Roberto Lo Giacco’s Custom Delrin Fixture for Milling Four Dog Tags at Once

Custom delrin dog tag fixture for the Bantam Tools Desktop PCB Milling Machine

Bantam Tools community member Roberto Lo Giacco, who’s based in Rome, Italy, recently shared a neat custom fixture he milled with and for his versatile Bantam Tools Desktop PCB Milling Machine. Milled out of Delrin, one of the best performing engineering plastics, the fixture firmly holds four aluminum dog tags at once. He also wrote up his R&D process and shared all his design files on his site

Roberto and his friends are working on a project for the upcoming massive Maker Faire Rome event taking place in October. The project requires them to mill a couple hundred dog tags. While the reliable Bantam Tools Desktop PCB Milling Machine can handle that with ease, fixturing one at a time would be quite time consuming. Roberto just made the task four times faster with a little ingenuity.

For the design, Roberto started out bylisting his constraints and requirements and then moved on to Fusion 360. The fixture must:

  • Reduce the milling time by fixturing as many tags as possible at once

  • Be compatible with the fixturing tools the Bantam Tools Desktop PCB Milling Machine provides

  • Be applicable for both sides of the tag

  • Not scratch the tag surface

  • Hold the tag tightly (strongest forces are horizontal)

  • Have the tags precisely located on all the three axes (engraving depth is only 0.1mm)

Four dog tag fixture
Four dog tag fixture on Bantam Tools Desktop PCB Milling Machine’s spoilboard.
Gif of four dog tag fixture.

Roberto writes:

As you can see, the horizontal cutouts provide the flexibility necessary to grab the tags by their longest sides while the bolt and nut pair should be able to exercise enough force to squeeze the rig. If you have a look at the image [below], you’ll see this rig will have one side accessible when mounted: I can reach the rig from the back to do/undo the bolt for tightening/releasing.

I had a piece of black Delrin (a.k.a. acetal resin) laying around which was a piece of cake to shape into its final form. I then used a hand drill attached to a vertical guide to drill the hole for the bolt. Accuracy is not of the greatest importance for that, I just had to be sure to go straight. Add an M5 x 70mm bolt (not very easy to find, I must admit) and an M5 nut, and this is what I ended up with.

The result is amazing in terms of usability, precision and, above all, time. I managed to shelve out one-third of the total work-time with great benefits for my family-time. Apologies for masking the engraved tags: I don’t want to spoil the surprise for our visitors at MRF18.

Dog tags in delrin mold.

The entire Fusion 360 project is published in the cloud but also available for download: I’m eager for comments and suggestions. The component assembly including the machine bed, spoil board, alignment bracket and tall alignment bracket is also available in the cloud.

Thanks so much for sharing, Roberto!


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