Trying to find an enclosure with opening for tube

[thehoj]

I'm putting together a real mctube pedal and I'm trying to find an enclosure that has a hole precut in it which the top of a 12ax7 would fit through.. Anything like that exist? Or will I have to cut my own?

[davent]

Halfway down the page. http://www.hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=Chassis&ORDER_ID=354822142

[diydave]

This german company has some.

http://www.tube-town.net/ttstore/index.php/cat/c361_TT-Chassis-Metal.html

Otherwise, use a 22mm wood-drill to drill a nice hole in your box.



Be sure to drill your box onto a wooden surface. Otherwise it won't work.

[~arph]

I don't think a wood drill will drill through aluminium 

[jasperoosthoek]

I don't think a wood drill will drill through aluminium 

I do know a wood drill will drill through aluminium.  I know because I tried and it works pretty well .

Wood drills work fine on any soft metal (aluminium, copper) and also plastic. But add some oil or WD40 to avoid overheating the drill. Good idea from Dave to add wood to the back. If you also want to have two holes on either side of the to be drilled 22mm hole (to fix the socket) you can use those to temporarily screw a little piece of wood to the other side. The wood Dave suggested helps to center the drill while drilling. It will work without the wood but the drill will wander off sometimes. Good luck!

[served]

Yeah! It works. I have been using a file to make my holes suitable for tube sockets. So far the largest drill I had was 12mm, so it was a hard work to make it 22.
But this thing works well. Other thing that I thought that would be useful is a punch. It will make a hole by hammering it, but I never got to it. This wood shovel will do the trick.

[~arph]

Ah cool, I will remember this when I start builing my first submini amps.. I stll have a large supply of 5672 pentodes.

[petemoore]

  Hole saw

[thehoj]

Great, thanks for these links, and information.

[JKowalski]

A thick unibit is more suited to drilling large holes in aluminum. Cheap, too. Also nice because it centers decently (on smallest step), and doesn't try to take a ton of material off at the same time. Drill a size, then pause to cool down, then the next size, pause, and so on.

[PRR]

CLAMP THE BOX!! I fear drilling accidents more than electric shock. Even a 1/8" hole fly-away can draw blood, and I've seen gory pictures of larger accidents. Clamp it so it STAYS.

> I don't think a wood drill will drill through aluminium

Sure it will.

If your store does not stock 22mm spade-bits, I know a 13/16" will bore for a typical 9-pin socket.

You want the kind with good corner-spurs. Some wood bits have nearly square corners, because in a deep wood hole you don't _need_ corner-cutters. When drilling chassis metal, you want the corner cutters to go all the way through before the main edge starts scraping. This scores-out a neat disk.

The bit may dull quicker in aluminum than in wood. If you are going to make a million, get a punch (and punch sharpening tools). But a $6 bit will last for many dozen holes in Hammond Aluminum Box or similar.

I don't find oil to be essential if you are mostly cutting on the corner-tips. When you have to hog-out a big mass of aluminum, the Al will stick to a dry bit, you need it to slough off.

You MUST use a hard wood backer! You need the center pilot well-guided, and the soft metal won't do that. You don't want the metal bending away from the bit. I like scraps of oak flooring, but selected hunks of South Yellow Pine (sold as "pressure treated lumber"-- don't snort the sawdust) are also hard enough.

Hole-saw works, but "costs too much" for a few holes. And cheap ones annoy me. I'd rather use a cheap spade-bit. With corner-lips, it is in effect a 2-tooth hole-saw. And in soft metal, you can run up the speed so 2 teeth does the job quickly. If it gets ruined, big deal; usually it stays sharp enough for further use (they never stay sharp forever even if you only chew soft pine).

I have not used Uni-Bit. It does require eating all the metal (instead of scoring-out a disk). That one does not have a 13/16" step. It does work more gently, and does self-center well.

[jasperoosthoek]

I bought an expensive unibit years ago. 38 euros or about 50 dollars. I saw it as an investment. No one touches it but me, nobody.

You must hold the bit at a perfect right angle to the plate you drill. A drill press helps a lot. If you don't do that it will eat more on one side and wander off easily. IMO a wood drill is easier to get the hole exactly where you want it to be.

[diydave]

I've used the 22mm wood drill on numerous occasions: tube amp-chassis and diamond plated aluminium sheets. Worked like a charm every time. But yes, clamp the box AND the wood board, or you will get nasty holes instead of nice clean ones.
Maybe you can do a testrun first on a sheet of scrap aluminium or the likes, so you get the feel of it. It would be a pity to ruin a box just because you were unsure about how to drill the hole.

Anywho, suc6 with it should you dril the box yourself.

[KazooMan]

I support the unibit recommendation.  You will get perfect holes every time and you can clean off the final burrs with a soft touch of the next larger diameter.  You can find these bits for very little money.

The spade bit is an accident waiting to happen.  I do a lot of woodworking (more than making pedals) and I have used just about every tool there is to make larger diameter holes in wood (and also in aluminum for making pedals and chassis).  Spade bits are notorious for grabbing an edge and jamming in the work.  This either (1) stalls your drill (best result) or (2) wrenches the handheld drill out of your hand, thus shutting it down when you lose control on the trigger, or (3) when you are using a drill press, wrenches the piece you are drilling out of your hand or out of the clamps and creates a "whirling chassis of death".  You only need to see the latter one time on a drill press to learn many valuable lessons. 

A spade bit is not designed for cutting metal.  It barely suffices for cutting wood.  It will make fast work of cutting a hole through a stud to feed a cable for wiring, but it is not designed to make a really clean hole.  For wood, a Forstner bit would be the best choice.  For aluminum chassis and pedal boxes the unibit (stepbit) is the way to go.

[Processaurus]

CLAMP THE BOX!! I fear drilling accidents more than electric shock. Even a 1/8" hole fly-away can draw blood, and I've seen gory pictures of larger accidents. Clamp it so it STAYS.

Absolutely.  And the slowest setting on the drillpress for a hole this big.  Big holes in metal can get sketchy.   I just got the giant unibit from harbor freight for $12:
http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html

They're a safer option in general for drilling hammond boxes because the work can't jump up on the bit more than a fraction of an inch, because the next step holds it down.

[defaced]

^Those are actually good quality bits.  I used them for my steel tube amp prototyping chassis.  Well worth their tiny price. 

[DaveM]

CLAMP THE BOX!! I fear drilling accidents more than electric shock. Even a 1/8" hole fly-away can draw blood, and I've seen gory pictures of larger accidents. Clamp it so it STAYS.

I'll third that.  I have a 2" long scar running up my thumb from such an incident. Drilling a 1" hole with a twist drill in a drill press.  Small piece of sheet metal with square corners.  Slowest speed setting, hadn't bought a drill press vise yet. I knew the bit might catch, so I put on a thick glove and wrapped my hand in a rag, in case it caught. Well it did, cut through the rag, glove and a portion of my thumb in a single swipe.   Buy a little 4" drill press vise, they are $10 at your local Princess Auto (or Harbour Freight for you Americans).  Your hands will thank you.

I wouldn't try a spade bit with aluminium. I dislike them for wood, they are a spinning, sharp blade that likes to jump around while it drills. Once again, unibits can be had cheap if you watch for sales.

[Ronsonic]

Let me also suggest that using gloves to protect your hands while drilling or machining is a danger in itself. If the fabric catches and gets snarled things get ugly fast. Generally not considered good practice.

I've worked in places where gloves were needed to handle hot work pieces and the practice was to cut the back of the glove open so it would come off easily if it got caught. Still not a very good answer.