After a few rounds of prototyping I came up with something that I even tried making molds of and casting myself. Let's just say that worked, but only barely. I discovered that these initial attempts had a flaw - the kids would rotate the clicker so that it aligned with the sight bar when they took their bow down, thereby making it impossible to return the clicker to the exact spot next time they assembled it. Having a look at the Cartel Magnetic Clicker (Midas) the base has a unique shape, which I used to make an inset in the mount. This inset makes it impossible for the clicker to be rotated on the mount, so as long as the mount is in the same place on the sight extension, the clicker will always be in the same location.
This design works really well. It's also not terribly expensive when ordering from Shapeways. Shapeways uses SLS machines with nylon, and the print quality and tolerances are really great. The problem is, the cost is still a bit higher than I had wanted it to be. It's about $12 as of this writing (Dec. 2017) to get from Shapeways, plus shipping. Many have been ordered through Shapeways by myself and others over the past couple of years.
Fast forward to 2017. I needed three more of these and wanted to find a way to bring the cost down. Printing these on a more common FDM type 3D printer would make these considerably less expensive.
The design I came up with has portions that cannot be printed on a FDM 3D printer without support structures. Many people have access to these types of printers at schools or libraries or they may even own their own machine. The cost of printing something like this on a FDM machine would be a lot lower, so I did a little re-thinking.
By removing just a few parts and re-orienting the insets for the captive nuts (used for providing metal threads), I was able to make a modified version that can be printed on a FDM printer. In my area, the library has a Lulzbot Taz that you can order 3D prints from at very minimal cost. I didn't know for sure if it'd work, but I sent it off to be printed. It successfully printed* and cost a whopping $0.68! That's more like what I had originally hoped.
Here's a summary of the Shapeways printed version versus the Library FDM printed version,
Shapeways Version
- Very high print quality
- Very good tolerances
- Wide variety of colors
- Lightweight material
- Reasonable turnaround time
- Unfortunately, more expensive than I had wished, but not outrageously expensive.
Library FDM Printed Version
- Tolerable print quality, but not great. It's usable, but definitely visible layering and some artifacts are always present. In some cases, the first few layers printed spread out horizontally and are thinner, resulting in deformations that must be dealt with using sandpaper and sharp blade carving.
- The material is much harder than the nylon used by Shapeways' SLS machines.
- The cost is very, very low.
- Turnaround time can be slow. I've had it take 3 weeks on parts before, but hey, it's really cheap!
I find that the FDM prints are usable, provided you don't mind the print quality and doing some cleanup to deal with the distortions. The Shapeways SLS prints are of vastly better quality, but I think the plastic used in the Library's FDM machine (PLA plastic) might be a little stronger.
So here's the interesting part.
While these have been available to order from Shapeways for some time, I've decided to make the STL file I used for the FDM printer available to download. If you have access to a FDM printer and want to try one, the link to the STL file is below. The units are MM.
While these have been available to order from Shapeways for some time, I've decided to make the STL file I used for the FDM printer available to download. If you have access to a FDM printer and want to try one, the link to the STL file is below. The units are MM.
Licensing
This means you can make them, modify the design, and share the modified design with others, but you cannot use it for commercial purposes (sell them).
Choices
So, if you want to try one of these, you have two choices now:
- Order one from Shapeways if you want the much higher print quality
- Print one yourself using the STL file if you don't mind the look and possible distortions.
As I said, I find that the FDM print has vastly inferior print quality but it's still totally usable and is very, very, very cheap. You decide what's important to you.
Here are some photos to help you decide. The Library FDM print is on the left, and the Shapeways SLS print is on the right.
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| FDM Printed Mount (left) |
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| Shapeways SLS Print (right) |
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| Shapeways SLS Print (right) |
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| FDM Printed Mount (left) |
ASSEMBLY INSTRUCTIONS
You will need: 2 #6-32 nuts, 1 #6-32 by 3/8" machine screw, and 1 #6-32 by 2" machine screw.
The nuts go into captive insets on the back of the lower adapter. You may choose to put a dab of super glue in the inset prior to inserting the nuts to hold them in place.
The clicker goes in the inset on the front of the lower adapter. Remove the rubber washer if you have one before putting the clicker into its inset. Use a short #6-32 screw to hold the clicker in place. If you need to, add washers so that the screw doesn't stick out the back so far as to interfere with the 2" bolt.
Insert the 2" bolt through both vertical holes in both pieces. Attach the mount as seen in the photos. Don't over-tighten the mount so much that it crushes the mount or your sight! Just tighten it firmly so it won't move.
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