Solutions to my Castings

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bvwjewelers
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Solutions to my Castings

Post#1 » Thu Sep 25, 2014 2:48 am

I have my castings fixed and wanted to share just what worked after receiving so much help here, and from reading others problems and tricks. I took some time and called Satin Cast to talk about the temps that are being suggested on Monday, and the breakdown of the investment along with other problems I was having. I spoke with Philip Read Product Manager and the one thing he made clear was no matter what your oven says on the outside on a temp gauge, it should not go over 1350-1375 (inside flask) at its core as the investment will break down, crack, and discolor. All of what I have always knew (and I’m sure most of you did too), and thought that seeing folks here taking temps up that high satin cast could take the heat and my problems were something else. My investment was breaking down thus having awful castings.

Philip and I spoke for about a half hour and at the end of the conversation he was sending me out at no charge some of his SATIN CAST DIAMANTE, saying that if folks were using high temps best try this investment. Looking forward to casting it higher, but honestly see no need.
He also wanted some samples of the cherry resin, and a completed resin model so they could try it out and see in their lab possible what the best would be for us.

I have had beautiful castings after making some minor tweaks and going back to the same way I cast lost wax with some small changes. My castings are now coming out like they have been tumbled and have a smooth bright sheen to them. I am not saying this will work for you, but I can say that your castings are looking just like mine did when I was tinkering around with no luck and after I was breaking down the investment, then hope this helps.

So.
I used Clean Cast White #242 from Stuller.

1. I added an air pump to my oven to help push air into the oven.
2. Mixed satin cast a little thick for 3 min, vacuum for 3 min, pour into flask and vacuum 1 min. let sit 30 min without moving it. I also used very warm water.
3. Flask sat in oven off for 4 hours+ before it turned on.
4. Oven temps on control 300 @ 2 hr / 700 @ 2 hr / 1350 @ 3 hr with 5 degrees per min ramp on each stage. About 11.5 hour burn out.
5. Flask size was 2.5 x 3.75
6. Raise flask off base of oven floor
7. Once the oven finished I go by my outside control panel for temp and cast when it says 500-600, this takes 2.5 hours from 1350.
8. I'm using a electro-melt and my metal is ready to go when that temp is reached, and I then move to vacuum caster and pour.
9. Let sit for 5+ min and quench

Note: I used a UV nail lamp box to cure my resin for no less than 4 hours.

I am not going to speak for others who have had great luck casting so hot, but for me it only made my investment break down and have porosity in all metal types. I have had discoloration in my flask from resin melting out, but it has not affected any of my castings.

After speaking with Philip at Kerr my suspicion was correct and raising the temps on the investment above 1350 was killing my castings, and tinkering is what got me in trouble with my castings over these past few weeks thinking it was not getting hot enough. One thing I feel is very true like Robert and akgold (and others) have been saying is airflow, airflow, airflow and knowing your temps in YOUR oven, and when to cast that flask and how when it’s the correct temp.

The only thing I really did to get back to something that was consistent with lost wax, was raising my time a bit longer, air flow, raising flask off the bottom of oven, and casting at a temp that works for my oven, when reading the temp on it….that being 500-600 while the temperature on the inside of my flasks were closer to casting temp.

The on picture of the two rings is of a 50/50 new gold old gold just to see how the castings would work with my setup. All in all nothing a emery stick can’t fix and still came out great and took these photos right after I got the investment off. The single ring is all new clean cast #242 gold.
I have been holding out on my more complex designs until I got this down and will post some photos of those soon.

Cheers.

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noahbern
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Post#2 » Thu Sep 25, 2014 3:46 am

Great info! Do you put your flasks with the sprue side up or down?
I put mine up, same way i do when i use the vacuum..
What type of flasks do you use?

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bvwjewelers
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Post#3 » Thu Sep 25, 2014 4:09 am

Sprue side is always down so the resin can flow down and out. I use the perforated flasks that come from Otto Frie.
http://www.ottofrei.com/Stainless-Steel-Perforated-Flasks.html
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TAJS
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Post#4 » Thu Sep 25, 2014 4:18 am

Thanks and congrats! ....those look great!

