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-   -   a couple printed ideas (https://vansairforce.net/community/showthread.php?t=147771)

Steve Melton 04-08-2017 05:21 AM

If you print with finer resolution tell them to adjust the settings to achieve roughly the same part thickness. mine are printed using a .5mm nozzle that extrudes .6mm.

there is enough margin in this design that just about any printed fairing will be fine.

humptybump 04-08-2017 05:36 AM

Steve makes a good point regarding print/slicer settings. They have a strong correlation with nozzle size and layer thickness and material.

While I often use two perimeter walls and two (or three) top/bottom layers on a Lulzbot TAZ printer, I use four perimeters and four top/bottom layers on a Delta Kossel printer.

lstinthot 04-08-2017 05:51 AM

I'm not sure what software you are using but EAA members are able to download Solidworks for free. Then there is a website to upload your designs to share, https://grabcad.com/library/software...cent&query=Eaa.

I'm just beginning to start using the software. It's not too hard to learn.

Snowflake 04-09-2017 12:05 AM

Why switch to ABS? Is PLA sensitive to fuel?

Steve Melton 04-09-2017 04:21 PM

Maybe a glow in the dark ABS for under the wing?

Steve Melton 04-19-2017 04:14 AM

more testing
 
fuel soaked fairing, another week on the torture pipe. no signs of relaxation.



another fairing soaked three weeks in avgas. VC-3 thread lock turned pink but otherwise seemed secure. turned set screw one full turn on the torture pipe. no signs of weakness.



attempting to drive this fairing to failure. fuel soaked one week. two turns of the set screw. significant load and twist in the allen wrench. no immediate failure. will leave it on the pipe for a couple weeks.





My photo of a Grand Canyon California Condor last week, ~ 10ft wing span. It was making fwd progress in a 40 kt headwind without flapping. Check out those wing tips.


Snowflake 04-19-2017 02:20 PM

FYI - On Friday I placed a couple of test pieces of PLA-printed parts into an avgas bath to check durability. No degradation was visible by Saturday evening, will check again this weekend to see how they're doing. So far, i'd say PLA parts are acceptable for the bottom of the wing.

RV7A Flyer 04-19-2017 02:32 PM

Are y'all expecting your fuel drains to leak continuously?

If they don't leak like a sieve, isn't the drain fairing *dry* all the time, other than on occasional drop of fuel when you check it during pre-flight?

Weeks on end in avgas soak test seems, um, overkill to me...

Steve Melton 04-19-2017 02:38 PM

well yeah, now is the time to kill them if we can.

Saville 04-20-2017 06:20 AM

Quote:

Originally Posted by RV7A Flyer (Post 1166905)
Are y'all expecting your fuel drains to leak continuously?

If they don't leak like a sieve, isn't the drain fairing *dry* all the time, other than on occasional drop of fuel when you check it during pre-flight?

Weeks on end in avgas soak test seems, um, overkill to me...

No harm in doing the test.

Snowflake 04-20-2017 08:03 AM

Quote:

Originally Posted by RV7A Flyer (Post 1166905)
Weeks on end in avgas soak test seems, um, overkill to me...

Well, that's exactly the point of a stress test. It exposes the system to worst-case scenarios and sees what happens.

Someone mentioned earlier that the PLA material that is easiest to work with on the 3D printers might be a bad choice for fuel fairings as it's sensitive to almost everything. My first test was fuel, next will be sun exposure for a week (as soon as I find somewhere with a week of sun). The sun test will be worst-case, too, as these will live under the wing in the shade. Even if I have a pitch- or roll-control problem occasionally I suspect the cumulative time spent inverted isn't climbing that fast...

Of course, in this case, if the material did break down I suspect my only risk would be to lose the fairing... And with gravity and downwash I suspect it wouldn't hit any other part of the airplane while departing (unless my flaps were down, I guess). So it's all very low risk to start with.

RV7A Flyer 04-20-2017 10:26 AM

Quote:

Originally Posted by Snowflake (Post 1167048)
Well, that's exactly the point of a stress test. It exposes the system to worst-case scenarios and sees what happens.

