

    I printed the attached .stl file with a Makerbot Replicator using their ToughPLA and matching extruder.
    One special thing I did was to print vertically (with supports). Was a little surprised this actually worked, but it makes it extra strong.
    See attached photo to see what I mean.

    You need to print at 99% scale for some reason to make it fit right.

    See attached image for how I added some extra material in the hinge (green) to make it a bit stronger.
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  • Thank you for your trials and tenacity on this, Rayman!
  • RaymanRayman Posts: 13,797
    edited 2018-03-16 20:59
    I tried printing the same way on a less expensive XYZ pro printer with ABS filament and it also came out looking good.

    Perhaps any FFF printer can work, if it can print vertically like this.

    Printed with "brim" and supports.
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  • ercoerco Posts: 20,244
    DOH! Stephanie, I should have brought the battery door to your seminar!
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