One obstacle is the quality of the surface produced by standard Fused Deposition Material (FDM) of the popular plastic filament style 3D printers. FDM is getting good finish when printed at 0.2mm per layer or less. But not good enough for casting LWC model.
Another style of 3D printing using an Ultra Violet (UV) curing resin can produce layer heights as small as 0.025mm (25 microns) This is outstanding resolution. Several versions of this process exist. Some use a LASER beam to scan the layer. It's called Stereo Lithographic Apparatus (SLA). Another process uses a full layer exposure like a B&W negative for each layer. It's called a Digital Light Process (DLP)
Shown here is a Wanhao Duplicator 7 (WD7) I own. I bought it specifically for use in producing casting models. There are resins available that (should) burn out the same or nearly the same as wax in the Lost Wax Process. The key word is "should". More coming about that claim.
For more than several years I have been producing CAD models to produce programming to run my Computer Numeric Control (CNC) wax milling machine. A switch to producing Stereo Lithographic files (.STL) for 3D printing is a no brainier. The only difference is the output file created.
The first step in this new approach to lost wax casting is learning how to operate this new printer. It is totally different than my previous 3D printers. I have done some write up in my 3D Printing website. Here is the link:http://rd3dpds.com/resin-printer I have also posted some blogs on the subject: http://rd3dpds.com/blog
This article describes the outcome of this great experiment.
I have just completed my first casting of silver using the casting material from the WD7 printer. I was able, after some trial and error, to produce very decent quality 3D prints from the WD7. This printer works like a camera and film. The exposure for each layer of the print is critical to getting a sharp layer. The model I used here was as good a surface as I produce using wax carving. A good start. The printer is not a problem.
The issue I have discovered, is getting a clean burnout of the resin used to create the model. It is marketed as "castable resin". I followed the burn out schedule of time and temperature which is the same as I use for wax. The manufacturer claims very low ash, but does not state "no ash". Ash is the solid material left behind when all the volatile material is vaporized by high heat, 1350 degrees for 3 hours.
In the pictures can be seen the result of a non-clean burnout. This is a very disappointing result. This pendant (although I stamped my mark on it) is not of the quality I would offer for sale or as an example of my quality standard. The quality is very poor. It is the worst result I have ever cast. Of course all my other casts were made using wax masters.
At this point 3D printing is not going to be my go-to method for LWC. I will stay with WAX masters for the bulk of my work, thank-you...
I will continue to experiment and research casting resins. The 3D process will allow me to create models for LWC that can't be made by hand or CNC milling. That remains my goal. I am not going to let this failure be my only attempt. But I also don't want to stop doing my LWC until I get it working.
Right now I have a nice, but some what messy, very high resolution 3D printer. But I have a resin burn out that is very far from ideal.
The photography makes it look far worse than when I hold the pendant in my hand. It IS as bad as it looks, the camera doesn't lie.
I'll find a way to make this process work. I have spent enough time for now. The white residue from the alcohol wash may have contributed, but I doubt that. I'll try another resin cast the next time I have some wax masters to cast. I may need to try a more expensive castable resin. I have to admit this is the cheap stuff. It is also water soluble which was the initial attraction. Other resins require isopropyl Alcohol to clean up and dissolving of the resin residue.
There are other ways to skin this cat. The 3D printer can make hard models that are then used for making rubber molds that can be injected with wax. The wax is used for casting. The cost is material and another extra step.
Bottom line for me right now. The printer is certainly capable. The model material seems to be less than capable. It could be my technique. I have to decide if the time is worth the investment. I already get excellent cast product using wax. Being a pioneer with a new technique is hard work...
My last post was concerned SLA type 3D printing. There is a variation to the SLA laser beam where a full frame binary B&W image is projected at full frame for each layer of the print. Two variations of this process exist. One uses a video projector and the other puts the video LCD screen up against the resin tank with a bright UV light source behind the screen.
The process is called DLP (Digital Light Processing) and creates higher resolution 3D prints than SLA and can be done in some systems at much lower equipment cost.
This has changed my mind about the affordability of high resolution 3D printing in my world of dimensional art. I made a business decision.
I have a DLP 3D printer ordered. This new printer costs about the same as two of my FMD (plastic filament printers) That does fit within my budget.
The DLP printer can produce ready-for-investment masters for lost wax casting. That is my purpose for this printer. The full frame image permits printing multiple items at the same time and no increase in printing time. One ring or 20 copies all print in exactly the same time.
I chose a low cost simple machine. Not purposed for a high production rate but absolutely suitable for the scope and amount of work I produce. It will be a great learning tool. I will also be experienced to advise others or make upgrades in this first system.
Most of my reporting on this new tool will occur in my 3D printing website: http://rd3dpds.com. Eventually I’ll post more here, when I start producing dimensional cast items.
I have investigated this process for use in jewelry making and any other high surface finish 3D printing. The hardware cost has been coming down, but the cost of materials and the finish work such as UV hardening, and support removal are still cost and labor intensive. With enough production need the cost can be reasonable, but it is a system that should be utilized to its fullest extent.
