OK! We’re seasoned veterans of resin 3D printing already by this point! We’ve printed test models, dialled in all our settings, and can print anything, right?
Sadly, no. There is yet more to learn.
Most free models out there aren’t pre-supported. And sometimes you want to do wacky things like scale a model up or down. And sometimes the presupported models aren’t that happy on your printer.
What we need to do is understand how best to prepare 3D models on the build plate without any supports, in order to get the best, most reliable prints once we add those supports ourselves. And one of those tricks with “best” is to try and ensure that the supports attach to parts of the models that we aren’t as worried about so any dimples caused by removing the supports are noticed least.
And now, we’re into a wierd mix of art, science, and understanding the results on your own printer. Please we very much aware that your mileage may vary!
Angle models to support themselves
One of the key tools when it comes to placing models on the build plate in the slicer software is rotation. You aren’t altering the model – just changing the angles the model sits on the plate. If you can rotate the model so there are fewer isolated sections or overhangs that need to be supported, it significantly reduces problems supporting the model. If generally the models limbs point towards the ground? Printing it with the head near the bottom and the legs higher up means every level attaches to the level below without any additional supports. Even small changes in angle can make a big difference. A characters chin? If it starts away from the neck and below the rest of the head? Well, that will need to be supported. Change the angle so the chin is the same or higher than the rest of the head? Its attached, won’t need supporting in the same way … and is much more likely to print.
The fewer supports needed to give isolated starting points something to attach to, the better.
Angle models to let supports connect to locations that matter less
Removing supports can leave slight blemishes on the output – just like cutting sprues from parts can leave slight blemishes. The supports are tiny, but can be noticeable, particularly on areas like faces or key details.
Think of a model of a person. If its all the other factors are pretty equal, would you place the model face up, or face down? All the supports will attach from the build plate – so you probably want the model facing up to avoid connections on the front and face that you’ll mostly be looking at.
Basically, try to make the most important details face up!
Angle models to avoid them being flat
One real key to making prints successful is to angle the models slightly to reduce the amount of the model being printed with every layer. The smaller each layer is, the less force the print is subject to as every layer is pulled off the release film, and the more likely it is to be successful – too much force could deform the layer – or just pull the print off the supports!
Think of a 40mm x 40mm x 5mm square base for a model. If you angle that, you reduce the surface area on the plate massively! Try an angle of 10-20% – it really does make a huge difference.
Angle models to reduce the height
The higher the models are, the more layers you need to print. More time, more cost, more impact on the life of the screen, more chance the printer gets rocked, or the power cuts. Reducing the height of print makes it more likely to be successful overall.
Try to avoid hollow spheres or the like when printing – instead of pulling a bit of plastic from the base, you effectively make a sucker that sticks the plate to the base! That … will not end well. Angling a model so a hollow cup or basin is sidewise will massively help prints end up well.
Try to have joins towards the bottom of a print, rather than the top
If you have a delicate model, with two legs moving up towards a join, any slight variation in the position of the legs could cause extra tension or cracks in the join. Starting at the join, and then moving up the legs? That’s more likely to be successful as you don’t have the tension of the legs working against the join.
Of course, these all contradict each other. You want to reduce the height of the build, so you lay the model of a person down. You need to ensure its angled to reduce the surface area – so you tilt it up 15% increasing the height! You need to angle it to reduce overhangs – so you tilt it around to have the a pointing arm going up – increasing the height again.
It’s essentially a game of compromises, balancing improvements for the whole print success against smaller detail and cost. It truly is an art. And there are no guarantees of success until you actually print the model.