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Locating holes for tube sockets

Apologies if I’m brain dead and this turns out to be a stupid question. I’m building a tube amp and need to punch holes in the metal top of the chassis for 9 pin tube sockets. How does one precisely locate the holes? I have two PCB’s with two nine pin tube sockets on each board. I can’t just lay the sockets on the metal and trace around them because the PCB’s are in the way. If I lay the sockets on the metal without the boards to locate them, then they won’t line up when attaching the sockets to the PCB’s. I’ve been pondering this for weeks and can’t envision a solution. Any help will be greatly appreciated.
 
I think the easiest way is to print out the PCB artwork if you have it, otherwise you'd have to generate it yourself. Then, just tape it to your chassis and mark all the center points/locations with a spring loaded center punch.

If your PCB's have centered thru holes for the socket locations, then use them as a template.

jeff
 
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Work with the centers of the sockets when measuring the distance not the edges of the sockets. I'm assuming you have chassis punches of the correct diameter. Using a dial caliper measure center to center to get all the hole to hole distances. Using a free 2D CAD program (anything) draw your hole centers and circles. Print it 1:1 on paper. Lay the paper as best you can over the sockets, insert tubes if easier. Move and adjust holes if needed and reprint. Repeat until things are perfect. Now print one more and tape or rubber cement it to the chassis. Drill your pilot holes in centers. Punch holes. Hopefully it will be perfect. Paper is way cheaper than a chassis!

To be really accurate you can cut the holes out of the paper with an xacto knife and poke the sockets through to see exactly what you'll get in metal. Don't worry about diameters, your punch does that, you just need small dots to mark centers and start pilot holes.
 
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Joined 2018
Make full size Templates on paper.
Unless the PC board has traces within the tube socket pin circle, a small hole drilled into the PC board centered under the socket is helpful.
If under-chassis



Whenever I design something, I always spend the time prepping - laying out things on paper, double checking clearances.
Same goes for front panels - knob/control spacing (taking into consideration knob diameters), switches, indicator lights, etc.
 
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Thanks very much. I’ll try photographing the boards and print them out. I’ll have to adjust the sizing until I get it 1:1. Then I can lay it on the metal to mark it. See any problem with doing this?

I cant see that way working, but you can try. You only have two holes, thats two dots precisely spaced, a caliper and a good eye will get it within a tenth of a millimeter. Remember diameters are not important only the centers are, your punch will make the diameter but it needs accurate centering. Do you have a digital caliper?

https://www.amazon.com/dp/B074BRTM2...wg=PdqXv&ref_=sbx_be_s_sparkle_mcd_asin_0_img
 
If the PC board has a silkscreen layer with the socket outline on it, try placing it on a copy machine, then use the copy as a drilling template. Some copy machines are not exactly 1:1, but usually close enough. Check the copy before using it.

If you have a scanner, scan the board to PDF, then print the PDF. Adjust the printer scaling in the PDF print function to make an exact 1:1 copy. My 10 year old Canon laser printer needs a 102% scale factor.
 
Traces

Make full size Templates on paper.
Unless the PC board has traces within the tube socket pin circle, a small hole drilled into the PC board centered under the socket is helpful.
If under-chassis



Whenever I design something, I always spend the time prepping - laying out things on paper, double checking clearances.
Same goes for front panels - knob/control spacing (taking into consideration knob diameters), switches, indicator lights, etc.

There are traces under the socket but not directly in the center. I can drill a hole in the center missing the trace. I guess I could then lay the board on the metal directly and mark the centers. I don’t see a need to transfer to paper.
 
You can use tape and highlight to draw the circle, then take the tape to put on the metal to drill/punch. Or just punch center of both tubes on the tape then you get the center point.

hole.png
 
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Thanks everyone!

I believe the easiest solution is to drill a small hole in the PCB’s in the center of each tube socket on the board. I should then be able to easily mark the metal directly with the PCB’s without measuring or messing with transferring to paper. Seems like the easiest and likely the most accurate solution. Thanks!
 
Can you please show the PCBs?
Both sides and if possible center camera with center of pcbssoall edgesform a perfect rectangle,and at samedistance,sothey can be superimposedin Photoshop ifnecessary.

What the Guitar pedal guys do to clone commercial pedals.

A couple books and desk lamps make the task easier, don´t trust your hand steadyness.
 
Sadlyno, it´s too late, parts will get in the way.
I thought you still had the unpopulated ones.

In fact not sure drilling is possible or useful now.

If you wish, post a couple pictures, one from each side, so at least we know what are we talking about.

Maybe you can still make a template out of tracing paper.
 
If you are using hole punches, then you can make some wiggle room by drilling a pilot hole larger than the bolt in the punch, but smaller than the hole. As long as the punch is lined up correctly when it is tightened, the hole will be correct. It is better to have the outer die on the top, and the cutter underneath - if the metal is thicker then sometimes the cutting edge is not uniform.
If you are unable to make precise meassurements, and have sockets fitted, maybe you can put some plasticene or similar on the top plate, make impressions of the sockets, and then position the hole cutter die using the imprint. I coat the plate with masking tape, so pencil marks can work too.

Using the bare board as a template can be an issue after soldering the sockets, because they may be slightly off centre. Safest is to cut the holes from the board, then place the sockets in the board using the top plate as the template, and then solder. That ensures all have the same height and location, and are level.

Now I have discovered that my local alu plate supplier will convert a drawing quite cheaply, and laser cut the holes for me in 3mm plate, so that is what I will be doing in future.
 
Actually I found that punch cutting - it was better to have the top overlap part of the punch underneath then the cutting edge on the top (at least for hammond steel chassis). Then the edge of the socket is pulled down into the case. You then end up with a more rounded top edge.

You can easily use a circuit board template to scale then centre punch the hole through the template mark into the metal. Put a piece of wood underneath. The indent then allows the drill bit to sit and not skate around. Alternatively use a bench press drill. Again centre punch but it's alignment pre drill makes it much easier.

I think my for my next V2 amp I'm tempted to start with a simple metal sheet only - get holes drilled including the socket mounting holes before moving to a chassis as one. Mine are point-to-point so a little different.
 
Hi Nickuk, yes you are right, the outer part of the cutter can leave a scuff mark too, so better underneath. I cut some holes in 3mm alu recently, and the edge was a bit jagged on the top (where the cutter was) just due to the thickness of the plate, but I expect that can be cleaned up with filing.
 
Hi Nickuk, yes you are right, the outer part of the cutter can leave a scuff mark too, so better underneath. I cut some holes in 3mm alu recently, and the edge was a bit jagged on the top (where the cutter was) just due to the thickness of the plate, but I expect that can be cleaned up with filing.

Hehe I hate metalworking for the simple reason of scratches. In the end with raw aluminium, after filing, you can buff after to minimise the scratches.
 
Apologies if I’m brain dead and this turns out to be a stupid question. I’m building a tube amp and need to punch holes in the metal top of the chassis for 9 pin tube sockets. How does one precisely locate the holes? I have two PCB’s with two nine pin tube sockets on each board. I can’t just lay the sockets on the metal and trace around them because the PCB’s are in the way. If I lay the sockets on the metal without the boards to locate them, then they won’t line up when attaching the sockets to the PCB’s. I’ve been pondering this for weeks and can’t envision a solution. Any help will be greatly appreciated.

A lot of valve sockets have a centre pin and so a hole in the pcb which I use for punching a marker for the drill.
Or drill a small hole in the centre of the pcb socket footprint for a guide (if possible.)