Creating Custom Fixtures with 3D Printing

Creating custom machining and assembly fixtures is often a costly and time-consuming process. Using 3D printing, custom fixtures can be created in a fraction of the time at a cost that is justifiable for short run parts and one-offs.

To demonstrate this, I have this scaled model for an engine cover. This shape is highly complex and cutting this from modeling foam can be a challenge because of the materials brittle nature.

 Because of the constraints of the machine I used to build this model, the cutting operations were done in two setups. The first setup cut everything except the end face of the part using a rotary axis. The second operation will only clean up the ends of the part with the piece clamped in a traditional vice. This second operation is a challenging endeavor though. This part is quite thin (<1.25mm) and shell shaped with no parallel faces to be held by a vice. The part will also require a large amount of support during the second operations to keep the part from breaking. To make this possible I designed a fixture that can easily be clamped in a vice and provide a large amount of surface contact with the inside surface of the part. This complex shape was made by directly cutting a clampable block shape with the original CAD model for the part.

I printed this model with a Stratasys F370 in ABS. The build took 2 hours and 23 minutes to complete.

This fixture was designed to use self-tapping screws to affix the part in place. For larger parts, mounting hardware could be built into the fixture like embedded hardware or heat-pressed studs.
 

ABS was chosen for this fixture because the machining required is low impact. For demanding setups, the F370 offers a higher strength material, Diran 410MF07. Other high strength materials offered by Stratasys include Nylon 12 CF and the ULTEM series, both available on the Fortus 450mc.

Using the Stratasys F370, I was able to quickly and easily create and implement a custom machining fixture for a highly complex one-off part.  

Collin Manchester
Application Engineer, Manufacturing Solutions
Computer Aided Technology, Inc.