Comments (6)
While 3.3 mm is the right core hole for threading an M4, it would be too small here.
First, we recommend to "cut" the threads directly with the screws and don't use a thread-cutters. Screwing in a screw in a 3.3 mm whole would require too much force from our experience.
Second, a 4 mm hole in CAD will be much smaller in the print. Maybe around 3.7-.8 mm (never measured it). We found 4 mm to work well in terms of rigidity, reliability and ease of installation, so it should stay 4 mm.
from exomy.
from exomy.
Fair point regarding calibration. I assume you tuned your slicer using the Horizontal Expension parameter?
https://bradshacks.com/3d-printing-tolerancing/
I was not aware of this parameter and with that in mind I have to agree, that a smaller hole size would have been better.
I updated the wiki, adding a recommendation that people test the threads before printing all the parts.
https://github.com/esa-prl/ExoMy/wiki/3D-Printing
I will reopen the issue, but can not change it myself. As I'm not working at ESA anymore, I don't have access to Solidworks anymore nor the 3D printers (which should be calibrated ;) to test the fit. It would be good to change this in the future however.
from exomy.
Actually Cura has an even better feature. Horizontal Expansion enlarges or minimizes also the basic print size of your object. Cura has (in expert and all modes) a feature called Hole Horizontal Expansion. That leaves the overall object size unchanged and affects only the hole radius. See this video for an explanation.
Apart from the bogie bearings I also had to reprint the bogies because the bolts for the servo's did not hold. I also hope the mast will hold on the chassis top. These holes also seem a bit wide.
One more remark about slicer settings: In Cura set, in the Shell settings, a tickmark in the item 'Print Thin Walls'. Otherwise in both the three bogie bearings and the six wheel_brackets part of the walls are missing because they are not printed.
from exomy.
Getting threads to hold reliably in PLA over time is problematic particularly with shock loading if you are going to drive over obstacles. I have found brass knurl nuts very easy to fit with a soldering iron and make an enormous difference to thread performance in all 3D printed parts. Has anyone tried this on ExoMy as yet?
Regards, Frazer
from exomy.
Hey @Penguin-fach,
Agreed, brass inserts are amazing. I'm a big fan of them myself and an ExoMy with full brass inserts would definitely be great.
Currently we use brass inserts to fix the top to chassis. This is a part that we expect to be removed somewhat regularly. Thus the reusability you gain with the brass inserts should pay off.
On the other parts, we stuck with the direct cutting method to keep the complexity and assembly time of ExoMy low. So far we had threads which were too loose, but no failures in the threads occurred during operation.
We received an email of someone who wants to modify the STEP files of ExoMy to work with brass inserts, but I don't know what their current progress is.
from exomy.
Related Issues (18)
- Test
- Incomplete sentence in the wiki HOT 1
- Control web page not working without Internet connection HOT 1
- Error during installation of Docker HOT 1
- Wrong Docker startup code in wiki HOT 1
- Cable protection required HOT 3
- CAD drawings HOT 3
- pi camera image and direction control not visible in web page HOT 1
- P02_Drill_Default: STEP File with wrong content
- 3D print part in a more common format ? HOT 1
- Default Wheel STLs
- Funktion HOT 2
- Number of required servos is unclear (16 or 12?) HOT 3
- BOM xlsx file contains hidden rows which might be overlooked by people HOT 1
- some website wiki improvement suggestions HOT 4
- Minor typo HOT 1
- American Providers BOM HOT 4
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from exomy.