Open drag chain optimized for printing

I tested a lot of drag chains from a lot of people but I was never fully satisfied with the designs. So I made my own design with a focus on the hinge section. If you want to read more about the design process see below.

Key features:

• No overhang on the hinge bolt, achieved with chamfered bottom
• Chain is closed with a piece of 1,75mm filament
• No clean up work needed after print
• Chain is smooth after printing, no wearing in needed. 

Print instructions:

• No supports
• 0,2mm layer for better surface and smooth operation

How to use:

1. Print the elements you need.
2. Squeeze the female section of the links firmly and snap it in to the male section.
3. Cut 1,75mm filament pieces
4. Insert filament pieces in the chain to close it.

Limitations: The tolerances on the chain are a little big wider to allow smooth operation. This means this chain tends to sack/hang when in midair depending on the tolerances on your machine

Provided dimensions

Currently I can provide the dimensions below. If you need a different size, let me know, maybe I have time to create a version for you.

• 19,5 mm drag chain.
  • 19,5 x 13,4 mm outer dimensions
  • 9,75 x 10,9 mm inner dimensions
• 22,5 mm drag chain.
  • 22,5 x 13,4 mm outer dimensions
  • 12,75 x 10,9 mm inner dimensions
• 29,5 mm (to be released)

Provided files

For each dimension four files/types are provided.

• chain_link_xx.x                         (normal chain link)
• chain_link_xx.x_fixie                (normal chain link with hole to fixate it)
• chain_link_xx.x_end_female   (end piece female connection)
• chain_link_xx.x_end_male      (end piece male connection)

Source files in the Alibre Atom format is available but the website does not allow the upload. If you need it send me a message.

Design approach

 My major critics were:

• The male part of the hinges has to much over hang which can lead to unclean prints.
• The tolerances where to tight and the chain needed to be worn in to get smooth. But it was never really smooth.
• A lot of chains have small custom clips to close them which you have to print. 

So this chain is designed with the following principles in mind:

• Optimize the hinge section to avoid overhang and sagging during the print.
• No custom clip to close the chain needed.
• Chain is smooth directly after print.

To achieve my current design I went through roughly 10 revisions. Where the most work went into the optimization of the hing section. The chains I tested or saw online normally use a cylinder as the hinge, some chamfer this bolt, too. But in the end these bolts are a cylinder, sticking out a wall with 90°, thus creating an overhang. As a result of this I encountered the problem, due to my fast printing of small parts, that these cylinders tend to sack due to missing cooling time. So I wanted my design to have no overhang in this area.

For the sake of completeness another approach could have been to tune the slicer settings, with the result slowing down the printer. But because I needed a lot of chain (~ 1800 mm), I wanted to avoid increasing the incremental print time of each link.

What I came up with is a cylinder that is supported from the bottom by a chamfer which only covers a part of the circumference. This was an easy solution for the bolt area but made the joint/female section on the chain more challenging. Because the support chamfer of the bolt rotates 45° in the joint, the joint had to be cut free on the areas of the movement. This needed a ridiculously high number of constraint in the sketched but worked out nicely in the end.

There is still room for improvement on this design but currently it full fills all my needs and I used the chains on my 3d printer and an MPCNC I built. Possible improvements could be:

• Tighten the tolerances to reduce hanging/sagging of the chain without sacrificing the smoothness “without clean up”.

I would be happy to see some of your makes posted :)

Source files in the Alibre Atom format is available but the website does not allow the upload. If you need it send me a message.