How to Print Raftless


Raftless printing is an advanced technique you can use to reduce waste, improve the quality of your parts, and generally improve your MakerBot experience. It can be a bit tricky to setup, but once you have it working it is simple to use.

The basic strategy of raftless printing is to print the first outline of the first layer at a much slower speed than normal. This allows even the most difficult outlines to stick to the build surface. Once the first outline is drawn, the rest of the object is built. Getting the first outline to stick 100% is the most critical part of the build and if that fails, then the entire print will fail. It's literally all or nothing.

Step 1: Create a new Profile

You will want to be using the latest version of ReplicatorG, and the latest Skeinforge included in ReplicatorG. As of this writing, that is ReplicatorG 0023 and Skeinforge 35.

This guide assumes you have a properly calibrated and functioning Skeinforge 35 profile. If you do not have your printer working nicely with a raft, then you need to do that first. Only attempt this once you are printing nice models with a raft.

Create a new profile by opening ReplicatorG, opening a 3D model if you need to, and then clicking the 'Generate GCode' button.

This pulls up the 'Choose a skeinforge profile' window. Select the profile you currently use for slicing, and then click 'Create…'. Give your profile a descriptive name and click 'OK'. The Skeinforge configuration screen will then pop up to allow you to modify your profile.

Step 2: Enable Outline

Since raftless printing requires a perfect first outline, we've included the Outline plugin in Skeinforge which draws a box around your object for the first layer. This box 'primes the pump' and gets your extruder in the perfect state for printing the first layer.

Click on the Outline button and make sure the 'Activate Outline' box is checked.

You may experience that you obtain best results by disabling the 'Wipe' checkbox in the 'Wipe' panel.

Step 3: Update your Raft settings

Raftless printing is made possible by adjusting the settings in the Raft plugin. We will still be using the plugin itself, just not to generate a Raft.

  1. Set the "Base Layers (integer)" option to 0 (zero).
  2. Set the "Interface Layers (integer)" option to 0 (zero).
  3. Set the "Object First Layer Feed Rate Infill Multiplier (ratio)" to 1.25.
  4. Set the "Object First Layer Feed Rate Perimeter Multiplier (ratio)" to 0.5.

Step 4: Test Print!

Printing with a Raft is simple, and the raft itself will self correct for Z height irregularities. This is why it is the option we recommend to new operators. Typically, the starting Z height for a raft build is higher than the starting Z height for a raftless build.

Now that you have enabled raftless, its time for a test print. Raftless printing requires you to have your Z height calibrated exactly. The easiest way to do this is to simply print test objects until you have it working.

Coming from a raft based print, your initial Z height will be too high. This is okay, because you need a baseline to work from. Your first test object is pretty much guaranteed to fail, so don't worry. This first print is to gather data so you know how to tweak your build.

In order to fully test your raftless setup, I highly recommend printing an object that has a complex outline geometry. I highly recommend that you use a gear as a test print object. The teeth means your extruder will constantly be changing direction and if the first layer is going to rip up, it will rip up with the gear.

Once you can print a gear flawlessly with Raftless, you'll be able to print anything with raftless.

Step 5: Adjust your Z height

After you have printed the first test object, you may need to adjust your Z height. If you have your Z height set too high on a raftless build, the print will simply not stick and you'll need to try again.

If your Z height is too low, it is very dangerous. You can easily run the nozzle into the build surface and damage it. Be very careful and slowly work your way towards the ideal Z height. It is very important that you be careful.

For testing purposes, it's very easy to adjust your Z height: find the line in your GCode file that looks something like this:

G92 X-57.5 Y-60 Z108.2 (set zero)

This line is what tells ReplicatorG what the current position of the extruder nozzle is after it has moved to each endstop. Changing the Z number will make ReplicatorG start the print at a different height. This parameter is very dangerous. A typo can easily slam the extruder into the build surface.

Also, this parameter is not quite intuitive. Because the numbers tell ReplicatorG what its current position is, changing the numbers has a non-intuitive effect. To be more specific, here is the effect of changing the numbers:

INCREASING the Z, will set the starting layer height LOWER because ReplicatorG thinks its starting from a higher distance.
DECREASING the Z will set the starting layer height HIGHER because ReplicatorG thinks its starting from a lower distance.

Therefore, when you adjust your starting distance DOWN to get your layers to stick, you will need to slightly INCREASE the Z number. I prefer to adjust that number in increments of 0.2mm.

Step 6: Test and Repeat

You can manually adjust the G92 line in your GCode file and then print the file. This will allow you to adjust the Z height without re-slicing the file. Make small adjustments, print the file, and then try again. Once you have the correct G92 settings, open your start.gcode file which is located at: replicatorg-0023/skein_engines/skeinforge-35/skeinforge_application/prefs/YOUR-PROFILE-NAME/alterations/start.gcode

Remember: once you change the start.gcode, you will need to regenerate any GCode for models that you want to print using the Raftless technique.

Step 7: Print and Trim

One of the only downsides to Raftless printing is that the first few layers bulge out slightly. This is because the first layer is slowed down, and Skeinforge has no support for automatically moving the first layer in to compensate. Hopefully it will be fixed in some future version, but for now it is very simple to trim the first layer with an exacto knife to get the proper size.

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