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Pouring elevator counterbalance lead

FinnFlyer

Well Known Member
Anyone have experience pouring the lead?

Trying to keep tail as light as possible I figure that if I pour the lead all the way out into the front of the tip it should reduce the amount of lead required.

Drill up a hole in E403 to 3/4 or 1" near tip, put alum foil in the fiberglass tip, clecko it on, cover inside of tip with a board, tip pointed down and pour the lead into inside opening between board and E403.

The question is: how well does lead flow and how fast does it solidify? Would a 3/4 or 1" hole in E403 be enough for the lead to flow from inside to outside of E403 and fill up both sides to same level before the lead stops flowing?

Finn
 
Anyone have experience pouring the lead?
Yes, I built an early RV6 kit and we had to do that.

Drill up a hole in E403 to 3/4 or 1" near tip, put alum foil in the fiberglass tip, clecko it on, cover inside of tip with a board, tip pointed down and pour the lead into inside opening between board and E403.
A 3/4" hole will be more than enough. Molten lead flows just like water and you will have heaps of time to do what you need to before it solidifies. I did not do this with mine. I just poured the inner and outer side of the rib separately.

The problem you will have is final balancing and securing the lead to the elevator rib. The plans probably show this( don't know, I built a RV6 ) but you need to secure it with two AN3 Bolts at least. Lead is easy to drill if you go SLOW on the drill speed. I used a wood arbour bit like this one https://ffsupply.com/product/wood-bit-arbor/ to cut a level surface countersink on the inboard side of the rib so the bolt heads would clear the horizontal stab outer rib. It will cut easily if you use low speed and low feed.
Make sure you over balance it to allow for the weight of the elevator paint and trim servo( If you have one).

Good Luck
Cheers
Graham
 
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Thank you Graham.
That is encouraging.

The (old) drawing show two 1/4" coarse bolts and nuts embedded in the poured lead.
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Between the 3/4" hole, the opening at the tip (removing baffles there), and possibly a few additional smaller holes in E403 connecting the lead on both sides, I think the lead will stay firmly in place. The lead will be fully supported by the skin and fiberglass tip, so the connecting areas of lead will only be to hold outside/inside parts together. Still probably would be a good idea to add a couple of bolts and nuts.

Thanks for the the tip on the spade bit for drilling (or removing lead later).

I will have the servo and mechanism in place, as well as additional 5 oz for vinyl or paint, when determining lead needed.

3M 1080 vinyl is 150g/sq m or 0.5 oz/sq ft. I don't if a light paint job could be made lighter?

I do intend to mount a 3/16" or 1/4" rivnut on the outside in case I later need to add more weight (big washers).

Finn
 
Lead temperature

Check and then monitor your temps. Don't get too high. Once it flows well, stabilize the heat

I've never worked with lead before. This particular lead is "Lead Ingots from Wheel Weights".

No clue what the temperature should be. I guess I'll put it a small coffee can, heat it with a propane torch until it flows to an even level in the can and then pour it? Or should I get a cooking thermometer and heat to what temp?

Finn
 
No cooking thermometers in lead. It melts at 640 degrees. Poof goes moms thermometer. pours easily wear safety glasses, gloves, don't drink whats left over. ha ha
Used to make sinkers bullets etc for past 60 years. Ain't dead yet don't breath fumes.
Oh by the way its hot and burns easily
 
Do it like the manual says

Just rivet in a small ?dam? where the plans indicate use the 2 course thread bolts and skip the large hole. Make a single pour for each side (4 total)

Works good lasts long time. And its easy

Cm
 
Be careful with wheel weights, most of them aren't made out of lead any more. The old ones are.

Obviously use in a well ventilated area and try to to breath it.
 
Drill up a hole in E403 to 3/4 or 1" near tip, put alum foil in the fiberglass tip, clecko it on, cover inside of tip with a board, tip pointed down and pour the lead into inside opening between board and E403.

I haven't ever personally tried this method but my guess is that even with alum foil, you will end up replacing the fiberglass tip after you are finished........

I recommend following the instructions.
No need to measure the lead temp. Heat until it is melted and then (carefully) pour.
 
Experimenting

Thank you all for the data and advice to follow instructions. :)

Obviously the fastest would be to follow plans, but this is supposed to be recreational/educational. ;) And I really want to save weight where possible (without spending a fortune on a titanium tail spring).

So fiberglass (resin) deformation would be a real issue. Getting fancy I could coat the inside of the tip with fiberflax sheet (I think that's what it's called) and then the alum foil. Or submerge the tip in water (heatsink). Or put the tip in a small container with gypsum (sheetrock compound) and let that harden -- that should hold the shape of the fiberglass tip. BTW, these are old gel coated tips.