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bvwjewelers
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Post#5 » Thu Sep 25, 2014 6:10 am

Came out great. =)
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fcort
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Post#6 » Thu Sep 25, 2014 8:53 am

Great info and that you for sharing! This is a huge help to us all!
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akgold
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Post#7 » Thu Sep 25, 2014 9:12 am

Nice job good info you used the SATIN CAST DIAMANTE or satin cast 20? And the models using Clean Cast White #242 from Stuller 14 karat?

I also wondered how long your curing your B9 models. I have also thought about doing a test on a couple of cans of the exact same model cured
together at exact same time. and the same investment. then raise the cans off the bottom of the kiln say about 2 inches or maybe set them up on a rack in the middle of the kiln and also turn one up and leave one down.
I have thought for a while now that this resin doesn't melt or flow out like wax does but without a little camera in there to watch it through the process I don't know I just imagine as it gets to combustion that the fumes travel up problem is the ash left over would not come out if there is ash.
good Job
You should consider sending Kerr a model that is cured and a model that is not cured to see if they could develop a resin to eliminate curing resin.
I'm so far behind I think I'm First !!

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bvwjewelers
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Post#8 » Thu Sep 25, 2014 10:39 am

Thanks akgold! I used SC20 and the #242 was from Stuller. My cures are for no less than 4 hours. I basically keep them in the UV until I invest them at 5 or 6 pm. I sent them like 10 resins to play with, can't wait to see what they do.
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akgold
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Post#9 » Thu Sep 25, 2014 2:02 pm

Can you post a picture of your vacuum caster? just curious.
looks like you have the method down now. Can't wait to hear from Satin Cast.
I am going to see how using satincast 20 and the stone in place formula added will change the high end temps
it makes the investment very hard and does not melt away under water you have to beat is out with a mallet and ultrasonic in Strong pickle to get the investment off it.
I'm so far behind I think I'm First !!

matinum
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Post#10 » Thu Oct 02, 2014 8:13 am

Try the first part of your burn out at 200 degrees rather than 300. The first part is about dehydration. Elevating the flask above the boiling point produces steam which is detrimental to your surfaces and in many cases, detail.

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Robert Howle
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Post#11 » Thu Oct 02, 2014 9:07 am

Thanks Matt.
Dance like nobody's watching!

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PandaP
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Post#12 » Thu Oct 02, 2014 10:36 am

Awesome info! Thanks!!

anthid
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Post#13 » Thu Oct 02, 2014 7:37 pm

Thank you for all the info!

When someone is claiming good results raising temps, as long as we don't know the actual flask temp, we should also consider that his raised controller temp probably translate to a lower (and more inline with manufacturer recomendation) flask temp.

And about your air pump, are you using it on all the program or only @1350? Do you know the aproximate air flow or air volume pumped? It would be a tremendous help to determining the the minimum threslhold needed for a complete combustion.

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Robert Howle
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Post#14 » Fri Oct 03, 2014 5:50 am

All ovens are different. Again u really just have to make sure u have good air flow into the oven to aid in oxydation of the residue. You may not need to do this. My old oven worked just fine until i had to replace it. new one just had a really small opening in the door and at the top. U can get good results with just additional air holes (drilling) and raising the flask off the oven floor.

Robert
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anthid
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Post#15 » Fri Oct 03, 2014 6:13 am

Thanks Robert. I have done a couple of tests with Satin Cast and Plasticast with similar results, both light and heat curing resins, so I am pretty sure I need more airflow. I have calculated the natural airflow in this web (scroll down to "Natural Draft Air Flow and Velocity Calculator"):

http://www.engineeringtoolbox.com/natural-draught-ventilation-d_122.html

And looks like I have an airflow of 6CFM at 1350. If would be great if people do their own CFM calculations. Probably we can get more robust insight on how many airflow do we need to get a clean burnout.

