Countersinking?

[Pars]

I've never done this before, but partly due to seeing a pic of an amp that Nate had built, I was thinking of countersinking two screws on the bottom of the l'espressivo torpedo prototype that I am building for my brother. So, a couple of questions:

[*]Is a Hammond 1455 case such as what is used thick enough to countersink a 4-40 flat head machine screw in?

[*]Countersink bits: do you need one for each size you are doing? I would be most likely to use 4-40 or 6-32.

[*]Angle: I see 82

[n_maher]

The hardest part of doing this is going to be holding the workpiece in place. The mill is well equipped for this, most drill presses are not.

[Pars]

^ I have a drillpress vice which can hold it. Otherwise, I usually don't have problems holding stuff by hand on a piece of wood.

[Nebby]

What drillpress vice do you have? In the past I've used an odd mix of clamps with scrap pieces of wood but now that I no longer have access to a wood shop I'm basically starting from scratch.

[Pars]

Just a crappy one from Harbor Freight. I wouldn't recommend it as it tends to lift up at the adjustable head when tightened, thereby angling your work for you

Like this one

6" Jaw Capacity Drill Press Vise

[spritzer]

I do most of my countersinking with a hand held drill and just one bit for the standard 3-4mm screws I use.

[fishski13]

I've never done this before, but partly due to seeing a pic of an amp that Nate had built, I was thinking of countersinking two screws on the bottom of the l'espressivo torpedo prototype that I am building for my brother. So, a couple of questions:

[*]Is a Hammond 1455 case such as what is used thick enough to countersink a 4-40 flat head machine screw in?

[*]Countersink bits: do you need one for each size you are doing? I would be most likely to use 4-40 or 6-32.

[*]Angle: I see 82

[swt61]

I do most of my countersinking with a hand held drill and just one bit for the standard 3-4mm screws I use.

But you're a Viking!

I usually clamp the piece to my drill press table securely, then set my bit depth, so that all countersinks come out the same.

Countersink bits are not created equal either. You want to make sure it's intended for metal.

[Pars]

the Hammond metal is thick enough for a 4-40 flat head, but i don't know why you would want to, especially on the underside. countersinking a flat head to look nice in metal is a bitch. the only countersinking bits i've found have a single-sided cutter - this makes for an uneven cutting rotation. you could also cut the hole for the diameter of the screw threads first, then slowly drill the countersink with a larger standard bit. eye-ball the angle of the flat head and try to find an appropriate larger bit with a similar angle at the business. clamps and WD-40 are your friends.

A couple of reasons:

1. Countersunk is teh sex, at least from looking at Nate's. Check page 169 IIRC in the Amp Build thread here.
   
2. These are for mounting the pair of 0.25" standoffs under the PCB in a slide-in case. Normally I would run a 1/2" or so screw up from the bottom and fasten the PCB with a nut, but since the board slides into the case, this would be difficult. Since flathead screws apparently are measured from the head, it would be easier to come up with short enough screws. 2x 1/4" panhead screws are too long; you really need something like 3/16" which aren't easily found. I ground some 1/4" down for now.
   

[Emooze]

I agree with countersinking being the sex and I absolutely recommend it. You just need to be careful with the angle. Be sure to get a bit that matches the angle of the screw you are using. It just won't look right if the hole and the screw don't match up.

[fishski13]

I agree with countersinking being the sex and I absolutely recommend it. You just need to be careful with the angle. Be sure to get a bit that matches the angle of the screw you are using. It just won't look right if the hole and the screw don't match up.

i.e. watch the angle of your dangle.

[Mister X]

McMaster Carr #3210A683 is fine for most screw holes.

# 4286A14 for larger holes.