Making the wax models

Today we collected our silicon mould and started to remove the walls. The silicon was firm and smooth so that was good.

Removing the walls from the silicon mould

After removing the bottom of the box we saw that some of the silicon slipped beneath the edges and filled up parts of the mould. Luckily it was very easy to remove those edges with a pair of scissors. The quality of the mould is good enough to make wax moulds with it.

Silicon ould without the wooden box. Some silicon got into the moulds

We bought a cheap pan with a teflon layer to melt the wax in. First we wanted to melt the wax with a heat gun, but we found out that the wax needs to melt slowly and evenly. Then we decided to just use Tom’s furnace to melt the wax with. There was almost no smell while heating the wax.

Heating up the wax

Then we poured the wax in and let it cool down for an hour.

Silicon mould with the wax poured into it

When the wax moulds were remved they looked like this:

Finished wax moulds

We see a little bit of detail loss on he srface. The wax moulds are somewhat smoother than the original printed test pieces. We will send the for wax moulds together with the digitally edited cat-able resin piece to the caster this afternoon.

Making the silicon mould

Yesterday we edited our last test piece from the cast-able resin. We printed a version which was not digitally restored and then tried to restore it manually with wax to see if this method works better than restoring it digitally. The restoring was done with a soldering iron to melt the wax and then dab it onto the surface. We also tried to scrape away material at the edges with some sculpting tools to make the ornaments on the crown more detailed. The cast-able resin has a soft wax layer at the surface, but is a lot harder beneath the surface layer. It turned out to be harder than we expected to edit the piece.

Restoring the cast-able resin piece with wax and a soldering iron

Dripping the wax onto the model

So now we have four different types of test pieces which will be casted.

Four types of test pieces

After the restoration we started with the production of the wax moulds. To make a piece of the crown from wax, we need a silicone mould where we can pour the wax into. We plan to make the silicone mould by pouring liquid silicone together with harderer in a wooden box. In the box we will stick our four crown pieces with some double sided tape on the bottom of the box. Then we will pour the silicon in and let it harden for twentyfour hours. Then we can break the walls of the box away and we have our silicon mould!

For the box we used a piece of mdf board. To assure that the silicone would not stick too much to the box we used clear tape to cover the inside of the wooden box. We also used sculpting clay to cover all the edged of the box so that there are no sharp corners in the silicon mould.

We found out that the cast-able resin pieces did not stick too well to the double sided tape, probably because of the thin wax layer, so we decided to stick them to the bottom of the box with the sculpting clay. We are not so sure if the pieces are well enough attached to the bottom. If that is the case, then the silicone can slip between the edges and fill up the cavity beneath the test pieces. Hopefully this will not be the case.

Making the wooden box for the silicone mould

 

The finished silicon mould

We mixed the silicon with the harderer and poured in into the wooden mould.

Pouring the silicon in the mould

Then we put the mould in the vacuum oven. Just to be sure we put the temperature a low as possible. The silicon rose a lot in the mould so it would have been better if we made the sides of the box a bit higher. To prevent the silicn from pooling over we let a little air in the oven bit by bit. This worked fine.

Removing air bubbles with the vacuum oven

There were quite a lot of large air bubbles so maybe some of the silicon slipped beneath the edged of the test pieces.

Inside the vacuum oven

This is the end result. It seems that most of the bubbles in the mould are gone so we are positive that the wax moulds will turn out fine. We let the silicon set over the weekend and on Monday we will start with the wax pouring.

 

 

Printing the cast-able resin test pieces

On Wednesday, we arranged to change the current grey resin for the newly arrived cast-able resin. This resin is used a lot for investment based jewelry casting. Because we want to use a similar method, the resin should fit our purpose perfectly. When heating cast-able resin, it will melt out of a mould, leaving space to pour liquid metal. We discussed this method in this post.

Another option is to create silicon moulds from these pieces. Hot, liquid wax can then be poured in the silicon moulds and the resulting wax models will be used for the investment or sand-casting. To make the silicon moulds, both the cast-able and non cast-able resin prints can be used, so in order to compare the two types of prints, we decided to print the same pieces as we did before and make a silicon mould of all four pieces.

