Casting the bulb

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Casting the bulb

Postby jray » Wed Apr 13, 2011 5:16 pm

My plan is to cast the bulb halfs this weekend. Besides the obvious safety precautions, any advice from those of you that have already done this. I've worked lead before years ago but nothing this size. Thoughts on working time if I have to make a double pour, also how much shrinkage did you get in the middle during cooling?
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Re: Casting the bulb

Postby Kevin » Wed Apr 13, 2011 5:56 pm

We used a ladle to move the lead from the pot to the mold. As such we were adding continuously so we didn't have any layering issues where it cooled enough between ladles to not be one piece. My dad ran the ladle and I feed in additional lead to keep him going until the mold was full. I didn't notice a huge amount of shrinkage but it certainly came out of the mold nice and easy so there had to be some.

There have been others that have just poured it in (no thank you) or used a pipe from the pot over the mold. The trick with the pipe is it needs to stay hot enough through the pipe to not setup on you in there. Somebody had rigged it on some concrete blocks with the pipe tilted up using 2 elbows. Then when they were ready they just pushed it down and out came the lead into the mold. That method should get you the lead as it would push to the bottom and the other metals, if any, should move to the top. One I saw that was interesting was a old propane tank cut in 1/2 and use the fitting already welded in place.

Regardless of method, It's a good idea to have a place for any spare lead that get's melted so it's in a usable size and not set up in your pot for posterity.

Exciting times !!!!
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Re: Casting the bulb

Postby Chad » Wed Apr 13, 2011 8:40 pm

If I were to do it again...
I would not use wood for the fire source. Borrow or rent one of those turkey frier burners. More heat, consistently.
I'd use a ladle instead of messing with the pipe.
Do not add raw lead chunks to the mold in an effort to reduce the amount needed to melt- they act as lead cooling surfaces and create voids.
I did like casting the whole thing as one piece, but that works better for the bolt from below method.
Definitely one of the highlights of the overall build!
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Re: Casting the bulb

Postby Kevin » Wed Apr 13, 2011 10:16 pm

Oh, and a furniture dolly really makes it easy to move the bulb around the shop floor. I made up a quick one because I knew it was going to get crap on it during finishing which it did. Easy to roll under the transom so you can work on other parts of the boat too.

Chad, slightly off topic question. But did you drill your holes for the bolts after the fact or did you mold something in place. Just curious because it seems like a copper tube would survive the molten lead. It's probably best to just drill the hole as needed afterwards though.

And someone needs to try the milk trick as a lubricant while drilling the lead.
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Re: Casting the bulb

Postby Chad » Wed Apr 13, 2011 11:29 pm

I drilled the holes after pouring, fairing, and routing the fin recess into the top. I used the same drilling template I used to drill the bottom of the foil to mark the holes on the bulb. I have a small (p.o.s.) benchtop drill press, and I was able to block and shim the bulb level on the bench, then maneuver the drill press around under it to drill the holes. I probably just used WD40 or 3 in 1 oil or motor oil for a cutting fluid, I don't recall. It wasn't too tough that I remember. I did drill some good size counterbores in the bottom for washers, and THAT got a little exciting as the big bit alternately grabbed and froze and threw lead chunks around.
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Re: Casting the bulb

Postby Chad » Thu Apr 14, 2011 1:50 am

Lead melts just over 600 degrees F, and starts to emit increasingly dangerous fumes above about 1700 degrees F, and boils around 3100 F. It is very hard to get to 1700 degrees F, and you shouldn't try to.

Don't sand the lead- use a power planer, a block plane, a course rasp, or a surform tool. The idea is to make shavings, not dust. I wear a good dust mask for this stuff, not a respirator, but that's me. I'm making dust (at worst), not fumes, is how I see it. Clean your work area when you're done, and wash your hands before eating, smoking, or picking your nose.

LOTS of folks cast lead for hobbies and work (fishing weights, typesetters, etc.), so it's not like handling nuclear waste. My area has a hazardous waste collection facility that takes the leftovers, no problem. Sure, if you ask somebody at your local city government what you should do, they're probably going to overreact since lead is such a buzz word these days. Solid lead is vastly different than lead paint.

There's plenty of good info on the interweb about playing safely with lead. Basically it says don't boil it, and don't eat it.
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Re: Casting the bulb

Postby jray » Thu Apr 14, 2011 3:47 am

Looking forward to the process. Thanks for the ladle idea, I will be using that method instead of the pour that I was originally thinking of. All the safety stuff I was already aware of and has been addressed. The plus to this evolution is I have recruited help and have the gas burners with extra fuel tanks in standby. I was not aware that unmelted lead added to help fill space will cool the mould to fast and cause voids. No one seems to have had any problems with it setting to quickly so that's a relief. I haven't tried to get pictures up on this sight yet, this all works like it should and I'll give it a try.
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Re: Casting the bulb

Postby slowpoke » Thu Apr 14, 2011 4:22 am

Jon I used my plumber's torch and MAPP gas to make sure things got hot enough and stayed that way, so I have minimal layering. the MAPP gas burns MUCH hotter than propane. (yellow can) ;)
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Re: Casting the bulb

Postby Kevin » Thu Apr 14, 2011 5:17 am

Jon,

To attach pictures use the full edit mode and got the upload attachment tab at the bottom. Pick your file and hit upload. If the picture is really high resolution it may stop you. I think the limit is 1mb per file if I recall correctly. Chat me up if you have issues. If you can post to FaceBook, then you should be able to get it to work here.

