Screw Head Clearance Holes in Heat Sink

[HarryJ]

I am needing to make clearance holes for screw heads in an aluminum heat sink with fins (see photo). I am going to use a two flute mill to make the holes in the fins down to the heat sink base. Should I make a single plunge pass with a 5/16 end mill or work up to 5/16 diameter using smaller diameter end mills? My concern is bending the thin aluminum fins when the end mill makes contact with the top of the fins.

 

[GrifterGuru]

Line/fill the slots between the fins with some sacrificial wood strips. It helps to stop them deflecting/bending under cutting rotation and pressure.

 

[mmcmdl]

Wax works great for this also .

 

[ChazzC]

Line/fill the slots between the fins with some sacrificial wood strips. It helps to stop them deflecting/bending under cutting rotation and pressure.

Popsicle Sticks or Tongue Depressors

 

[Ulma Doctor]

left over rafts from 3d prints??!

 

[Jeff.64]

It will be loud (been there, done that). In addition to the wood packing between the fins, place a piece of wood on top to the keep the packing strips from vibrating out. Have the packing strips extend above the top of the fins to allow clamping them in place.

 

[HarryJ]

left over rafts from 3d prints??!

Good idea! We have a 3d printer at work. I'll have my boss make some custom spacers for me.

 

[whitmore]

I wouldn't waste 3D printer time on this; howzabout a wad of plaster of paris? Comes
off with warm vinegar... and it doesn't need any foreknowledge of the void to be filled.

 

[ChazzC]

Play-Doh?

 

[homebrewed]

Play-Doh?

Or modelling clay. Over the years I've used it for all kinds of oddball fixturing things. It's oil-based so residue cleans up with solvent.