Millett "Starving Student" hybrid amp - Page 226

Thanks Zkool.
I've ordered both the 2" and 1.5" ones, to make sure about heat. I'm really not sure of how I'm gonna do the the heatsink holes as I don't got the tools to cut just half the panel out (dunno the word for the tool). So I'll probably just cut the holes through and then seal it again with a fine piece of wood glued/screwed on the inner side of the top side, where I could then stick the mosfets through.

Do you mean with the fancy, "intersecting oval" kind of shape you have on the rear part of the top?

An example for one of the oval openings...
Use a hole saw or Forstner bit to cut two circles the correct distance apart - say you're using a 1.5" bit, so you'd drill a circle for the left half of the heatsink, and drill another circle for the right half of the heatsink, leaving you with, roughly, the shape of an 8 turned on it's side.

Then, get a relatively inexpensive Coping Saw and cut the rest out. You can thread the coping saw through the circlular holes and then cut the excess out.

You could also use a sharp chisel and a very, very steady hand. I'd leave some excess on the inside so you can get a nice even sanded finish.

Then, repeat for the other heatsink, just overlapping the other oval.


* oh wait, you mean not drilling all the way through the panel... you'd need a router for that. *

I just searched and can't find what you found....I'm specifically interested in the rubber grommets? I just drilled the holes for my tubes and am curious if it will look better with some grommets...but can't seem to find any the right size.

It's not grommets, but hole bushings. I used these on one of the SSMH PCB prototypes (the black one):


They were used on the Millett MAX (prototype in pic):


but their use first started way back on the revMH Millett Hybrid:


n_maher came up with the idea as a way to cover his nasty tube holes.

Here's the specific info:
Mouser Part #561-MP10012

and the catalog diagram:


You want to cut a 1" hole. These snap in, leaving a 3/4" hole opening for the tubes - just perfect.

Yep, that was what I was planning to do. I thought I will screw up with the frostner bit, so leaving some excess would be the solution when I try this.
But yeah my problem is that I'll have to go all the way through the case as I don't have that kind of tools to just cut out half (tools like zkool grr).

So OR I'll just go through the top of the wooden case and close it again from the inside with a very fine board of would (but this wouldn't really make the heatsinks stable, and if I push them down I would probably go through them very easily :S) OR I just put on an extra piece, like on the sides, but then I thought about making those side 'railings' thinner. I already tried drawing it in sketchup, but it just doesn't look good. So perhaps it'll be better if I use thinner railings.

You could always use a sheet of thin steel for that bit instead of a thin piece of wood. Some places sell carbon fiber sheets that should also hold up to any physical scrutiny you put on it

Hey yeah that's actually a great idea which I'll probably do.
While I'm at it (the metal ), I could create some other small metal accents, so that the bottom of those heatsinks don't stand out. Maybe I could buy the feet in the same kind of metal, and also make a wooden knob with the front (or just the pointer) covered by a metal. Lookin' guuud.... Keep the ideas coming as long as it's doable for someone with limited tools and access to resources

Depending on where you live, the place you buy it from may be able to cut it to size for you. If not, and the piece will not be seen, you could always just bend it back and forth until the metal fatigues enough to break!

I actually wouldn't recommend that part. I would just consider other materials besides wood to work with. Plexiglass is easy, and you can get good results cutting that with only a utility knife. I think the melting point should be well above what the heatsinks could put out, but don't quote me on that!

Plexiglass sounds good as well. Floating heatsinks.
About the metal. The feet I would probably buy then, though shouldn't the round plate fort he know be easy to cut (if I use a good metal) with a metal saw? I'm pretty sure I have one of those lying around.

tin snips - $5 at the flea market. They'll dull easily, but a pair from Sears with a better steel so it resists dulling is $15 and has a Craftsman lifetime warranty covering anything you might do with them (including burning a hole in the blade from cutting a live wire).

thanks for the tip. I googled those and to be honest, never saw something before. It seems to work because of it's dubbel 'leverage' (dunno the word). Wouldn't like it to be used on me .

I'll keep that in mind and see if I can come across one of those in a local shop.
I'm planning to stick with the metal, but if it really wouldn't work I'd go with rschucks other idea of acryl, would be nice as well.

One more tip. Snips come in 3 flavors. Left cut, right cut, and straight cut. If you can only afford one pair, you want the straight cut (typically yellow handles as opposed to red or green handles).

Yeah I read about that. But I think I'll be glad if I can just fine one of this.
Little question though, are the r/l cuts necessary (by this I mean, are the necessary for clean curved cuts?) or can it be just as well done with the straight ones and a little more effort.

Thanks for that

thanks for the link tomb...

anyway...
Well my build was going so nicely..then I managed to get the center pot hole on the faceplate off by about 4mm!! So I temporarily mounted the power switch next to it to try to make it line up better but it looks worse i think lol. Going to have to redo the faceplate i think.

I had it measured perfectly as well but just don't have the appropriate tools.

I really need some sort of pillar drill. I'm looking at some smaller ones on the net that mount a hand-drill and use that as a pillar drill. Would one of those suffice for small hobbyist casework kind of jobs?