2.5.3 STEP3.MAKING THE INITIAL SUPPORTSTHE FIRST FEW RUNS WITH THE L...

4.2.5.3 Step

3.

Making the Initial Supports

The first few runs with the laser are not for the part itself but for small supports that

the actual part will rest upon. The supports can be viewed as small feet, rather like

those on a heavy sofa or piano: they are needed on the bottom of the part to lift the

lowest layer off the floor of the elevator platform. In particular, the supports are

needed:

• So that the Zephyr blade will not hit the platform

• To compensate for platform distortion

• So that it is easier to remove the finished part

• Internal supports are also needed for any "overhanging" structures

When making the supports, after the first laser cured layer is formed, the stage

needs to be pulled down about 12 mm (0.5 inch) for the SLA·5oo(Jacobs, 1992). This

"deep dip" allows the viscous, honeylike fluid to more easily flow over the surface of

the first layer of the supports. The elevator then rises up to be positioned 100 microns

(0.004 inch) below the surface. It is usual to wait about 5 seconds and then do the

laser curing again. This creates the second layer -but

still, this is concerned with the

supports, not the part itself. This procedure repeats until the supporting stubs are

large enough. The operator usually makes these decisions.