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  #21  
Old 02-12-2019, 06:19 AM
fixnflyguy fixnflyguy is offline
 
Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 1,465
Default What I did..

On my -4, I made a simple wood mold that mimicked the rib shape and depth. I took my completed elevator, minus the weight and set up on balance point, then filled baggie with lead shot and taped to rib tip, adjusting amount until slightly nose heavy (compensate for paint). I then melted and poured into wood mold. After cooling, drilled and counter-bored for mounting bolt through rib. Test fit with bolt/nut while in balance jig to obtain slight nose heavy condition. I then primed the lead weight (rib already primed, and installed the weight with Proseal to completely water seal the weight in the rib. The finished product looks almost molded in, and was painted during final paint. In the event it would still balance nose heavy, it is possible to drill a hole to remove weigh, then touch up paint. I do not like the idea of a bonded or glued weight, because if it comes loose, your elevator will likely jam, and obviously, you risk flutter with loss of balance, hence, mine are bolted and sealed in place. The whole process from mold making to installed took an afternoon at best.
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RV-4/N76WE
8A7 / Advance NC
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  #22  
Old 02-22-2019, 06:20 AM
FinnFlyer FinnFlyer is offline
 
Join Date: Aug 2018
Location: Bell, FL
Posts: 582
Default I did it!

https://drive.google.com/open?id=1yP...xIuWa1BMUgprc7

Picture series here:
https://drive.google.com/open?id=1yj...7vevEQl2T8EBV2

Poured melted candle wax into tip/fiberglass tip.
Made mold of Plaster of Paris
Melted the wax out
Put a backing plate/board on the inside of the rib and poured the lead

On the right elevator the board moved away for the tip about 1/16" so had to file the excess lead away (tight clearance to horz stab tip) and I need to add a few ounces. Will add lead filings to resin and put fiberglass tip on with resin in tip.

On the left elevator I made the plaster thinner and got a better mold, although I should have ground out the bumps in the fiberglass tip before making the wax form for that.

Used a propane torch for melting wax and lead. Small soup can for the lead.

Lesson leaned: always add a few more ounces more than what is needed and/or reheat the can while pouring the lead to get the last bit out of the can.

On both I added a 3/16" nut plate so can bolt on extra weight after painting.

If I were to do it again, I'd probably buy powdered lead, mix it with resin and pour it though the 3/4" hole into (permanently attached) fiberglass rib and inside arm like I had originally planned to do with the lead. Of course powdered lead is much more expensive at $10/oz plus shipping.

Finn
P.S. How do you make pictures show up in posts??
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  #23  
Old 02-22-2019, 07:38 AM
OkieDave OkieDave is offline
 
Join Date: Mar 2017
Location: Oklahoma
Posts: 114
Default

Quote:
Originally Posted by FinnFlyer View Post
If I were to do it again, I'd probably buy powdered lead, mix it with resin and pour it though the 3/4" hole into (permanently attached) fiberglass rib and inside arm like I had originally planned to do with the lead. Of course powdered lead is much more expensive at $10/oz plus shipping.
What about lead shot embedded in epoxy? Something no bigger than, say, 7??
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  #24  
Old 02-22-2019, 08:04 AM
FinnFlyer FinnFlyer is offline
 
Join Date: Aug 2018
Location: Bell, FL
Posts: 582
Default Density

Quote:
Originally Posted by OkieDave View Post
What about lead shot embedded in epoxy? Something no bigger than, say, 7??
The object was to move the weight as far forward as possible in order to minimize the weight needed. What would the density of smallest possible lead shot be compared to solid lead?

I guess that would also be the question if using powdered lead.

Finn
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  #25  
Old 02-22-2019, 08:31 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,311
Default

Quote:
Originally Posted by FinnFlyer View Post
The object was to move the weight as far forward as possible in order to minimize the weight needed. What would the density of smallest possible lead shot be compared to solid lead?

I guess that would also be the question if using powdered lead.

Finn
I knew you could do it!!

You can google packing of spheres. Packing factor of small vs large is no different. The resin/lead ratio would be fixed. However, if you mixed a large shot with some small enough to fill some gaps, then it would greatly improve. 00 buck and 7ish might work well. Just be sure it is lead.
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Last edited by BillL : 02-22-2019 at 08:44 AM.
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