Casting resins cherry, emerald

Discuss casting techniques
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Archerm
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Re: Casting resins cherry, emerald

Postby Archerm » Fri Jun 09, 2017 2:15 pm

If you do a search you will find my whole procedure from start to finish. The only difference is I am now using different uv curing lights.
rsaldivar
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Re: Casting resins cherry, emerald

Postby rsaldivar » Fri Jun 09, 2017 2:51 pm

so , how do I help you , you have a curing problem and I'm giving you the answer , let my try again

after growing and cleaning , put them in your oven overnight at 150 F and then use UV to cure an hour ea. side, then tree up , This is the best cast results method Iv had
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Re: Casting resins cherry, emerald

Postby Dovydas » Fri Jun 09, 2017 4:29 pm

I have used cheap UV nail curing box plus microware method, no luck. Last time I did casting I used envisionTEC othoflash curing unit. Went for about 8000 flashes when ET recommend 1000 and result was the same. I gave some pieces to the local casting factory to cast and they managed to cast really well. Not sure if curing is a problem in my case.

Thanks
Last edited by Dovydas on Sun Jun 11, 2017 11:01 am, edited 1 time in total.
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Jewelermdt
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Re: Casting resins cherry, emerald

Postby Jewelermdt » Sat Jun 10, 2017 3:06 am

I put my flask with spru down. On a ribbed ceramic platform. So there is air flow under flask. My oven has a couple chips off around the door and a vent in center. I get great castings. Not sure what ramp my oven does. Website says gets to 1000 degrees in 15 min. It's a Vulcan that's been wired direct to a polygon programmer.

I would do as suggested and get some temperature cones to check your oven. You might have a bad coil. Or drill a hold and get a thermometer to check it.

Here's a picture of a very lightweight mounting. Came out great.
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wawatobi
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Re: Casting resins cherry, emerald

Postby wawatobi » Thu Jul 13, 2017 10:22 pm

I leave my prints in the uv nail curer often for two days. I use a twenty watt uv lamp for four hours before that. When I hurried for time and don't leave the prints to cure for more than twelve hours the castings often have some imperfections. You can't cure too much. I use a traditional burn out cycle lately and get good results. I only use emerald now.
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nzfinescale
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Re: Casting resins cherry, emerald

Postby nzfinescale » Wed Dec 20, 2017 10:17 pm

Just got my best ever castings back from my contract caster.

So time to offer a few thoughts on this issue.

I'm printing Emerald and getting prints cast into 'brass' by a contract caster. I have little knowledge (and zero control) of their process and it is clear that the actual metal they use is quite variable (which doesn't matter much to me). Unfortunately this means my conclusions below may be impacted by actions by the caster I'm unaware of, but I'm pretty confident in my conclusions just the same.

There seem to be 2 schools of thought on getting great results: 'Model curing' and 'Investment choice'. If I go way back to my undergraduate chemistry it is more than likely that any chemical interaction with investment will be from uncured monomer/low molecular weight components rather than well polymerised resin. It is possible that some investments are more tolerant of this. SO it is quite possible that both schools of thought are correct. Full cure OR resin tolerant investment will give good results. Full cure AND the right investment should be belt and braces, but probably a good idea if you can manage it.

I cannot comment on investment, other than to note that my caster uses the cheapest thing going (that may not be entirely fair ;) ) that is NOT optimised for resin parts. My failure rate has been high. Enough nice castings to keep me motivated, not enough to keep me happy.

So for me, I need to make sure that my models are fully cured. How to do that? Well for starters those dinky little 36W nail curing units do NOT do the job reliably. I've cured continuously, under water, for days in that thing and still had poor castings. 3 days, under water, in full New Zealand summer sunlight works really well. NZ sun is something else. You'll burn in 10 minutes and it is no coincidence we have the world's highest skin cancer rate. If 3 days of that doesn't achieve a full cure, then it's not very photo sensitive.

So the take home for me is that full curing takes a lot more than many posts on the forum suggest. If you cannot control the casting, then FULL curing may help sort casting problems. Without doubt there are better curing ovens available but at a price. I'll be using the sun from now on as I'm seldom in a rush and my usage does not justify a flash curing oven. In winter I'll just have to go skiing instead!

Lawrence
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Jewelermdt
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Re: Casting resins cherry, emerald

Postby Jewelermdt » Thu Dec 21, 2017 3:30 am

The Emerald B9 resin cures very well using a microwave. I use baby oil, doesn't evaporate as quickly as water. Plus holds heat longer. Cook for 3 minuets let stand for 15. Do this three times. I have B9 curing box at the store. But I will sometimes use the Microwave if I feel it's not cured enough.
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Re: Casting resins cherry, emerald

Postby Chalamba » Thu Dec 21, 2017 7:07 am

Curing boxes dont have to be expensive to be efective.
This is mine which cost me all together- two scrapped lamp reflectors, 5m 405nm led strip -9$, 36w transformator - 12$, turning table - 5$, and the top led diod 20w ( left from my attempt to improve my old nail curing box, not sure if needed at all) -20$
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nzfinescale
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Re: Casting resins cherry, emerald

Postby nzfinescale » Thu Dec 21, 2017 8:59 am

Hey Chalamba

Good thinking, and I actually tried this. The theory is certainly sound, as light outside the curing wavelength (approx 405nm) is essentially wasted.

So what I did was place around 1ml of liquid resin in a small vessel and placed it inside a set up a bit like yours. After 20 minutes the thing was still liquid. Stuck it outside in the sun and it formed a 1mm skin in far less than 20 minutes.

On that basis I figured the sun was doing the job waaaay faster, so why reinvent the wheel. As a trained scientist, I'm a little embarrassed that this was a long way short of a controlled and structured experiment. I may well revisit it more objectively next year, but there are still a few months of summer left here so I'm not in a hurry.

In any case, my message was not so much how to achieve curing, but to note that very well cured Emerald casts pretty well even under conditions where you might expect it not to. My point was firstly to support the other contributors who have pushed this message, and secondly to note my experience that 'fully cured' may require a lot more uv than one might expect. 3-4 days under water in the nail curer was not enough for some of my pieces (which are not thick). It is somewhat problematic that there seems to be no objective way to assess curing. One way to counter that is to go way over the top - which is probably what I have done.

Certainly there are many ways to cure models. If there are problems casting them though I suggest trying a weeks holiday in the sun. If that improves the casting, then exploring more practical curing methods is going to be worth the effort. That's what I'll be doing when the days get shorter.

Lawrence
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M-Williams
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Re: Casting resins cherry, emerald

Postby M-Williams » Thu Dec 21, 2017 11:29 pm

Try out this one. It cures the most stubborn resins in about 2 Hours.
Zoo Med PowerSun UV Mercury Vapor Reptile Lamp 160-Watt .

Marc.

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