Casting jewellery

#142

Hi folks! I wanted to jump in to clarify a few things about post-curing our Castable Resin.

– The “nail spa” UV boxes we recommend will work to fully post-cure pieces sufficiently for casting, but as most of them are fairly low in terms of power, the length of time is important. On average, a jewelry print will need to stay in the box (preferably flipping it over halfway through) for about 8 hours. Larger or pieces with greater thickness/density will take longer.

– Our Castable Resin undergoes both a color and tactile change during post-cure: the blue will turn a greyish-greenish, and the piece will feel stiff and brittle, compared to the uncured state which is more pliable.

– There is a difference between post-curing to a technical standard and to a point that makes burning out and casting work well. This is directly related to your investment type and casting method – you will see conflicting anecdotal evidence of successful castings from pieces that are post-cured at a huge range of times, temps, and methods.

– Casting resin requires an approach that differs from casting wax in a number of ways, but the primary point to keep in mind is that wax melts and resin burns. The two materials behave differently during the burnout process, which is why we continue to refine our recommended burnout and work with our customers so that everyone can reach casting success with this relatively new material/process.

A special thanks to everyone who participates in these discussions. Our active user community is often a wonderful resource for learning and feedback!

#143

This is interesting. I was looking at the b9 model cure, and have arranged to send them some of my castable prints for curing. How does your model compare? Specifically, they reckon their unit’s bulbs will last about 60 years of usage. What’s the lifespan of your device?

From your website, it looks like you don’t ship to the UK (where I am), any plans on changing that? If your model works well, lasts well and gives me consistent, castable material, I’d be more inclined to buy something that’s tailored to my actual printer.

#144

@Charles_McManus

The bulbs in my unit are specified by the manufacture to be 50,000 hours (6 years), but that would be under ideal conditions and that is certainly a stretch. The truth is that I don’t know for sure because I haven’t seen one fail. My experience with these lamps is only over six months, the development cycle of the product. The 60 year (525,600 hours) claim by the manufacturer of the B9 Model Cure I find hard to believe. I suspect it is a typo, probably meant to be 6 years, based on the same LED specification as my unit. For what it is worth, the LEDs are relatively inexpensive and they simply snap into a socket. So, if the time comes it won’t be anything more than a minor headache. Hopefully this is an acceptable answer. It is an honest one.

You ask how Curebox compares to the B9 Model Cure. It differs in many ways. A few major differences are that Curebox has temperature control, a much larger chamber, and a touch screen UI. It is designed to provide an engineering grade cure which is slow and consistent. It is not fast, and that is by design. That is another fundamental difference between Curebox and the B9 Model Cure.

As for shipping to the UK. Well, I designed the unit to be used internationally and intend to sell it around the globe. At launch, I wanted to limit sales to the US just to not get overwhelmed with logistics. I am willing to open up sales to additional countries upon request so I can do that if you decide you would like to order one. I will look into that now that you are asking the question. Please note, Curebox was just announced Sunday and does not ship until January 16th.

Hopefully that answers your questions. I am happy to discuss curing some sample parts for you. We can certainly arrange something if you are interested.

#145

That’s an interesting indicator; I was concerned that I had over-cured pieces that were exhibiting this colour shift. Does this mean that anything that hasn’t changed colour should be regarded as strictly undercured and therefore less than ideal for casting?

#146

Here’s an Instagram picture of the top of my kiln after a resin burnout, it emphasises Caylee’s point about resin burning rather than melting. For me, airflow through the kiln is a must, particularly for resin, so the plugs are left out and all the ash floats out the kiln. I’ll be spending the rest of the day, after casting, cleaning the workshop…

A photo posted by Dougie Kinnear (@dougiekinnear) on Nov 3, 2016 at 1:57am PDT

#147

The color change is technically a kind of bleaching effect, and is dependent not only on length of exposure time but also the strength of the light source. It’s possible for a piece to change color more subtly – to a darker greenish blue, for example, which is not substantially different from the uncured color – and still be functionally castable.

I would emphasize the feel of the material over the color to determine casting readiness, as that change to tough/stiff and brittle is the best indication. If the piece is still pliable or soft, but has undergone a color change, it could reliably be said to be insufficiently post-cured for casting.

