First chassis - a photo journal

[DeathRex]

Stepper bits in hardware stores are close to $40 each. I got some from ebay for about $8 each and have been happy with them. But for making a clean finished hole for a tube socket, I really like the chassis punches. Much cleaner holes than even a Bullet drill bit. Harbor freight has a set for $28, but you have to get tube sockets to match the hole sizes. It says it has a 1/2, 3/4, 1, and 1 1/4 but it's actually a 7/8", 1 1/16, 1 3/16 and a larger size. The 7/8" and 1 1/16" are perfect for 9 pin and 8 pin sockets. I got several sockets from ESRC tubes before I got the punches. AES has Chinese 9 pin ceramic sockets 7/8" for $1.05 part# P-ST9-511.

[20to20]

Stepper bits in hardware stores are close to $40 each. I got some from ebay for about $8 each and have been happy with them. But for making a clean finished hole for a tube socket, I really like the chassis punches. Much cleaner holes than even a Bullet drill bit. Harbor freight has a set for $28, but you have to get tube sockets to match the hole sizes. It says it has a 1/2, 3/4, 1, and 1 1/4 but it's actually a 7/8", 1 1/16, 1 3/16 and a larger size. The 7/8" and 1 1/16" are perfect for 9 pin and 8 pin sockets. I got several sockets from ESRC tubes before I got the punches. AES has Chinese 9 pin ceramic sockets 7/8" for $1.05 part# P-ST9-511.

I've learned there is a hole size difference with punches depending on the punch "type", chassis or conduit. I've been considering the punch route, but because they require a hole to be drilled first and then cut the final hole, I'm looking into setting up a drill for a single step hole. If you have to drill a hole first, to use a punch, you might as well make it the size you want. Cleanliness of the cut is important of course.

Will a punch cut a hole so cleanly that dressing the hole in not necessary? I'd assume any hole will need some dressing up, drilled or punched. A vairable speed drill, with cutting lube, should make a flat hole and need minimal dressing.

I've already got my 9 pinners from AES and a bunch of nice vintage sockets from other chassis that take a 3/4" hole. My octals are vintage 1-1/8".

The decision is whether to spend $40-$50 each for a G'lee punch that makes the exact hole size needed, and also require a draw stud hole, buy steppers that may wallow and burr the hole, or buy a single bit to do the one shot hole.

[DeathRex]

Will a punch cut a hole so cleanly that dressing the hole in not necessary? I'd assume any hole will need some dressing up, drilled or punched. A vairable speed drill, with cutting lube, should make a flat hole and need minimal dressing.

I've already got my 9 pinners from AES and a bunch of nice vintage sockets from other chassis that take a 3/4" hole. My octals are vintage 1-1/8".

The decision is whether to spend $40-$50 each for a G'lee punch that makes the exact hole size needed, and also require a draw stud hole, buy steppers that may wallow and burr the hole, or buy a single bit to do the one shot hole.

Don't need to clean a punched hole. Radiodaze has these punches starting at $19.25 for a 3/4". http://www.radiodaze.com/catalog-306-page64.pdf
Stepped drill bits do make fine holes, much better than standard drill bits, and with a drill press, it should work just fine.

[TomMcNally]

Having built over 40 amps on steel or aluminum chassis, let me
offer some advice.

1) get Greenlee chassis punches. The cheapo Philmore or
Harbor Freight stuff is good for a few holes, then it's junk.
In building an octal based amp, I use two sizes, one for
the tube sockets (I think 1 1/16") and a 1/2" for the
speaker binding posts and fuse holder.

2) a step drill is fine for less critical holes where you are going
to cover the hole where it won't be visible. Again, no cheap
clone bits, get a genuine UniBit brand.

3) a drill press isn't necessary. I use a battery powered Makita
hand drill. When drilling holes, use a center punch and a
tiny sharp bit, and work your way up.

4) get a Dremel tool and some Gyros brand fiberglas cutting wheels
to cut holes for IEC sockets and to clean up the mess made by
twist drills. I can cut an IEC hole that needs NO filing in
about 60 seconds.

5) to make an amp that looks good, don't use cheap hardware,
spend a little more and get stainless phillips head. Nuts with
integral lockwashers make things go much faster

6) as mentioned in another post recently, get a Riv-Nut tool and
don't use sheet metal screws for anything

7) other handy tools include, a china marker or silver sharpie to
mark your holes. An Automatic Center Punch to dimple the
chassis so your hole starts where you want it too (small bit!)
An inexpensive slide caliper to measure things so you know
what size hole to use. A drill index you can stick your bolts
through so you know which size bit to use. A simple
carpenters adjustable square to help locate your parts.

Remember - don't drill ANY holes until you have all of the parts.

Pics of my stuff at http://tmamps.com

... tom

[mesherm]

Tom pretty much summed it up. I definitely agree about Greenlee punches. The Harbor Freight punch set is absolute JUNK. I couldn't even get ONE hole done on a standard Hammond steel chassis AND it roached the chassis up so bad I had to get a new one.
Step drills are also good for deburring drilled holes IF you can access both sides. I use a hand de-burring tool for the hard to reach holes.
The Dremel and abrasive blade method works well after some practice.
Mark the cut lines very carefully in order to minimize hand filing. Hold the chassis securely to minimize vibration. I usually start a cut in the center of the line until the blade has cut completely through the chassis. Then work toward the corners with the blade about a third of the way deep. The Dremel motor will get quite warm so a work glove is advised. I suggest practicing on some scrap sheet metal to get the feel.
I now use the drill bits with hex ends because they don't slip in the drill chuck.

[20to20]

Having built over 40 amps on steel or aluminum chassis, let me
offer some advice.

Tom,

I've seen your site. Your amp building is peerless. Your advice about chassis punching is most highly regarded here. Thanks for the extensive reply.

