Training knife - making a fixture
Originally this was going to be a two-part blog, design the knife and then make the knife. However, because of a few issues, specifically, the knife is larger than the travel on our mill, we decided the fixture was a bit more involved. Creating the fixture is now Part 2, and Part 3 will be the actual creation of the knife.
For the complete video, click below:
First a big shout out to James on our marketing team, as he has access to a 3D printer, and printed me a sample knife so I could see if I wanted to make changes to the design. After getting the sample, I decided to refine the contour a little, adjust the hole diameter, and space the holes better.
Visit James' blog UnprofessionalEngineering the podcast is pretty good, even if he hasn't had me on as a guest yet.
Since the knife is longer than the "X" Travel on our mill, we will have to cut half of it, flip it around, and cut the other half. I'd like to be a little bit more productive in this task, so I designed a fixture to hold two pieces in the mill.
First we started with a simple rectangular shape.
From there, we add two bosses, which are the same size and distance as the first two holes in the knife design. This will be used to locate the knife.
Then we create a tapped hole in the center of the bosses, so we can screw the knife stock down.
From there, we drag and drop our part into the fixture drawing, and use an Assembly > Joint command to locate them together.
When complete, and assembled, the fixture, with parts ready to mill, will look like the image below. I'm using an aluminum strap, with the 5/16 bolts, to hold the parts down. I figured this was the best way to reduce vibrations of the relatively thin aluminum bar stock.
In part 3, we will mill the knives, and finish up. I hope you enjoyed this blog, and please leave a comment on anything you'd like to see designed or made.
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