Dyne's Treadwell

[Dyne]

Current Status: CAD Work and Acquiring Parts


Build Log Index

• This Post: Table of Contents and Adventures in CAD that I probably won't end up using.
  
• Post #20: Lens Retainer
  
• Post #25: Casting Lenses
  
• Post #32: First purchases and first attempt to commit to the build
  
• Post #37: Results of Printed Lens test (from post #34)
  
• Post #43: Second attempt to commit, ending waffling on drive system
  
• Post #47: Tank Mixing setup
  
• Post #49: Telescoping neck thoughts
  

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Introduction

According to the files on my computer, I did my first work on my Treadwell on September 12 of 2016 (which sounds about right, as it was just after last Dragoncon).  Mostly I just collected reference and did some CAD for the wheels, which is hardly a stunning accomplishment.




I've described elsewhere the reasons I didn't progress much further than this for the intervening five months (short version: Halloween, immediately followed by loss of motivation due to a 3D printer I thought was broken, two long-lasting colds, and politics).  But I recently have recovered said motivation and figured out the printer was fine, so work has resumed.

I am starting with the head, largely because this is the most complex part of a Treadwell.  As I've mentioned in other posts, I'm not trying to reproduce any specific Treadwell, but it will be recognizable as a Treadwell.  I will also be updating/refining the design in a few minor ways.  I will be releasing files and drawings as I go, though it may take some time to get to that point.

In any event, I recently printed savagecreature's model of the interior lens from the Paterson slide projector, used for Treadwell's eye.  I did a basic model of one "eyebox" and printed out a short slice from the lens end of the eyebox to see how they worked together.  Text added is temporary.





Obviously, the eyebox in the plans here on the site do not accommodate the flange of the lens holder.  I'll be fixing that as soon as I get a chance to work on the model further.

As you can probably see, there's a slight gap between the lens holder and the eyebox top and bottom (above "other eye").  This is probably fine, but I can easily adjust them.

I am planning to print my eyeboxes because they will have modeled in details.  Because of my printer's build volume, I'll have to cut each one in half and rejoin them.  Each half of each eye will probably take 12-14 hours to print.  That's a long print, but not a challenging one, and it'll take nowhere near as long to print as the parts for a BB-8.

That's all I have time to write for now.  Until next time.

[savagecreature]

Cool! I love to see other people use the files we have here. You're making me wanna build a treadwell

[kresty]

Cool! I love to see other people use the files we have here. You're making me wanna build a treadwell

I'm starting to want to build one too.... Lego of course.

[Dyne]

I have adjusted my eyebox model a bit to accommodate the flange, and printed again.  The first time I was pretty close, but the flange indent had a gap because I didn't pay enough attention to the reference photos.  Second time was pretty close to perfect, aside from some quality issues with my prints that I haven't yet sorted out following my hotend upgrade.



I added tabs for the mounting screws.  They should clear the lens retainer just fine.

The above print worked well as-is, but I'll be tweaking the measurements slightly to make it fit better.




I will supply a proper PDF version of the plans once they are further along, but for now here are some screenshots from Fusion 360.  They will get more complicated as I add details.  As with all of these images, clicking will take you to the larger image.





You'll notice that I just take one edge of each "eyelid" (the top and bottom extensions of the eyebox in front, the ones that the lens holder sits between) and project that line straight back to meet the slope of the top and bottom walls.  There's no particular reason I did it that way, and I could save a bit of plastic and weight if I just continued the walls further and joined up with the eyelids only a few mm behind the lens holder.

Edit: Nevermind, I've already done it, and updated the drawings.  They also now include the distances of the rear face (on the overview sheet).

(I'm hopefully going to be doing animatronic internal eye mechanisms to go inside these (think something like a simplified version of Johnny 5's eyes from Short Circuit), assuming I can fit them and link the mechanisms together.  I'm also wanting to fit a Raspberry Pi camera to use with OpenCV onto this mechanism, in order to allow Treadwell to automatically focus on faces when I'm not puppeteering the head myself.  If you've seen the latter half of part 25 of James Bruton's Ultron build, you'll probably have some idea what I mean.  If there's insufficient room with servos for the eyes as well, that camera will have to go outside the eyeboxes.  Which is fine; then I would be able to have matching lenses that weren't just shells.)

[Dyne]

I've been using this project to experiment with some of the features of Fusion 360 that I don't normally use (which is a lot of them; it's a big program, and I've only used it off and on since last summer).

Among those features are the drawings I posted before.  The first version of the Overview sheet was literally the first functional drawing I've made in the software. (Speaking of that drawing, in detail A where the Eyelids join the upper and lower wall, there's now a 45 degree slope rather than a ~90 degree angle. That's to avoid the need for support when printing.)

Speaking of drawings, here's another one.  This is the head assembly.  I'm still trying to settle on a workflow for assemblies and better sort out how joints work, but I currently do have the head tilt working.  I've improved my title block since the last drawings, and added the company name in Aurebesh to the logo.



