The dumb ideas I get sometimes

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stephenc
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The dumb ideas I get sometimes

Post by stephenc »

Ok I might be a tiny bit over critical with the title ....
Like a lot of others I happen to like watching Mr Pete on YouTube , I'm also not usually the envious type but dang it he has one item I want .

Namely the lead flywheel mold . I can't honestly say its a practical thing to put time into .
How many small flywheels does a guy need ? I can tell you how many I need exactly 1
With a spare or two in case of mistakes . but that sure isn't deterring me from wanting one .

So yesterday I spent about 4 hours doing the cad / cam to cut a prototype mold .
Its a little smaller then I want at an inch and three quarters diameter but it'll fit inside a some scrap stock I have on hand .

I think I'm going to cut the mold Tomarow and see what sort of issues pop up before I spend money on stock to make a bigger mold .

I suspect I'm also going to need an endmill with a larger corner radius then I have on hand at a minimum and possibly a tapered endmill to add a bit of draft to get it to release .

I'm sort of banking on the shrinkage being enough for it to pop out of the mold without a whole lot of persuasion though .
Even a blind squirrel gets a nut every now and then
earlgo
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Re: The dumb ideas I get sometimes

Post by earlgo »

If you look at a commercial bullet mold, you will see that the mating faces have very small grooves in them to allow the air to escape the mold as the lead fills it.
Also you might consider heating the mold a couple of hundred degrees so that you don't get unwanted rounded corners where a cold mold freezes the lead too soon. Even a small bullet mold needs to be heated up to prevent rounded corners on the grease grooves and base. In that situation casting a few throwaways does the trick. In your case, depending on the mold size, you may not have enough lead to do some re-melts before the mold cools again.
Good luck with your molding.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
stephenc
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Location: youngstown ohio

Re: The dumb ideas I get sometimes

Post by stephenc »

I have a 20# pot so I can get threw a few pours . if it works the mold I want to make will be somewhat in the 2.5 to 3 inch range. So it won't be huge either .
I'm going to make the blocks out of aluminum , easier to pre heat and for all the more use it'll get wear won't be an issue .

I'm a bit on the fence about venting . I'm kind of sort of hoping to get slightly rounded corners , maybe it'll help it release the part easier .
On the other hand if I have poor fillout I can go back and add some more venting , if I get a little flashing it won't hurt anything .

Of course like everything I do the good ideas always come after the fact .
I'm not going to change this mold because its not worth the effort to redo my work .
But on the next one I'm going to make the center hub wide enough on one side to be able to add a set screw without having to drill and tap at an angle
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tornitore45
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Re: The dumb ideas I get sometimes

Post by tornitore45 »

I have cast lead items in a wood mold. Dry it and pre-heat it in the oven. You can cast a couple of parts before it deteriorates.
Somebody may have a heart attack reading this but in the end is getting the job done.
Mauro Gaetano
in Austin TX
stephenc
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Re: The dumb ideas I get sometimes

Post by stephenc »

no heart attack here , if it works its for me :)

i didnt get very far along , i tore the heel off my boot and spent most of the day tracking down a size 13 ee .
but i did get one cavity cut . it turned out pretty darn nice , there was a few minutes of terror involved . i did the 3d profiling for the spokes with a 1/16" ball endmill a 4flute tool at that . only taking off .003 per pass feed speed was 55ipm . watching that tiny tool dive into the work was a bit nerve wracking .

the molds small enough i can make it fit lee handles , i should finish this up tomarow and maybe try a pour or two
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stephenc
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Re: The dumb ideas I get sometimes

Post by stephenc »

i managed to get the mold mostly finished this morning . all thats left is to drill a couple holes for handles and make a center pin .
i think it came out pretty nice .

ill heat up some metal and see if it works this evening .
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tornitore45
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Re: The dumb ideas I get sometimes

Post by tornitore45 »

Very nice job
Mauro Gaetano
in Austin TX
jscarmozza
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Re: The dumb ideas I get sometimes

Post by jscarmozza »

That's a very nice piece of work! Smoke it up good before pouring, and please post a photo of the results.
stephenc
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Re: The dumb ideas I get sometimes

Post by stephenc »

thanks it does look good doesn't it , to bad looking good is all its good at .

ok some conclusions have been made . much like i thought without draft it just doesn't work . i pre heated the mold a little and the first two pours that had poor fillout came out of the mold with a bit of persuasion .

it was all down hill from there , once the mold was hot and i got good fill it was extremely difficult to even open the mold . and then getting the part out was impossible , i tried 5 pours trying to open and drop the part from just barely froze to waiting an hour for it to cool down on the last one and without exception they came out in pieces .

with all that said i am very confident that with a couple degrees of draft it would work quite well .
but , the cost of the tools and materials makes it a expensive toy .
if i go with a ball mill instead of tapered tools for adding draft the run time goes from about 30 minutes per cavity to nearly 4 hours to achieve an acceptable surface finish .

as much as id like to have a flywheel mold that actually works ,the time and money id have to invest doesn't make sense .
but it was a fun experiment
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John Hasler
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Re: The dumb ideas I get sometimes

Post by John Hasler »

I'd use my rotary table and an end mill to add draft.
stephenc
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Re: The dumb ideas I get sometimes

Post by stephenc »

That would be the easiest method , but the problem comes in the price of tools .
An endmill with say 2° of taper is easy to come by , and not horribly expensive .
Until you add in the needed corner radius . then you go from lots of options to a very few expensive options .

My sharpening skills aren't up to adding my own corner radius on an 1/8" or 3/16 tool and getting the results I want .
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Bill Shields
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Re: The dumb ideas I get sometimes

Post by Bill Shields »

You can use a straight ball mill to make the fillet then run a taper around at a slightly higher Z value.
Too many things going on to bother listing them.
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