Silk screen chassis

[JHow]

I have read a little bit here where some of you have done silk screening for chassis (JM Fahey, cminor9).

I did some silkscreening years ago. Can someone give any pointers for silkcreening amp chassis? or point me in direction of suppliers?

[J M Fahey]

You start by drawing the front panel using real measurements so you don't have to scale later which can introduce errors.
I use old Corel Draw 5 which I got free with a scanner long ago, but there must be a lot of Software Packs out there, even some free ones.
Most are overkill for such a simple task.
Then you print it on "Vellum", translucid (not transparent) architect's design paper and burn your screens with it, or just send the file to a screen maker.
It may look like a lot of trouble for "just one" but you can print as many as you like , and you can easily erase your screen and draw something else.
You can also put a few designs on a single larger screen (front/back panel, Logo, Speaker label, even custom picks) and print all at once or mask what's not needed.
You can print straight on the actual chassis or to play it safer, on thin metal/plastic/wood , and glue that panel onto the actual chassis or just use jack and pot nuts to hold it.
Nowadays for a single one, laser engraving beats it, but for even a small production it is competitive.
The only problem is that printing takes seconds, but later you have to clean the screen and squegee thoroughly.
I print at least 8 or 10 of each, and on more popular models go for 30 to 50.
Use-everywhere logos get printed in 50 to 100 amounts, also stickers which are given freely to Musicians to decorate guitar cases, drums, trucks and cars, whatever.
Free publicity is something always welcome.
I have not gotten into T-SHirts yet, I should do something about that.
As for US suppliers, can't help you, but Mr Google probably has something to say.
Good luck, whatever you do.

[JHow]

What are you using for "ink" on a metal chassis? Paint?

[J M Fahey]

Yes, on metal it always is some kind of paint, although silkscreeners usually call it "Ink", for traditional reasons.
The type used depends on substrate, the background on which you print it.
The most difficult is Chromed or stainless steel, (Tube Laney/Electro Harmonix) where you have to use 2 component epoxy paint, which often requires some kind of oven for full curing, not recommended for the amateur. Best finish anyway, thick layers (you can feel it with your fingers), longest lasting, expensive.
The most versatile/general purpose type is similar to regular Synthetic Oil Paint/Enamel, which dries overnight, and smells funny for a couple days.
I use "Bright/Enamel Vynil" or Nitro "Ink", which dries in 10 minutes but does not hold on bare metal, you can scratch it away with your nails, unless you apply them on a chassis previously painted with car-type Nitro or Acrylic paints, no big deal.
Being chemically compatible, they blend and hold very well.
I always use car type (guitar type) classic paints, because they dry quickly and without ovens.
As an example I'll show the process:
1) Aluminum front panels, already cut, bent and chemically treated to make the paint grab better.

2) Panels already painted with Sherwin Williams "Supermorblack" or "Cadillac Black" Nitro Paint. Dry in 10 minutes.
Not very clear picture being black on black.(The table gets its fair share of paint too)

3) A just printed front panel. Notice the very simple equipment, just a wooden base, wooden frames, a couple hinges, not much more.

4) 8 front panels drying among some still empty cabinets, my minimum amount to make it worthwile, anyway just one can be printed if needed.

5) Another use of silkscreening, part of a 100W power boards batch.


Well, that's about it.
It's a versatile technique, you can reproduce faithfully, if you wish, many old amps (say Gibsons, Vox, Selmers, Silvertones, whatever) that are *not* mainstream.
You can buy some reproduction Marshall, Fender blackface and some very few other panels, but on every other one you are on your own.
Good luck.

[JHow]

...
4) 8 front panels drying among some still empty cabinets...

Sorry to ask so many questions. I hope you don't mind. I'm not out to steal trade secrets, so I will be respectful if there are techniques you don't want to reveal, but I am curious. After looking closely at your pictures, am I right that the holes for the pots and switches are not not full size? If so, I am wondering how does the paint take the punching afterwards?

[Steve Conner]

Thanks for posting the pics JM, very interesting!

I too am curious why you printed the panels before drilling, and also what primer you use on the aluminium.

[J M Fahey]

Gee, thanks.
Aluminum is hard to paint, because it has a thin, non porous "glass" surface, which you have to remove somehow.
1) Primer: I use 2 component Wash Primer. It contains some phosphoric acid which etches the surface.
I cheat a little and to increase the surface roughness I let panels stand vertical overnight in water+some spoons of lye, it eats the surface and removes all grease .
Then wash them with clean water and let dry.
You know you did well, because before water droplets separated on the surface, as if it was oiled , and afterwards water clings to the now micro-porous surface.
You can also sand blast it, "scratch" it creatively with wet emery paper and some detergent drops, or wet steel wool, or become creative with some wire brushes, like on Silverface Fenders; the idea is to remove that thin "glass" layer.
As you see, I took the chemical path plus painting the panels.
Iron panels are much easier, just ask for practical tips to your friendly car painter who does it every day.
2) I paint before punching because I make small runs, and it's faster punching a centering dot and using it as a guide.
All my punching dies have a centering "tip".
The other way to do it, needs setting "stops" against which I must push the chassis to make one particular hole in all panels, then readjust for the second one, and so on.
Time-effective only on 100-up runs.
I make only around 20 amps a month, in 3 or 4 "breadwinning" models, plus custom orders, so my production techniques are tuned for the special market niche I carved.
I'm exactly between the boutique handmaker and the small factory.
PS: my punches cut cleanly through paint and aluminum, edges are sharp, only "problem" is that the front surface is painted, but the metal edge is silver, anyway most holes get covered by nuts, push-in switches, fuse holders, etc., so no big deal there.
PS2: easy paint adherence test: run a sewing needle scratching the surface: if you get a "V" shaped scratch, silver inside and with borders still painted and slightly raised, your adherence was *perfect*; if you see a scratch much wider than the needle tip, with rough unpainted edges, showing that your paint cracked and fell out ....

If I had

[clyde1]

Nice work! I had one-piece chassis that I inherited. I had to remove the former maker's markings and silk-screen my own moniker onto them. I first had them nickel-plated, which turned out nicely. I had a screen made, got all the supplies and proceeded down this unknown avenue. It was a gong show from start to finish. Because the chassis were angle-front, I had to build a special jig to hold them. The first ones didn't go so well and I managed to get four done the first day. The beauty of nickel-plating was that the paint could be easily removed when the screening didn't turn out. I also had some powder-coated chassis and found out quickly there was no room for error. I have now abandoned this approach and have faceplates with different control layouts for the same generic chassis, a la Fender. I get a shop to do the silk-screening however. Once-bitten, twice shy!

[Steve Conner]

Clyde1, did you ever make guitar amps in Scotland?

[clyde1]

No Steve, I'm in Canada, but I have been to your wild domain several times to visit friends in Airdrie.

[Jag]

Where in Canada Clyde? I'm in Edmonton (I'll be in the other Airdrie next week).