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Robert Howle
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Post#16 » Fri Oct 03, 2014 7:02 am

Don't have a clue as to do what u are suggesting. I am a biology and chemistry major/ jeweler, and not an engineer. Others maybe can, but I cannot help u with the CFM issue.

Robert
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james c.
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Post#17 » Fri Oct 03, 2014 8:53 am

Does anyone know the cherry resin to 10k, 14k, 18k, and Sterling Conversion ? Or is it the same as wax.

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behold3d
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Post#18 » Fri Oct 03, 2014 10:18 am

damn it Jim... i'm a doctor not a mechanic!

sorry couldnt resist

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Robert Howle
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Post#19 » Fri Oct 03, 2014 12:06 pm

The resin is approx 1.1 in density comparison to wax which is 1.0 (specific gravity). So when doing the math use .9 x the weight of the model to deterimine the amout of metal use. In other words the weight of the printed and cured model x .9. Then take that number x the specific gravity of the metal u wish to use.

These are the values I have been using for over 30 years. From a casting how to book over 30 yrs old.

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ericarchuleta@surewest.net
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Post#20 » Wed Oct 08, 2014 3:33 pm

About 4 years ago I was at a Jewelry symposium and one speaker was a scientist from Germany who did a special study on what caused porosity in casting uv resins and how to fix it!
HE said the two main causes of porosity when casting resin is investment break down caused by over heating the investment and resin expansing/shrinkage/gas from the resin caused by over heating the resin two fast. So the ramp up on your burnout cycle/heating setting and time is very crucial! Curing your resin post print is also very important
starting your oven at 200F is very good and a slow ramp up is crucial. For the first 3 hours make sure you oven never gets hotter than 540F.the slower the ramp-up rate on the oven setting the better for the first 3 hours, this is one of the most important steps to follow
That is why I suggest firecast!
firecast castable resin from madesolid uses satincast and satincast Xtreme, the highest setting for the heat schedule is never higher that 1200 f and you cast at 1000F it works great, Zero prosity, know need to modify your oven with firecast, However if you cast a lot, like everyday or close to everyday, a air pump modification to your oven will increase your odds.......When I view your pictures of casting I see a need to add exit sprew to your marquis solitaire casting connected to the marquise basket setting on the side or bottom of the setting.(that part of the marquise basket setting, the casting looks like porosity and is very rough however your thicker models results look great)...if you view the solitaire setting sprew set-up with the dark exit sprew on the home page of this website, this is a great example,(thank you Gary for this example) their are several different ways to use alternative sprews with thin casting, Make sure your exit sprew is the same size of the shank (only with thin shanks)this way it will cool more even! it's all relative.
If your vaccum casting and you have little experience try casting thicker heaver pieces by then selves. once you have gotten success try two pieces at a time and work your way up to a sprew tree.
If your centrifugal casting with a sprew tree setup, mark your flask with a notch on one side top or bottom. Use the notch as marker so when you make the sprew tree, you put your heavy pieces on the inside of the flask on the same side of the notch off you sprue tree....when you cast make sure the flask notch is sitting at the bottom of the casting holder where the flask sits when you cast, (think gravity) this way your heavy castings wont add pressure when the medal flows into the flask and break any thin casting on the casting tree, thinner pieces will cool faster, so this will cause stress and oxidation on the metal and can cause porosity,(the rough surface on the marquise basket setting is a perfect example of this) the heavy pieces will cool quicker by the absorption of the flasks holder(flask crateal) this will help even your cooling rate between the thick and thin, this will increase your odds and eliminate that rough surface on the marquise basket setting, If possible always use an electro-melt never a gas torch, unless you have no choice, the trick to casting porosity free rose gold castings is an electro-melt(electro-melts are famous for not being accurate on the heat setting always check when getting a new machine or using an old machine)
I have over 37 years casting precious metal and over 10,000 pieces
Thank you for sharing your experience and casting
Good luck

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