Re: Scored a Nice 16" Parabolic Reflector. HID or Short Arc? Test Beamshots w/ HID.
I figured out the necessary dimensions to mount the lamp and center the arc at the reflector's focal point.
The arc location is 1.575" (40 mm) from the face of the lamp's Anode end. The parabola has an externally threaded mounting sleeve that was not shown in the original drawing, but is sketched in, below.
This drawing is marked up to reference the arc location to the rear flange of that mounting sleeve.
A 2" schedule 40 PVC pipe is a slight interference fit with the smooth ID of that threaded sleeve. So, I can use the PVC as the first layer of HV isolation, between the lamp adjuster and the reflector/frame assembly. This will enable gross tuning of lamp center, to enable a range of lamp sizes to be fitted.
I think, with a little creativity, I
will be able to use the x,y,z mirror stage from the lamp housing as my lamp adjuster.
Here it is disassembled, below. The part on the left is the part that moves in and out, z axis. The tilting stage (x,y) is on the bottom of that, barely visible through the hole and under the bottom edge.
The part on the right is the rear cap, upside-down in this view:
Here is the x,y stage removed from the end of the z axis piece:
Remember that the positioning stage had no airpath. Well, it does now. Almost. I turned down part of the OD to allow annular airflow. Then I cut a path in the front face to spread air out in the gap between the z axis part, and the x,y part:
Finally, I hogged out a few gaps between key features I can't ruin, from the outer lip around the front face. The result is an air path to feed cooling flow from a fan mounted to the side of the mounting tube, to the back of the x,y stage.
Below is a VERY rough approximation of how the parts will interface. Note that the main mounting tube, a piece of 2" PVC, is NOT shown here. It will be attached to the flange of the 'top hat' in this picture, and will cover the whole assembly, except for about 0.5" of the heatsink. There will be clearance inside that tube for the guts to move.
A small blower will be located on the side closest to the camera, mounted to a hole in the (not shown) outer PVC mounting tube. The PVC shown here represents the 2nd layer of HV isolation, to which the heat sink and lamp assembly will be mounted. I might use Delrin or Nylon instead, but you get the idea.
The heat sink will wind up only about 2" long and will be partly nested inside the insulation piece:
I still need to drill holes in the x,y stage to feed air to the back of the heat sink.
Here is the 12v blower I found. It is 3" across by about 1" thick, quiet, and powerful enough for this task, I think:
Next, I need to figure out how, exactly, I am going to mount the whole thing to the reflector such that there is room for the adjustment range, and airflow. Then, machine a suitable heat sink from that giant donor, above, and start putting it all together.