Cin-D LOU EyeLids3
Fig.28 - We will now mill away a slot that is centered between the two holes. A short piece of 1/4" wood dowel has been inserted into each of the two holes in the gang of four shorter, and gang of four longer parts. Notice the new parallel beneath the parts that positions the gang higher to have room to mill the slot. The parallel is also thinner than before because we are now clamping groups of four parts rather than eight.
Fig.29 - We need to establish a new Z height at the top surface for the gang of parts. One technique is to bring the Z-axis down while holding a feeler gage in the gap between the tool and the part. A 0.010" thick feeler gage is typically used. Stop when the feeler gage begins to drag when slid back-and-forth inside this gap.
Fig.30 - The spindle Z-axis handwheel has the same style 200 increment (0.200" feed) numbered dial as used on the other axes. Loosen the locking thumbscrew (seen at the bottom of the dial in this view) and position the numbered dial at '190' which is the same 0.010" gap left by the feeler gage. Move the tool off of the part, turn the Z-axis to '0' and the bottom of the tool is now zeroed to the top surface of the parts.
Fig.31 - The slot we are about to make has a fixed size and is centered between the two holes. The vice jaws are opened slightly and the gang of parts is slid so that the first hole centerline is aligned with the left side zero reference on the vice jaws. Simple math using the 0.500" cutter diameter is used to set the centerline of the spindle in the X-direction so that the left edge of the cutter is aligned with what will be the left side of the slot.
Fig.32 - Here a rouging slot has been made in the Y-direction to establish the left and right extremities for the full slot to be. The depth of this slot will be at the part centerline, 0.225" down from the top. Each of these roughing notches was made in four depth passes (at Z = 0.050", 0.100", 0.150", and 0.200") leaving 0.025" on the bottom for finishing. Go slow and make sure your setup is rigid.
Fig.33 - With the ends of the slots defined, go in and waste away the center island of stock to be removed in four passes down to the 0.200" depth. Then carefully make a final depth pass from side to side to finish the full slot at the final 0.225" finish depth.
Fig.34 - Here the finished slot is shown for the first gang of four longer parts (the upper eyelids) while the second gang of four shorter parts (the lower eyelids) are still in the vice.
Fig.35 - With a bit more math, the quarter-rounds can be manually generated in stair-step, etch-a-sketch fashion at the several locations on the part. Ten steps at 0.22" were used to make rounds that are 0.220" in radius (close enough). At each Z-depth there is a corresponding X-advance that produces the stair-step. The excess stair-step material will be removed in a follow-up manual filing operation.
Fig.36 - Finally we can see the fruit of our labor and layout the eight parts we have made. We actually only need four parts (left and right side upper and lower lids, but it is easy and better to make more just in case there is a problem. We are not done yet. The parts still need to be notched and bent.
Fig.37 - Look closely and see the four parts in the upper group have now been notched. A marking pen was used to mark against the full-size paper template where the notches were needed. The notches were produced back on the bandsaw as shown in the following figures.
Fig.38 - The setup for making the notches begins by fashioning a stop block that is a close clearance fit around the bandsaw blade. A cut is made in a strip of brass. The strip is then carefully C-clamped to the table such that only a desired amount of the blade sticks out in front of this stop surface.
Fig.39 - This is a close-in view showing how the miter gage (with a backer-piece extension) is used to hold the part that is about to be notched. The part is slid side-to-side to align the marked location to the bandsaw blade. The miter gage is pushed forward to produce the notch and is stopped when the part contacts the stop block. This setup is actually quite repeatable and easy to do. This view shows notching a test part, not one of the eyelid frames we have been making.
Fig.40 - Another view showing the notches produced with this setup.
Fig.41 - Each of the notched parts is now manually bent into their final curved shape. There is one upper and one lower on the right and left side. It is easy to get reversed and scrap a part at this stage. Use a pair of needle-nosed pliers and the full-size paper template for reference. Take your time and go slow. Don't bend the parts too far too many times.
Fig.42 - This view shows some of the tedious manual operations to finish the eyelid frame parts for good fit and function. It involves some trial-and-error fitting. The reamer from before can be put into a hand drill to dress out the holes. Be careful as it is easy for the part to snag on the reamer and spin in your hands causing damage to the part or personal injury.
Fig.43 - A view showing the nearly finished four parts in relative position when the eyelids are closed.
Fig.44 - A similar view showing the nearly finished four parts in relative position when the eyelids are open
There is more finishing work to do. We still need to epoxy on the ping-pong ball actual eyelids and mount them into the head structure with the R/C servo actuators. This is enough for now to show some typical part making operations on the bandsaw and the mill.
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