Best method for drilling hole for tube socket

[Rick899]

I am going to start the next project which is a Valvecaster type tube preamp pedal to be built for a BB size box.   I believe the hole for the tube socket is 7/8"  (caliper says .827 inches) and the biggest bit I have or have used for pedals is 1/2".   So do you just use a 7/8" drill bit or is there some other tool?  I know this is a basic question but I don't want to risk ruining a box. Thanks.

[defaced]

Step drill bit from Harbor Freight is what I use: http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html
Price to performance ratio is quite favorable 

[DavenPaget]

If you don't fancy a step drill bit , use a hole saw and deburr afterwards .

[wavley]

Step drill bit from Harbor Freight is what I use: http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html
Price to performance ratio is quite favorable 

I love my step bit, but it's not big enough for a tube socket.  I use a nibbler tool from harbor freight.

[defaced]

How bigga tube socket you using?  The set I linked to is good to 1 3/8", which is plenty big enough for novel and octal sockets.

[seedlings]

If you don't fancy a step drill bit , use a hole saw and deburr afterwards .

You're drilling aluminum, which is pretty soft.  Take a socket to the hardware store and pick up one of these the right size- probably 7/8" or 3/4".  I also use one for footswitches.  Deburr as Daven says (I use a dremel).


CHAD

[frequencycentral]

I use a hand reamer.

[iccaros]

I use these
http://www.harborfreight.com/7-piece-bi-metal-hole-saw-set-68112.html

If Its for a amp chassis, I use these http://www.harborfreight.com/knockout-punch-kit-91201.html
just go to lowes and buy stronger drive bolts for $2.

[DavenPaget]

I use a "dremel" clone which looks the same , is quite heavy , performs well , but i had to buy ALL the bits .
Buffing , sanding , cutting , grinding , collets , drill bits and burr set ...
SGD21 : Tool only
SGD15 : Wasted about 15$ getting buffing burr , few small grinding stones , grinding disc , BIG nylon brush (my hand went NUMB .) , steel wool and brass wool circular ( not the full circle , but with brushes perpendicular to surface )
SGD45 : RS Stock ... Full entire set .
SGD8.40 : 30piece diamond burr .
SGD16 : Flex shaft ( i am not bothering buying this )
21+15+45+8.40=79.40 .
Oh by the way , black and decker's suck . They feel like toys . Still a whole lot cheaper then a RTX set .

[Rick899]

Thanks everybody for all the replies so quickly ....  I see I have several choices. I went to home depot (before I saw all these replies). The biggest regular type of drill bit they have is 3/4";  too small.

1. Someone suggested a spade bit. I have only used those on wood. I don't want to risk leaving a jagged hole. Also the box is one of those painted BB boxes from Small Bear. The original paint job looks like it is enamel, smooth and shiny and  a nice enough finish for me so I want to minimize as much as possible the possibility of chipping the paint around the edge of the hole.  I know the socket base covers that, but still ...

2. I have a Chinese Dremel clone but nothing that attaches to it to cleanly and precisely cut a hole that big.

3.  That leaves the step drill bit   (and I just happen to have a good coupon from Harbor Freight for a set of those) or the 7 piece bi-metal hole saw set (This sounds good:  "cut smooth precise holes in aluminum") ...  I may actually have a hole saw that I have used for wood but I don't know if it is good for aluminum.

Which do you all think is best for making sure as much as possible  (also, I know put masking tape over the area to be drilled) that the paint around the edges of the hole won't be chipped?  

Or are they equally good?

Incidentally, does anyone know where to find an actual size template for drilling the holes for a valvecaster?  Thanks.

[wavley]

How bigga tube socket you using?  The set I linked to is good to 1 3/8", which is plenty big enough for novel and octal sockets.

I only have one of these http://www.lowes.com/pd_27992-281-10234_0__?productId=3070405&Ntt=unibit&pl=1&currentURL=%2Fpl__0__s%3FNtt%3Dunibit&facetInfo= and I don't live near a Harbor Freight anymore, next time I visit my folks I'll pick one of those big guys up.

[DavenPaget]

2. I have a Chinese Dremel clone but nothing that attaches to it to cleanly and precisely cut a hole that big.

Which do you all think is best for making sure as much as possible  (also, I know put masking tape over the area to be drilled) that the paint around the edges of the hole won't be chipped? 

Step bit or the bimetal hole saw and some masking tape .
Of course not even dremels can't cut holes . They aren't supposed to do that .
Step bits are for slow drills , not those massively torquey hammers or those mains drills .

