The part is scanned or photographed
The image is imported in Quad2Dat, and scaled
properly. The finger edge is covered with quads.
is not used here, you can avoid displaying it (in
menu View > Options, go to Display tab and uncheck
Important tip: Quad2Dat
has the bad habit of crashing when you save. So
save often, using different names (since the crash
occur when you save, you may get only a partial
file and loose all your previous work).
Export your work as a LDraw file. Edit it (using
either LDDesignPad or MLCad) to remove
the template part. Translate the finger to the top
at Y = -7 (Edit>Select>All, then click on
the "Enter position rotation" icon, and
type -7 in Y box)
Using LDDesignPad, inline any primitive used
(we'll later use Edger
to find edges around the shape, and Edger does't
process primitives). Note: for rounding errors it
may be even better to "explode" primitives
within Quad2Dat before exporting the .dat file.
The tip of the part is thinner so we need to
rotate it by a few degrees, using MLCad. First the
rotation origin is set to the base of the finger
(X=8, Y=-7, Z=52.5).
We then rotate the shape. Select it (Edit>Select>All),
then click on the "Enter position rotation"
icon. The dialog box shown on the left will open.
We use the rotation around a vector. The rotation
vector is chosen to be approximately perpendicular
to the finger. A 3° angle gives a correct slope.
Alternatively you could perform this rotation
using regular X-Y-Z rotation by first aligning the
finger with the X axis (a 30° rotation around
Y), then rotate 3° around Z axis, then restore
the orientation with a 30° rotation around Y
in the opposite direction.
The next step is to draw an edge line around
the shape. Edger is the tool of choice here (see
setup Edger as an LDDP plugin). Run
Edger on previous file, and open Edger-result.dat
file in LDDP. Get rid of all conditional lines created
by Edger, only the edge lines are useful here (though
the surface is flat, rounding errors during the
rotation operation leads Edger to generate conditional
Notice that there are unwanted lines around the
ring primitive, once again caused by rounding errors
(this could be avoided by exploding the primitive
in Quad2Dat). We get rid of them using MLCad. First
change all line colors from white (15) to edge color
(24) to see something on the white background, then
select and delete unwanted lines.
is now needed to create the sides of the shape.
Assuming you put a copy of Ytruder
in your job folder containing all tutorial files,
the command line is:
Ytruder -s 0 50914-tip4.dat 50914-tip5.dat
since we do an extrusion symmetrical across plane
Note that regular lines are correctly generated
instead of conditional lines when there is a sharp
bend in the shape.
we merge the top surface, side surface and top edge
line in a single file. Be sure to insert comments
between sections to later recognize them.
It's time to have a look at facet orientation.
Insert a "0 BFC CERTIFY CCW" statement
and check with LDView using red/green
BFC mode. We see that the side is backwards, in
LDDP select all text lines in side surface section
and reverse their winding (Tools > Reverse Winding).
File: 50914-tip6.dat (before winding inversion)
Still within LDDP,
we now create bottom surface. Copy the top surface
and top edge line sections. Edit the comments appropriately.
Select the duplicated sections and mirror them (Tools
> Mirror Lines on > Y Axis). Since mirroring
a facet reverses its winding, select the bottom
surface section and reverse its winding (Tools >
We now need to create the middle sheet, and first
the edges where it meets the ribs. In MLCad,
open top edge line file (50914-tip4.dat) and remove
all outside lines, keeping only those bordering
The middle sheet is flat, while the lines we
have are leaning towards the tip. Using MLCad
the lines are projected onto plane Y=0. Select everything
(Edit>Select>All), then click on the "Enter
position rotation" icon. Fill the dialog box
as shown (all three Y coefficient of the rotation
matrix are set to 0). The flattened lines are then
translated to plane Y=-2, then duplicated to plane
the middle lines are appended to the main file
Finally, using MLCad we
add two surfaces that covers all the middle cells.
Since the part is not transparent, no attempt is
done to follow the edges exactly, resulting in a
minimum quads number. Should the exact surface be
needed, we could draw it using Quad2Dat,
rotate and flatten it the same way we
did for the middle lines.