Homebrew PCBs

On Thu, 20 Oct 2005 21:58:52 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> Hmm, this is a good point so it bears checking on.  I currently use
> a clothes iron and press it by hand and use about 5 inches square of
> the sole plate at any one time.  I weigh about 225 pounds these days
> and am pushing down on the iron with a fair amount of force - lets
> say half my weight 112 pounds - which I am sure is more than I am
> pushing down.
> 5 x 5 = 25 sqaure inches of surface area
> 112 / 25 = 4.48 pounds per square inch
> This has worked very good for me so far (although I suspect I have
> beginners luck).  So, a 12" x 12" board would require
> 12 x 12 = 144 square inches x 4.48 pounds per square inch = 645
> pounds of presure on that plate for a large circuit board.  This
> would be pretty hard to achieve without some form of mechanical
> advantage (unless I keep putting on weight since I quit smoking!)
> Chris


My worry was not so much about the magnitude of pressure in general, but  
how to adjust if from board size to board size.
With the fuser i can choose to let the wide or the narrow side run  
through, thus i can keep the "length" in the fuser similar with all the  
different boards i make. I have not found variations of a factor 2 or even  
3 a problem. The rubber roller is doing a pretty good job at keeping  
things in contact.


If a press should work, i think it must have a rubber plate below the  
board, a rigid material both sides will probably cause trouble. Also, i  
would be afraid of temperature patterns, they can be quite extreme with  
heating elements that are concentrated in one area. A pressure gauge could  
be made easily, just take the bathroom scale and put it between the press  
plate and the screw/lever you use to tighten it.

At this point, i'm just not seeing the advantages.
But you know - never listen to the nay sayers. Look at the arguments why  
it mightn't work, fix them, and do it.

ST