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

Steve Melton 08-19-2019 07:00 PM

Kroger mirror max pitch and yaw
 
pushing the angles to what we can comfortably do = 33 pitch and 33 yaw. the eye angle is 24 deg for my install. if you wanted to maximize visibility to the left then 33-24 = 9 deg + 10 deg for the adjustable mirror = 19 left and -1 deg range for a 3333 mirror config. and you get a little more because the mirror is also convex. this would also yield more downward view since the pitch is 33. we have printed a 4545 config and it was fully functional but the surface was not as smooth as reduced angle prints.

a 2100 config yields a good range to the right and the tail is clearly visible without excessive view upwards.

it just depends on what one is looking for. it's nice to have options :)

this has been a fun project and I only built one model. the computer did the variations and stamped the config number. this is a good project for someone to try that wants some practice designing and printing and when you are flying with your buddy you can say, hey, I printed that bracket!





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we use this printed drill jig for the holes. what is truly amazing is that the measured distance variation from the side of the rail to edge of the hole in the final drilled part is within 0.002 inch. it does make me wonder if the tool was printed from nylon graphite could I reduce the variation to 0.001 inch. I think it's time to beef up the tool, switch to nylon graphite and go for 0.001 but the real goal in my mind is 0.0005 inch.


Snowflake 08-20-2019 08:34 AM

Quote:

Originally Posted by Steve Melton (Post 1367777)
we use this printed drill jig for the holes. what is truly amazing is that the measured distance variation from the side of the rail to edge of the hole in the final drilled part is within 0.002 inch. it does make me wonder if the tool was printed from nylon graphite could I reduce the variation to 0.001 inch. I think it's time to beef up the tool, switch to nylon graphite and go for 0.001 but the real goal in my mind is 0.0005 inch.

Steve, why not print the holes? They're just clearance for the locking screw, so even if they don't print perfectly round that shouldn't be a problem... Just print them a few thou larger to compensate?

Steve Melton 08-21-2019 09:00 PM

Quote:

Originally Posted by Snowflake (Post 1367904)
Steve, why not print the holes? They're just clearance for the locking screw, so even if they don't print perfectly round that shouldn't be a problem... Just print them a few thou larger to compensate?

the web is thin .122 width with .116 drilled hole leaves .006 or .003 per side. you can't print that thinly at least I can't. if the web breaks thru it is not a problem since the load path is from the larger bar and nut. I went down a rabbet hole to see how tightly I could control the drilled hole with a printed fixture. going down rabbet holes is a pastime of mine. it's turns out so far I can't do better than .002 hole center variation and it depends how you hold you mouth taking the measurement so it could be more. the nylon graphite drill fixture out to be finicky when trying to hold tolerances. the nylon graphite tool looked fine, I just could not get a straight hole reamed thru it, weird. the ASA is much better and we will stay with that material for the drill fixture. however the nylon graphite is noticeably stronger and there is still room for development there.

this is the hole in question that I was trying to make perfectly centered. from a non-uniform printed hole to perfectly round and straight, multiple drill bit and reamer combinations for the tool guide hole did not yield much benefit. there is still room for development for this. perhaps an printed teardrop shaped hole would be beneficial but that is for the future. it's good enough for now and the final parts have a nice smooth action at the thread. fun stuff!

as far as the mirror function goes, I like it. it's not too big or too small. the tail is clearly viewed in the mirror. it's a keeper for me. it's easily removable if it gets in the way. I'm ready to throw this over the wall to Amanda.

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the first hole is drilled thru from the top side.



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punches thru the lower side. this hole is enlarged with the drill fixture at a later operation for the brass plastic nut.




Steve Melton 08-24-2019 10:06 PM

Nylon/Carbon Fiber Tooling resolved
 
Some experimentation ongoing for drill small diameter holes in parts. Printed in black to be able to see the part details better.