Finn

I haven't ever personally tried this method but my guess is that even with alum foil, you will end up replacing the fiberglass tip after you are finished........

I recommend following the instructions.
No need to measure the lead temp. Heat until it is melted and then (carefully) pour.
 
BTW, these are old gel coated tips.

Finn

The older white gel coat tips are made with polyester resin (I think all of the current grey ones are as well, they are just made with a different type of gel coat).
Polyester resin is even less tolerant to high temps than epoxy is.
If you want to minimize the weight of the counterweight by keeping the mass as far from the hinge point as possible, I would recommend using plaster or something similar to make a mold the size and shape you would need, and then mold the balance weights separately. Then drill and mount them with bolts.
 
Best plan

Thanks Scott, sounds like the best or safest plan!

Will also give me the opportunity to work with molds -- something I haven't done since making molds for wingtip lenses for my RV-3 back in the last century.

Finn
 
I did this too . . . you can do it!!

If you want to minimize the weight of the counterweight by keeping the mass as far from the hinge point as possible, I would recommend using plaster or something similar to make a mold the size and shape you would need, and then mold the balance weights separately. Then drill and mount them with bolts.
+1

Properly heated lead will pour like mercury. Just take some old spoons and use them to scrape off the scum (dross) on the top just before pouring.

Plaster works quite well for the shape, you can make the blank from wax (or something) then make the mold around the correct shape. Slowly heat the plaster and get ALL the water out of it. It will pop and splatter the lead if it's not dry. I heated my molds to ensure the lead does not chill too quickly as it is being poured. If it does, it will look like the Vans counterweights(bad).

Once poured it does not take long for it to solidify. Old wheel weights make a good part, clean, smooth, & strong.

Good luck.
 
"Properly heated lead will pour like mercury."

I recall HS Science class where the teacher would pour Mercury into our hand and we would pass it from student to student, rolling it from hand to hand, only caution was not to drop it.
 
"Properly heated lead will pour like mercury."

I recall HS Science class where the teacher would pour Mercury into our hand and we would pass it from student to student, rolling it from hand to hand, only caution was not to drop it.

I don't think I want to do that with molten lead. :)

I received a posting reply by e-mail that does not show up when browsing this thread. Why would that be?

lr172: "Two concerns. One, The lead needs to be quite hot and I don't think it cools quickly. If it comes in contact with the F/G, I would expect some deformation and possibly charring. Two, What if you put in too much? How do you get rid of the excess?

I have an easily accessible block of lead that is only 1/2" from the forward edge of the horn. Not sure what you are gaining here. Is an ounce or two worth the risks?

Larry"

I'll substitute the F/G fairing with a plaster mold. That will make the original question moot because then I can pour from both sides.

I'll get rid of the excess the usual way, shave or drill it off.

I just measured it (adding a 5 oz bag in the middle if the elevator to simulate vinyl/paint). Left elevator requires 33 oz at 11" from pivot point, 41 oz at 9". 8 oz difference.
For the right elevator the difference is about 5 oz.
Perhaps I'll only achieve a 1" difference. But that's still 5 to 6 oz total. Consider how many hours spent with a fly cutter making lightening holes in ribs, spars, and so on, I think that's worthwhile, especially on a FP prop RV-4 that's notorious for being tail heavy with a passenger.

(Another possibility mentioned in an old RVator is to use lead shot in resin, but I'm sure I wouldn't get the same density thus negating the whole idea of moving weight as far forward as possible.)

Finn
 
Oddly enough, I am getting ready to pour some lead for a BB8 Droid which my daughter and I have been building. The dome (head) is attached magnetically to tower which pivots at the center of the sphere (big beach ball 3D printed part). The dome needs to have a significant counter balance (about 20lbs). I researched pouring lead and I here is what I am doing.

I 3D printed the shape of the weight and created a hydraulic concrete hemisphere using the print as a mold. Next, I when my wife was gone for a few hours, I put the 30 lb concrete mold in the oven and cooked it at 300F to get the water out. I plan on sealing it with high temp automotive silicone so it pops out of the mold.

I found 25# bags of lead shot on line and will be melting them with the hot plate I use to reconstitute epoxy hardener and a propane torch. You can buy $40 electric lead melting pots at Cabellas or on eBay if you don't want to work with a torch.

I also have some elevator counter weights to make for my Velocity. Figured I do the BB8 first before I did something that is more critical.

