Depending on your printer’s build surface size, you may have difficulty printing a keyguard for a larger tablet. The keyguard designer lets you split your keyguard design into two parts that you can print separately and then glue together. The keyguard designer tries to be smart about where it cuts, but it also lets you specify exactly where you’d like the cut.
Let’s say that you’ve designed a new keyguard, and it looks like this:
Unfortunately, when you load the STL file into your slicer, you see that it is larger than your build surface, no matter how you rotate the model.
You provide instructions regarding how your keyguard should be split using the Split Keyguard Info section of the Customizer:
If you leave the “split line location” value at “0”, the designer will attempt to automatically split your keyguard design into two parts. It chooses a line as close to the center of the keyguard as possible, between two columns (or two rows if the keyguard is oriented in portrait mode), leaving you with the largest possible surface to apply your adhesive. The specific location of the cut depends on whether your grid has an even or odd number of columns; for a keyguard in portrait orientation, the decision would be based on the number of rows.
The “show split line” option will give you a good idea of where the design will be split. If you set the value to “yes,” you’ll see something like this:
If you look in the Console pane, you’ll see a line of text that looks something like this:
If instead, the design had an odd number of columns, the designer would place the cut here:
If you look in the Console pane, you’ll see a line of text that looks something like this:
It can be helpful to compare these measurements to the size of the print surface of your printer to ensure that you’ll be able to fit both pieces on your printer.
You can manually set the split location wherever you want by setting the “split line location” value to something other than “0”. Note that the measurement is relative to the middle of the keyguard.
Be sure to set “show split line” to “no” before rendering your design.
You perform the cut by choosing “first half of keyguard” (or “second half of keyguard”) from the “generate” pull-down of the “Keyguard Basics” section.
A new image will appear that looks like this:
Go ahead and generate the STL file as you normally would.
Now choose “second half of keyguard” from the same menu, and a different image will appear:
Again, generate the STL file.
Print print each of these pieces and then glue them together. We prefer a two-part epoxy for this purpose, but you may have success with super glue.
Note that the thicker the keyguard, the more surface area you can glue. Thin points, such as those at the top or bottom of the keyguard, due to exposure of the message and command bars, may be very difficult to glue and may never come together securely.
Joining Your Keyguard Halves with Dovetails
By default, the designer splits your keyguard with a simple straight cut, resulting in two flat surfaces that can be glued together. As an alternative, you can choose “dovetails”:
Dovetails are often used to join two pieces of wood:
You can see that each part of the joint looks “kind of” like the tail of a bird. Dovetails are used in carpentry to create a very solid and strong joint. You can choose this option to create a strong joint between the two halves of your keyguard, as well:
Dovetail joints work best with rails that are at least 6 millimeters wide, but can be used with rails as thin as 4 millimeters. If you choose to split your keyguard with dovetails, you’ll need to choose some additional options:
You can choose the width of the dovetails and how tight or loose the joint will be. The smaller the dovetail gap, the tighter the two halves will fit. You may not even need to use glue to attach the halves. On the other hand, you may need a looser joint if your printer overextrudes slightly or is slightly less accurate. A loose joint also allows room for glue. Note that adjustments to the tightness affect only the second half of the keyguard, so that’s the only part that you need to re-print if you make an adjustment.
Sliding the Dovetails Vertically
Depending on the dimensions of your keyguard and the dovetail width that you select, you may end up with small parts of your design that are entirely disconnected or are hanging on by a thread:
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This will occur at the top or bottom of the keyguard, or at the top or bottom of an opening cut into the keyguard.
You may be able to fix these problems by sliding the entire set of dovetails up or down slightly.
How to Quickly Determine the Best Dovetail Joint Tightness
The “natural” tightness of the dovetail joints you create will depend on the characteristics of your printer – its dimensional accuracy and the degree to which it over- or underextrudes filament.
It would be slow and expensive if you had to repeatedly print your entire keyguard with different values for joint tightness until you get just the joint you want. You can shortcut the process by printing a small “test” keyguard instead. Follow these instructions:
- Set Tablet Case > have a case to yes
- Set Tablet Case > height of opening in case to 104
- Set Tablet Case > width of opening in case to 100
- Set Grid Info > number of columns to 0
- Optionally, set Keyguard Basics > keyguard thickness to 4
- Set Special Actions and Settings > split line type to dovetails
- Set Special Actions and Settings > approx dovetail width to 4
- Set Keyguard Basics > generate to “first half of keyguard”
- Render/Print
- Set Keyguard Basics > generate to “second half of keyguard”
- Render/Print
- If the joint is just right, STOP! Use the current value for tightness of dovetail joint for your full-size keyguard (and write down the value for future use).
or
If the joint is too tight, reduce the value of Split Keyguard Info > tightness of dovetail joint and go back to step 10.
or
If the joint is too loose, increase the value of Split Keyguard Info > tightness of dovetail joint and go back to step 10.
You should be able to use this same value for all keyguards you split using dovetails.