Alloy rocker cover

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mite5255
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Re: Alloy rocker cover

Post by mite5255 »

My Furnace is made from a old beer keg 15.7 inch dia with a wall height of 13.7 inch
When life gets tough, remember: You were the strongest sperm :)
mite5255
Posts: 1740
Joined: Thu Jun 02, 2011 1:11 am
Location: Caboolture Qld Australia

Re: Alloy rocker cover

Post by mite5255 »

I've acquired the alloy cover below, so I'll use it as a pattern, my pattern making skills just ain't that good :roll: :roll: ,it needs some work done to it as it does have a few nicks and scratches. The drawing shows were I envisage sprue, shrink bobs and gating will go,the bobs should hold about 25 cubic inches metal each, probably won't get much done these next days off as wife wants me to do some work around the house.
IMG_0932.JPG
When life gets tough, remember: You were the strongest sperm :)
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Jammer
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Location: Ohio

Re: Alloy rocker cover

Post by Jammer »

How will you adjust for shrinkage?
quando omni flunkus moritati 8-)
mite5255
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Re: Alloy rocker cover

Post by mite5255 »

Hi Jammer,Mr Miyagi ;) says it can be done with little or no shrinkage, sooo I'll give it a go

ike
F.C. wrote:Proper gating... PROPER GATING!!! That, AND adequate RESERVOIRS!! You can use the provided originals and make a duplicate that WILL fall into tollerance. You also need to cast with an appropriate alloy of aluminum. A356.

What you need to focus on is ability to cast the appropriate quantity of melt. What is your limit? You may have to upgrade your furnace and crucible, possibly your sand a bit... I don 't know what your limitations are.

A356 melts and pours like butter... it's sweeeeeet. ;) I can direct you where to find scrap of that alloy you can acquire for little to nothing. Very little issue in degassing with that alloy, primarily accommodated by proper furnace control. I have taken original case covers with blown out sections of it and sculpted in the missing pieces with wax and used the repaired component and cast workable duplicates in aluminum (identical to the original component) that mated up perfectly with the case it was supposed to. Shrink WILL happen when there is no metal to continue to fill the mold void as the part you cast continues to chill. Proper gating and reservoir accommodation will counter that. Those pieces you show as potential patterns I'd jump on in a heartbeat and go for the glory. If you want to give it a try, I'm in your corner Mite. :D :D Plan on revising and upgrading some of what you have as sand and/or equipment because I do not know what you have in ability with regard to volume of melt, how your furnace works, and mold flask size. I can direct you how to accommodate any deficiency you have.... just ask. I'm here for you. Promise the client nothing with a generous time frame for proof of delivery, then when you deliver a product and he determines it works, charge appropriately. YOU WILL DESERVE IT.
When life gets tough, remember: You were the strongest sperm :)
mite5255
Posts: 1740
Joined: Thu Jun 02, 2011 1:11 am
Location: Caboolture Qld Australia

Re: Alloy rocker cover

Post by mite5255 »

I also brought this cover from a mini to have a try on some thing a bit smaller, , the mini cover fits one of my existing flasks so I'll try this first before I make larger flasks. When the cover arrived it looks like it was die cast so I may have a few issiues getting it out of the sand as the sides are damn near parallel
Image
below is the result, this happened five times, I put the metal hooks in for my last try,I also rubbed the inside with graphite, I'll have another play today

Mike
Image
When life gets tough, remember: You were the strongest sperm :)
mite5255
Posts: 1740
Joined: Thu Jun 02, 2011 1:11 am
Location: Caboolture Qld Australia

Re: Alloy rocker cover

Post by mite5255 »

Had another three goes today and no success, when I give the cover a slight tap the sand does fall out. I do have some sodium silicate so next week when I come off shift may give a SS core a try, at the moment this is problem solving exercise before trying to make the six cylinder one that I have.... I'll be on Christmas break from Monday next week so hopefully over Christmas I may get a bit more done

Mike
When life gets tough, remember: You were the strongest sperm :)
dallen
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Location: Oklahoma

Re: Alloy rocker cover

Post by dallen »

are the holes plugged in the cover, if so you may try drilling vent holes in them and using low pressure air to lift the cover off the sand. my big pulley pattern with the deep pockets I had hell with till I put in three very small vent holes which allowed the cover to break the suction between the pattern and the sand.

I would also plug the oil filler hole and use a core up to the top of the filler neck then with a big open vent to the open air.

You've probably already done this but one or two coats of some paint that will leave a really slick finish will also help.

Happy Holidays
DA
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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Jammer
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Re: Alloy rocker cover

Post by Jammer »

Yes, painting and a good graphite rub is what I was thinking. You may have to go with a core for the inside. Don't give up!
quando omni flunkus moritati 8-)
dallen
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Re: Alloy rocker cover

Post by dallen »

pictures of the whole setup lets us see better what your up to. :D :D :D

buddy of mine gifted me five gallons of oil for my furnace today.

DA
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
F.C.
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Re: Alloy rocker cover

Post by F.C. »

Your sand structure looks excessively grainy. I see massive amounts of light colored bits in it. What is that? What is your sand mix composed of? Further, those three hooks won't serve to keep that sand mass intact with the upper half of that mold. The hooks are too thick, and, what you do utilize for rebar reinforcement needs to be thin and attached to a structural support within the upper half of that mold frame. I'll see about finding you an example pic, if not, I'll sketch you what I'm talking about.
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