Creating front panels with the toner transfer methode
If you start making pcbs on your own and look about it around the web you will quickly encounter the “toner transfer method”. This descibed printing the pcb-layout with a laserprinter onto somehow coated paper and ironing this printout directly onto the copperside of the unetched pcb. The heat causes the lasertoner on the paper to bake into the copper, enabling you to directly etch the pcb, without going the traditional way with uv-exposure and chemical developer. The black toner prevents the copper from being etched. After etching you can get the toner away with diluent or aceton.
Now one of the collegues describing the method also takled about making aluminium front panels with toner tranfer. Cause i am increasingly nerved by inkjetprintouts, clearcoat and expensive special adhesive transparent slides i decided to give it a try. Here i will describe my experiance making protoype front panels and the process in whole.
Drilling front panel
First you need a bare eurorack frontpanel with the right width, you get them from the electronics distributors. Drill your holes until the panel fits your jacks, pots and switches. I think its not a good idea to drill an already labeles front.
Scanning front panel
The i scan the panel to have a graphics template. If you dont have a scanner try to take a picture with a camera. If you got a zoom move away from the panel and zoom in, you will get much more parallel edges than makeing a picture in wide-angle.To have good quality you should make the graphics 300 dpi (dots per inch). You can scan directly with 300 dpi in your scanner dialogue or scale the scan later up in your graphics program. The latter involves a quality loss but thats no problem. The scan wont be printed out, its just the template for your graphics. Make small crosses in the middle of your holes for easier later positioning.
It is not the badest idea to print your layout out from time to time and lay your pot-knobs and screws onto it. It is enoying to see knobs overlaying words.
Print it out
When the layout is finished you will want to print it out. You take a sheet of “special paper” (later more about what is special) and glue it in the middle of a normal A4-sheet. You just need to glue one of the smaller edges. This edge should point in the direction of your laserprinters paper entry. The “special paer” is just a sheet of coated paper. I use a shet from a big electronics distibutor, some use the paper you bake cockies on others use glossy paper or transparent slides. Just pay attention it is suitable for laserprinting and wont melt.In your printer dialogue set quality to HIGHEST and darkness to DARKEST to get as much toner on the printout as possible. IMPORTANT: print the layout mirrored!
Removing dirt and fat
Before ironing you should remove dirt, fat and dust from the aluminium panel with alcohol.
Tape panel on the printout
To prevent accidently shifting i use simple adhesive tape to attach the frontpanel to the paper. The cross markings i mentioned above will help you find the right position.
Ironing – mind the table!
Now you can iron the front with the attached printout. I set my iron to full power. Some advise less heat, i tried with the result, that i could scratch the toner from the surface after ironing. The more heat you apply, the better the toner will bake onto the frontpanel. Some collegues warn that to much heat will somehow liquify your printout killing clear outlines, i didnt encounter these problems yet.
Mind a good underlayment from corg or felt or both or something other. The heat is tremendous and will ruin any expensive table without problems. I big towel as underlayment wont do – we need some resistance to be able to pres the iron onto the panel.
I also put a cotton sheet (e.g. T-shirt) between iron and panel to protect the paper from mechanical damage and distribute heat better. Then move the iron slowly for about 2-4 Minutes with slight pressure all around the panel, rotate it until all is systematically ironed and very hot.
After ironing the panel is very hot. Wait about 10 Minutes and put it in some water with some dish detergent.
After another 10 minutes – you can also wait longer if you like – you can peel of the paper. The Graphics should be durable now and quite resistant to (light) fingernail scratching. Sometimes the letters look a bit gray, there might be some paper fibres baked on the toner, you can peel them off with your wetted finger.
Not perfect but a good compromize between time and money.