Someone mentioned earlier that the PLA material that is easiest to work with on the 3D printers might be a bad choice for fuel fairings as it's sensitive to almost everything. My first test was fuel, next will be sun exposure for a week (as soon as I find somewhere with a week of sun). The sun test will be worst-case, too, as these will live under the wing in the shade. Even if I have a pitch- or roll-control problem occasionally I suspect the cumulative time spent inverted isn't climbing that fast...

Of course, in this case, if the material did break down I suspect my only risk would be to lose the fairing... And with gravity and downwash I suspect it wouldn't hit any other part of the airplane while departing (unless my flaps were down, I guess). So it's all very low risk to start with.

That was kind of my point...although I can see the "fun" part of subjecting these things to all of these tests, I'd say you satisfied them within a few hours to a day of soaking the thing in gas.

Make a couple, put them on and go fly and see how it holds up. Part of the advantage of 3D printing is the ability to rapidly prototype parts, test them, subject them to field conditions, and update the design accordingly and re-manufacture.

Instead of weeks of unnecessary testing and waiting for the results, you could have saved a fraction of a gallon of gas and gone 1/10th of a knot faster this whole time! :) (J/K...I have the JD Air Parts fairings on my fuel drains AND my vents!)

Snowflake 04-21-2017 07:42 AM

Quote:

Originally Posted by RV7A Flyer (Post 1167084)
That was kind of my point...although I can see the "fun" part of subjecting these things to all of these tests, I'd say you satisfied them within a few hours to a day of soaking the thing in gas.

Oh, I agree. But after two days, I knew I wouldn't get back to the airport for a week and didn't have anything else to do with the test piece... So I just left it sitting in the gas.

Quote:

Make a couple, put them on and go fly and see how it holds up. Part of the advantage of 3D printing is the ability to rapidly prototype parts, test them, subject them to field conditions, and update the design accordingly and re-manufacture.
As it turns out, the first ones I made don't fit well because the hole that matches the flange is *just* a little too small, and the hole for the boss that the set screw binds on is way too big. So tightening the set screw pulls the whole thing off-center and it doesn't fit the wing anymore.

I've already modified the design and am now just waiting for time on the printer to make more... One of the downsides of using downtime on the printer at work is that you have to wait for downtime... But that issue will be fixed in a month or so... I ordered my own printer... :)

Steve Melton 04-23-2017 05:58 PM

brass to alum galvanic corrosion?
 
a brass tube (C260) section fits nicely into this fuel drain fairing and protects the alum drain boss from the set screw turning and provides a secure fit but is it a source of galvanic corrosion?










Snowflake 04-24-2017 07:52 AM

Steve, what about using a nylon-tipped setscrew if you're concerned about marking the boss on the tank?

I came across another issue last weekend as well... Some builders put the flange on the inside of the tank. That puts the boss too close to the wing to get a set screw to bind on.

Bill Boyd 04-24-2017 08:43 AM

Quote:

Originally Posted by Snowflake (Post 1167953)
Steve, what about using a nylon-tipped setscrew if you're concerned about marking the boss on the tank?

I came across another issue last weekend as well... Some builders put the flange on the inside of the tank. That puts the boss too close to the wing to get a set screw to bind on.

For everything else, there's GOOP / E-6000 adhesive ;)

What's the compatibility of the plastic with this type of stick-um?

Steve Melton 04-24-2017 10:05 AM

Quote:

Originally Posted by Snowflake (Post 1167953)
Steve, what about using a nylon-tipped setscrew if you're concerned about marking the boss on the tank?

I came across another issue last weekend as well... Some builders put the flange on the inside of the tank. That puts the boss too close to the wing to get a set screw to bind on.

I tried the nylon tipped set screw but didn't like it. It's too slick. Need some friction to achieve a secure hold. Why would the sump boss be installed in the inside of the tank and allow trapping water? That's not in the direction of goodness.

One time I needed to drain my tank away from the home base because of low octane fuel contamination. It was nice to be able to remove the JD fairing easily. I wanted the same with these plastic fairings. So far I have not used any adhesive on the fairing and they have been secure.

