Mirroring with Flip Along
For new students of SketchUp, the Flip Along command is one of the most confusing. Yet, it is a feature that is difficult to avoid in woodworking, as we continually “flip” or mirror components in our furniture. For example, all four legs of a table may be identical except for the orientation of the joinery. Flipping performs a mirroring operation which properly orients one leg design for all four unique locations. Having one component that works in all positions is extremely powerful and time saving.
Just in case you are thinking “rotation” – the rotate tool is not an alternative. A “rotation” does not mirror, therefore does not accomplish the desired result.
One thing contributes to the confusion with Flip Along – that is, there are three alternatives to every flip. Do you flip along the red, green, or blue axis? You have to make a choice, and It’s not always clear which one to pick.
The following shows how to perform flips using a small stool as an example. This stool, with only six unique components, has thirteen total pieces. Flip along produces all those extra pieces.
Here is the assembled view of the stool. Both rails and legs are flipped however, I will show the flipping on legs only.
Step 1: Here is the one leg component which will be flipped into all four positions. This particular leg is the left front leg.
Step 2: The separation of the front legs is 10 3/4-in. Therefore, I use the tape measure tool to create a guide line to help me position the front right leg. To make the guide line click the tape measure tool on one of the inside vertical edges of the left leg, then drag the parallel guide down the red axis. Type 10 3/4 and tap the enter key.
Step 2: With the move/copy tool, click on the left leg and tap the Ctrl key. Drag the copied leg down the red axis. When it attaches to the guide line, click the mouse to fix the position of the copy. Note that you should start the move/copy on the upper left hand corner of the left leg. This is the corner that needs to stop on the guide line.
This copied leg is in the right location, but is not oriented properly as evidenced by the mortise locations.
Step 3: In this step we use the flip along command to mirror or properly orient the leg. Right click on the copied leg to the right. Pick the Flip along command and another box appears offering the alternatives of red, green, or blue axis. We moved the copy down the red axis, so choose the red alternative.
Note that the mortises are now oriented properly.
Step 4: To create the rear legs, we will again use copy and flip. The separation of the legs in the green axis direction is 7-in. Therefore, place a guide line this distance from the inner edge of the front leg.
Step 5: Select both of the front legs (use select tool along with Shift Key). Pick the move/copy tool and tap the Ctrl key to make copies. Move the copies down the green axis. Stop when the copies attach to the guide line. Again, it helps to click the move tool on the upper right hand corner of the front leg. As this is the corner that needs to attach to the guide line.
Note again that the rear legs are in the right position, but the mortises are not properly oriented.
Step 6: This step “flips” the two rear legs to properly mirror and orient the mortises. Select both rear legs (use the Shift Key with the select tool). Right click on one of the selected legs and pick the Flip along command. Select the green axis for the flip in this case, since we moved the copies originally in the green direction.
With one leg design, we’ve got a full complement of legs, all with joinery properly oriented. If I change (edit the component) any one of these legs, all the copies are instantly updated with the change, and the changes are all properly oriented.
I still remember the first time I uncovered the mystery of flip along, and recognized how powerful this was going to be.