First, we had to print the cast-able models, so we had to change the resin in the machine. Because Tessa never changed the resin in the Form2 yet, it was a new process to all of us. Being very cautious to not spil a single drop of resin on the clean glass, we managed to take out the printing platform and replacing the resin tank. Once everything was cleaned and changed correctly, we started our print and the tank started filling with the cast-able resin. Due to the orange cover of the machine, it looked like a black material.

The next day, Thursday, we returned to take out the print. When opening the cover, we were very suprised with the beautiful, bright, blue colour.

The two pieces printed in cast-able resin

After taking out the prints and taking off the support material, we noticed a clear difference with the non cast-able resin. The cast-able material is a lot softer, stickier and can even bend a little. Even though we were very careful taking off the support structure, we could not avoid scratching the surface a little.

The cleaned cast-able resin prints

Once the pieces were released from the support, we went to the city centre to meet Maaike and discuss the progress.

Resin print samples

We were able to collect our Form 2 resin prints on Monday morning and we are very happy with the results.

Finished pieces hanging on the building platform of the Form 2

Removing the pieces form the building platform with a scaper

It did require some work to clean up the samples but this was very easy to do for such a high quality result. First we soaked the prints in isopropyl alcohol and then we cut away the support material.

Prints soaking in isopropyl alcohol

Cutting away the support material

Cutting away the support material

Cutting away the support material

Now we could actually see very clearly the differences between the raw scanned data of the crown and the digitally re-touched version that we had made.

The hollow inside of the print

Left: retouched version. right: unedited version

We will still need to clean up some of the attachment points for the support material but this gives us a great insight into what the quality and finish is like compared to the Ultimaker printers.

The cast-able resin has also arrived so we will work with Tessa on Wednesday morning to change the resin over and print a sample in this resin to see how it differs from the normal grey resin that we used today.

In the meantime we will work on refining the digitally touched up model and attempt to re-create build the crown digitally in solidworks to see how this looks compared with the raw scanned and digitally touched up versions.

1st Sample Printed, more on the way

We went to see Bertus on Thursday afternoon to see if he had any success 3D printing the scanned crown on the Ultimaker and also to give him an update on the project and what we were planning to do moving forward. Unfortunately the print had failed, so we decided to try splitting the model and printing in two halves. We set this up and then left it to print overnight so that we could check the results in the morning.

The Ultimaker printing one half of the crown

Detail of the printing on the Ultimaker

On Friday morning we met with Tessa to begin printing our samples on the Form2 in normal resin. This was so that we could check the quality of the printer and get some experience with using the Form2 before trying to print our final models in the more expensive cast-able resin. Before the meeting we had prepared our files as per the online tutorials. We edited the support structures so that they would not start at the edge, otherwise the edges could get damaged when we remove the support structure.

Two sample pieces with support structure

We started the Form 2 print going at around 1pm and it said it would take 6 hours to print but Tessa assured us it was okay to leave the print on the machine until Monday.

Form2 printing our sample pieces

After setting the Form 2 print going we went to check on our Ultimaker prints from Bertus.

Finished pieces of the Ultimaker

Crown with the two halves put together

This time the prints came out quite nicely and we now have a full size 3d print of the crown. It is not the highest quality, and we had some warping of the plastic, but it is really good to use this as a representation of the size of the final products we trying to build. If we want to produce a silicon mould from the Ultimaker 3D prints it will require a lot of work sealing the model and getting it prepared fro casting. We look forward to finding out if the Form 2 prints are any easier to prepare for silicon casting.

Hurdles and setbacks

Unfortunately, the company that we ordered the wax filament from had to cancel our order as they no longer had any of this filament and were not able to order in any more of it so we would have to look elsewhere if we wanted it. We spoke with Jouke (our course coordinator) to see if there had been any better results with ordering the cast-able resin but this too was experiencing delays and it did not look like we would get it in time.

We had a phone conference with Maaike on Thursday, 5th of October and let her know that we would not be able to get the samples for Monday and as a result we decided to ask if we could postpone the tests from the casting company. We then discussed with Maaike changing our initial plan of testing to work more with what we currently had available so that we would not have to wait on sourcing and shipping of other materials.

From here it was decided that we would print sample sections of the crown on the Form2 in the standard resin and then test the results of making a silicone mould to produce wax parts for investment casting.

