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aluminium heatsinks - drill bits


bleoberis

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I'm currently attempting to mount a pcb to a mid-sizes heatsink & drilling holes using a makita hammer drill and some standard makita drill bits. Only problem is - the heatsink isn't like a standard hammond thin chassis, so the drill slides a little on the surface of the thick panel and doesn't 'catch' to even commence drilling a proper hole.

What are the best drill bits to use? Titanium?

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I'm currently attempting to mount a pcb to a mid-sizes heatsink & drilling holes using a makita hammer drill and some standard makita drill bits. Only problem is - the heatsink isn't like a standard hammond thin chassis, so the drill slides a little on the surface of the thick panel and doesn't 'catch' to even commence drilling a proper hole.

What are the best drill bits to use? Titanium?

punch it with a nail or screws, deep enough for the bit to sit on and drill away :D

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+1 agreed with the above 2 post, then use a smaller bit before using the larger correct bit, works every time as aluminium is soft, as long as its a decent brand bit no need to go to titanium.

 

Practice makes perfect, even try it something else 1st b4 you do this on the genuine article.

Edited by pchan
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Yes, use a centre punch or similar. Also, when tapping aluminium, use a little metho as a lubricant, and clear the aluminium chips from the tap frequently by backing off the tap 1/4 - 1/2 turn. Makes life much easier :-)

Regards,

SS

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Does your drill only have a hammer setting as this might be your problem!

 

Any decent HSS drill bits will work ($40-60 a full set). Don't buy cheap ones as the cutting angle and face are generally useless.

 

Just saw your using Makita bits! They may need sharpening also but I'd lean more to the hammer problem.

Edited by bjc
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I'm actually learning something here, what is a centre punch? 

 

my last holes were the neutrik holes on my alum chassis for my NC1200, the screws did very well for me :D

 

to be clear this is what i did :

 

1. Create a layout print on A4, put on top of the panels and stick it together.

2. Punch the crosshair (i made it on my printing) with screws until about 0.5-1mm deep.

3. Use 3mm bit to make a pilot hole (later change to 10mm to make it faster)

4. Use Step drill bit on my Drill Press.

 

now, if i had the size for it (which is 25mm), i'd rather just drill straight with metal drill bit.

 

i hope this helps :)

Edited by henry218
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Hmm I think you're joking Henry? :D

 

Anyway, here's a pic of an adjustable automatic centre punch. Put the tip on the workpiece and press down. A spring loaded weight shoots down internally and hits the punch end, which leaves a dimple in the surface. A manual type that you hit with a hammer works just as well.

 

 

Cheers!

 

SS

post-133526-0-24006300-1404087297_thumb.

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Hmm I think you're joking Henry? :D

 

Anyway, here's a pic of an adjustable automatic centre punch. Put the tip on the workpiece and press down. A spring loaded weight shoots down internally and hits the punch end, which leaves a dimple in the surface. A manual type that you hit with a hammer works just as well.

 

 

Cheers!

 

SS

ok, so it works similarly to nail punch for the timber floors? :D

 

what I'm wondering is, how does that makes anything centres??? its just because of the bigger butt so you can hammer easily? the button 10G screws is big enough for the hammer too :P

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Here's a pic of a fan forced load bank that I made, where I used it for marking the holes. The load bank is for work, but it just so happens to consist of 8 x 1 ohm resistors, wired in 2 banks of 4... can sink 500 watts continuous :D :D :D

post-133526-0-45364000-1404087626_thumb.

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oh i get it now, so you use the item that you want to mount itself to mark the holes :)

 

at times when its not possible, printout with layout of the holes is the best route. i can't use those centre punch to marks the holes for my PSU & NC1200 mountings, the centre hole for my neutriks too :D:P

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Hi Henry,

 

The holes are marked out in the usual manner and then punched with a punch, which is pretty much identical a sharp nail punch (unless it's the automatic type). I'm fortunate to have a surface table and surface vernier height gauge available, which makes it easier and more accurate.

 

The old screw or nail often work just as well as a centre punch, but they may work better if you grind a shallower angle on the tip, so that it is not as sharp.

 

Cheers!

 

SS

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Hi Henry,

 

The holes are marked out in the usual manner and then punched with a punch, which is pretty much identical a sharp nail punch (unless it's the automatic type). I'm fortunate to have a surface table and surface vernier height gauge available, which makes it easier and more accurate.

 

The old screw or nail often work just as well as a centre punch, but they may work better if you grind a shallower angle on the tip, so that it is not as sharp.

 

Cheers!

 

SS

ah, ok. great info. 

 

cheers

Henry

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If not for all the years that have been wasted by people trying to hammer in screws using a spanner, we'd have colonies on Mars today!

 

Well if I dont have a hammer, Im not going to use my fist... :D    Thats OHS abuse... :P  However my head is harder....

Edited by pchan
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If you drill a lot of heatsinks, a drill press is essential. Not only will it drill straight but you will put much less wear on your drill bits and it's faster. I use a cheap $80 Ozito one from Bunnings and it's perfect for the job. A cheap press will have a fair bit of run-out so still center punch. I'm using WD40 as a lubricant when drilling/tapping aluminium.

 

Here's a pic of a fan forced load bank that I made, where I used it for marking the holes. The load bank is for work, but it just so happens to consist of 8 x 1 ohm resistors, wired in 2 banks of 4... can sink 500 watts continuous :D :D :D

How about a 2400W programmable load:

12319074083_c234895fc5_o.jpg

Well it's actually only 1600W effective, but there are 2400W of resistors :P. There are two 800W 4ohm banks and two 400W 4ohm banks, this way you get 1600W power handling at 1,2,4,8 and 16ohm.

Edited by TMM
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