Follow-up to Who Builds Custom Reflectors? Answer: You can.
I got a lathe after starting that thread and getting a quote from Carley which was higher than my budget. (The Carley people are great, by the way.) I've had some fun with the lathe building up my skills, but it was finally time to attempt the real purpose for getting a lathe: cutting a reflector.
I used a Java program to do the iterative trig and geometry calculations for an aparabolic contour. The program takes design parameters (max depth, max width, focal point, amount of spill reinforcement, etc.) then calculates a contour that fits. The program also calculates angled final boring passes (15) and final cuts (300) in terms of my lathe handwheels to facilitate actual turning operations. This design is for a D-sized light; reflector max I.D. is 1.3".
On the left is the look down the barrel. The phosphor of the 1W HD is nicely reflected. Some tool marks are evident. The right provides some perspective on the dimensions. It's much deeper than the usual reflector.
The results are very encouraging. The lathe operations actually went much more quickly than I thought they would, though I was only after prototype quality. It was not especially fun being a human CNC machine! When my daughter distracted me, I lost concentration and nasty, deep tool chatter resulted; gotta tighten my gibs plus sharpen and more rigidly hold my boring tools ... and ship the family to the park for an hour.
I'll be busy the remainder of the day, so beamshot pictures will have to wait. It's got a very bright hotspot (actually too bright so I'll redesign) fading to a controlled dispersion sharply cut off at 40 arc degrees (most reflectors are more like 90) ... well directed without wasting spill.
I got a lathe after starting that thread and getting a quote from Carley which was higher than my budget. (The Carley people are great, by the way.) I've had some fun with the lathe building up my skills, but it was finally time to attempt the real purpose for getting a lathe: cutting a reflector.
I used a Java program to do the iterative trig and geometry calculations for an aparabolic contour. The program takes design parameters (max depth, max width, focal point, amount of spill reinforcement, etc.) then calculates a contour that fits. The program also calculates angled final boring passes (15) and final cuts (300) in terms of my lathe handwheels to facilitate actual turning operations. This design is for a D-sized light; reflector max I.D. is 1.3".
On the left is the look down the barrel. The phosphor of the 1W HD is nicely reflected. Some tool marks are evident. The right provides some perspective on the dimensions. It's much deeper than the usual reflector.
The results are very encouraging. The lathe operations actually went much more quickly than I thought they would, though I was only after prototype quality. It was not especially fun being a human CNC machine! When my daughter distracted me, I lost concentration and nasty, deep tool chatter resulted; gotta tighten my gibs plus sharpen and more rigidly hold my boring tools ... and ship the family to the park for an hour.
I'll be busy the remainder of the day, so beamshot pictures will have to wait. It's got a very bright hotspot (actually too bright so I'll redesign) fading to a controlled dispersion sharply cut off at 40 arc degrees (most reflectors are more like 90) ... well directed without wasting spill.
