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  #41  
Old 12-16-2016, 10:13 AM
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RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
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Quote:
Originally Posted by N941WR View Post
I just went with the Dynon senders. I was an early beta tester for them, long before they started selling them. I just replaced one a few months back, after 9 years and 750 hours. Buying them is much cheaper and easier then designing and making them.

The only issue is that the Van's BNC connector really isn't designed for a fuel tank. I really gooped on the proseal on the inside to keep them from leaking and haven't had an issue. Some of the early builders reported fuel leaking out of the center of the connector, and I was so worried that I made sure that wouldn't happen to me.

The senders are spot on and putting them in was a great choice! These senders are so accurate that if my EFIS tells me I need 10.2 gallons, it will take 10.2 gallons.



Those are very nice!
I had a bit of trouble with the Dynon senders, because the useful range of voltage was so narrow. The system was quite accurate for fuller or nearly empty tanks, but terrible in the mid-range. I ended up swapping them out for the Princeton C-to-V senders, which you can set up to use the full 0-5V for any tank size, and they work great...
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  #42  
Old 12-16-2016, 10:57 AM
nilberg nilberg is offline
 
Join Date: Dec 2012
Location: Katy, TX
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Quote:
Originally Posted by amaris View Post
Hi Bjorn,
They're great. Do you have any specs or drawings you could share that I could send to my FIL?
Thanks.
Allen
I do not have the measurement or drawing and now they are sealed inside the tanks.... I did it more or less 'freehand' anyways using a cheapo Harbor Freight mini-lathe.

I did it this way as I didn't believe the plastic tubing used in the Van's version would hold up over the years, ending up with a short between the plate and rib. This solution use a solid block of delrin as isolation.

Here's how (from memory and pictures) I made to two parts ('Rib insert' in the middle, and the 'Donut' shown on the left in the first picture in my log).

Both used a 1" delrin rod as raw material.

The dimensions were selected so I could use the screw, washers and nutplates described in the OP07 (AN509-8R14, A3135-017-24A, K1000-08).

Rib insert:
- Cut a piece 5/8" or longer (it's easier to cut back/sand later...)
- Drill a hole all the way for a AN509-8R14 screw (using the lathe is easiest).
- Reduce the diameter of one end to about 1/2", keeping about 3/8" as 1"
(The reduced diameter is the one going into the rib, the 3/8" width of 1" diameter, represent the 3 stacked rings used in Van's kit)

Donut:
Take a piece of 1" drill a 1/2" (using the lathe) hole all the way through.
Cut it into 3/16" thick slices. Lathe is best but waste material, I has plenty so I didn't care.

Now use some scrap with the same thickness as rib.
Drill a 1/2 hole in the rib-scrap
Sand the 'Rib insert' slightly to fit into the 1/2 hole. Alternatively scrape off a few 1/1000 in the lathe.
Insert the ehhh.. the 'Insert'. The donut fits around the insert (1/2" end), grabbing the rib-scrap between them.
I found it best to have the donut flush with the insert. Too thick and the washer gets deformed when tightening the screw. If you lack grabbing power, sand some off the insert. Finally countersink for the washer/screw.
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  #43  
Old 04-16-2017, 07:26 PM
Andy who? Andy who? is offline
 
Join Date: Jun 2013
Location: Royal Oak, MI
Posts: 26
Default Washer material

I'm planning on putting the no longer sold capacitive system in my tanks but need some expert advice on the materials for the washers. The plans that I have seen call out umhw or something like that. I'm not exactly sure I know what that material is even after a little google action. My first thought is just to turn a two piece setup out of Delrin rod instead of multiple washers and tubing. The aircraft spruce catalog mentions delrin is resistant to fuel. I just want to make sure I don't have a material slowly dissolving in my tanks. Any material experts that can lend some advice? Thanks in advance.
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  #44  
Old 04-16-2017, 08:54 PM
rapid_ascent rapid_ascent is offline
 
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Location: Dublin, CA
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Not an expert. I think Delrin is a copyrighted name so it can't be used by everyone selling the same material. UHMW I think is the generic name for the same thing.
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  #45  
Old 04-16-2017, 11:31 PM
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DrillBit DrillBit is offline
 
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UHMW is ultra-high molecular weight polyethylene, and I believe it is the material Vans supplied in the capacitance sender kit in the form of thick washers stacked up to separate the cap plates from the tank ribs.

Delrin is another kind of plastic, a polyacetal, if anyone is chemistry curious.... Delrin machines very nicely whereas UHMW seems to be really fussy if the tooling isn't sharp. Fuel resistance to gasoline and even gasoline/ethanol is good according to the manufacturer: http://www2.dupont.com/Plastics/en_U...ign/DELDGe.pdf
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Last edited by DrillBit : 04-16-2017 at 11:41 PM.
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  #46  
Old 04-17-2017, 10:12 PM
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shadowbrush shadowbrush is offline
 
Join Date: Mar 2013
Location: KUAO
Posts: 87
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Does Dynon offer a converter to use capacitive senders with their D180, anyone know?

Thanks,

Holger
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