Things are moving quickly

We received an e-mail from Maaike on Monday to ask if we would be able to get samples ready for casting at Groningen by the following Monday. The company she was in contact with had some free time that they could see us and go through the process but there didn’t seem to be too much point travelling there if we didn’t have samples ready for testing. This would mean that we would need to get the cast-able resin and source a printable wax filament by at least Thursday to then have time to print the samples and clean them up ready for Monday the 9th of October. We would also need to crop the scanned crown data to create smaller sample pieces, digitally restore one of these prior to printing and manually restore a sample after printing to be able to compare all of the results.

Our deadlines all changed from our initial meeting but this is something we need to be ready to deal with when it comes to working with industry partners and clients, we would do what we could to get ready in time.

We contacted the Applied Labs and asked when we could book in a time to get an induction for using the Form2 printer and ask about using the wax based filament on their Ultimaker printers. Tessa is the manager of the printing lab area and was very helpful with letting us know where to find all of the tutorial information for using the Form2 printers and running through the introduction for us using the printers ourselves. She also let us know that it was fine to use a different filament on the Ultimaker printers, but that we would have to find out the correct settings for this ourselves. This is what the Form2 printer looks like:

Form2

The wax based filament that we found is called “Moldlay” and it was recommended for use in investment casting. We found a company in the Netherlands that listed this filament on their website and could ship the filament on the same day of order. We placed an order for the filament and continued working on getting everything else ready for Monday. We worked through the tutorials for using the Form2 printer and prepared the digital models for printing samples.

 

Sculpting the 3d models

After scanning the crown on Friday, we took a good look at the result.

Unfortunately, the original crown is quite old and some of the details have been worn off. The following image shows how the loss of details on the ornaments of the crown is clearly visible. Luckily, some sides have more detail than other sides and therefore we know what shape the details have and what we could do to improve them.

The visible loss of detail in the ring of the scanned crown

In addition to the loss of details, the existing paint layer is quite thick and due to the accuracy of the scanner, the lines where the paint was worn off are clearly visible. If the model is printed and cast without smoothening this, the lines will be visible on the cast iron, giving the final product an unwanted finish.

The cracks and paint lines are clearly visible on the model

On top of this, the original structure to mount the crown on the fence is still partially present. Three ‘feet’ were used to stick the crown to the concrete poles. After scanning, the three feet and a bit of concrete is still present in the model. These will have to be removed, since the new way to mount the crown is going to involve a different method.

In order to mount the crown, three feet were added and are still in the scan.

In order to get rid of the paint lines, mounting structure and bring back some of the details, we have a few options during the project. One of the options is to edit the 3D model. Another option would be to retouch the print of the model and depending on the method of casting, the wax can be retouched as well.

We decided to test how hard it would be to digitally retouch the model as this was the most accessible option to begin with. The only problem with this is that most 3d programs do not like the complexity of the model or cannot edit the ‘mesh’ this model consists of. Therefore, we had to search for a program that is able to sculpt 3d models to digitally edit the crown. The following is a list of the programs we used and why they did or did not work for us:

Slicer (Open source: https://www.slicer.org/)

After investigating in a project a few years ago, we read that this project used a CT scan to scan their objects. Using the images, they were able to create a model using Slicer. We hoped that this program also included some modelling options for pre-scanned items, but we were unable to find them.

Meshlab (Open source: http://www.meshlab.net/)

Meshlab is an interesting program for 3d models, since it includes a lot of different filters and options to edit, smoothen and finalise the model. Unfortunately, due to the unfriendly user-interface and the inability to undo actions, simple tasks, such as removing a bump were really difficult.

Geomagic (Wrap) (Trial version: http://www.geomagic.com/en/products/wrap/overview)

Geomagic is a professional program to create scans, edit them and improve models in general. Because this is a professional program, we could only use the trial version. After installing using the “Mesh Doctor”, the limitations appeared. All options were greyed out and you could not save the result.

SculptGL (Open Source: https://stephaneginier.com/sculptgl/)

This web based program was perfect for us. It allowed us to load the object and sculpt it like it is clay by adding, removing and smoothing material. Using this program, we were able to remove the mounts and make the paint layer smoother.

