D420 assembly tool for $90? Not!

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rsingler

Scuba Instructor, Tinkerer in Brass
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Location
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The D420 CAD video shows the use of the Flow Vane Face Spanner PN 43.420.012 in screwing the valve assembly into the precise position necessary to complete service.
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The Venturi sleeve (flow vane) needs to be in the correct position, and the flow vane ring needs to be correctly aligned to add the washer and Pre-dive switch. So of course I ordered one!
It comes in, and whaaaat!?? Ninety dollars? Well, I want to do this right. So...okay.

So I get home, and this is what my $90 bought.
20200709_194318.jpg

You gotta be kidding me, right?

In the interest of DIY'ers everywhere, here is an $8 alternative.
To start with, the tool is basically a cylinder with two notches, with a handle that tells you you've aligned the flow vane ring properly. The cylinder is 29mm ID and 36mm OD. The handle is aligned with two 5mm notches. That's it.
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But when you go to the hardware store, you discover that it is particularly difficult to find a cylinder of those dimensions. Here's a cheap compromise.
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A sink drain is too narrow, but the transition to the sink attachment point is just right! A copper 1 1/4" coupling is similarly sized. Both are $5-6. If you don't have a 1/4" dowel lying about, that's not very expensive.

For the plastic version, start by trimming off the sink connection, and carve two notches 5mm x 1.5mm diametrically opposite each other.
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Drill two 1/4" holes exactly in line with the notches (that part can be a little tricky - start with a tiny hole for centering).

Cut off the excess drain. Thread in the dowel, and boom! You're done.
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Regulator reassembly requires that when you screw in the valve assembly, you don't go until it stops, but instead stop when it's beginning to tighten, the big tooth of the flow vane (29) faces the mouthpiece and the two outer teeth of the flow vane ring (31) are at 12 o'clock and 6 o'clock.
20200710_183736.jpg

The handle tells you when you have the two outer teeth properly aligned.
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That allows you to drop the flow vane washer (32) in with the correct tab alignment.
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With the big tooth of the inner flow vane (29) facing the mouthpiece, the pre-dive switch (33) also fits easily.
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Then it's a simple matter of screwing down the flow vane plug (35) with a pin wrench and you're done!

This $6 tool makes it easy!
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Of course, one might ask, "Why bother in the first place, when I can do the whole thing without a special tool, and just use my pin wrench?"
20200710_191048.jpg

Well, if you're a little OCD, the handle does help with tooth alignment. And the project is simple and fun.

DIY!
 

Attachments

  • D420 Rev 7_19.pdf
    599.2 KB · Views: 123
Yay for DIY, stick it to the man. Adding this to the files, for when used D420s start showing up and get into my buy price range.
 
I'd also bet the 3D printer gurus can do them at a significant savings....
Well, if someone wants to do the design, the well of the tool is 15mm, though that is more than necessary to clear the hex adjuster. Maybe that allows the tool to be resurfaced and renotched after a wrench turner kills it.

Go for it!
 
I'd also bet the 3D printer gurus can do them at a significant savings....
Define savings, lol. I could probably make for about 50 cents in plastic, and an hour of print time. I'm a sucker for problem solving though, so if @rsingler pm's me the critical measurements, I'll probably bang out a design in the next few days!
Respectfully,
James
 
https://www.shearwater.com/products/teric/

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