It is difficult (though possible) to truly over cure this material as it relates to its castability. The longer the material is exposed to UV light and heat, the more fully developed it becomes and the less likely it is to have a core of uncured resin (a common cause of failed or poor casting.

How do I know if prints are cured enough?
#148

@Caylee, that’s not quite right. Uncured resin casting failures are caused by unreacted monomers bonding with sulphate anions at the resin gypsum interface. Depth of cure is irrelevant. It’s hard to push that surface cure to 100% due to vitrification with low intensity UV light.

Hey @ESpy, good to see you here.

#149

Hello

OK i tell you my story about UV light = curing-system.

  1. first was the sun - didn’t work too much with casting

  2. nail spa with classical bulbs - was working but result was better than first but poor.

  3. bigger outdoor 120 degree angle LED light with changed chip
    (did it with somebody Phisics from University )
    it was a chamber with temp measure (not control) we achieved stable temp 37-39 C
    chamber has been made of foam used for building houses especially for windows. :slight_smile: keeping the temp.
    Pretty good- desired as Formlabs rememmends 40 degrees almost achieved.
    Result after print?= resin was looking as it would be little liquidy; dots on the surface-
    no rigid/fragile resin for sure
    device was working 3 weeks- result was better but medium quality
    here the point was to concentrate the light. Light everywhere was not satisfied. I wanted curing in point
    in a ring for example

  4. nail spa with bulbs 12W each not 9W- the kind as a friend who is offering here.
    result was much better- but with porosity, and small wholes which needed to be welded etc.
    Just not smooth

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  5. decided for searching and purchase for a couple of lasers with bigger spot light.
    Ordered small lens in some to spread a little the strong spotlight. Set them on 3 tripods with light directed to the center.
    Was working good. So the DOT = spotlight has been extended and became stronger focused
    and light could cover the e.g. 3 small solitare rings
    and result after casting was totally satisfied
    time of curing 3-4 minutes!

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    There was one BUT: working time of laser is very short (when workin continuously)
    and lifetime of laser finished after 3 times.
    I was happy that cured prints for gold- so investmet had some cash revenue of it.
    Gain new knowledge and started to search something else.
    Result was OK and short time but too expensive to buy all the time new laser.
    laser spotlight.jpg800x489 181 KB

  6. This is my latest stable version of my curing UV light.
    It has cooling system. Curing is very fast. Ordered special big lens with angle for focus the light.
    No need heating. Light just doing here its job. Heating is necessary to “dry” the resin by temp. + light for more easy curing. But if light is strong - no need heating. In Formlabs’ printer there is no 40C temp heat - there is a laser. It is enough. That’s why I wanted to try the lasers with the same lightwave to cure the printed resin.

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    This light has been concentrated and it is strong. Cheap in using (low energy consuming),
    the best satisfaction than before with the good effect so far. Quite fast curing.

About nail spa (with better bulbs 12 W / each bulb x 4 pcs).
I cured prints for 4 days for 5-7 hours per day and didn’t receive such curing effect
as in curing system No 6.
Nail spa is not working enough in my opinion as good as I require- or casting company’s requirements. Maybe for others will be satisfied the result. not for me. Below silver casted in Germany.

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For me – I prefer to use No 6 now.
no6.jpg1200x1083 603 KB

Please note that I am not caster and this is only my experience.
I wanted to create a system that prepares these prints to cast in outsourced companies where I have no control on anything. I just send a print and believe to receive beautiful casted piece.
So I need to prepare a print to burnout with their waxes and their schedule of burnout as perfect as possible. They don’t preparare for me special burnout just because 5 prints requires other temp of burnout.
If you cast by yourself, so you can do according to Formlabs’ burnout schedule or as you want.

Also I have never seen any sample of desired form/piece of cured a sample from Formlabs.
(I prepared this text few days ago but was busy to post it. so I am not changing anything
_I am glad someone touches this subject about post-curing effect ,
and thank you that FormLabs explains something about it, It is important.)

