Avian’s Blog

A couple of months ago I was writing about 3D-printable replacement drive rails for my Chieftec PC enclosure. Back then I've designed and printed some parts that were functional enough to use for mounting a new set of 3.5" hard drives into my computer and I have been using them since. However I was bothered by the fact that the new rails required two parts to be glued together. I've now updated the design so that the latch snaps onto the base part of the rail. It's purely a friction fit and hence assembly of the new rails doesn't require any glue.

Having to glue together 12 rails for the complete set of drives was bothersome. However the main reason why I wanted to avoid using glue was because I couldn't find one that would bond well to the PETG plastic that my parts were printed from. Every glue I tried produced a very weak bond that soon fell apart. I tried to modify the design so that it minimized the stress on the bond, but that didn't really work. I've heard that this specific glue produces good results with the filament I used, however I could not find a shop that would have it in stock.

Coming up with a design where the latch just snaps into the base required two more round trips between CAD and the 3D printer. I find that the most troublesome part of any 3D printed design is always the place where two parts need to slide or engage with each other. Each printer has slightly different tolerances. Often this differs even between prints on the same printer. It's hard to find the exact amount of space you need to leave in the STL files between surfaces. Too much and the parts fit too loosely, too little and the parts don't fit together or break when they are assembled.

I've written in one of my earlier posts that I was also worried about the 3D printed rails getting soft when in contact with the warm hard drives. I've been using them now for close to 2 months and so far I haven't seen any signs of deformation due to heat. On the other hand, the winter has barely ended. I expect the drives to reach higher temperatures in summer.

I've put the new designs in place of the old ones. There's now also a README file there that has some condensed instructions for printing.

In the end, this took way more time than I anticipated. 3D printers are fun and convenient, but getting to a design that works well can still be very time consuming. In this particular case it was also mostly due to me being stubborn and wanting a replacement that functions more or less exactly like the original. It turned out that even without the latch the rails function quite well. There are sheet metal springs in the case that grab onto the holes for the screws on the rails. At least in my enclosure, these springs alone provide enough friction that drives are held pretty well even without the additional security of the latch action on the rail itself.