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Fully 3D Printable Swerve Drive

Bryce2471

By: Bryce2471
New: 06-04-2018 01:26 AM
Updated: 06-04-2018 02:38 AM
Views: 1076 times


Fully 3D Printable Swerve Drive

Fully is a bit of an exaggeration. But you should be able to build this design with only a markforged onyx one printer and a manual lathe. there are 6 parts to be modified on a manual lathe, and 5 printed parts. (not including the 3/16" rollers, which I'm guessing can be bought somewhere) The rest are COTS.

I've only ever designed one part for printing that actually got made, so I would love some feedback on this design.

Here is a link to the CAD.

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06-04-2018 08:24 AM

cbale2000


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by Bryce2471
Fully is a bit of an exaggeration. But you should be able to build this design with only a markforged onyx one printer...
Oh, is that all? I just need a $3500 3D printer and a common lathe? Well let me jump right on that then.


All kidding aside, the design looks fairly straightforward, but I do have a few concerns:
  • That bearing you're using to pivot the wheel (which I assume is custom) is terrifying to me, this looks like the most likely point of failure, not to mention hard to assemble.
  • The wheel drive shaft looks under-supported to me, especially depending on the infill % you use.
  • Are you worried about the drive being underpowered, given you'll have a total of 4x 775s on your drive system? Most teams I've see use 775 drives have used either 6 or 8 of them. I'd worry about frying motors in stall conditions.
  • From the CAD, it looks like the 2nd stage gear set is only supported by a single bearing, if this is the case, you might want to consider adding additional support.

Otherwise, the overall layout looks good.



06-04-2018 08:58 AM

Seth Mallory


Unread Re: pic: Fully 3D Printable Swerve Drive

Looks nice. I would like to see the interior of the design. GRT has run 3D printed swerve for the last 2 seasons.



06-04-2018 11:27 AM

JesseK


Unread Re: pic: Fully 3D Printable Swerve Drive

A photo that makes me want to build something - this is peak summer CD for me.

I'll take a closer look at the CAD when I get home. For an office swerve bot, this may be doable on sub-$1k printers.

Is the giant dome a large gearbox?



06-04-2018 11:35 AM

Bryce2471


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by cbale2000 View Post
Oh, is that all? I just need a $3500 3D printer and a common lathe? Well let me jump right on that then.
The point of this design is not that any team can make it. The point is that it requires very little manufacturing effort outside of the printer, which can be running 24/7.
Quote:
That bearing you're using to pivot the wheel (which I assume is custom) is terrifying to me, this looks like the most likely point of failure, not to mention hard to assemble.
This is definitely a concern. It's something that would be cool to test. I modeled it after the bearing at the bottom of this page. Partly because it seems like it spreads the load over a lot of area, and because silver thin says it has "Greater stiffness and dynamic capacity than a four-point contact bearing."
Quote:
The wheel drive shaft looks under-supported to me, especially depending on the infill % you use.
You might be right, but I'm not sure how I could support it more, after being bolted and surrounded by material on both ends.
Quote:
Are you worried about the drive being underpowered, given you'll have a total of 4x 775s on your drive system? Most teams I've see use 775 drives have used either 6 or 8 of them. I'd worry about frying motors in stall conditions.
Yes. Although, there are several examples of 4 775 swerve systems working well in competition. Most notably 2767 in 2018.
Quote:
From the CAD, it looks like the 2nd stage gear set is only supported by a single bearing, if this is the case, you might want to consider adding additional support.
It has a thunderhex bearing between the gears, and a small 0.5" OD bearing at the bottom.
Quote:
Otherwise, the overall layout looks good.
Thanks. It turned out just small enough to fit in the onyx print area, and a little lighter than expected, so I'm happy.
Quote:
Originally Posted by Seth Mallory View Post
Looks nice. I would like to see the interior of the design. GRT has run 3D printed swerve for the last 2 seasons.
The full CAD model is available at the link below. You should be able to view it in a browser. I can post a cross section and internals view as well.
Quote:
Originally Posted by Bryce2471 View Post
Here is a link to the CAD.



06-04-2018 12:06 PM

Bryce2471


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by JesseK View Post
A photo that makes me want to build something - this is peak summer CD for me.
That's good to hear. If you feel like making this design, or a derivative, feel free to make a copy of the CAD. Just make sure to let me know how it works.
Quote:
I'll take a closer look at the CAD when I get home. For an office swerve bot, this may be doable on sub-$1k printers.
Yeah the primary reasons I designed with a markforged in mind are my team is considering buying one, and it seems like the stronger filament might be required for FRC application. There's no real reason why a proof of concept couldn't be built with a cheaper printer.
Quote:
Is the giant dome a large gearbox?
It houses the wheel module, so I'll go with yes.



06-04-2018 12:52 PM

nuclearnerd


Unread Re: pic: Fully 3D Printable Swerve Drive

This is my favourite thing this week, especially the integrated axle fork / azimuth bearing / pulley piece (part 20). I'm very skeptical that a plastic part (esp. a 3D printed part) will work well in this application though - especially withstanding the loads from the cross-roller bearing, the wheel axle, and the miter gear shaft. Have you done any simulation for this part? Do you plan on printing a test assembly?