The brass sleeve prevents a set screw mark on the alum boss. From my research, the galvanic corrosion of yellow brass C260 and 6060-T6 should be minimal. If you don't mind a little set screw mark on the drain boss then the original Rev 1 fairing is the way to go. Otherwise use the Rev 2 fairing with the brass sleeve.

The torture test on the pipe is on going. One with two turns and one with three turns after contact. There have been no failures. I am amazed that the insert nut can hold the load.

Steve Melton 04-24-2017 10:10 AM

Quote:

Originally Posted by Bill Boyd (Post 1167975)
For everything else, there's GOOP / E-6000 adhesive ;)

What's the compatibility of the plastic with this type of stick-um?

I'm sure the GOOP would provide a secure bond since ABS plastic is used for a lot of trim on cars. It may be so good that you would need to chisel it off. I would use VC-3 sparingly if choosing an adhesive for these since it remains relatively soft in case you needed to remove the fairing to drain the tank. So far I have not used any adhesive.

Berchmans 04-24-2017 04:52 PM

Dis-similar metals
 
Why not use a piece of Aluminium tubing?

Steve Melton 04-24-2017 05:10 PM

Quote:

Originally Posted by Berchmans (Post 1168122)
Why not use a piece of Aluminium tubing?

yep, I looked but the right size was only avail in brass. help me find similar in alum.

Brass C260 Seamless Round Tubing, 13/16" OD,0.755"ID, 0.029" Wall

Captain Avgas 04-24-2017 09:46 PM

Quote:

Originally Posted by Steve Melton (Post 1167829)
a brass tube (C260) section fits nicely into this fuel drain fairing and protects the alum drain boss from the set screw turning and provides a secure fit but is it a source of galvanic corrosion?

Hi Steve, the 3D printing thing is really fascinating and I'm sure many VansAirforce members are watching the developments in this area with great interest.

In answer to your question I think that there would be considerable galvanic reaction between the brass tube and the aluminium fuel drain flange. These two metals are a long way apart in the Galvanic Series. I recommend you use an aluminium tube instead of the brass.

AlexPeterson 04-25-2017 07:37 AM

The drain valve is brass, and the flange into which it threads is aluminum, so these two materials are already in intimate contact on every RV. For galvanic corrosion to occur, it needs the presence of an electrolyte, such as contaminated water (salt, dirt, etc.). And, it needs to be wet a cumulatively long time for problems to happen. Additionally, isn't the aluminum boss, onto which the split brass tube clamps, typically painted?

Nice work on the fairing!

Snowflake 04-25-2017 07:49 AM

Quote:

Originally Posted by Steve Melton (Post 1167998)
Why would the sump boss be installed in the inside of the tank and allow trapping water? That's not in the direction of goodness.

That was my thought as well. Still, one less potential customer for the fairing, unless it's sold with adhesive rather than a screw mount.

Quote:

One time I needed to drain my tank away from the home base because of low octane fuel contamination. It was nice to be able to remove the JD fairing easily. I wanted the same with these plastic fairings. So far I have not used any adhesive on the fairing and they have been secure.
I wouldn't use a liquid-style adhesive, but i've been thinking one of the 3M "command adhesive" style that can be removed by stretching it might work well. Either that or 3M double-sided body molding tape like they use to hold protective door strips and manufacturer's emblems on cars.

Quote:

yep, I looked but the right size was only avail in brass. help me find similar in alum.
Wouldn't a shorter strip of flat aluminium bent to fit work just as well, say half an inch long or so by whatever height you need? You can model a recess for it in the plastic. You could even model a couple of slots to fold the ends into as well, so it would be retained during installation.

Captain Avgas 04-25-2017 10:26 AM

Quote:

Originally Posted by AlexPeterson (Post 1168306)
The drain valve is brass, and the flange into which it threads is aluminum, so these two materials are already in intimate contact on every RV.

The fuel drain valves supplied by Vans are cad plated steel. At least mine were.

AlexPeterson 04-25-2017 11:57 AM

Quote:

Originally Posted by Captain Avgas (Post 1168365)
The fuel drain valves supplied by Vans are cad plated steel. At least mine were.

Ah, yes, you are correct.

Steve Melton 04-25-2017 07:10 PM

I'm going to find a sleeve in alum.