Anyway, Here's a few for fun to inspire you.

Good luck. Kevin.
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Last edited by Kevin on Thu Apr 14, 2011 4:05 pm, edited 2 times in total.
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Re: Casting the bulb

Postby jray » Thu Apr 14, 2011 1:08 pm

slowpoke wrote:Jon I used my plumber's torch and MAPP gas to make sure things got hot enough and stayed that way, so I have minimal layering. the MAPP gas burns MUCH hotter than propane. (yellow can) ;)


I still have my acetylene B tank that I used for soldering. Thought about doing the same thing you suggested, help get things going and keep them just hot enough until it is done. Thanks!!
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Re: Casting the bulb

Postby slowpoke » Fri Apr 15, 2011 3:33 am

DO NOT TOUCH LEAD THEN LICK YOUR FINGERS!

El Roca's lead pouring rules:
1. Work in a WELL VENTILATED AREA.
2. Wear Leather gloves, safety glasses, and a respirator.
3. After pouring lead, wash your hands, or better yet, take a shower.
4. Try your best NOT TO INGEST LEAD.
Follow these simple rules, and stay healthy. DON'T touch lead and then lick your fingers!
Rocky Shelton
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Re: Casting the bulb

Postby jray » Fri Apr 15, 2011 1:20 pm

Good safety tip!!! Thanks. :lol:
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Re: Casting the bulb

Postby M&S » Fri Apr 15, 2011 8:18 pm

I'd also ad that leather (real leather) shoes are a good idea as they will not melt if splashed or poured on by the ladle.
My set up does have a 3/4" globe valve in line and does need to be coaxed open with a MAPP torch. The safety it gives is to shut down the flow once it is started. I think that any water based material used to make a mold should be be pre-cured over heat (briquets or a small wood fire before pouring) so you don't experience super heated steam bumping the lead out of the mold cavity.
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Re: Casting the bulb

Postby jray » Sat Apr 16, 2011 2:21 am

Got the protective equipment, also some great advice and a plan. What I don't have is a good weather forecast. Suppose to be rain and snow next three days. Looking like it is eazy up time! Baring a total side ways blizzard the casting will happen.
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Re: Casting the bulb

Postby jray » Sun Apr 17, 2011 9:55 pm

Snowing blowing nasty day, just finished the bulb and some sanding on the hull. All went very well, had to open up every thing in the garage and move in slightly with the burner and moulds. Pictures to follow if I can get them to load. Bulb weighed in at 153# strut is twenty. It should be easy to get everything to the weight I'd like to see. :D
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Re: Casting the bulb

Postby jray » Sun Apr 17, 2011 10:45 pm

A try at some bulb pictures.
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Re: Casting the bulb

Postby jray » Sun Apr 17, 2011 10:53 pm

Second Try at pictures!
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Re: Casting the bulb

Postby slowpoke » Mon Apr 18, 2011 12:00 am

Great job Jon, and that's the prettiest set of molds I've seen! Looks like you'll be sailing soon! :D
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Re: Casting the bulb

Postby jeff.dalsin » Mon Apr 18, 2011 2:58 am

I second the quality fo the molds! Loots like they result in nice bulb halves.

I made my second set of molds out of quick-cure concrete. Looked like they should have been around a snitch's feet! Fuggeddaboudit!
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Re: Casting the bulb

Postby jray » Mon Apr 18, 2011 3:09 am

I made the plugs, Steve took them and made the moulds, any credit for the moulds is his. They worked very well which is great as we need to get one more set cast before long for his boat.
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Re: Casting the bulb

Postby jray » Wed May 11, 2011 2:58 am

Just wondering where everyone ended up on weight. I'm going to be in easily at 185# strut and bulb, a little short on length as the strut was built to the plans and I wanted to through bolt it to the bulb. Two inches short of max rules length. No progress on the bulb since joining the halfs and drilling holes. Fairing starts this weekend.
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Re: Casting the bulb

Postby slowpoke » Wed May 11, 2011 4:49 am

Jon, my bulb initially came in at 140#, but I added weight when I poured between the two halves and ended up with 172#. My foil was the surprise, it came in at a whopping 18#, putting me over the limit until I drilled and countersunk for the bolts to hold it all together. Right now I think my bathroom scale puts me right at 185#, but I'm going to drill out a little more lead to put me a pound or two under the limit, and fill the holes, just in case my scale isn't accurate!
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Re: Casting the bulb

Postby jerome » Wed May 11, 2011 6:52 am

I am way over because of my heavy oak foil but could not care less ! No one to compete with in Turkey. Will be the only i550 in those Turkish water for a lllllong time !
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Re: Casting the bulb

Postby ryderp » Fri Jan 20, 2012 10:12 pm

Are there any molds out there that can be reused? I'm about ready to cast the bulb.

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Re: Casting the bulb

Postby Chad » Sat Jan 21, 2012 1:53 am

I'd be happy to make another bulb pattern if that helps anybody. The method I used takes a half hour to shape all the stations on 1/4" ply, then another half hour to fair the foam in between. It ends up as a course foam surface, but it's very fair- I just wrapped it in cling film and plunged it into my concrete mold. A smooth surface finish would be a waste of effort- plan on a couple minutes with some drywall mud in the concrete mold, then the ordinary fairing process once the bulb is cast and joined to the keel.

The plug is light enough to ship around, so it seems like it would be a handy thing for the "class" to have (again). :?
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