POLL... predrilled Vox AC-15 board available soon

[sluckey]

Hoffman is considering offering a pre-drilled board for the Vox AC-15 project that's currently being discussed in this forum. All holes will be done on his CNC machine so the boards will look very professional. The board will be approximately 14" long. He wants some user input concerning drilling so please take the poll.

Option 1. Drill holes for turrets only. This option is a no brainer. Just drop a turret into every hole on the board.

Option 2. Drill holes for turrets and wire pass-thru. Pros... This option allows for wires to be installed from the bottom side of the board for a cleaner look. Similar to the Marshall style. Cons... You will have to use a guide template to load the turrets. You may put a turret in the wrong hole so be careful.

Option 3. Drill holes for turrets, wire pass-thru, and standoffs. Pros... No drilling required, except to enlarge the holes for the 6 standoffs. Cons... May need to drill extra standoff holes if installing this board in a donor chassis.

If you are not familiar with this 'Marshall style' AC-15 project you can get more info here...

     http://home.comcast.net/~seluckey/amps/VAC15/ac15.htm

Here's a pic showing the 3 drilling options.

[EL34]

I'll throw out a few things about adding extra holes

My CNC uses a 3/32 carbide bit to drill the holes and so all the holes will be 3/32 just like turret lug holes

The wire holes being the same size as the lug holes may cause confusion and turret lugs mounted in the wrong holes
The red dots in the image above that Steve Posted would all look exactly like a turret lug hole
You would have to drill the mounting holes out larger and maybe the wire holes if you use a large diameter wire than the wires mentioned right below

These wires that I stock will go through a 3/32 hole, so there is no need to drill them out larger
20 gauge Teflon, 20 gauge pvc, 20 gauge cloth and the 18 gauge PVC stranded wire.

Mounting holes cannot always be determined ahead of time because donor chassis may have things on the other side right where you want a mounting screw or nut
Examples of that would be chokes and output transformers
Many times I have had to put a standoff mounting hole in another location because the screw head of nut would be right under an output tranny

And lastly, every extra hole adds more $$ to the price because it is machine shop time
As it stands now there are 133 turret lug holes
There would be 48 more holes for wires and 6 more holes for mounting holes
So that's 187 holes total
The 14 inch - 133 hole board would be around $18.16
The 14 - 187 hole board would be around $21.87

Just throwing out some info to help you decide

Here's a CAD drawing of the board with only turret lug holes
This board is now 14 inches long



Here's a CAD drawing with the wire holes - Black holes and the mounting holes - Blue holes
This board is now 14 inches long

[Ed_Chambley]

How about a version with all the holes drilled, turrets installed with all jumpers soldered in-place.


After building one the passthrough holes are very nice in keeping leads where they need to be.  It will be necessary to use the jumper guide and mark for those.  It would be very easy to mark the passthrough holes at the same time.


I know some do not like passthrough holes and on simpler builds I normally do not use them.  On this one it is a very nice addition.

[lego4040]

 

[tony_hunt]

The 14.25" No.3 is well worth the small up-price.
Left to my own dvices, I accurately and consistently screw up drilling board mountings.

[proaudioguy]

Whatever you all decide will be cool.  I always wanted to have one of these and this will motivate me to build one in a year or two.  If you are doing a limited run please let me know so I can get one.  Oh and not that it matters but I prefer eyelets.

[HotBluePlates]

Tough vote...

If the only hole size is 3/32", it is better to drill only the turret holes. As Sluckey said, the user may get confused and put a turret in the wrong place.

I would have voted for turret holes and pass-through holes, if the pass-through holes were more like 1/8". That would allow more selection of wire to fit the holes, and would prevent the chance of installing a turret in the wrong place. Tooling limitations being what they are, a buyer probably doesn't want to pay for the setup time to changeover the CNC machine repeatedly.

Mounting holes seems attractive, until you actually assemble something. I'll bet money that unless you always use the exact same chassis (which has its own pre-drilled mounting holes for the board AND the transformers) that you'll hit a snag where something doesn't line up right, or you wish a hole in the boad or the chassis was in a little different spot. (Not that I've ever run into that problem...)

[Jack_Hester]

I would have voted for turret holes and pass-through holes, if the pass-through holes were more like 1/8". That would allow more selection of wire to fit the holes, and would prevent the chance of installing a turret in the wrong place. Tooling limitations being what they are, a buyer probably doesn't want to pay for the setup time to changeover the CNC machine repeatedly.

I wouldn't mind them all being turret-sized holes.  That way, I can take my Sharpie and mark the pass-thru holes for oversized drilling.  Then, the mounting holes, for the next oversized drilling.  I do this on the boards that I fab for myself. 

Jack

[sluckey]

It's really easier to deal with enlarging the pass-thru holes than it may seem at first glance. I make mine 1/8" and size the standoff holes for 8-32 screws.

Most of the pass-thru holes are on the edge of the board. (There are no turret holes on the long edge.) Then there are 4 holes on the power end of the board for screens and B+. That only leaves 4 holes in the center of the board and they are all in line. Really simple once you study the pattern.

Once the pass-thru holes are enlarged, the possibility of swaging a turret in the wrong place is eliminated because the turret would be a sloppy fit in a pass-thru hole.