Do you use your Makita with a socket to do the draw quickly? Does a quick draw make a cleaner cut?

The material I have to work with is 16ga. and 18ga. steel.

Remember - don't drill ANY holes until you have all of the parts.

Advice dripping with wisdom...

I now use the drill bits with hex ends because they don't slip in the drill chuck.

Mike,

Man, I hate when that happens..!! These hand tightening chucks are a convenient PIA... You just can't tighten them by hand enough for some jobs. You think you're drilling a hole deeper and it turns out it's just the DAMMMMMED BIT SLIPPING AGAIN!!! Grrrrrrrrr...

[20to20]

Don't need to clean a punched hole. Radiodaze has these punches starting at $19.25 for a 3/4". http://www.radiodaze.com/catalog-306-page64.pdf
Stepped drill bits do make fine holes, much better than standard drill bits, and with a drill press, it should work just fine.

D-Rex,

Thanks for the link. I'll probably get that 3/4" punch. It seems like a no brainer to try that punch and try a 3/4" bit, just to satisfy myself on quickness and quality. Most of what I have planned, still floating in heavy mist and fog, centers around 6BQ5's, 12ax7's and an octal rectifier.

Next mission... find purty screws

[EWBrown]

Harbor freight has a set for $28, but you have to get tube sockets to match the hole sizes. It says it has a 1/2, 3/4, 1, and 1 1/4 but it's actually a 7/8", 1 1/16, 1 3/16 and a larger size.

These "electrical knockout" punches are larger than their stated diameters, as these are intended for mountong the threaded end fittings which are used on EMT (electrical metal tubing) conduit, which is rated by its internal diameter.

The threaded ends of the conduit end fittings are of a much larger diameter than the ID of the metal tubing. I bought a set of Greenlees "knockout " punches at the local sunday flea market back in NH, a few years ago, for $10, and they are of very good quality, and the largest in the set is just right for punching the large diameter hole for the 10 Watt "James" SE OPTs. A nw set of these is close to $100, and the set I bought appeared to have very little, if any, use on them.

The real "ne plus ultra" for the Greenlee punches is the manual hydraulic pumps, these make punching holes in heavy thick industrial electrical cabinets, about as easy as poking holes with a sharp pencil into warm butter

I used these hydraulic pumps at a company I ised to work about 30 years ago. They operate on teh same principle as those cheap hydraulic jacks from the auto parts stores, but in "pull" rather than in "push" mode.

/ed B

[20to20]

I bought a set of Greenlees "knockout " punches at the local sunday flea market back in NH, a few years ago, for $10, and they are of very good quality,

Ed,

I passed on a flea market pouch of punches a couple of months ago because they weren't clearly marked as to their type. I was a-a-a-fraid!

[jonnyeye]

On a whim today I stopped in at the local flea market and browsed a couple of the tool stalls, and guess what I found: Greenlee radio chassis punches in 1/2", 3/4", 13/16", 1", 1 1/8" and 1 5/16" sizes, plus a 15/32" keyed punch (for fuses and some switches)... got the lot for the bank-breaking total of $25.

I've been looking for a set for a while! I could have skipped all the way home...

[Ty_Bower]

guess what I found: Greenlee radio chassis punches... for the bank-breaking total of $25.

Some guys have all the luck.

Look what I had to do today with my nasty old Harbor Fright step bits. They're starting to get dull already, and tend to heat the aluminum and smear it around like bad butter. Keeping the bit oiled while drilling definitely helps. I turned a Bondo'd chunk of Al into a nice piece of primed Swiss cheese. I mitered a half decent looking box out of red oak, too.

[EWBrown]

The Harbor Freight and Philmore (sold by Triode Electronics) punch sets are made from relatively soft / mild steel, and will dull very quickly, even when punching aluminum, as they have not been properly hardened. . Steel chassis will blunt them very quickly, even after just one or two punches.

Same applies to drill bits, the cheapest "gray market" (flea market pouch grade) ones imported from China, Taiwan and India, will work fine on plastic and wood, but steel will kill then, sometimes on the first use, and they are barely suitable for multiple uses aluminum. Cheap is what cheap does...

As the old adage goes, "you gets what you pays for"

The Greenlee and the older "Pioneer" punches are industrial grade quality and should last a very long time, and just about "forever" for hobbyest usage.

Stepped drills are fine, but they work best with a drill press. With a hand drill, the holes will tend to be somewhat more "ragged" and uneven, because the hand-held drill will tend to vibrate and wobble.

/ed B

[elbinster]

I've never been lucky enough to lay my hands on good punches, and have just made due with hole saws and stepped drill bits. My first chassis plate (Aluminum) was cut with a hole saw rated to also cut metal. A hole saw connected to a hand drill made some nice, ragged and sharp edged holes about 1/8" larger than desired. A dremel and some thin strips of sandpaper made them presentable. For my next chassis plate (Brass), I upgraded to stepped drill bits and a drill press. That allowed me to make holes the correct size, but is far from ideal. The Harbor Freight bits did seem to dull as the day went on, but keeping them oiled should help. So yea, my third chassis will require me to go find some punches.

If you do use any drill bits with a drill press, I'd recommend staying back from it so when the bit grabs the plate and gets it spinning, you're chances of being eviscerated are reduced.

[Geek]

If you do use any drill bits with a drill press, I'd recommend staying back from it so when the bit grabs the plate and gets it spinning, you're chances of being eviscerated are reduced.

There's a few simple ways to avoid this:

- Don't use dull bits.
- Set your speed correctly for the hole size/material.
- Make sure the piece is flat against the table (best use a piece of MDF underneath... you'll get cleaner holes too)
- Hold piece firmly with a leather gloved hand.

Cheers!

[SteveH]

Very very nice !