I know what your going to tell me about different alloys and different types of the material, but i have a sinkpad and an aluminum star, and need to cut one to 10mm for a light mod, i have scissors that will cut pennies, so is that harder or softer then an aluminum star (low power light, not worth sinkpadding)
Well aluminum like 6061-0 is so soft scratch it with your finger and 7075-T6 well youd better ha e a a bunch if sharp drill bitss or sharp carbide bits in mill it all depends on alloy composition and heat treating don’t know if that helps
I’m assuming that stars are a cheap alloy… That’s why I just took the first Google result.
I think either way, your better off filing it than using scissors though
Sinkpads cut fine with sheet metal snips, I don't know how those compare to your scissors that cut pennies though. I usually chop off the majority with the snips, then file to final size. Marking a center point and using a compass to scribe a true concentric cut line helps a lot.
If we’re talking about PURE aluminum vs PURE copper, pure aluminum is harder than pure copper. I’m not sure exactly what kind of alloy is used for a star. But I’m guessing that, since pure metals have better thermal (and electrical) conductivity than alloys, the aluminum is probably pretty soft, albeit not as soft as copper.
Just realized I didn't actually answer the question... :Sp
Whatever alloy is used in Sinkpads is definitely tougher than whatever alloy is used in aluminum boards.
But I can think of competing arguments both ways as to aluminum MCPCBs being easier/harder than copper to cut with snips. It will cut easier, but being softer it may be more susceptible to deformation near the cut line that could separate the layers on top of the PCB. Best bet on the AL boards is to trim off a little at a time and see how it reacts, then go from there.
the sinkpad is pure copper, the aluminum is a fasttech aluminum star, perhaps the cutting could damage it since the led is already reflowed in place.
PURE aluminum is not used in mcpcbs or flashlight pills, etc, where people keep quote the high thermal conductivity of pure aluminum. Generally these alloys are used 5052 6060 6061 in for pcbs.
I would cut outside the line and file the rest, and bevel the too edge to prevent shorts.
This does bring up a good point. LOTS of people will talk about the high conductivity of aluminum. But aluminum alloys have considerably lower thermal conductivity than pure aluminum. For instance, the ubiquitous 6061 has only 70% of the thermal conductivity of pure aluminum.
Aluminum is softer.
Recently, when I upgraded my X9 I had to cut a copper rod and that was real PITA. I did it with a dremel and a carbon wheel, took forever, heated up fast spend one carbon wheel just for that job…
Question answered.
The Metals Scale of Hardness
Lead - 1.5
Tin - 1.5
Zinc - 2.5
Gold - 2.5 - 3
Silver - 2.5 - 3
Aluminum - 2.5 - 3
Copper - 3
Brass - 3
Bronze - 3
Nickel - 4
Platinum - 4 - 4.5
Steel - 4 - 4.5
Iron - 4.5
Palladium - 4.75
Rhodium - 6
Titanium - 6
Hardened Steel - 7 - 8
Tungsten - 7.5
Tungsten Carbide - 8.5 - 9
So I guess this isn’t suitable for a flashlight but would make a good heat sink.
