When printing we generally try to avoid a raft as it often adds unnecessary time and cost to the print in addition to sometimes reducing the finish on the bottom of the print. With that being said there are many times where a raft is useful and will improve your overall results. Below is a short list of such cases:
- Tall and skinny objects that may either wobble or have trouble sticking to the platform
- Large flat bottomed objects that have a very strong tendency to warp or not stick
- Objects that you don’t want to have squished into the platform
- Objects that are difficult to remove from the build plate
- Objects with support material directly on the build plate that doesn’t stick well
These objects are being rafted for a variety of reasons and it is important to be aware of some of the very basic settings on rafts that have been exposed in MakerBot Desktop V3.7 as they can completely change your experience when using a raft.
Raft-Model Spacing
This setting controls how close on top of the raft the first layer of the actual print is. Increasing the numbers will make the raft stick to the printed object less well but may result in a stringy looking base of the print. Decreasing the number too far can result in the print fusing to the object too well.
Raft Margin
This setting is one of the most important settings to be aware of when trying to create better adhesion to the build plate either to prevent warping or on a tall and skinny print. This setting is how far out from the edge of the print the raft extends. A small number may be necessary to fit a huge print on a build plate properly. A Large number can drastically improve the ability for a print to stick to the platform as any warpage will often be soaked up by this extra bit of raft rather than your print. If you can’t quite seem to get a large print to stick in one corner, putting it on a raft and adding several mm to the raft margin from default should significantly help with the print, although there may be other underlying issues that are causing the problem.
Base Layers
Increasing the number of base layers can be a great way to get some decent prints out of a printer with a severely uneven print surface. This works by using the initial base layer to create a more level platform for the second base layer to print on. Using too many base layers will significantly add to your print time and cost as they are slow to print being as they require a lot of plastic.
Surface Layers
The surface layers are the layers that sit directly below your actual print. If the surface layers aren’t turning out or are drooping, adding an additional surface layer may help. If the surface layers are drooping confirm you don’t have either really low Interface Density or Base Layer Density as these could pushing the bridging ability of the printer further than needed.
Knowing some of these settings and the basics of how they work should hopefully help you decide if you require a raft and if so help you create a raft that better serves your needs than a standard setting raft.