Use grinder to shape heatsink?

the toughest part for me when modding lights is creating a heatsink. they often arent simple drop-ins.

can i use a bench grinder to grind aluminum heatsinks to proper size? (i want to use 2"x2" shallow finned sinks, and grind them down to 36m round)

i am aware that aluminum can be tricky to work with, but obviously have little knowlege. (i know that drilling requires low rpm and oil)

any suggestions on technique/grit, etc???

thanks,
Bob

Carburundum wheels and aluminum do nasty things, the aluminum is soft enough it will fill the gaps on the wheel with smear that wont have any abrasive action I use either carbide bits or fiberglass cut off discs to shape aluminum. In factories there are even signs warning NOT to grind aluminum on them sometimes they have a specific grinder just for aluminum. if there is a centered hole in the soon to be heatsink run a screw through it secure it with a nut to prevent rotation on the screw and chuck it in a drill press and use a file to reduce its OD

so, perhaps a dremel with carbide bit or fiberglass cutoff disc might work?

Bob

ps i have some Planter's for ya if you would like to make me some 36mm heatsinks!

it's possible, but it also depends.

the main thing you need to look at is how it will be sinking the heat.
will the heat be transfered to the body on the sides, or the top or bottom?

if it's going inside a maglite, and transferring heat via the sides then you're not going to get very good results with a grinder, because you wont' be able to make a perfect circle so that it contacts the mag body at all points.

if the contact point is the bottom of the heatsink (lets say an aluminum disc that goes ontop of a minimag tube for example) then being a perfect circle isn't necessary, because it just needs to mate on the bottom.

Simplest method; scribe diameter, use mini hacksaw to cut away excess then file to scribe line. You can keep diameter true (almost) by setting heat sink low in vise and use top of jaws as eyeball guage.

If you have a vertical belt sander (or access to one) you can get very good round shapes with true sides, I use 80 Grit zircon belts on mine with excellent results. Also be careful, things get very hot very quickly.

Large quanities; epoxy heat sinks to junked auto valve stems or steel slugs and turn on lathe, remove by heating in oven (when Momma ain't lookin'). Clean up remaining epoxy with Methyl Chloride paint remover.

To make something round by hand grinding/sanding:

glue a round object to the work piece. like a checker piece.

add a bar to the grinder/sander 's work table that is shorter than the round object you glued to the workpiece.

by putting the round object up against the bar, you limit how much you can grind/sand off. To adjust the size of the finished workpiece, adjust the position of the bar on the grinder/sander 's work table.

Work slowly, rotating the workpiece to get all sides.

be careful.

Dremels solve all problems not immediately resolvable through the use of high-explosives, duct tape or JB Weld. Yes, an emery wheel on a dremel works quite nicely on aluminium (but is also quite delicate - you'll break quite a few of them before you get the part properly shaped ). Use the fiberglass wheel to get your rough shape, then use the emery wheel for finer adjustments to shape and finish. The emery wheel won't load up with Al because it wears away into dust while grinding and therefore doesn't clog.