11 July, 2014

Ti2 Sentinel - I Did It!

Original post
Well, I couldn't resist any more and got a Sentinel, even though I still haven't decided what I'm going to use it for. Advice: if you're thinking of buying one, you should do it soon, because it's not a commercial product, they're not being produced anymore and once the stock is sold out, it's gone. If you don't mind a knock-off, the original post above has where you can find one on eBay.

It came in this messy packaging. Inside was this simple telescopic square plastic tube.
I guess using telescopic packaging meant they only needed 3 sizes, and all lengths of each size could use the same packaging. I bought the S8M, which is the middle one here:

It's wonderfully smooth and solid. Surprisingly heavy, though.
I love how you can see the manufacturing artifacts. Like the tips of the notches in the picture above are a lighter colour. I think that's because the tumbling media couldn't get to that part.
Similarly, the line where the loop joins the top of the cap above is also shinier and lighter in colour, probably because the tumbling media couldn't reach it either. Speaking of tumbling, it seems to have darkened the titanium surface. Raw titanium is actually a lighter colour. I thought tumbling could only affect the texture, not the colour of a surface.

The cap actually secures in between 2 to 2.5 turns, which makes it very fast to open and close.
I understand Mike Bond paid special attention to the threads. They're square and Higbee start. I just wonder if they could be dual-start, so it would be easier to find a starting point. The o-ring part enters easily. It actually feels a bit too smooth, like the o-ring might be too small, but they tested it and found it to be waterproof.

This is the cap inside the barrel:
And the cap on its own:
Now, the main thing I don't like about this is there's a lot of wasted space:
  • Firstly, the whole cache is 6" long but the usable space inside is barely 3". From the technical diagram the length inside should be 3.742", but the caps are so thick, the usable space is only about 2×1.375". I can't even fit in a normal plaster without sticking part of it into a cap.
  • The caps' walls are very thick. From the picture of the cap inside the barrel, you can see it narrows the usable diameter considerably.
  • Like I said, it's heavier than expected, and I noticed the weight comes mainly from the caps. The barrel itself is actually quite light.
  • The design seems to have prioritised strength over portability, but I think there's no point making the caps that much thicker than the barrel wall.
  • I bought this because the dual-ended design meant things wouldn't get stuck inside, but the caps are so deep and narrow that things can still get stuck in them. They're actually deeper than my aluminium capsule below.

It's really sad that hardly any of the Singapore coins fit in it, much less so the Australian coins. I used it as a first-aid kit at first, but like I said even plasters don't fit easily, so I switched to an M&M's tube.

I like:
  • The streamlined outside - almost the whole tube is the same diameter as the barrel. It can be used as a rolling pin. Although this means the caps fit inside and take up space.
  • Square threads!
  • The dimple in the bottom cap allows it to stand.

If I were to redesign this, I would:
  • Make the cap walls thinner - no more than half as thick.
  • Make the caps shorter - no longer than the current length of the bottom cap
  • Make the threads shorter, if possible. Maybe make them thinner. Double start.
  • Have less "stages" in the hollowed out caps. Maybe just one section. No point making so many sections if they're going to be narrow and have things stuck in them.
  • Flatten the top and bottom so it can stand on either end.
Hmm, I think I can do some of these with a lathe?

So, really solid and secure, but I think the design could have been more space-optimised.

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