06-04-2018 01:28 PM

Mark Wasserman


Unread Re: pic: Fully 3D Printable Swerve Drive

Pretty cool lookin'

Replace the azimuth cross bearing thing with a simple bushing area. One bushing surface should be aluminum (a ring pressed onto part 20). Axle should not be plastic (aluminum better) as Brendan mentioned. Make sure you have a way/method to set your bevel gear backlash and depth.



06-04-2018 03:17 PM

JesseK


Unread Re: pic: Fully 3D Printable Swerve Drive

As far as print-ability, here are 2 sample questions with respect to your other photo for the cross-section.



Without support material, some of those hanging pieces will not print correctly. Most of the time the added time for support material isn't a big deal for designs that are known to work. Yet to iterate quickly, adding support material may increase the print time significantly for a tall part. Just something to consider.

I've successfully done FRC parts with a 60 degree angle from normal (i.e. 30 degrees from horizontal) printed at the "best" quality and the part has been fine. Yet that was with flexible TGV filament, not PLA. Printer is the PRO on this site: https://store.printm3d.com/, filament is the "Tough Ink".



06-04-2018 08:40 PM

samthesnake


Unread Re: pic: Fully 3D Printable Swerve Drive

I like it! Unfortunately, I am somewhat new to OnShape. Is there a way to download and/or possibly export to STL? We want to modify and print a version. I promise I will post pictures if completed.



06-04-2018 08:44 PM

asid61


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by samthesnake View Post
I like it! Unfortunately, I am somewhat new to OnShape. Is there a way to download and/or possibly export to STL? We want to modify and print a version. I promise I will post pictures if completed.
Just right-click on any part and hit "export..." and it'll give you options.



06-04-2018 11:53 PM

jaredhk


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by samthesnake View Post
I like it! Unfortunately, I am somewhat new to OnShape.
Don't let that stop you! Embrace it.



06-05-2018 09:14 AM

cadandcookies


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by jaredhk View Post
Don't let that stop you! Embrace it.
Yes, join us. We have the easiest parts library to use, almost zero setup, and never lose data to crashes.



06-06-2018 01:26 AM

Bryce2471


Unread Re: pic: Fully 3D Printable Swerve Drive

Quote:
Originally Posted by nuclearnerd View Post
This is my favourite thing this week, especially the integrated axle fork / azimuth bearing / pulley piece (part 20). I'm very skeptical that a plastic part (esp. a 3D printed part) will work well in this application though - especially withstanding the loads from the cross-roller bearing, the wheel axle, and the miter gear shaft. Have you done any simulation for this part? Do you plan on printing a test assembly?
Thanks! Part 20 is probably my favorite too. Shout out to Owen from Mean Machine who kindly pointing out to me that the original version was hideous. If you are curious what it used to look like, you can roll the project back to V3.
Quote:
Originally Posted by Mark Wasserman View Post
Pretty cool lookin'

Replace the azimuth cross bearing thing with a simple bushing area. One bushing surface should be aluminum (a ring pressed onto part 20). Axle should not be plastic (aluminum better) as Brendan mentioned. Make sure you have a way/method to set your bevel gear backlash and depth.
Thank you. I like the simplicity of a bushing, but I'm not sure I would trust a sliding surface on a 3D printed part. I am already concerned that the rolling contact of the bearings might wear down the printed parts by the end of a season. The wheel shaft is made from 0.375" thunderhex.
Quote:
Originally Posted by JesseK View Post
As far as print-ability, here are 2 sample questions with respect to your other photo for the cross-section.

Without support material, some of those hanging pieces will not print correctly. Most of the time the added time for support material isn't a big deal for designs that are known to work. Yet to iterate quickly, adding support material may increase the print time significantly for a tall part. Just something to consider.

I've successfully done FRC parts with a 60 degree angle from normal (i.e. 30 degrees from horizontal) printed at the "best" quality and the part has been fine. Yet that was with flexible TGV filament, not PLA. Printer is the PRO on this site: https://store.printm3d.com/, filament is the "Tough Ink".
I'm not very experienced in this area, but I imagine having to use support material will not be a deal breaker if needed. I do suspect it will be needed, at least for the horizontal overhang on the bottom cap part. (Part 115)
Quote:
Originally Posted by samthesnake View Post
I like it! Unfortunately, I am somewhat new to OnShape. Is there a way to download and/or possibly export to STL? We want to modify and print a version. I promise I will post pictures if completed.
That's too cool! I can't wait to see the result.
Quote:
Originally Posted by jaredhk View Post
Don't let that stop you! Embrace it.
Quote:
Originally Posted by cadandcookies View Post
Yes, join us. We have the easiest parts library to use, almost zero setup, and never lose data to crashes.
I have to agree, after learning Inventor and Solidworks, the learning curve for Onshape was almost nonexistent. This was only the second thing I designed in Onshape, and the first was posted here.



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