[defaced]

3.  That leaves the step drill bit   (and I just happen to have a good coupon from Harbor Freight for a set of those) or the 7 piece bi-metal hole saw set (This sounds good:  "cut smooth precise holes in aluminum") ...  I may actually have a hole saw that I have used for wood but I don't know if it is good for aluminum.

Most wood working tools with a course tooth pitch will perform fine on aluminum.  I have cut many of 2" thick 5083 plate with a pneumatic circular saw and a wood blade.  As for which option to drill your holes, here are some things to consider:

- A step bit has can only make a diameter for some finite material thickness, probably around 1/8".  If your box where you need to drill is thicker than that, then go with a hole saw
- A step bit has many more sizes than a comparably priced set of hole saws.  If the size you need isn't in the hole saw set, then you either need to live with the miss-match, or use a step bit
- A hole saw will have less of a tendency to walk the hole, but will tend to bind because it's cutting on two parallel surfaces. If you will be doing this job on a drill press and will clamp the box rigid, neither of these are much of an issue. 
- A hole saw may have issues clearing chips which will cause excess heat, dulling of the blade, and binding.  Use cutting oil and intermittently cut to allow the chips to clear
- As Daven mentioned, both options will require a bit of torque, so it's best to use a proper mains powered drill, drill press, or if you have one, a bitchin cordless drill.  I've abused 18v cordless DeWalts worse than this, so I can say from experience they will work.   

Incidentally, does anyone know where to find an actual size template for drilling the holes for a valvecaster?  Thanks.

There are many different kinds of tube sockets ,and they're not all the same physical size even for a given tube pin style; you will need to get the dimensions of the one you are using and drill accordingly.  If you do not have this info, either measure your socket (best alternative), or go to Antique Electronics Supply (tubesandmore.com), and see if they have a socket that looks IDENTICAL to yours and see of those dimensions match yours.  While you're at HF picking up bits, seriously consider a set of these: http://www.harborfreight.com/6-inch-digital-caliper-47257.html  They're no Starrett or Mitutoyo, but they are great to have kicking around the house. 

[Rick899]

Thanks again for the replies.

Defaced: Luckily I have a drill press and only have to cut through an aluminum BB size box. I have those exact same calipers. In the first post on this I say that the caliper measurement of the base of the socket that fits in the hole is  .827 inches which is 7/8".  So I am going to get a 7/8" hole saw chuck it into the drill press, tape the box and clamp it down, put the drill press on the slowest speed and do it that way.

[DavenPaget]

Thanks again for the replies.

Defaced: Luckily I have a drill press and only have to cut through an aluminum BB size box. I have those exact same calipers. In the first post on this I say that the caliper measurement of the base of the socket that fits in the hole is  .827 inches which is 7/8".  So I am going to get a 7/8" hole saw chuck it into the drill press, tape the box and clamp it down, put the drill press on the slowest speed and do it that way.

Do remember that stepped drill bits deburr the holes at the same time .

[davent]

Unibits and reamers will cover it all.



And while you're out shopping pick up a deburring tool, pictured in the lower left hand corner, simple cheap and effective.



dave

[PRR]

A spade bit can work well in aluminum. Use a light feed. A sharp (new!) bit and moderate RPM will go through.

Ideally look for a bit with spurs longer than metal thickness. This will just cut the rim leaving a disk. You can find long-spur enough to go through sheet metal, maybe not through a die-cast box. Alternatively let the face of the spade hog-off the center of the hole just like it does in wood.

Back it up solidly with hard wood, oak maple or selected SYP heartwood. You NEED to guide the center of the spade bit, and break-through is less violent if not breaking through to thin air.

A ~~1" hole is BIG leverage. You need *strong* clamps so the bit doesn't grab and throw the box through your face.

If you are doing more than dozens of holes, there are better ways. But for just a few holes, spade-bits are by far the cheapest option.

Step-bits are safer and cleaner but cost more.

Hole saws come good and bad. Don't mess with bad "hole saws"... a sharp stone cuts better. Good ones usually cost more than a few DIY holes are worth.

[frank_p]

Is it me or I've seen somebody use knock out punches and punch drivers on this forum ?

http://www.harborfreight.com/hydraulic-punch-driver-kit-96718.html
http://www.harborfreight.com/knockout-punch-kit-91201.html

[DougH]

I use step-bits for tube sockets and they work just fine. But I wouldn't buy anything from Harbor Freight, personally, unless you want "flea-market quality" tools.

[ntblade]

Step drill every time!
It starts small and effectively drills its own pilot hole.

NTB