Resources for FreeCAD

Back in July of 2017, I spent some time learning how to use OpenSCAD. While I was learning OpenSCAD, I kept coming across references to FreeCAD. While OpenSCAD takes a programming approach to CAD. FreeCAD takes a feature-based, parametric 3D modeler approach to CAD. With FreeCAD there is a lot to learn and absorb. The following a list of resources that I found to be helpful in learning FreeCAD.

Resources

Websites

FreeCAD
Wikipedia's entry on FreeCAD
FreeCAD's Documentation Wiki
FreeCAD Manual
FreeCAD Manual: Preparing models for 3D printing
FreeCAD Tutorials
Full Circle's FreeCAD Special Edition

YouTube 

Learn FreeCAD
Power Playground's Playlist 'FreeCAD Tutorials'
Paul Randall's Playlist 'FreeCAD'
Paul Randall's Playlist 'FreeCAD Basics'
Paul Randall's Playlist 'FreeCAD - AdHoc Demos'

Joko Engineeringhelp's Playlist 'FreeCAD'

Re-calibrating my 3D Printer

I have owned a delta style 3D printer for a few years now. In the beginning, I spent a lot of time reading, changing settings, and printing various test models. This was a lot of work and fun building up a knowledge base. Lately, I have started creating my own models that fit together such as a box with a lid. This has led me to want prints that are more dimensionally accurate.

There are a number of challenges to getting dimensionally accurate prints. Starting with the space around the printer. Air Temperature, air movement, humidity have an impact how fast the freshly extruded material cools. The printer is next. The quality of motors, quality of the sensors, quality of the parts, and physical connections have an impact on how the print head moves. Then there is the filament. The type of filament dictates how much shrinkage occurs while the print cools and quality of filament have an impact on how smoothly the filament extrudes.

I performed a number steps to calibrate the printer.

• Checked all the physical connections to make sure they are firmly in place. Mostly this was tightening screws and nuts. 
• Checked the drive belts. 
• No broken teeth
• Each belt should have the same tension.
• Calibration Check and Adjustment
• Advanced Delta Printer Calibration
• Delta dimensional calibration tool
• Adjusted Delta Radius for each tower
• Bed Level Check and Adjust

Resources
Dimensional accuracy of 3D printed parts from 3D Hubs
A Guide to Understanding the Tolerances of Your 3D Printer from MatterHackers
Advanced Delta Printer Calibration
Delta dimensional calibration tool

How-to: Dimensional Accuracy Calibration for Delta Printers

Printing the Stackable resistor box with labels - Follow up

The other day, I posted about Printing the Stackable resistor box with labels. Today, I reprinted the same model using the suggested changes for the other day. I added three complete boxes to the slicer program, increased the size of the outer box by 102%, and changed the top/bottom fill pattern.

The results were not what I was hoping for. The drawer does not fit with the outer box. The drawer still has issues with the base being too thin. It appears that is was a mistake to rotate the drawer to be flat.

Printing the Stackable resistor box with labels

This week, I am trying to get a bit more organized. My current project is to better organize all electronic components that I have.

I got started by picking up a couple of HDX 15-Compartment Interlocking Small Parts Organizer in Black (2-Pack). This got most of the small components grouped together. This left with an issue. There is a fair number of resistors of different values in one compartment. This leaves me hunting and pecking through a mess to find the resistor I need.

After poking around Thingiverse, I came across a possible solution. The Stackable resistor box with labels. There two parts the case and the drawer. The case has an interlocking mechanism. Giving me a number of possibilities for connecting the boxes together and flexibility to print the number of boxes I need.

Preparing and Slicing

• Import the two parts into the Slic3r
• Changed the orientation of the models so supports are not needed
• Sliced the models
• Sent the models to the OctoPrint server.

Updates to the 3D Printer settings

• Changed the z height. Hopefully, this will help the print release a little easier.

Results

The overall print quality is good. The case has a little stringing on the inside. There are a few minor defects with the outer surface. The drawer also printed well. It also has a few minor surface defects. 

The change in z height didn't help with the removing the models from the bed. I ended up destroying the drawer when I removed it from the bed. 

When I tried to fit the drawer in the case, they would not fit together properly. 

Changes

Increase the size of the case.

Print two or three cases at once. This should allow a layer to cool and set before the next layer starts.

Change the top/bottom fill pattern to something other than Hilbert Curve.

Upgrading the Build Surface

For the last couple of years, I have been using blue painter's tape on a heated bed. Recently, I bought a new Anycubic Adhesive 3D Printing Build Surface High Temperature Resistant Sticker.

Installation of the new build surface was quick and easy.

To test the new build surface, I grabbed a Letter Opener model from Thingiverse. This model comes to a sharp point. I have had problems with the model lifting when it contains a sharp point.

The first layer went down smoothly and evenly. I didn't notice any wrapping or lifting while the printer was running.

Right after the printer finished and the bed was still hot, I tried to remove the skirt. I was able to get the skirt to start pulling away from the bed but it was difficult.

I then waited about 10 minutes for the bed to cool completely. It took a lot of effort to get the model off the bed.

Installation Steps

• Removed the old blue painter's tape
• Quickly cleaned the heated bed with Rubbing Alcohol
• Removed the sticker's backing
• Placed the sticker on the bed
• Rubbed the surface of the sticker to make sure there were no bubbles
• Heated the hot end and bed
• Reset the Z height 
• Checked the bed level

Slicer settings

• Bed Temperature for the first layer: 60 C
• Bed Temperature for the other layers: 50 C
• First layer height: 0.29 mm
• Layer Height: 0.2 mm
• Skirt: 4 mm for object, height 1 layer