Starting In Lost Wax/ Investment Casting

Home enthusiasts discuss their Foundry & Casting work.

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RONALD
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Joined: Sun Oct 26, 2003 7:27 am

Re: Starting In Lost Wax/ Investment Casting

Post by RONALD »

Tim, you are well on your way to becoming a Lost Wax Casting expert. We can write about all kinds of procedures here on this board, but you learn a lot more by getting in there and doing it yourself.

I have not found any problem with vacuuming my RTV, for a minute or more, until it stopped bubbling. If some of the catalyst had been boiled off, I may have not noticed it, because I let the molds sit for several days before getting back to them.

If you have bubbles in the RTV, as long as they are not at the surface they are not a problem. If they are on the surface, then depending on how many, you may have to do a lot of trimming on the wax pattern.

By the way Tim, that was a great article that you wrote for issue #1-2013, of the C&NW Historical Society Magazine. In that center photograph of your article, were you the guy sitting on the brake wheel, or the one waving his hat?
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

Hi All

I am getting ready to order an ingot of silicone bronze. Will I need both a degasser and a flux? I probable should order it at the same time so I have it.

Thanks

Tim

No, I was not in the picture. It was taken before 1910 in Stratford, Iowa.
He who dies with the most unfinished projects: Should of put more time into their hobby.
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

I came across this great youtube video on build trees.

He who dies with the most unfinished projects: Should of put more time into their hobby.
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

Hi All

How do you determine the diameter of the main sprue? I see 1/4”, 3/8”, and 1/2”.

Thanks

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
RONALD
Posts: 754
Joined: Sun Oct 26, 2003 7:27 am

Re: Starting In Lost Wax/ Investment Casting

Post by RONALD »

A long time ago I standardized my sprues by milling a mold for a 3/8" diameter tree in aluminum. I also have a 1/8" square mold made out of maple.

Doing vacuum casting, I find I do not need anything bigger. Of course, I do cutting and fitting to adjust the sprue to a particular pattern
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Sprue.jpg
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

TODAY’S LESSON RELEASE VACUUM BEFORE SHUTTING OFF PUMP!

Luckily the oil did not drip on the parts in the chamber.

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting "Casting Time L

Post by FLtenwheeler »

Hi All

Casting Time Line.

Inject wax and make up trees. How long can these sit around?

Invest the flask. Let sit for 4 hours.

Steam dewax for 45 minutes.

Place in 300° oven for how long?

Ramp up the temperature?

What is the time and temperatures for this?

Reduce the temperature of the burnout oven to casting temperature? 900°?

Start to melt metal. Pour metal once metal is at temperature. 1900°?

Dunk in water bucket. Done casting.

Do you invest the flasks first thing in the morning and pour in the afternoon. Or invest in the afternoon and pour the next day?


Thanks

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
RONALD
Posts: 754
Joined: Sun Oct 26, 2003 7:27 am

Re: Starting In Lost Wax/ Investment Casting

Post by RONALD »

1. I have wax patterns, etc., saved for years. There is no time limit, unless the mice get near your wax!

2. Usually best to apply a de-bubbling agent before investing to the pattern only.

3. Once invested, I sometimes have had to wait a week or more to get back to the project.

4. It may take longer to dewax than 45', you have to look down the sprue.

5. With my oven, I just turn on the fan to move the fumes outside, and set it to around 900' and let it burn out the wax residue. I then loosely follow one of the schedules like shown in the Kerr Jewelry Lost Wax Casting Catalog:
http://www.kerrcasting.com/company

6. I do both morning to evening, and the reverse, I have no fixed schedule.

In case you can not find the catalog, here is that page:
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FLtenwheeler
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Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

Hi Ron

If you have to leave the flask for a week, it would be before dewaxing, correct?

I have read that a rule, the mold should be 800 °F to 1000 °F below the melting point of the metal at the time of casting. Is this correct for Bronze?

Thanks

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
RONALD
Posts: 754
Joined: Sun Oct 26, 2003 7:27 am

Re: Starting In Lost Wax/ Investment Casting

Post by RONALD »

Tim, most of the stuff that we pour, compared to a delicate piece of jewelry, is so large that you could almost pour it at room temperature, but it would be risky. I usually cool the flask down to around the recommended degrees, but if you miss it by a couple of score degrees, with the larger mass we are pouring it should make little difference. Of course, I have lost my share of parts by the metal or flask temp being too low; you go back to the wax pot!

They don't recommend leaving the steam de-waxed flask around for too long before putting it into the furnace, but again, I have sometimes violated that rule also.
FLtenwheeler
Posts: 1595
Joined: Sun Jan 05, 2003 8:47 am
Location: Florida, on the Lake Wales Ridge

Re: Starting In Lost Wax/ Investment Casting

Post by FLtenwheeler »

Hi All

I have seen mention of wax release agent applied to the silicon molds. Is this necessary? The waxes I have seen state that they have a built-in release agent.

Hope to be injecting this weekend.

Thanks

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
RONALD
Posts: 754
Joined: Sun Oct 26, 2003 7:27 am

Re: Starting In Lost Wax/ Investment Casting

Post by RONALD »

I do not normally use a mold release, because as you stated most injection waxes include their own release agent.

But, if the patterns do start to stick, then I apply such an agent.

This occurs usually when I'm producing many copies, like those Switch Braces; I use 14 Switch Braces on each switch point set.
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