When printing a small horizontal hole a teardrop shape is beneficial. Filling the hole with support material does not lead to a straight hole when drilled. It is better to leave it open and compensate with a teardrop shape design so that the hole is rounder when printed. Note: larger diameter holes track the drill bit better without this teardrop shape compensation.

Teardrop design hole. Hole is printed horizontally with no support material.



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Printed horizontally with no support material. If a teardrop shape is not used the hole will be oval when printed in this horizontal orientation. the oval hole creates forces in drill bit that pull it off center when drilling the softer plastic.



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Added this teardrop hole feature to the nylon/carbon tooling. Printed one time with teardrop hole feature and it was good. that was the key.



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Bottom side uses a larger hole for the brass nut.



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Top side



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Web thickness = .122 inch. Drilled hole diameter = .114 inch.

.122 - .114 = .006, .006/2 = .003 per side web thickness.





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install a brass plastic nut for the tread and achieve a free spinning thread action thru the part. that's how it's made.



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clearance from thread to edge of the hole = .0015 inch. beautiful.



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three test pieces are boxed for Dave Schuler, the idea man for this design.

carlrai 08-25-2019 05:01 AM

Go Pro mount?
 
Hey Steve,

Just saw this. As always very cool design.

So sitting here Sunday morning with coffee trying to wake up I got to thinking, can you incorporate your Koger feature to accommodate a GoPro mount?
Is carbon filled material strong enough in section to support the camera. Could also be the GoPro Cube which is lighter.

I'm barely awake so this may be either a brilliant or really stupid idea.....

Best

Steve Melton 08-25-2019 10:22 PM

Quote:

Originally Posted by carlrai (Post 1369094)
Hey Steve,

Just saw this. As always very cool design.

So sitting here Sunday morning with coffee trying to wake up I got to thinking, can you incorporate your Koger feature to accommodate a GoPro mount?
Is carbon filled material strong enough in section to support the camera. Could also be the GoPro Cube which is lighter.

I'm barely awake so this may be either a brilliant or really stupid idea.....

Best

A gopro mounted inside the cabin could be supported with the current mirror mount design and material but the panel would need to be larger. The question is: can the Kroger rail mount adhesive withstand the load. if the rail is mounted well it could probably withstand the load for short periods but I would not recommend leaving it installed on a hot summer day. how large does a gopro panel need to be?

Steve Melton 08-28-2019 10:59 AM

rudder pedal extensions - weight
 
a full set of 0.75 rudder pedal extensions for both pilot and copilot sides total weight = 182 grams. that's easy on the weight and balance calculation. less than half the weight of equivalent metal, more foot surface area and custom lengths. includes anti-rotation feature.


Steve Melton 08-29-2019 02:52 PM

Nose wheel tow bar guide and paint protector
 
concept 1



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concept 2



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concept 3 - removed convex edges of tangs at ring intersection with fillets -- increased flex capability



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Material = ASA white


Steve Melton 08-31-2019 02:28 PM

preparing for 300F temperature testing
 
carbon/nylon transition duct for 2 inch dia scat size




carlrai 08-31-2019 03:28 PM

Quote:

Originally Posted by Steve Melton (Post 1369250)
A gopro mounted inside the cabin could be supported with the current mirror mount design and material but the panel would need to be larger. The question is: can the Kroger rail mount adhesive withstand the load. if the rail is mounted well it could probably withstand the load for short periods but I would not recommend leaving it installed on a hot summer day. how large does a gopro panel need to be?

I was thinking about my own set up which has the rail screwed in the center support of my slider which now reminds me that the position of the mount would have to be forward to clear the baggage compartment when slid back.
Also, how about reverse engineering the gopro mount itself and incorporate into the Koger fitting.
Happy to send you a mount if you're interested in pursuing.
Again, this all may be half baked until I get back into my RV-9A and confirm all the things I think will work.
On vacation on the beach in Florida. Keeping fingers crossed Dorian stays well east of the mouth of Tampa Bay. Will get my hands on my GoPros and post dimensions and a crude sketch of what I'm thinking about.


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