The image below compares the raw scanned crown with the retouch version from SculptGL. Left is before editing and right is after editing. The result is not perfect yet, but the more we can change in the model, the less we have to change once we have a printed version. Bringing back small details is really difficult in the model, so most of the refining has to be done at a later stage.

The comparison between the unaltered model (left) and the edited model (right)

First look at the crown and scanning the model

Today we could finally see the crown in real life! The crown is 14 by 14 by 13 cm large, and quite heavy! It was pretty damaged, just as we expected. A lot of the paint was chipped of and you could see some cracks on the surface. 

Click on the image to get a 360 degrees view!

Top view of the crown

 

Apparently there was a gold layer beneath the paint, which you can still see at some parts. Sadly we do not have enough budget to have gold layers on our reconstructed crowns, so they will be painted.

Bits of the gold paint showing through

When we looked at the crown from up close, we saw that there were a lot of split lines running horizontally from the yellow parts of the crown.

Spit line where two different parts meet

After a quick inspection, it was clear that the crown was casted from six (!) different pieces. We expected it to be one solid piece, so we were surprised about it.

Layout of the different parts

We are going to try to cast it out of one piece, because we would need to make 48 wax or resin moulds otherwise.

One of the problems of the original crowns that they got stolen easily. The crowns had three legs which fit into three holes in the poles. The were glued together with cement. This was not strong enough. We wanted to try a different approach by screwing the crown onto the pole. We will use the knob at the top to attach the screw thread on. We drill a hole with screw thread through the whole length of the crown as well. To prevent someone from unscrewing the knob we will pour glue through the hole of the crown before screwing the knob on.

Possible approach to attach the crown onto the pole

After we discussed some things about the crown we started with the scan. We scanned it in two parts with the Spider.  In the picture you can see the setup.

Set-up

Below is a picture of the raw data and the model. We were very happy with the results. The quality of the scan is really good, you can see the little details like the cracks quite clearly and the paint did not turn out to be a problem.

Raw data of the top part

3D model of the top part of the crown

The underside was scanned as well and the final model can be seen here:

Final 3D model with top and bottom part combined

We did it all in one go so the whole process went extremely smoothly. The 3D model can be saved as an stl file, so we will try to retouch the crown as best as we can. We will try to retouch it with Rhino, if that does not work we will try out other programs.

Playing around with the 3D scanner

Before we can scan the crown and make a 3D model we need to practise with the scanners. Maaike arranged for us a meeting with Bertus Naagen, a staff member at the TU Delft who has a lot of experience with 3D scanning. He introduced us to the two scanners they used at the faculty: the Artec Spider and the Artec Eva. We learned that the Artec Spider is used for larger objects which can be scanned from a larger distance. The Artec Eva is better used for smaller objects to scan in a closer range because it can scan more details.

Artec spider

Artec Eva

With help from Bertus we started with a scan of a statue of a penguin to try out the program and the machine. Both Artecs can be operated by hand but you can also put them on a tripod to reduce shaking. Because we wanted to scan every side of the penguin we used a rotating platform with a stool on top where the penguin could stand on.

Set up with the tripod and rotating platform

It took some practice to get used to the scanning, but at the end of the morning we learned a lot and were able to do a scan on our own. We learned that you have to move the tripod with the machine on it slowly. You have to be careful that all the parts are scanned, but the scan should not be too long otherwise the file is too large to process. If the shape is too complex to scan in one go, you can make two scans and merge them together with the software. We did this with the penguin as well, one scan from the top and one from the bottom and afterwards we aligned the two. We will need to do this for our crown as well if we want all the details to be there on the 3D model. After we made our first scan Bertus showed us how to make a model out of the raw data. We also learned some tricks such as erasing the ground from the scan and putting texture on the model. Once you know the basics, the program is quite easy to use.

After the basic instruction we could play around so we made some more scans, for example this one:

Example of a test 3D scan

3D model of Vivians face

Rohan and his 3D model

We also scanned our own faces which was really awesome. We first tried it with the Artec Spider but that didn’t really work so we switched to the Eva scanner.

Hair has a very fine texture and shines a lot so that is why the scanner could not scan our hair properly. Form Bertus we heard that he had some trouble with scanning shiny objects in the past. Sometimes he sprayed dry shampoo on the objects to make it more matte. We wonder if the crown will be too shiny for the scanner because of the paint. Hopefully it will work out.