The BOM lists some materials, but those just contain whatever I happened to attach to the parts and are not a true reflection of what I'm using.  If you are wondering what's up with the random fractional measurements, it's because I'm working in millimeters, whereas the original plans in our files were specified in inches ... e.g. the gap between the upper eyelids at grid D2 is 1 inch.  I've tweaked some of them and made up others as needed, so they won't all convert nicely back into inches.  Doesn't matter for my purposes, since I can type them into the software either way and get consistent units in the output, and much of this is going to be printed (probably not in ABS).

As you can see, I recreated the lens and its holder in CAD.  Mostly that's because the STL files were being weird (importing at the wrong size) and were refusing to convert into decent solid models.  I tried to reproduce them as best I could from Savage's originals and the photos.  

Here's an exploded drawing of that.  I didn't bother reproducing the rear half of the little flange because it isn't visible on Treadwell.




Incidentally, the plans already on the site are not quite complete.  In particular, they did not list several dimensions of the eyebox mounts, the angle they should be at, etc.  I just eyeballed it, and went back to reference as needed.  I will probably tweak the design of those parts so they can be printed separately and screwed to the eyebox.  If they were printed as an integral part of the eyebox, they'd need support.


I'm also experimenting with the render feature.  I could also do this in Blender or what-have-you, but it'd be a pain to export all the parts to a useful format, make sure they were assembled correctly, set up materials, etc., just for a still shot.  Luckily, Fusion 360 already had an appropriate environment available...

[savagecreature]

Awesome! Now I can retire

excellent work

[kresty]

Awesome! Now I can retire

excellent work

You still have other droids to post ;-)

[Dyne]

Awesome! Now I can retire

excellent work

Heh.  Thanks.

I have started working on the neck parts.

Encountered more STL weirdness.  Whereas the lens holder files imported at roughly 10 times their printed size, the neck STL that Paul supplied came in at about one third scale.  Bizarrely inconsistent, especially if they print correctly (not sure on the neck, but the lens holder did).  Of course, as I recall the neck STL was created in sketchup, which I've heard has issues when used for printable files.

One thing I've noticed is that the neck part is actually not a solid plate.

Have a look at the Head photo on the Electronics Today International article.  Most shots of the neck show that part edge-on, but when shot from a low angle like this it's pretty clear that it is more like a trapezoidal frame.  Which is good ... I struggled to understand how the head tilt mechanism could fit, otherwise.

I am still not sure how that tilt mechanism works, mind you.  There are no reference photos for the motor, which I believe is inside the head (according to the legend for that photo, anyway), or even how the little piston thing connects to it.  The same pic also indicates there's a counter balance spring attached ... somehow.

I'll also have to give some thought to whether to do the neck lifting mechanism (not the head tilt, but where the entire head and neck rises like it's mounted on a piston, ala WED 15-i662 on the sandcrawler, or the deleted scene with Luke and WED 15-77 at the moisture vaparator) ... and if so, how.  Doesn't seem like there's an easy way to conceal a standard linear actuator inside the body, given the way they are usually designed with offset motors.  Maybe something with an inline motor, more like the z axis on my printer.  They do exist, but hoo boy are they expensive.

Edit: After this post, I looked back through Paul's therpf thread.  I last saw it months ago, and I'd forgotten that he did modify his neck part after printing it.  I'll be designing my part to avoid the need for that.  He also shows how he did the tilt mechanism/spring.  I don't think that's how the original did it, but I think moving the servo out of the head was a good idea; no point lifting that weight if you don't need to.  I think the servo could be partially concealed by dropping it inside the neck frame.

[Dyne]

Ran into a slight problem this afternoon.

I got pretty far on the revised neck design, incorporating a servo model in the process, but fusion 360 choked after I rebooted my router. I couldn't restart the program, so I researched the symptoms. I concluded something was corrupted with the install (which has happened to others after network changes), and tried various things to get it to work. Eventually I attempted to reinstall, but that failed as well.

I've since learned that the router reboot happened to roughly coincide with that Amazon Web Service outage, and that impacted Autodesk's stuff. My install probably wasn't corrupted to begin with. Hopefully I'll be back up and running tomorrow.

Edit: I have it working again. At the moment, I'm making a crude prototype of an eye mechanism so I can sort out the kinematics.

[kresty]

Of course, as I recall the neck STL was created in sketchup, which I've heard has issues when used for printable files.

I've had 0 trouble with scale from sketchup, it exports STLs in mm and that usually works fine.  I do tiny things so sometimes Simplify 3D asks me if it's too small, but otherwise...

My problem with sketchup has been having good solids without holes and other problems.  Lately I've been using Cleanup3 (Sketchup Extension) to fix models before exporting and Solid Inspector2 (another extension) to check them (though I discovered a false positive with it today).  

Another great tool for cleaning up bad STLs - like random Thingiverse ones or whatnot - is Microsoft's 3D Builder (disclosure: I work for Microsoft on Windows).  Their repair function used to be "okay", but often had problems.  They must of updated something in the last month or two though because lately it's been fixing bad models pretty much perfectly.  (Previously it'd end up with strange planes and missing bits).  You can then re-export them back to STL or other formats.