#0107 Split Key Ring SIÊU BỀN - Đáp ứng nhu cầu dùng hằng ngày!

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I was originally looking for a key ring that was 1) easy to use 2) easy to print and 3) robust enough for everyday use - but didn't find anything that met all three criteria, so I designed my own STRONG Split Key Ring.  As a natural progression of design optimization, I developed this EVEN STRONGER Split Key Ring.

Two clearances (0.18mm and 0.25mm) and 3 sizes are provided:

• The 0.18mm gap versions are for well calibrated printers - test results are based on these.
• Use the 0.25mm gap versions if the 0.18mm gap causes excessive gap welding for you.

1. Small, 2g of ABS- used for key rings.
   • Tested to failure:  94.1 lbs. [42.7 kg] 
2. Medium, 4g of ABS - used as central hub for other key rings, or for heavier uses
   • Tested to: 114.7 lbs. [52 kg] and did not break.  My force tester sounded an alarm  that it went over its force limit.
3. Large, 6g of ABS - any heavier duty uses you can think of!
   • Tested to: TBD* but expected to be >140 lbs. [>64kg]

*My force tester only goes up to 112 lbs. [500N or 51 kg] - I didn't want to ruin it so I haven't tested the Large size yet.

NOTE: the above numbers are for reference only, using Polymaker Polylite ABS.  Results from your printer settings and material choice may vary.

Why is this stronger?

When testing, I noticed that the split ring consistently failed at the dovetail first.  Once that feature “lets go” under tension, the rest of the ring breaks apart.  Naturally I wanted to see if I could make the dovetail “hold on” for longer which I achieved by simply making the end loops uneven, allowing the dovetail to “grip” more, which would withstand higher forces. The idea proved to be true, so now you have an EVEN STRONGER split key ring.

BONUSES: these rings are not only stronger, they are ALSO lighter (less material used) AND prints faster than the original version!

A comparison of strength vs. size:

This gives you some idea of the iterative testing involved:

If you are looking for a quicker clip-in / clip-out option, check out my various carabiners, starting with this one.

How it works:

1. The 4 locking features hidden between the inner and outer ring prevents the ring from deforming while under load - they add a lot of strength.
2. The 4 locking features also align the outer and inner rings together.
3. The dovetail feature keeps that end from opening up to prevent premature failure - earlier iterations failed quickly when that end opened up.

How to Open and Close the ring: (also see GIF video clip in the deck of pics)

Step 1: To open, slide the Dovetail in the Z direction to release it.

Step 2: Open up the ring like a “Slinky” toy as shown above.

Step 3: Slide the key (or any object that fits) through the Dovetail or Endtail.

Step 4: To close, collapse the Dovetail end together FIRST, then collapse the inner and outer rings together.

I've pull tested the rings and the results (if they are printed per the recommended settings) are below but your results may vary.  Tested with Polymaker ABS.

Other variations also available:

1. STRONG Split Key Ring
2. STRONG Round Split Key Ring

Recommendations:

1. Print in ABS/ASA/PC.
2. Place (paint on) the seam away from the dovetail area - on the inside surface of the inner ring.
3. 3 vertical walls, 5 top and 5 bottom layers, 20% infill.
4. Avoid PLA - because normal everyday use means it will eventually end up inside a hot car somewhere…heat does not play nice with PLA.
5. A slight bit of welding at the gaps are expected in some cases.  Just twist and bend the ring a few times to break the welds loose in the gaps.
6. Beware of using PETG - why?  PETG has a tendency to weld strongly to itself, so for the parts with only a 0.18mm gap between the inner and outer rings, you will have a harder time breaking the welds loose if your printer is not that well calibrated.  If you want to test your luck, give it a shot anyway! But you'll likely have more success printing with the 0.25mm clearance versions. 

DISCLAIMER: It should go without saying, but please use common sense - DO NOT use any of these rings to carry the weight of precious cargo, like kids, pets, expensive camera equipment, or adults, for that matter.  No guarantees are made on their performance. By printing this model, you take full responsibility for its uses.

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Happy Printing!