This service supports your 3D printing workflow by providing auto-rotation and slicing functionality.

OctoPrint-PrePrintService

This service supports your 3D printing workflow by utilizing auto-orientation and slicing functionality.

The PrePrint Service is based on:

  • The auto-rotation software for FDM 3D printing Tweaker-3
  • The slicing software Slic3r

You can also use a similar and prefered tool-chain by using Cura as the Slicing software and with the Plug-Ins Auto-Orientation and Octoprint Connection.

Workflow

The full workflow can be deployed either on a single machine or more generally on two separated nodes as described below:

Workflow

The following steps will be done:

  1. Upload a model on Octoprint and click on the Slice button in the file bar.
  2. The model will be auto-rotated for a proper 3D print by the Tweaker-3 software.
  3. The optimized model will be sliced using Slic3r.
  4. The final machine code will be sent back to the octoprint server.
  5. The printing can be started.

Each step can be adjusted as described in the settings.

Requirements

  1. One server node that is connected to your 3D printer, like a Raspberry Pi.
  2. One server node for pre-processing, which has at least 2GHz CPU frequency. If the node connected to the printer is strong enough, one server suffices.
  3. Optional: Install Docker version 1.10.0+ and Docker Compose version 1.6.0+ on the more powerful node.

Setup

1. Install the Plugin

Install the Octoprint-PrePrint Service in the Plugin Manager , e.g., from the archive’s URL https://github.com/christophschranz/OctoPrint-PrePrintService/archive/master.zip or manually using the git’s URL on the Printer-Controller

2. Set up the (external) preprocess services in Docker

In order to make the service highly available, it is recommended to deploy the PrePrint-Service in Docker. If you are not familiar with docker yet, have a quick look at the links in the requirements-section.

Then run the application locally with:

git clone https://github.com/christophschranz/OctoPrint-PrePrintService
cd OctoPrint-PrePrintService
docker-compose up --build -d
docker-compose logs -f

Optional: The docker-compose.yml is also configured to run in a given docker swarm, adapt the docker-compose.yml to your setup and run:

docker-compose build
docker-compose push
docker stack deploy --compose-file docker-compose.yml preprintservice

The service is available on localhost:2304/tweak (from the hosting node), where a simple UI is provided for testing the PrePrint Service. Use docker-compose down to stop the service. (If you ever wish :wink: )

PrePrint Service

Configuration

Configure the plugin in the settings and make sure the url for the PrePrint service is set correct:

settings

Note that the octoprint URL must not be localhost, as the tweak-service is deployed in a docker network where it is unable to locate it’s hosts local network.

Finally, go back to the home UI, click on the Slice-Button of uploaded STL-Models and produce printable machinecode via this Preprocessing-Plugin.

Testing

To test the whole setup, do the following steps:

  1. Visit localhost:2304/tweak, select a stl model file and make an extended Tweak (auto-rotation) without slicing. The output should be an auto-rotated (binary) STL model. If not, check the logs of the docker-service using docker-compose logs -f in the folder where the docker-compose.yml is located.

  2. Now, do the same with slicing, the resulting file should be a gcode file of the model. Else, check the logs of the docker-service using docker-compose logs -f in the same folder.

  3. Visit the Octoprint server, click on the Slice-Button of the uploaded STL-Model in the file bar and produce printable machinecode via this PrePrint-Service Plugin.. After some seconds a .gco file should be uploaded. Note that in a small time frame a .gco file with only one line and 83 bytes can appear. This is expected and should be overwritten afterwards after a short time. If this doesn’t work, start the octoprint server per CLI with octoprint serve and track the logs. The following two lines are expected:

     2019-04-07 22:28:44,301 - octoprint.plugins.preprintservice - INFO - Connection to PrePrintService on http://192.168.48.81:2304/tweak is ready, status code 200
 2019-04-07 22:28:44,321 - octoprint.plugins.preprintservice - INFO - Connection to Octoprint server on http://192.168.48.43:5000/api/version?apikey=A943AB47727A461F9CEF9EXXXXXXXX is ready, status code 200

    If the the Octoprint Server’s URL is invalid, you will see this:

     2019-04-07 22:27:34,746 - octoprint.plugins.preprintservice - WARNING - "Connection to Octoprint server on http://192.168.48.43:5000 couldn't be established"

    If you see instead the following, please check the APIKEY: (403 - forbidden)

     2019-04-07 22:30:09,570 - octoprint.plugins.preprintservice - WARNING - Connection to Octoprint server on http://192.168.48.43:5000/api/version couldn't be established, status code 403

    If the the PrePrint Server can’t be reached, you will see this:

     2019-04-07 22:27:34,746 - octoprint.plugins.preprintservice - WARNING - Connection to PrePrint Server on http://192.168.48.81:2304/asdf couldn't be established

    Make also sure that your selected profile file is correct.

If you have any troubles in setting this plugin up or tips to improve this instruction, please let me know!

PrePrint-Service API

You can use this API to preprocess your models for 3D printing.

import requests

url = "http://localhost:2304/tweak"
model_path = 'preprintservice_src/uploads/model.stl'
profile_path = 'preprintservice_src/profiles/profile_015mm_brim.profile'
output_path = 'gcode_name.gcode'

# Auto-rotate file without slicing
r = requests.post(url, files={'model': open(model_path, 'rb')},
                  data={"tweak_actions": "tweak"})

# Only slice the model to a gcode
r = requests.post(url, files={'model': open(model_path, 'rb'),
                              'profile': open(profile_path, 'rb')},
                data={"machinecode_name": output_path,
                        "tweak_actions": "slice"})
# Auto-rotate and slice the model file
r = requests.post(url, files={'model': open(model_path, 'rb'), 'profile': open(profile_path, 'rb')},
                  data={"machinecode_name": output_path, "tweak_actions": "tweak slice"})
print(r.status_code)
object = r.text

The resulting object, either a tweaked stl file or a gcode file is accessible via r.text which can be some MB large.

Information of how to interact with Octoprint’s API is depicted here. For example, you can test the file upload API like this:

import json
import requests

# Octoprint's URL using the default port 5000 and the API including the API-key
url = "http://192.168.48.43:5000/api/files/local?apikey=A943AB47727A461XXXXXXXXXXXX"
model_path = 'preprintservice_src/uploads/model.stl'
files = {'file': open(model_path, 'rb')}

# Upload a file using Octoprint's API
r = requests.post(url=url, files=files)
print(r.status_code)
print(json.dumps(r.json(), indent=2))

I hope this workflow for 3D print preprocessing helps you!

Donation

This plugin, as well as the auto-rotation module Tweaker-3 was developed in my spare time. If you like it, I would be thankful about a cup of coffee :)

More coffee, more code

Happy Printing!