The maximum light output of the Wintech projector used in the Ember printer varies from unit to unit. At the factory the projector in an Ember printer is adjusted so that all projectors have the same output (roughly 22.5 mW/cm2). This allows the same printer settings to be used across all Ember printers. As a consequence most printers can be "overclocked" by adjusting the projector settings to get more power out of the projector.
There are several advantages of doing this:
1) More power = faster printing
2) Control. A user can adjust the light intensity to compensate for changes in the optical system. These changes are primarily due to the PDMS, as the output of LED/DMD is very stable for months running continuously.
3) ??? The lightcrafter software allows access to the projector and some additional functionality. I am sure there is something here interesting. One could also access to HDMI feed to the projector as well.
Note, you may want to do the more torque modification while you have the printer open.
Drill (1/2" bit)
2 mm hex key
Mini-USB cable (included with Ember)
4 mm hex key (optional)
Disk sander (optional)
Step 1: First We Clean
There is always a bit of resin on the build head and in the nooks and crannies around the resin tray. Now is a good time to clean it up, so that resin is not transferred to your tools and computer.
Step 2: Removing Ember's Back Panel
Six 2 mm allen keys hold the back panel on. Remove these and lift the panel off to reveal Embers guts.
Step 3: A Little Strategic Surgery
To access the Mini-USB receptacle a bit of plastic needs removed from the body. This is easily accomplished by cutting a notch with a sharp knife. The EMI shield can be cut with a pair of wire cutters (the metal is very soft) and folded out of the way with wire cutters. There is also a bit of interference between the Mini-USB plug and the HDMI cable, but nothing a disk sander can't solve.
Step 4: Break Out the Drill
If you have gone to this much work, it is worth the time to drill a hole in the back panel so the plug can be easily accessed. I have included a template marking the hole. My initial attempt was a little off, but this one should be spot on. A 1/2 inch hole was a little tight, but worked. In the future I would tape off the back of the panel to avoid marring the paint on the panel. After connecting the USB cable the panel can be put back on.
Step 5: Accessing the LED Driver
After the printer is re-assembled the next step is to download and install Lightcrafter. This requires creating an account with TI and promising not to distribute the software to those "Axis-of-evil" types. After that its simply a matter of firing up the software. Click "Get" in "LED Driver Control" and note the value. If this value is less than 255 setting the value of blue channel to 255 will result in an increase in the light intensity.
Step 6: Measure (optional)
In the case of this printer the initial output was 22.5 mW/cm2 (the factory default). Setting the blue channel increased the light intensity to 27.2 mW/cm2, which is definitely enough to make a difference in exposure time settings.
Note, if you are using an ILT1400 with a SEL005 probe the build arm will need to be removed. If you are using a G&R labs radiometer, just the build head needs to be removed. Fabricating a tray just for this purpose is handy if you have a lot of printers.
Step 7: Appendix: How Does the Light Intensity Change (and How Does the Greyscale Values Fit In)
The relationship between the LED current and the light intensity is approximately 2nd order. The other two plots are from an alpha model machine and show the 4th order variation with image greyscale values. This is a consequence of the DLP being designed with human vision in mind.