Modular Chassis

[jmccartney]

Latest incarnation. Didn't get much more than modeling done today.

This isn't anywhere near close. If you can't tell, I am having a hard time figuring out how to tie down the center of the bearing cover. I know already this one is way to weak at the center m3 screw.

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Adding picture of matching bearing cover.

[sho]

Hello James,

Thank you very much every times.
Good design ! Especially, center M3 screw is very important to work well.

It's moving ahead little by little everyday.

[jmccartney]

Finally think I am making progress. I will upload pictures tomorrow too tired right now. I have a decent print of most of the chassis now. Took about 4 revisions but I think its almost good to go. Of course the bearing cover is still something to deal with. I think I might rig it up for now, I would like to actually start putting some stuff together.

I am attaching screenshots of the 3 main parts that I finally settled on. They are the front, middle, and back. They seem to be very sturdy and snap together though I will be using some crazy glue on them when I am satisfied.

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(ignore the colors in the middle piece. Its printed as one whole piece at once in about 2 hours, the green parts though are support structures modeled because I wanted to print without support but these 90 degree angles need support so I threw them in with a .5mm gap. Probably could increase that a bit more to be on the safe side)

[jmccartney]

Pics of my chassis. Ignore the gap/alignment problem between the middle and front on the right side. I am re-using a front and back from a previously glued chassis to save time and need to remove some glue so they snap together.

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I will probably have to dremel out the center. I filled it in to make the structure more rigid, but forgot the pins need to come up through the bottom. Will have to change the model again.

[xoan]

I've been made some experiments with a similar approach, but not to use glue (at least for structural parts in the chassis). Orange sides in the first attachment are printed individually by turning them 90º, so clips are no so easy to break.

My RepRap (a FoldaRap 1.1) has a total print height of 150mm, so I've doing some stuff in the shaft. Printed at 0.25mm layer height with a Ø0.5mm nozzle.

A friend of mine have one spare 100:1 (or 150:1, doesn't remember) poor power motor from eBay, and... It works! Not so good, but it works: https://www.dropbox.com/s/v5l3x5yfse63vh...4.3gp?dl=0 (sorry for the incredible awesome good video quality )

I need more time to figure out how to assembly the motors, and how to made the legs and pins, but I guess I'm close to a semi-functional complete micropede RP prototype.

[steamboat]

Your print looks great!

[sho]

It's moving very smoothly !
We tryed many times, but you're 1st person to success to move like it.

[steamboat]

Lets wait and see how it moves and how this 0.25 mm printing stairs influences the friction in the gear. If you are lucky it reduces it like in a Shark skin. If you are unlucky it raises the friction like a cross-county ski sole

I will press my thumbs!

[xoan]

Let's go! 1-wave module: https://www.dropbox.com/sc/vobwa5ngd68ye...Zsa_3VoOoa

(my apologies again for my phone camera definition). Most of the parts have been --slightly like legs or cranks, or heavily like chassis and pins-- redesigned in FreeCAD in order to be printed in a RepRap (or any kind of FFF machine) in a not so high quality. I need to adjust several dimensions in the model, and hold the motor in the rear rib, but with some minor faults, it seems to work.

The 1-wave module is a good point, to allow mutations like a normal 2-waves micropede, or a large 3-waves or more animal. Even for a some kind of articulated reptipede (so i'll keep this idea to assembly the standard chassis compatible with the current state of core and Cambria shell)

Some test parts attached. No support needed (maybe raft, but if you are confortable with you bed adhesion, it shouldn't be needed).

• Layer height: 0.25mm
• Extrusion width: 0.5mm (200% or 2.0 width over thickness)
• Perimeters: 2
  

Cooling is also important, e.g. the crank, so at 50mm/s I'm not be able to print less than 8 copies at the same time (worm teeth becomes curling).

[steamboat]

Great Work! Thumbs up...

Will send the motors at least at the weekend...