4-400 tube socket hole size

[N3DRB The Derb]

using the Johnson 275 sockets, what's the correct hole size needed for a 4-400? The RF deck I have has a odd diameter, like the guy cut it freehand using a saw of some kind. it's not a true circle so you cant know.

I wanna punch it using a Greenlee punch and need to know what size to look for. I'm guessing 2 1/2" but does anyone for sure know the actual dope?  The 813/257B uses a 2 1/4" which I have a punch for.

[Jim, W5JO]

The one in my GK 500A is 2 3/4

[W3FJJ]

The 275 socket in my homebrew is
also 2 3/4" 

[KE6DF]

Here are some data sheets for Johnson sockets. Dimensions are included.

[N3DRB The Derb]

ok tnx OM's I'll see if I can procure one n start punchin. In the meantime, I'll start with a 2 hole 257B rf deck since I can punch them out now.

[N4LTA]

Last time I looked for one - I found out that they are EXPENSIVE. I ended up uisng a bi-metalic hole saw.

Worked better than I thought it would.

[WQ9E]

A good quality hole saw in a drill press will work fine. 

CLAMP the work piece to the press table, under no circumstances should you try to hand hold it.  That is a big safety no no since the saw could easily bind in the piece and pull it out of your hand.  Besides the safety issue, clamping provides much more precise work and for a good outcome setup time generally exceeds the actual machining time.  I use a cross slide vise on both of my presses for most work and they make precise setup easy.

Back the piece you are drilling with a piece of scrap wood to support it.  This keeps the bit from deforming the piece and causing a ragged and over-sized hole.  Use a reasonable feed rate, too slow and you will burn the bit while too fast will overload the machine and cause chatter and poor cutting.  Depending upon the material you are cutting you might benefit from using a cutting/drilling fluid.

For those who don't have a drill press, one of the Harbor Freight 5 speed benchtop units that often goes on sale for $39 is better than trying to fudge and use a handheld drill.  I have large floorstanding regular and radial presses from Delta but about 7 years ago I bought one of the HF units when I was helping my sister in law do some work at her house since my Delta units are far too big and heavy to be considered portable.  Although I put it through some pretty extreme abuse including using some large Forstner bits outside in 95 degree weather for several hours it stayed cooler than I did.  I have it back in my wood shop set with some small sanding drums and it has kept on ticking without complaint.

As Norm says, always wear safety glasses!

Rodger WQ9E

[WA1GFZ]

The hole only needs to clear the pins and air holes. Mounting holes are only 2.25 inches apart I would keep it as small as possible to avoid feedback

[N2DTS]

You can make short work of a hole with a good file.
I like the large ones with the curved side for bigger holes, I often use something to make a hole smaller than needed, then file it to size (mark the outline).
On alluminum, it takes very little time and effort to remove a lot of metal with a good file, and gives a nice edge.

Also, you can get very nice large punches (greenlee) with the bearings and rachet drive in a set at home depot, not hamfest prices but not bad.
It goes 1/2 inch to 2 inches, for making holes for conduit....

Brett

[N3DRB The Derb]

I heard that the conduit punches dont give the right sized hole when you are not in fact using them for conduit. I dont know if that true or not, but I think I'll stay with the 730's. "Radio chassis hole punch" sounds a lot closer to what I'm doing than "Slugbuster". 

[N2DTS]

Well, the slugbuster? set is high quality.
The holes are a different size, but that is handy for some parts, and as I said, a file makes short work of most holes.

I have a collection of regular chassis punches and the 'slugbuster' ones, which gives lots of choices in hole sizes.
The file makes a nicer hole though...

Brett

[WA1GFZ]

I had to punch some additional holes in my breaker panel so bought a home Depot Greenlee. They are the same as chassis punches. It came with the bearing on the jack screw. A 1/2 round file works very well for us poor guys.

[N3DRB The Derb]

I got my punches offa ebay and I've never paid over 14 bucks for a single one. I got 3 for 10.50 all in good shape except one which just needs a little dremel action on the cutting edge on one point. I bet I can get a whole set up to 2 5/8" for less than 75 bucks.