That means it needs full time operation and not occasional utilization.
The process uses a focused laser beam (a) to “paint” the structure layer by layer, on a surface (c) immersed in a polymer solution (b). The light beam partially solidifies the polymer at the focus/surface point. The build platform (e) moves the item (d) away and usually out of the liquid polymer material as layers are added.
The results are usually the ability to produce a very fine, smooth, and accurate surface finish. Post curing and extensive support removal and detailing by hand are required.
Some of the polymer material is suitable for direct used for investing and casting. Other polymer material can be used in the vulcanized or cold process rubber mold making. Then wax burn-out masters can be produced. Many options are available for producing and using the final print output.
The process although high quality is still expensive and labor intensive. There must be a real purpose and plan to make full use of the technology. If everything I made originated in a CAD drawing, The process would be more attractive for the things I create. I would love a “free ride” to play with the process but to purchase such a system, it would have to pay its own way in increased sales.
I currently don’t produce enough jewelry items for SLA to replace my CNC machining. That’s bottom line reality.
|What hand carving looks like.||Three in their cans, one more to go.|
A small inventory of handmade wax carvings is accumulating in the studio ready for lost wax casting. The 100 degree Texas weather and non-air-conditioned studio are not conducive to firing a kiln up to 1200 degrees for 10 hours. One casting session was done a few weeks ago when the weather dropped into the 80’s for a few days.
Crying about the Texas heat seems to be a favorite excuse. That’s actually not a serious problem as I am not operating like a “got to get it done” business. However, it’s nice to mix the silver casting along with doing the wax design.
There is a hankering at the moment to do this one-of-a-kind hand carving of the wax. That could be because the hand carving is performed in an air conditioned office area. But it is also more than the comfort. It is a lot of fun to make something entirely by hand.
Designing with computer drafting (CAD) is also a favorite process in the comfort in the office. But the several CNC machines that do that intricate machine carving are out in the unconditioned shop. Ugh!
Creating by hand the very fine detail that my computer numerically controlled (CNC) machines can produce is not possible for me. That’s why I like using the CAD software drawing approach. With a good drawing, a CNC machine can usually make it. There is a lot of artistic effort and sense of accomplishment in creating the drawings. The machining process needs to be fully understood and exploited. The results are very rewarding.
The hand work is a totally different approach. A sketch is created but never a CAD drawing. It’s just not needed. A picture or a model of what is intend is also useful.
Sometimes just sitting down and cutting wax usually works but is not a great idea. A general plan is a definite advantage. A good idea with a sketch or picture solidifies where to go, is the best first step.
Working drawings are almost never presentation quality. Not trying to sell the piece before it is made. A presentation is usually SOP (standard operating procedure) for professional high value commissioned work. Someday it may be needed but no demand for commissioned, high priced work exists at the moment. Ha!
Actually, requests to duplicate previous pieces do come in. So far they have been fun re-work and the results ok for both me and the customer. Recently, orders for a whole series of flying horse pendants and pins from one example made on spec for my daughter, came in. Custom ring designs are occasionally requested.
A rubber mold duplication system is available to do wax injection molding with popular repeat designs. It is perfect for use duplicating hand carved originals. A CNC part can be duplicated by running the program again or using the mold process. It’s nice to have options.
Hand work presents or reveals the real artist in me. Every mark or flaw on the wax is there because I put it there. There is considerable enjoyment, to create directly through manual hands-on effort. It is different (and a lot slower) than sitting back and watching the machine do all the perfect cutting.
Having and using both methods is an enjoyable advantage. Some items need, even demand, the cool precision detail of machine carving. Others designs deserve the warmth of fine handmade work.
I am getting better with hand carving. Seeing the outstanding hand work done by others induces a desire to stay involved in quality handmade work. No allowance for my peripheral neuropathy limitations is ever an excuse for poor work. Hand work is just a bit slower, with care how to hold things. Right now it does not prevent carving anything imagined. It’s good for my spirit to work directly with my hands. It’s a type of personal satisfaction felt in creation of the work. Best therapy available.
Machine and hand carving are both rewardable. One method is no “better” than the other. There is no contest between them. So, no winners or losers. Just skills to develop and results to be enjoyed
A day’s work turned into two. I had two investments out of four crack after firing, so I had a bit of a do-over. But this is the result. The rose hearts are always good sellers so I need to keep a few on hand. The ruling lines are 5/16” spacing. Click on picture to enlarge.
The Pegasuses (Pegasii ?) are an experiment. The three little ones are charms or very small pendants. The two larger are definitely pendants. They are Sterling silver but have been acid treated to raise a coating of fine silver. These two pieces will be glass enameled red. They are wearing in-line roller skates. It’s the mascot of my daughter’s Pegasus skating club.
The large tags are an experiment too. The one marked “Adams” is a commission, but I also decided to make a generic “Texas” version.