Servo to cable attachment.

Joel GoodpasterJoel Goodpaster ✭✭
in Animatronics
I'm looking for some input on a servo mounted push/pull type cable setup.  I'm looking at having some pieces 3D printed unless I can find something premade.   What types of setups are you using?   Custom made, or off the shelf? 

 This will be for a standard RC servo, and I'll be using a nylon lined 5 mm casing with a 1.2 mm 7x7 cable, so fairly small and flexible. I had a couple printed before, but my design was too thin, and the alignment didn't come out right. The second design is thicker and I corrected the alignment. (Pictures below)     Having pieces printed isn't really expensive, but it would be nice to have options.  Let me know  what you think, suggestions, questions, etc.

First design
 

Second Design

Comments

  • Chris EllerbyChris Ellerby Admin
    The design looks great.  One option is to have the parts printed in nylon or something more durable using a service like shapeways.  You can also clean up your prints by sanding them and filling in print lines with bondo/resin/etc. and then mold the parts.  That way you can cast as many as you like, and not have to worry about wear as much.

    What printer are you using?   I'm actually waiting on a 4+ hour PLA print right now, part 4 of 16.  Fun, but slow!

    /Chris
  • Joel GoodpasterJoel Goodpaster ✭✭
    I've been going through 3Dhubs.com for my prints.  Can't justify a printer yet....yet. lol    I wasn't very happy with the print quality on the pieces for the first design.  It was very rough and the layers actually split at one point.  Tried a closer supplier, and wasn't as good as the previous one.

    I had them printed in ABS, and once I got the final design, I was going to sand, and then acetone smooth them.  Nylon is a possibility though. 

    It might be possible to mold and cast them. Honestly never considered that.  Might have to price it, and see which would be more cost efficient.
  • Christopher VaughanChristopher Vaughan ✭✭✭✭✭
    Hey Joel here is mine, so you can examine it. I have made them bi-directional and a included the servo holder in the design. This is for a standard Hi-tec servo. https://www.dropbox.com/sh/d9ke5nmam732ht5/AACdFVDTRHF9wcA6ItMOeMp5a?dl=0
  • Chris EllerbyChris Ellerby Admin
    Thanks for sharing your models Mr. Vaughan! I'll have to print your design out and give it a shot.  I'm printing in PLA right now, which does not have the delamination problems you get with ABS, but it is not as durable and can't be acetone vapor smoothed.

    Oh, and my 4 hour print from my previous comment died just over 3 hours in.  Nozzle clogged with PLA (finicky stuff)

    Joel:  If you are not ready to purchase a 3D printer you may be able to find some locally at a hacker/maker space or library that does a maker program.  I'm actually a member of a LA hacker space called CRASH Space that has a few printers.  I plan on purchasing one eventually, but I've yet to find the right printer.

    /Chris
  • Christopher VaughanChristopher Vaughan ✭✭✭✭✭
    No problem Chris! By delamination I assume you are referring to it curling on the build platform. The best solution is to cover your platform in blue painters tape. Take acetone and melt some abs in a mason jar, paint it on and let it dry. The abs will not curl. As for acetone vapor processing, do not do it with your animatronics parts, they will warp slightly and not function properly, unfortunately the best thing to do is sand, sand, sand. If you need a super smooth surface for a part and it can be painted (like eyes) I like 2 part filler sandable auto body primer. You can get a gloss finish out of it. I'm going to do a tutorial at some point on 3d printing, I'll make sure you get a copy Chris.

    Best

     
  • Chris EllerbyChris Ellerby Admin
    The delamination issue is actually with the individual printed layers in a part.  As the material cools it can occasionally warp a bit and cause layers to separate.  This typically happens with very large parts.  A sealed printer with heated air can help prevent this, but most consumer printers are open-air.

    Smooth On also has a new product called XTC-3D that you can brush onto printed parts to smooth out surfaces and hide print lines.

    I'd love to see that tutorial!

    /Chris
  • Christopher VaughanChristopher Vaughan ✭✭✭✭✭
    Ah, never had the problem, I have an enclosed printer. Yeah I haven't tried the new smooth on product yet, have you? Im curious as to the effectiveness of it.
  • Chris EllerbyChris Ellerby Admin
    I've not tried it yet, but I hope to give it a shot soon.  I may try it on this project, which has 16 pieces (printing on a printer that does not do massive parts), so once I glue them all together I may try it just for fun.  This piece does not need to look great as it's just for mechanical and sculptural scale reference, so it would be good for experimenting with new materials like XTC-3D.

    /Chris
  • Joel GoodpasterJoel Goodpaster ✭✭
    Chris E. -Closest maker space I can find is about 60 miles, but still worth keeping in mind.  For now, it will be order and ship.

    Chris V. - Do you have any issues with the 'arms' flexing at the far end?  I like the design. Mounting might be easier with this style also, if someone is looking to make a servo bank.

    Thanks for the responses!  Nice to be able to bounce ideas off people.
  • Christopher VaughanChristopher Vaughan ✭✭✭✭✭
    no I have it mounted to wheels and not servo arms, no flexing problems. As for servo blocks yes that is exactly what this is. If you print 2, the hole in the center of the platform is 1/4", for a threaded rod. you can stack them on top of each other and mount computer fans to the front to keep the blocks cool.  
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