Anybody tried a large flatbed laminator for toner transfer?
2004-07-16 by Thomas P. Gootee
I was looking for a better way to make larger lots of pcboards at a time when I remembered that several years ago I had "accidentally" purchased a fairly large laminating machine at a gov't surplus auction. It's a "Commercial 210M" model, made by Seal. The bed and heated lid/press's mating surfaces are flat and measure about 18 x 22 inches. I am wondering if anyone has found a way to make these types of machines work well, for making pcbs with the toner transfer method (laser printed pattern on common glossy paper). It sure SEEMS like it OUGHT to be able to work well. And it SURE would be *NICE* to be able to fill an 18 x 22-inch area with boards and do them all at once! This thing is heavy! It has an external frame composed of two 1/2-inch x 2-inch (cross-section) steel members on each side, holding up the bed and the lid's axle, with 3/4 x 1 1/2 steel c.s. members on each side comprising the lid/press's support and the lever/cam/closing mechanism, that rotate on a 1/2-inch diameter steel axle in the rear. And there's a 3 5/8 x 2 inch U-beam going from one side to the other, between those, from which the lid is suspended, by adjustable "swinging" 1-inch-diameter hollow bolts (so the lid can self-level as it closes). The levers'/cams' large handle goes all the way across the front of the unit and is connected to the opening/closing mechanism by steel members that measure 3/8 x 1 inch c.s.. The handle swings about 180 degrees between the closed and fully open positions, which raises the front of the lid about 10 inches and the rear about 2 inches. It has a temperature control knob and a temperature gauge (thermometer), which go from 150 deg F to 350 deg F. It's rated at 1350 Watts, 11.3 Amps, 115 Volts. The inside surface of the heated lid seems to be made of something like hard rubber. In the base, where the lid touches when closed, there was a smooth "cushion" about 3/4-inch thick, which sat on what looks like a sheet of asbestos-type material (no lectures on asbestos, please). My first experiment was just to place a pcb with a toner transfer pattern sheet in the press (see my pcb toner transfer web page at http://www.fullnet.com/u/tomg/gooteepc.htm , for specs of paper used, etc), which was set for just under 300 deg F, and close the lid for three minutes. No good. The toner rubbed off quite easily. So I decided to try to go for higher pressure and placed a sheet of 1/4-inch-thick wood on the press's pad and put a pcb and toner pattern on top of the wood. That made closing the press significantly more difficult, and, I assume, applied more pressure to the pcb. The results were a lot better, but were spotty. Apparently the inner surface of the lid is either not evenly flat, or maybe not evenly resilient, or, it's being deformed irregularly by the pcb, or something. So, I tried placing a 1/16th-inch-thick sheet of aluminum on top of the pcb and toner pattern paper, just before I closed the lid, in an attempt to even-out the pressure from the heated surface. The results were better, but not consistently great. I then pulled out the cushion/pad from the base and replaced it with a couple/few of sheets of 1/4-inch-thick plywood, to which I later added a 1/8-inch sheet, all in an attempt to get more pressure applied, and in a more uniform manner. The wood looked smooth and flat, but I put a 1/16" thick sheet of aluminum UNDER the pcbs, as well as on top of them, just in case. Eventually, I had it all set up so that closing the lid required quite a bit of force on the handle; probably well in excess of 50 pounds for the last few inches, to get it to the fully-closed position. I did make some excellent boards, with toner that could not be rubbed off with fingers or with a stiff toothbrush, no matter how hard or fast I rubbed on it. But, whenever I tried to put more than one board in the press, the results were spotty again, with maybe one out of four boards being good. And, occasionally, even with only one board in the press, there would be small areas where the toner was not fused well-enough and it could be rubbed off by my thumb or by the toothbrush. I assume that the solution involves either more pressure or a better way to get the pressure distributed. I was sandwiching multiple boards between two 6x18 inch pieces of 1/16th" aluminum (two halves of a "kickplate" made for the doors of houses. And I did have the boards separated by a couple of inches. But perhaps if I used separate pieces for each board (or maybe even NO aluminum sheet on top of the boards, since the pressure is now much higher), it might work better; or MAYBE even a *thicker* (i.e. stiffer) sheet of metal, covering the whole inner (heated) surface of the lid. But, I had boards that had to be made and shipped (for the Curve Tracer kits that I sell; see http://www.fullnet.com/u/tomg/gooteect.htm ), and work to do. So I have gone back to using the clothes iron, for now... Sigh... Any suggestions? I need something that works perfectly every time. A handheld iron does that, for me. But I'm on a continuing mission to automate or streamline as much of the process as possible (I've got a nice etching tank, with two 50 Watt heaters, digital thermometer, and a 250 gph submersible pump that pumps sodium persulphate across the boards at high speed, which works very well. And for drilling I'm converting a small x-y milling table to CNC and mounting a surplus z-axis over it, "real soon now"...) If anyone can suggest something else I should try to get the laminating press to work well, I'll really appreciate it! Thanks. Regards, Tom Gootee tomg@... http://www.fullnet.com/u/tomg ----------------------------------- [Non-text portions of this message have been removed]