I alos found that it helps to first wet the entire board with the resist a brush or finger then pour more resist in the center and start it spinning. My spinner is built from a garden variety 12V 4" computer fan. Don't remember the fan's rpm but my rpm control system consist of holding down the button till the rpm seems good then pulsing it button to maintain it. One can tell by sight what works good for RPM you can see the puddle of resist spread out. I start out just a little slow but within a couple of seconds I go to high speed.
It gives a very nice even coating that is not too thick. I do thin out out the resist I am using just a little.
Unfortunately sourcing finished boards from China has become so economical that I out sourced my last two project boards rather tha doing them my self.
Craig
--- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:
>
> Ben,
> As the board get larger and larger it's harder to keep it balanced on the spin table so it doesn't fly off. Also it's harder to get a good coat without streak out towards the outer edges. It's not that you can't do a 6"x6 or even an 8"x ∗" but it may take several trys to get it to get a coating that will work out.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com, "Ben L" <bhleavi@> wrote:
> >
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@> wrote:
> > >
> > > If the boards are 5" x5" or less then you could spin coat the boards, it gives a fairly nice coating.
> > >
> > > see: https://picasaweb.google.com/115378886522213655693/DYIPCBs?authuser=0&feat=directlink
> > >
> > > Craig
> > >
> >
> >
> > Why just 5" x 5"? Are you saying that Spin Coating will not work on a larger than 5" x 5" board? I if so, Why?
> >
> >
> > Ben
> >
>