Maybe I overcure- I don’t know. Maybe this resin material cannot be overcured. Also don’t know.
But surface of my work is 70-80% clean now so far. Important – there are no wholes in casting pieces now.
(but maybe it is because the effect of just proper and good casting)
So no need to weld the wholes. Just there are some things/flaws and dots
when need to do little more filing the surface

Also heard from one german casting company about highier point of temperature in burnout schedule.
That they are using more than 950 C temp to burnout the resin. This is their experience.
maybe anybody can do experiment with this temp or just similar.

Thanks for reading

#150

Impressive!!!

If you could give us some détails on the differnet parts used for curing n°6.

I have tried 950°c, haven’t seen any difference.actually to me it looks like resin is completely burned at 600-700°… ( have seen that when the investment broke in 2 at this temp)

#151

hi David

maybe change the investment for more rigid. are there available?
just my concern
I was reading a lot about casting and I am just theoretic - hobbist - amateur hehe
don’t take my thought seriously :wink:

good news that burned out at 600-700. this is good. heard that need much highier temp.

about curing: my every system is different; just light 405nm remains the same.

#152

@David_Maillot

hello David,
have you received smooth surface after casting?
maybe you can share pictures of your experience
thanks

#153

Yeah, I’d figured the colour issue was more of a reaction with the dye then much else; I’ll keep on testing for brittleness. A colour shift that coincided with full (or near-full) cure would be nice, probably requiring not much more than a full reformulation of the resin & laser settings…

Have you done anything with Jim Binnion’s paper advocating vacuum ovens for curing?

Hi Eric - seems the appropriate place to be asking questions on this beasty :slight_smile:

#154

I haven’t been on the forum for a while, but I’m back!

I just wanted to share experience I’ve had with two different types of nail dryers. I first bought one of the UV tube type nail dryers, and it did a good job. I let the pieces cure for anywhere from 8 to 24 hours. And I do get be change from blue to a greenish gray in castable version two.

However, because I am actually using my nail dryers to cure my gel nail polish also, I bought an LED version, which cures the nail polish in 45 seconds, as opposed to three minutes on the UV unit. So I naturally assumed that the LED unit would cure the Formlabs castable resin faster. IT DID NOT. I was totally surprised by this, but after a couple of hours, the resin was still tacky and bright blue. I cured it for much longer, and it never changed colors, and still remain to tacky.

I will check out the new things that people have posted in the forum for curing, but just wanted to share my experience. The UV unit was about $75 from Sally beauty supply, and the LED unit was from Amazon and cost about $40.

I cast my first items successfully using the 14 hour burnout and the Kerr Satin Cast investment. When I go into production, I will create an RTV (room temperature vulcanized) mold from the resin and shoot waxes. My biggest problem with casting myself is I tend to overheat the metal. I just invested in a Kerr Electro-Melt to get the temperature right, and I’m casting on a Kaya-cast vacuum casting machine.

I am very pleased with the results of Castable v2 and the 50 micron setting. There are some minor flaws in this ring, that I believe were caused by overheated metal.

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#155

Hi Peter, I am finding its somewhat hit and miss at the moment - Sometimes - not often - the surface is almost as good as wax but more normally there are varying degrees of roughness. I am using a mirror lined curing box with 90 watts of 405nm nail lamp type bulbs. It should cure the heck out of anything. However even after 3 or four hours in that box the surface is not always good. I am about to do a range of tests I am printing a load of identical rings and I am going to cure them for a range of times increasing by one hour from 1 hour to eight hours, Then I am going to cast them all at the same time in the same last and compare the surfaces. I will let you know the results.

#156

@PeterG

Photo 06-11-2016 17 07 28.jpg4032x3024 1.05 MB

#157

This is typical, investment cracks under the pressure of the expanding resin…

I have ordered a bottle of blue cast, should get it this week.

Will let you know how it goes.

https://www.dropbox.com/sh/sb57azrdcoynu5l/AAA2oJW7oqAEUowk77B2A_3_a?dl=0

#158

hi David
are you from Europe?

#159

French, but I live in French Guiana ( South america) why???

#160

I am thinking to send you samples of your files 2-3 pcs. Whatever you want
I could print and cure my way. You could cast.
what do you say? just only to test
just let me know if you are interested in
thanks

#161

maybe anybody else also interested in
we can make a test together
Let me know
might be interested experience