what size bit for axiz module?

[DKlaser]

I have a sink for a 445 module that needs a hole in the center of it so that I can press the module into it. What size bit are you guys using to get this done? The module mesures 11.90mm or .4685" neither of which are standard sizes.... So help a guy out here.... Are you using a drill press or a boring bar on the lathe to get this done?

 

[123splat]

I have used a 12mm Drill bit in a press with dubious results. The best fit that I've gotten is with a 12mm end-mill in the center chuck of my 7x12 mini lathe. That gives a loose fit that requires a setscrew. I've tried using a .24 (6mm) boring bar, but you really have to watch out for flex of the bar. All of the above available on eBay and at Grizley.com.

 

[kiyoukan]

use a 15/32 drill bit.
If you have a drill press with a bit of vibrations it will come out to being almost perfect you might have to press fit.
I use a 15/32 then use a 12mm reamer if i don want to press fit.
But some 15/32 bits dont need it.
I found using 12mm bits made the hole to large.

 

[Wolfman29]

I found that my 12mm drill bit works perfectly. With just a bit of thermal glue, it's perfect!

 

[Sputnik77]

As kiyoukan said, a 15/32 (11.906mm) works best for the Aixiz modules, as they dont come in at 12mm, just shy. The 15/32 will usually wallow enough to make it just a slip fit.

 

[DKlaser]

Once again you guys know your stuff. The 15/32 bit was perfect. I had to gently press it into the sink and it is definitely tight enough that I do not have to add any type of holding device or compound. Best part is the bit was free, my job rocks!

 

[Sputnik77]

Once again you guys know your stuff. The 15/32 bit was perfect. I had to gently press it into the sink and it is definitely tight enough that I do not have to add any type of holding device or compound. Best part is the bit was free, my job rocks!

A bit of thermal compound would still be a good idea. The contact of the module on a hole that was cut to size with a drill will not be all that ideal. A reamed hole is necessary for that type of fit. Especially since you running a high power 445!! It doesnt hurt.

If you had an accurate way of measuring the hole, you would find its only making contact at 3 points around the circumference. A typical 2 flute 118deg point jobber style drill will actually cut a triangular-ish hole.

 

[kiyoukan]

That is true, a 12mm reamer helps but that only takes more materiel away so even more of a need for thermal compound.
and its a good idea to put the compound on the threads of tail end of the aixiz housing. to help the heat transfer to the back half of the aixiz housing and into the heatsink.
If you want to go crazy like i do put thermal compound on the diode before you press it in.
Not alot is needed but it makes sure that there are no gaps.
Heat besides ESD is the number 1 risk of killing a diode.
Honestly ive thought about buying a ton of copper ones.

 

[Sputnik77]

That is true, a 12mm reamer helps but that only takes more materiel away so even more of a need for thermal compound.
and its a good idea to put the compound on the threads of tail end of the aixiz housing. to help the heat transfer to the back half of the aixiz housing and into the heatsink.
If you want to go crazy like i do put thermal compound on the diode before you press it in.
Not alot is needed but it makes sure that there are no gaps.
Heat besides ESD is the number 1 risk of killing a diode.
Honestly ive thought about buying a ton of copper ones.

You can buy "over/under" reamers. An "under" 12mm reamer would probably be spot on. Or an expanding reamer for that range of hole. You can get them fairly cheap.

Compound is always a good idea, and sometimes, the difference in heat transfer to the case, with compound, is enough to actually feel with your hand. At least as a function of time, you may feel it get hotter, quicker. it would eventually level out.

 

[Hemlock_Mike]

Two flute drill bits don't drill a round hole. The reamer is best if you can afford it but compound and a set screw works good for me.
I've never tried a 4 flute end mill however.
HMike

 

[Sputnik77]

Two flute drill bits don't drill a round hole. The reamer is best if you can afford it but compound and a set screw works good for me.
I've never tried a 4 flute end mill however.
HMike

An end mill is better, however with a plunge type cut, they can still create holes that more resemble a polygon than a circle. The more rigid the tool the better, carbide end mills or drills for instance. This is partly due to the spiral flute design of drills and endmills. This is why reamers use a straight flute. Its also why boring, with a single cutting edge tool is the most accurate at creating a round hole, and the most preferred method in actual manufacturing industry , whatever size the hole may be.

However, most of the time, a drilled hole will suffice for this kind of stuff.

 

[DKlaser]

I went ahead and pressed it out and added thermal compound. Good thing too because I suspect that thing is getting HOT. It metered @ 2419mw tonight.