[EL34]

All the 20 gauge solid core wire I stock, and that includes cloth, PVC and teflon, goes through a 3/32 hole no problem
And the 18 gauge stranded PVC wire I stock goes through a 3/32 hole no problem
So unless you are using some massive diameter wire, you are good to go
If you want the wire holes larger, just drill the small holes out
That would be easy to do since the holes are already there and you have a guide hole already in place

I just cut a couple boards today with all the holes, but I cut the boards 1/4" too short and so the mounting holes at the right end are not on the board.
There's still other places at the right end of the board where two more mounting holes can go
I'll make two people a deal on these two boards if anyone is interested.
PM me if you want one of these boards
There's a pic down below of those two boards

Here's the hole diagram for the boards
The two boards I cut today end right where the two blue holes are at the right end of the diagram below

[eleventeen]

My suggestion would be, if you are thinking about supplying with the thru-holes, to supply at least 1 and maybe 2 copies of the "map" = the piece of paper showing the layout. (I'd be sorta surprised if you didn't do this anyway)



I have never turreted a bare board, so maybe this is an out to lunch suggestion.


Tape 1 "map" over the bare board so that the holes line up.


When you are ready to turret the board, take a sharp pencil or a pointy something and poke through the turret holes. Follow up w/a sharpie. Should leave a slight mark indicating where turrets go. Turret base covers up the mark(s) in the board, no? Or you swab them off w/alcohol if they bug you.


Alternatively, are not all the wire-thru holes are at the very edge? Take a piece of paper masking tape or blue painters tape and cover all those. Turret away on everything else.


If someone accidentally turrets a wire hole, they drill out the turret from the bottom, so it doesn't show, right? Nobody does this without some spare turrets, the expectation is that you are going to botch a couple. If they turret the whole line of wire holes....then that ain't so good, I guess.


For the extra $3, if someone wanted the "look" of the fed-thru wires, that's a no brainer.

[EL34]

My suggestion would be, if you are thinking about supplying with the thru-holes, to supply at least 1 and maybe 2 copies of the "map" = the piece of paper

All my drawings are always on the library page, so you can print out whatever you want

[EL34]

I shortened the board as per Steve's suggestion, so now it is 14 inches long

[EL34]

Haaa, I was able to modify the two boards I had previously cut too short
As per Steve's suggestion to move the end mounting holes inward and cut the board size down to 14 inches

I drilled a few new lug holes and cut the left end down by -.25 inches
On the right end I drill two new lug holes and moved them down one row so that the 8/32 mounting screws are not too close to a lug


It was easy to put the lugs in the correct places and not in a wire hole
The wire holes are all along the top edge and the bottom edge of the board and just four wires holes on the interior
On the interior wire holes I put lugs next to them first to mark them

I installed the lugs in one board because I have been wanting to shoot a lug press video for a while, so now was a good time to do that
So here's one board with the lugs installed

[sluckey]

Now that's purty Doug! 

Time to lace and load. 

I'll be trying to get you to drill my next board. In fact, have you considered a drilling service such that people could submit a 100% full size pdf drawing, you convert to your format, and sell the drilled board? On a one of a kind basis?

[EL34]

No, not PDF and hand labor
I don't have time for that monkey business

There's a way easier way to do that

I have a custom turret lug design program on my web site
You can design your own board and the program sends me the finished machine code for my CNC to drill your board.

Lots of people have designed their own board using my program here.
http://hoffmanamps.com/php/TurretBoard/TurretBoard.php

I just finished uploading the Turret lug video to youtube
This video is the AC15 board


http://youtu.be/bpVai-RajFM

[sluckey]

There's a way easier way to do that

I have a custom turret lug design program on my web site
You can design your own board and the program sends me the finished machine code for my CNC to drill your board.

I'm aware of that. But AFAIK, the program is not scalable. IOW, if I want 0.25 spacing between lugs, can you make that a user option?

[EL34]

I'd have to have a look at my program


The whole program was written with a fixed horizontal spacing of .296875"
Background images and a bunch of stuff are all set to that spacing


It's not something that could be done easily

[EL34]

Ok, I had two of the AC15 boards ready, who wants one?


One is just drilled and one has the lugs installed

[EL34]

The AC 15 board with the lugs installed has been spoken for
I have one with just the 187 holes drilled


I am gathering up some of the parts that I did not not for Steve's AC15
I just received
750P silver mica caps
16uf/475v F & T electrolytic caps
33uf/450v electrolytic caps

I still have 3 resistor values to procure and I will have all the parts for the board

[EL34]

I sold both the AC15 boards I drilled but now that I see there is some interest, I will make more
I am still gathering up some of the parts that I did not stock


I'll post back here when everything is in stock and ready to go

[sluckey]

Doug, you may want to also stock the F&T 16/16µF@450V dual can. That's what I used. Your already carry the 32/32 and 50/50. Same clamp fits all 3 cans.

My can is in the lower right corner of this pic...

[EL34]

Update

I have the dual 16/16 450v F&T's on the way
And I also stock the 16uf/475V F&T's

As an option on the parts list, I will make a note on the parts list that you have a choice

In my case, I would prefer not to drill a Cap can hole and use a mounting bracket for the dual F&T 16uf cap
I would probably do like I always do, mount the main filter caps along the front edge of the board under the pots

[EL34]

Ok, the AC15 board is done and all the info can be found in this post
http://el34world.com/Forum/index.php?topic=17184.0

Go to the post above for details

[kagliostro]

Very COOL Doug

K

[EL34]

Thanks Franco