Using any type of tool that makes vibrations can be a problem for me. files have the same effect. I can do it but I have to dope myself up so much I cant last much more than 15 or 20 minutes before it's lights out time.   

using a drill is really hard on me. punches r the way to go. one quick hole and turn the wrench, done.

[KE6DF]

The trick to ebay is to not chase things.

For no apparent reason, things get bid up some times. If they do, then say good buy and wait until the next one comes along.

People often pay over $100 for tubes like 805's that the audiophools have bid up. Sometimes way over $100.

But recently I put a $10 bid on a National Electronics 805 that looked NOS.

For some reason, no one else bid and I got it for $8. -- plus the seller had an extra one which he through in for free -- so I ended up with two 805 for a total of $8.

Another example was a UTC transformer -- there again, they often get bid up to ridiculous prices. But I once put a $15 bid on a brand new, in the box, pristine CG-305 plate transformer (4800vCT at 300ma), and no one else bid so I got it. The guy who sold it mis-described it as a vari-match audio transformer, but the picture and part number told me what it was.

I too have a couple big greenlee punches I got off ebay for $15 each.

One is 2.75" and the other about 2.25". The big one is just right for old Weston meters. The smaller one is right for making a hole for below chassis mounting of 805/810 type sockets.

I really think the 2.75" hole would be too big. I looked into that once, and I think you wouldn't have enough metal left around the screw holes. You probably need something like 2 1/2 or 2 5/8"

Too bad we live so far apart or you could borrow them.

These punches are the like of thing to share as you only use them a few times per year.

But keep looking on ebay and you will find the right one at the right price eventually.

But don't be fooled by the "conduit" sized punches as they punch a hole bigger than the stated size (to accommodate the OD of the conduit).

[N3DRB The Derb]

But don't be fooled by the "conduit" sized punches as they punch a hole bigger than the stated size (to accommodate the OD of the conduit).

yeah thats what it was. I knew there was something fishy about those thangs. that was it.

ebay is crap for manufactured gear, and crap for anything that could be used in audiophool circles. outside of that, I've found it to be not too bad way of shopping. I do get some things at incredible prices now and then.

My rule on ebay is simple: what would I pay for something if I saw it at a hamfest? I bid to that amount and no more, if it goes over that too bad. I wait for the next one. ( which I've found....almost always) a better one shows up within 2 or 3 days.

I'm pretty sure a 2 5/8" would be the bees knees for a 4-400, but I gotta go actually trial fit a socket and find out. 2 1/4" is good fer 813's, not enuff for the big base tubes. oops, looked at the datasheet - 2 7/8" between mounting holes. hmmmm.

[Detroit47]

Derb

If you want a special size punch made I can do it for you. I am a tool and die maker/ NC programer machinist. I'll just charge you for materils and heat treat.

Johnathan N8QPC

[N3DRB The Derb]

7FTO out on the west end is gonna set me up with some ball bearing ball busters on loan. even do some meter holing.

Thanks for the offer. 

[KE6DF]

Derb

If you want a special size punch made I can do it for you. I am a tool and die maker/ NC programer machinist. I'll just charge you for materils and heat treat.

Johnathan N8QPC

Johnathan,

Can you make 4" round punches? I have several  UTC transformers in the round cans that need a hole like that. I'd be willing to pay you something for your time as well as costs.

I'd also understand if it's more work that you want to take on.

Dave

[Detroit47]

Dave
I can make whatever you like. Do you want the finished hole to be 4 inches? Send me an IM and I'll give you a phone number to contact me. In the past I have made several custom punches round and square. I have also constructed custom clamps for vacuum variables, and filament connectors for large tubes 3cx3000, 10000, 20000.
I can also make custom sockets I just finished some for GS-35b's. I have been a Tool and Die maker for over 30 years if you can draw it I can make it. Your paper drawing can also be turned into cad data for your use or for other machinist's use.

73 Johnathan N8QPC