RV-4 04-25-2017 08:34 PM

FUEL DRAIN FAIRINGS
 
Hi Steve

Will it be possible to have a copy of your file ( specially the one you used for your friend's RV-4 )??

''I did a check fit on a neighbor's RV-4 that has a significant proseal build up around the flange to wing skin and the fairing would not fit flush. I will make a custom enlarged flange recess area for his. ''

Thanks

Bruno
rv4@videotron.ca

Steve Melton 04-26-2017 05:16 AM

Quote:

Originally Posted by RV-4 (Post 1168527)
Hi Steve

Will it be possible to have a copy of your file ( specially the one you used for your friend's RV-4 )??

''I did a check fit on a neighbor's RV-4 that has a significant proseal build up around the flange to wing skin and the fairing would not fit flush. I will make a custom enlarged flange recess area for his. ''

Thanks

Bruno
rv4@videotron.ca

Bruno, I gave my neighbor an oversized fairing for a fit check but I don't think he ever got around to checking it because he has been busy. I sent you a copy of the both the regular and oversized fairing. The oversized fairing should allow for the proseal buildup. Blue skies. Steve

jthocker 04-26-2017 04:39 PM

Quote:

Originally Posted by Steve Melton (Post 1168569)
Bruno, I gave my neighbor an oversized fairing for a fit check but I don't think he ever got around to checking it because he has been busy. I sent you a copy of the both the regular and oversized fairing. The oversized fairing should allow for the proseal buildup. Blue skies. Steve

Is that me?

Steve Melton 04-26-2017 06:07 PM

nope, that's my RV4 neighbor. your bullet nose test print has started as of 30 minutes ago. modeling effort in Solidworks, 5 minutes.




not too bad. this test was to understand if this 1mm thick bullet nose would print without any internal support. it's workable. this piece cost = $0.57 plastic. but will they withstand 200 mph?




9.5" tall x 3.5" diameter x 1mm thick. no internal support. ABS material.


Steve Melton 04-30-2017 06:35 PM

alum sleeve fuel drain fairing
 
thicker than the bronze sleeve but still workable. no threat from galvanic corrosion.




Steve Melton 05-06-2017 08:12 PM

it's not round any more
 
the steel conduit deformed. the plastic fairing did not. two weeks on the torture pipe. the plastic fairing is still in good shape.











I couldn't believe it so I tried again.







this concludes my testing.

home depot conduit is weak. do not use it for any structural parts on your aircraft. :)

Steve Melton 05-28-2017 05:03 PM

in your face lighting mount - RV8
 
another 3D printed idea, ABS plastic.




paint prep




lights shift upwards 0.125 inch after this fit check


Saville 05-28-2017 07:05 PM

If you are looking for ideas - how about a holder for a canopy bow mirror?

humptybump 05-29-2017 04:40 AM

If individuals want 3D prints to not look like 3D prints, then "finishing" is a good option. It's pretty easy and the results can be impressive.

ABS stands up well to the process of sanding the raw print. Then filler primer followed by sanding. Finish paint, sanding, buff, and polish. (Yes, DanH's tutorials on cut&buff work here too).

non aviation related photo for reference only ...


madhun 05-29-2017 05:41 AM

Forgive me if you've already tried this but have you renamed the file to filename.doc and tried sending it, would just need to be renamed at the recipient end.

JR threadlock should be ok on ABS as would Tamiya if you don't have any luck!

Steve Melton 05-29-2017 06:07 PM

Quote:

Originally Posted by Saville (Post 1176203)
If you are looking for ideas - how about a holder for a canopy bow mirror?

which mirror?

Saville 05-29-2017 07:10 PM

Quote:

Originally Posted by Steve Melton (Post 1176478)
which mirror?

Onces I cut out from a sheet of acrylic mirror. If you like I can send you a form to use for the mirror shape.

Steve Melton 05-29-2017 07:19 PM

Quote:

Originally Posted by Saville (Post 1176489)
Onces I cut out from a sheet of acrylic mirror. If you like I can send you a form to use for the mirror shape.

OK, let's give it a go to see if it will work. I'll send you a PM.

Steve Melton 06-04-2017 03:30 PM

RV8 mirror housing
 
idea #1







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