MTCW,
 
I don't think I want to do that with molten lead. :)

I received a posting reply by e-mail that does not show up when browsing this thread. Why would that be?

lr172: "Two concerns. One, The lead needs to be quite hot and I don't think it cools quickly. If it comes in contact with the F/G, I would expect some deformation and possibly charring. Two, What if you put in too much? How do you get rid of the excess?

I have an easily accessible block of lead that is only 1/2" from the forward edge of the horn. Not sure what you are gaining here. Is an ounce or two worth the risks?

Larry"

I'll substitute the F/G fairing with a plaster mold. That will make the original question moot because then I can pour from both sides.

I'll get rid of the excess the usual way, shave or drill it off.

I just measured it (adding a 5 oz bag in the middle if the elevator to simulate vinyl/paint). Left elevator requires 33 oz at 11" from pivot point, 41 oz at 9". 8 oz difference.
For the right elevator the difference is about 5 oz.
Perhaps I'll only achieve a 1" difference. But that's still 5 to 6 oz total. Consider how many hours spent with a fly cutter making lightening holes in ribs, spars, and so on, I think that's worthwhile, especially on a FP prop RV-4 that's notorious for being tail heavy with a passenger.

(Another possibility mentioned in an old RVator is to use lead shot in resin, but I'm sure I wouldn't get the same density thus negating the whole idea of moving weight as far forward as possible.)

Finn

I didn't fully read your thread before posting that. Upon re-reading, I realized that you had only cleco'ed the fairing on (I originally assumed it was rivetted on) and were using a barrier to protect the f/g, though not sure how the wood fits in there. Either way, after re-reading didn't feel my post was appropriate, so deleted it.

My lead chunk is only 2" wide, starting 1/2" back from extreme forward end. CofG would be 1.5" from edge vs yours which will be 1/4 or 1/2". So that is 3 oz. I did not go nuts cutting out lightening holes that weren't already in the parts. To me, it just wasn't worth 2-3 lbs savings. However, we all have different goals and appreciate your approach. My issue was really the risk of ruining the f/g parts in exchange for saving a few ounces. I questioned if that was a good gamble.
Larry
 
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...Either way, after re-reading didn't feel my post was appropriate, so deleted it. ...

OK Larry, but you certainly made a very good point on the fiberglass. Alum foil probably would not protect the F/G from deforming.

Finn
 
I couple of points about working lead. I've done a bunch of it, melting down wheel weight, scrap lead, gun range reclaimed bullets, shot, etc. for casting ingots, bullets, and fishing weights.

1) do it outdoors, its going to be smokey. Naturally wear protective gear.

2) you only need to get it to around 700 deg F. Any camping stove or propane stove will work. Never tried an electric hot plate.

3) Most lead is dirty and should be "cleaned" before pouring it. Melt it in a pot, toss in a bit of dry sawdust or chunk of candle wax, and stir. It will be smoky, probably catch on fire, but this "fluxing" will draw out the impurities (dross) to the surface where you can skim it off with a slotted spoon. Note to the poster who is going to be meting shot, i just did 37 pounds of shot and ended up with 32 pounds of clean lead ingots so expect to flux and remove alot of dros out of melted shot.

4) If your going to use a soup can or similar to melt lead, be warned they have a plastic coating in them that needs to be burned off with a propane torch before using. I would look to the dollar store or Goodwill and find a stainless or cast iron bowl for cheap. Also pick up a cheap stainless ladle and big spoon. Drill half a dozen 1/8" holes in the spoon for your dross scraper. Hammer a nice spout on one side of of the ladle for your lead pour.

5) Make sure your mold is 100% dry from moisture. Pouring hot lead on something with water in it was cause an instant and violent explosion as the the water steams off. Same goes for adding more solid lead to a pot of melted lead. Ensure everything is dry! If in doubt, heat it up with a propane torch or baking in an oven prior to putting it in the pot.

6) Dry wood will work fine as a mold. It will char a bit on thicker pours, but its pretty easy to work with mill or router to create the shape you need. You can also try and line it with high temp RTV sililcone. It has a working temp of 650 deg F so it will hold up enough for one or two castings. Again, ensure it is DRY by baking the wood in the oven at low temp to remove the moisture and sap. I haven't tried, but lining it with aluminum foil would probably work as well.

As with most things, if you youtube "casting lead ingots" you will find hundreds of vids on melting, cleaning, and casting lead.
 
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.
 
I did it!

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Picture series here:
https://drive.google.com/open?id=1yjdECzaqgWmFZ7IEM27vevEQl2T8EBV2

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??
 
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??
 
Density

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
 
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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