Modding Star Diameter

Quick question for anyone that's had to make a star a bit smaller - do you have to insulate the edge where you removed material?

Also, do these stars all have to be electrically isolated from a (conductive) heatsink?

I guess I don't understand how the +/- tabs on the star are isolated from the star itself. I guess they must insulate the star, then add a circuit to the +/- points then insulate the whole over the circuits but not the points?

sorry, really new to this...obviously

If you look at this thread:

post #6, you'll see a picture of an XM-L star that I cut way down to fit in my headlamp.

I saw a diagram on the web once that showed how an mcpcb (metal core printed circuit board) is constructed. There's the metal base, then a thin layer of insulation material, then the circuit traces,then another thin layer of insulation on top, with holes in that layer for the solder pads.

After I cut down my star, I filed the edges to make sure that there were no burrs from the circuit-trace layer touching the metal base. I then used a DMM to check that the traces were not touching the base. I didn't do anything else to the exposed edges.

Oh you may need to scrape away some of the top insulation layer if you want to solder to the circuit traces other than where the original solder pads are.

Because the circuit traces do not touch the metal base, you don't have to electrically isolate the metal base from a heatsink.

+1 do mine the same way, Peteybaby esplaned it well!

superb explanation, suitable for a wiki

off to continue my design w/ one less (very big) unknown

thank you very much!