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FAIL!!!

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FAIL!!!

Unread postAuthor: Heimo » Sat May 08, 2010 2:50 pm

well I cannot let JSR have all the fail fame so, here is what happened

Today I decided that the time has come that I am going to make myself A hybrid. the hybrid I am going to make is going to be made from T6 aluminum (6061) and every thing went smoothly except I forgot one small thing and that ruined the combustion chamber.

I started out as usual, to make a mold for the item I want to reproduce in metal (sorry for the crap picture my shop ain't well lit)
Image

the mistake that ruined the chamber is visible in that picture I forgot to remove the paint from the metal pipe used as a core this created mold gas and this gas caused the failure.

here you can see a picture of the finished casting in its rough stage

Image

every thing was still fine then, until I started to cut off the sprue's then I discovered a flaw in the casting

Image

yep that is a bubble, it was caused by the burning paint on the steel pipe. this ruined the casting (the finished product will look much better than this, this is just before any finishing took place)

anyway I will try again next weekend

when I get a casting that I am satisfied with I will start a thread in the discussion aria

just out of curiosity this chamber has id of 35mm and a wall thickness of 10mm anybody care to calculate the burst pressure?
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Re: FAIL!!!

Unread postAuthor: SpudBlaster15 » Sat May 08, 2010 3:39 pm

Heimo wrote:The hybrid I am going to make is going to be made from T6 aluminum (6061)


Just to clarify, the solidified casting will have a temper of 0, so if you're using the 6061 alloy, your chamber will be 6061-0, not 6061-T6. If you want a T6 temper (Which more than doubles the tensile strength and increases the yield strength by a factor of 5), you'll need to artificially age harden the chamber post casting.

The gas bubble in the chamber wall is unfortunate, but you should be able to re-melt the piece and do the process over again. Just make sure you strip the paint and remove any residual oil or grease on the steel core.

If you assume there are no defects in the casting, the chamber (6061-0) will begin to yield at approximately 4 600PSIG, and undergo complete tensile failure at around 10 000PSIG. Due to the extremely high likelihood of casting defects being present in anything manufactured using a backyard foundry, I wouldn't use it above 10x or so.
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Unread postAuthor: POLAND_SPUD » Sat May 08, 2010 3:58 pm

you're joking right?? that looks great even if it failed
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Re: FAIL!!!

Unread postAuthor: Heimo » Sat May 08, 2010 4:42 pm

SpudBlaster15 wrote:
Heimo wrote:you'll need to artificially age harden the chamber post casting.


it was my original intentions to do so.

one more thing I forgot to do, is to degas the melt. if I degas the melt and I pour through a filter to remove the impurities I guess I could get pretty decent results the failed casting is going to get recycled but first I am going to cut it up to have a look on the inside

something else I may do is to cast this in aluminum bronze, this is a high strength alloy used to make non sparking tools anybody else think this is a good idea? or should I cast this in normal brass the same type used to make plumbing fittings if you guys think that aluminum bronze is overkill.

I only used a steel pipe to create a core because I was too lazy to make a core box

something else I would really like to do is to cast this in gunmetal/red brass unfortunately I have been unable to find a source

So what do you guys think aluminum/plumbing brass/aluminum bronze/Japanese art bronze or gunmetal? (I will have to alloy the gunmetal myself though) any other suggestions?

thanks Poland_ spud but wait till you see the next one, cause this one is crap in my book the next next one will be of higher standard
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Last edited by Heimo on Sat May 08, 2010 4:49 pm, edited 1 time in total.
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Unread postAuthor: Mr.Sandman » Sat May 08, 2010 4:48 pm

That look very good even as a failure, I love metal casting and am thinking of rebuilding my foundry as it has become dilapidated over the years. I think we should have a metal casting/machining section to this site.
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Unread postAuthor: clemsonguy1125 » Sat May 08, 2010 4:54 pm

Mr.Sandman wrote:That look very good even as a failure, I love metal casting and am thinking of rebuilding my foundry as it has become dilapidated over the years. I think we should have a metal casting/machining section to this site.

That would be great, did your mini metal lathe work well
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Unread postAuthor: Mr.Sandman » Sat May 08, 2010 5:39 pm

clemsonguy1125 wrote:
Mr.Sandman wrote:That look very good even as a failure, I love metal casting and am thinking of rebuilding my foundry as it has become dilapidated over the years. I think we should have a metal casting/machining section to this site.

That would be great, did your mini metal lathe work well

Not trying to thread hijack but I never received the lathe, it's on backorder for quite a bit, I shall see how long I can hold out. On that note harbor freight has a new website design clicky.
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