Retouching the print and receiving the metal samples

Currently we are in the final few days before the Science Fair which will be held this Tuesday. On this day all the groups from the Advanced Prototyping minor will present their work. Even though we got a fair amount of prints and models to show at the fair, we are not quite finished yet.

This morning (Monday) we took out the cast-able resin print we started Friday. We were very happy with the quality of the print, but there is still some room for improvement. That is why we will edit it manually.

A full-size cast-able resin print

After cleaning and taking off the support, we used a dremel tool to start cleaning up the edges. Even though we still have a long way to go, the difference is clearly visible and the lines are getting sharper and more detailed.

Using a Dremel tool on the cast-able resin crown

During the cleaning, we noticed an email from Maaike that she received the casts of the samples we sent to the casters in Groningen. We decided to get them as soon as possible, so we took the first train to The Hague.

The metal samples from Groningen

After receiving the metal pieces we noticed straight away that the marks on the back were not visible anymore! Luckily we cut the pieces a little bit different so with some puzzling we could to figure out which one was which. We also saw that all the pieces are very similar to each other. The digital and manual restoring is visible, but the usage of different materials (cast-able resin or wax from the silicon mould) has little to no influence on the result.

This lack of difference tells us that we can use both methods to restore the crowns, and since both methods differ a lot in time and money, we can choose the most suitable one. This means that we will chose wax instead of cast-able resin, because this is much cheaper.

One other observation we can make is that we still have to work on the details. Due to the casting, the crown will lose a little detail. We therefore have to overcompensate for it, which can be done by continue using the Dremel tool on the cast-able resin print.

For now we will continue to prepare for the Science Fair by making posters and other materials to explain our process as clear as possible to the visitors.

Rebuilt from the ground up

One of the methods for restoration that we wanted to explore was completely rebuilding the crown digitally. We did this in Solidworks by reverse engineering what we could from the existing crown. With this method the details will be much clearer than with digital retouching. However, the historical charm could be lost with a digital made model. That is why we will make a model to see how accurate we can get.

We knew the overall dimensions and could work out many of the angles and curves by taking multiple measurements from a datum point (ie the height and distance to centre).

Unfortunately due to the degradation of the existing crown there were a number of elements that we had no reference point for, such as the flower details that are repeated above the collar of the crown. For this we tried to find examples of similar details in other royal crowns but ultimately had to create our own interpretation of the details and so are not sure if it is accurate compared to the original.

This seemed to be the most challenging part of rebuilding the crown digitally so we started with it and once we had the flower details figured out we moved on to bulking out the rest of the crown. Screenshots of the process can be seen below followed by a digital render of the finished crown.

Although the model is very accurate it still looks very clean and modern. That is why we decided not to use this digital model, but continue with the digitally retouched model from before.

Printing full-size models

At the end of last week, we decided to print a full-size version of the crown. This was a challenge on its own, because the crown barely fits in the print area. After rendering the support structures, some of the material appeared outside the boundaries. Because this material would only have an effect on the bottom of the support, we tried to send it to the printer anyway. Luckily, the software was able to send it to the printer even with some parts sticking out and the printer had no problems starting the print.

After 28 hours of printing, the result turned out perfectly, a beautiful see-through model of the crown was hanging in the printer.

A full-size model of the crown, printed in clear resin

We were very happy with the successful print, since this print was not only meant to show at the science fair, but also to test if the full-size crown could be printed with the more expensive cast-able resin.

Removing the clear print from the support

Due to the transparency of the print, small details are hard to see and because some digital and manual modeling still has to be done, we painted the crown in the red and yellow of the original cast-iron crown.

Painting the clear full-size model

After finishing the digital modeling, we wanted to start a cast-able resin print on Thursday. Unfortunately, the program we normally used to make the models hollow, Netfabb, was not up to the task. After waiting for a long time and trying different methods, we decided to use Windows 3D Builder. This worked a lot quicker, but left some unwanted artifacts in the middle

Luckily, this did not matter for us, since the inside is not used in the casting, so we went on with the process. When we finally imported the model in Preform, the program used for preparing Form2 prints, and made it generate the print file, it got stuck at some point. Maybe due to the size or due to the artifacts, the program just could not prepare the print.

Removing detail from the inside of the model. Most detailed is on the left side and the least detail on the right side

On friday we tried to reduce the file size by removing detail on the inside of the model and removed the artifact by hand. After another long loading time, we tried to generate the print file again, and after a little less than an hour, we were able to upload it to the printer!

Now the printer is still busy printing and it will take 1 day and 7 hours to complete. Hopefully we got a cast-able resin print afterwards that we can use to make a silicon mould from and cast the wax models from.

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 the surface, but not too much. The wax moulds are somewhat smoother than the original printed test pieces. We will send the four wax moulds together with the digitally edited cat-able resin piece to the caster this afternoon and hopefully we will recieve them somewhere next week.

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.