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

Snowflake 04-06-2017 07:25 PM

Quote:

Originally Posted by YvesCH (Post 1163661)
You could also make a hexagonal opening in the inside to put a nut in there. then the nut would be pushed against the part when you tighten it to the Plunger. attached a quick sketch :)

Yep, already thought of that, and am working on it. I was even thinking about having the printer stop part way
through the print, dropping the nut in, and then printing in over top of it... But then you could never change it
if you cross-threaded it by accident... :P

With the slot for the nut like this (below) once the set screw is in place neither the set screw nor the nut can
fall out as long as the screw is in the nut. Just need to get some nuts and set screws in-hand and then I can
final-size the features and print the next iteration.

DaleB 04-06-2017 10:49 PM

Sigh... you guys are going to cost me money yet. Every time I talk myself out of buying a 3D printer you go and post stuff like this.

Steve Melton 04-07-2017 03:13 PM

ABS creep testing
 
the recommended torque on the set screw for this fairing = 1/4 turn but what happens if it is turned four times that amount? answer, not much. part remained secure and tight. no reduction of torque on set screw ( by feel ). plastic insert nut remained secure. no visible damage. no change in part appearance pre and post test. part returned to original dimensions. there was some visible set screw contact marks on the steel.

1.5 week creep test at room temperature with a full turn of the set screw after contact. mounted on steel conduit. a fresh fairing, not fuel soaked.
















Steve Melton 04-07-2017 03:21 PM

VC-3 thread lock pull test
 
as expected good results for insert pull test using VC-3 thread lock. this is the same thread lock used for my screws on the plexiglass. do not appear to affect ABS plastic and has excellent adhesion. to date I have not used any thread lock for flight testing this fairing ( a couple weeks ) and have had no loosening but it may be beneficial for long term install.

two pull tests





Steve Melton 04-07-2017 03:28 PM

more fuel testing
 
this fairing is going on three weeks of fuel soaking and pull testing to failure of the .032 wire on the insert ( 5 tests ). it does have some clamp marks from the vise but no chemical affects. it has been placed on the torture pipe for creep testing. it previously had a week of having a 35 lb load hung on the insert with no adverse affects. so far it is holding up fine.




lr172 04-07-2017 04:02 PM

Steve,

Any chance of you sharing your design/file for these fairings? I was going to make some of these from composite, but I imagine that I can find a local friend with a 3D printer.

Larry

Steve Melton 04-07-2017 04:30 PM

if you need one send me an email to: se melton 500 @ g mail .com

my yahoo account doesn't allow .stl files to be sent for some reason.

I've sent these around to scores all over the world (which is cool). you can have them printed anywhere, even UPS.

- ABS printed fairing, mine are printed as such: layer thickness = .2mm, 5 bottom layers, 4 side layers, 4 top layers, 35% infill

the material costs for a pair of these = $3. that includes printed fairing, nut inserts and set screws.

PilotjohnS 04-07-2017 04:44 PM

science
 
What great science. I cant believe you went to all this trouble. Shows everyone your love for aviation.

Now the next challenge is to model these in CFD and see how many knots they are worth at 8K and 180 kts? Anybody up for the challenge? or maybe in flight comparison tests before and after. I am really curious if they are noticeable. Even 2 knots is worth it.

keep up the good science.

Steve Melton 04-07-2017 04:50 PM

this is called a "Houch" for Walt Houchens. an incremental improvement.

lr172 04-07-2017 11:12 PM

Quote:

Originally Posted by Steve Melton (Post 1163965)
if you need one send me an email to: se melton 500 @ g mail .com

my yahoo account doesn't allow .stl files to be sent for some reason.

I've sent these around to scores all over the world (which is cool). you can have them printed anywhere, even UPS.

- ABS printed fairing, mine are printed as such: layer thickness = .2mm, 5 bottom layers, 4 side layers, 4 top layers, 35% infill

the material costs for a pair of these = $3. that includes printed fairing, nut inserts and set screws.

Thanks Steve. I'll send an email. Are the above details that my friend or firm that I pick will need to print these?

Larry


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