As promised in last week’s post this week I’m going to share with you how to identify if your 3D printed model has been printed correctly.
So what do I mean by correctly printed? Back in October of 2017, in a post which you can find here, I shared with you the new feature from Shapeways which allows the orientation of the print to be set. This means parts such as a locomotive shell can be printed with the roof on top ensuring the smoothest detail, rather than upside down like a bath tub.
However sometimes, even though the print orientation has been set, some models slip through the printer’s checks and get printed in a cost-saving way; this normally means upside-down. But how can you tell? Well, there are a few tell-tale signs which are caused by the print process which give away the orientation of the print. These signs can be seen when the model is first delivered but given the transparent nature of the material it is fairly hard to spot and nearly impossible to photograph.
So the first thing I always do with any model is soak them in Goo Gone for 24 hours, which makes them opaque, rinse them under warm water and leave to dry for another 24 hours. Below you can see a set of Alco C-855 shells which have been through this process. These shells were ordered with the print orientation set so they printed the right way up and at first glance they look good.
But a closer inspection reveals they have been printed upside-down.
The first clue is the direction of the print shadow. The print shadow is the area under a section which sticks out. In order to print this section support material is required to literally support it. However, where this support material comes into contact with the actual model it leaves a slighty rougher finish which is called the print shadow. For example, in the image below you can see the print shadow running up from the bolt detail around the base, which means the model was printed upside-down. As the bolt detail protrudes out from the base a bit of support material was required under it. Also looking at the doors and vents on the side of the body you can see these were also covered in support material in order to print the base which also projects out further.
This effect is repeated on the rear as shown below.
The second clue is the inside of the model. In the picture below you can see all the detail is crisp and smooth. This is because it hasn’t come into any contact with support material. This is the best finish on the model and sadly it’s the one location where it’s not needed.
The third clue is the actual top of the model. It should be smooth, like the inside, but as you can see it’s rougher and ‘furry’ with support material residue which has turned into powder because of the Goo Gone. The whole of the top of the model has been submerged in support material, because the model was printed upside-down instead of the right way up as requested in the orientation setting.
Now, these shells are not bad and the powder residue can easily be removed with a soft brush in a Dremel style tool, or by hand with a brush, leaving you with a good model. But the surfaces which should have been on top will never be as good as the finish on the inside and areas such as the doors and vents will also be a bit rougher.
So what should it look like? Below is another set of Alco C-855 shells. You can see that after the cleaning process the finish on the outside is not all the same colour. This is because a lot of the surface hasn’t come into contact with support material, as we wanted.
There is still a print shadow effect but this time it’s running down the model and not up.
The doors and vents still have some print shadow but only in a few areas such as the recess for door hinges etc.
The inside of the shell is rougher and covered in print shadow, as we would expect as it was full of support material.
The top is smooth and very well detailed which will show up when the shells are painted. In the pictures they look rough or lined but this is simply where the Goo Gone has not affected any support material residue and the surface is still a bit transparent.
Hopefully this will help you identify if a model has been printed in the correct orientation or not. But what should you do if yours arrives and you think it was printed the wrong way up?
Firstly check to make sure the model was designed to have the orientation set. I can’t speak for other designs but my models will state this in the description if it has been set and I can always confirm if you want to contact me and check. As for the Alco C-855 shells you need to purchase the Deluxe version as it’s not set on the standard.
Secondly, take some pictures of the incorrect model showing things like the print shadow running the wrong way. Then send an email to Shapeways at firstname.lastname@example.org. Include your order number, photos and let them know the model you received has not been printed in the correct orientation. Please note: this must be done within ten days of receiving the model. Their customer service team are quick to respond and will organize a re-print of the model if indeed it was printed wrongly. But again, you only have ten days from the time you receive your print.
As I said before any excess powder will need to be cleaned off and you will find the detail is good underneath it. You also need to clean this off otherwise any paint applied will flake off as the powder is loose.
You may also be wondering what I’m doing with so many Alco C-855 shells? These are for a fellow modeller and I’m making a fully powered ready to run A-B-A set for them. And I intend to share the whole build process with you in a set of posts which should be starting very soon.