Blender Repaired - With 3D Printing

No, I didn’t repair the program Blender as I’m still trying to memorize its keyboard shortcuts. I repaired a traditional blender with 3D printing & modelling.

The blender ceased to produced smoothies one morning because the drive gear responsible for transferring torque to the jug went un-silently into the long night.

Once I was supplied with the broken gear and photos of the shaft which the gear mated with, it was time to begin.

Material Selection

First stop for this project was material selection.

This can be based on numerous parameters, dependant on the parts operating environment, as a single example. Stefan, the creator behind cnckitchen.store, has released a YouTube video explaining key parameters for material selection.

Given the operating environment of a blender that ramps up to a high speed in a short amount of time, a material with a good impact strength would be required.

An additional material parameter I considered was printing difficulty and I ranked the materials I had on hand out of 5.

Printing Difficulty – Material Parameter

For successful Nylon prints I’ve upgrade my printers to achieve higher printing temperatures, dried out my filament prior to printing, prepared my print surfaces with adhesives and used an enclosure. When printing in ASA, I saw a big improvement in print quality by adjusting print speeds, and using an enclosure.

Given the higher impact strength of ASA (as seen in Stefan’s video) and lower printing difficulty compared to Nylon, it stands out as a good material for the blender repair.

3D Modelling

Having been supplied with the broken part I was able to start measuring features and sketching to work out how I was going to build up the 3d model.

3d-modelling-sketch-blender-repair-1 — Tracing part on grid paper to help sketch the part before modelling

Grid paper is handy for sketching and even more so when the part is small enough to trace. Tracing features can make measuring them easier and for this part I used tracing to confirm that the faces on the teeth were aligned on the parts centreline.

3D Model created from sketches

3D Printing

Test Prints

3D printing test prints or prototypes is good a step to confirm that 3D models have been recreated accurately. Prototypes are even more helpful when part size is small because multiple variants can be printed for test fitting onto mating parts.

Test pieces printed for test fitting onto mating shaft

Three test pieces were printed for this project varying the dimensions of the flats and the diameter that mates onto the shaft. Only printing the lower section of the part made measuring these features easier as well as test fitting.

To determine if a smaller section of a part can be printed as a test piece the form, fit and function of the part needs to be considered. The test pieces pictured above served to get the fit between mating components correct, while a separate test print of the full part was required to confirm the tooth features were 3D modelled accurately.

Print Profile

I completed these parts on my Flash Forge Creator Pro printer to make use of its enclosure as ASA is susceptible to warping. Another advantage of the Flash Forge printer is the Microswiss All Metal Hotend upgrade.

All Metal Hotend upgrade replaces stock PTFE tube

This upgrade kit removes the need for the PTFE tube in the Hotend allowing for higher printing temperatures. The PTFE tube can begin to breakdown at higher temperatures which can degrade print quality release harmful fumes.

I printed the ASA parts with an extruder temperature of 270 degrees C, 20 degrees higher than the stock recommended maximum temperature. The table below summaries the other key printing parameters I used.

Parameter	Value	Unit
Layer Height	0.2	mm
Infill	50	%
Top Layer Count	5	–
Bottom Layer Count	5	–
Wall Count	4	–
Nozzle Size	0.4	mm
Printing Speed	1200	mm/min
Bed Temperature	110	Degrees C
Extruder Temperature	270	Degrees C

Key Printing Parameters for ASA

Two parameters I found impactful for ASA were the layer height and printing speed, with these parameters being reduced to increase part quality.

Completed Blender Parts

A 5th full size part was printed for testing in the blender. This failed and revealed that I needed to increase the size and depths of the flats as shown in the images below.