I just happen to have some good vacuum equipment in my shop that I use for vacuum casting. Getting a hard vacuum isn't a big deal for me. I've laminated some large plywood sheets with a shop vac and a BIG vacuum bag (boat building) which is about the other extreme. Some associates built some fiberglass refridgerated rail cars with a similar technology.
I certainly wouldn't recommend going out and purchasing a $5000 or more vacuum pump just to make PCBs for a hobby. It's a cheap simple way to get good pressure if the hardware is on hand.
By the way, I can't take credit for the 'Bake 'n Bag' idea - but the poor old gray cells can't remember who suggeted it to me....
----- Original Message -----
From: ballendo
To: Homebrew_PCBs@yahoogroups.com
Sent: Tuesday, October 19, 2004 7:11 PM
Subject: [Homebrew_PCBs] Re: Questions about toner transfer method.
Hello,
Although I like your idea...
The MOST force you can get from a vacuum is 14.7 lbs/inch. At sea
level. Most vac pumps are rated in inches of mercury, and this is
29.92 inches. Most "common" vac pumps will give about 25 inches--or
less-- of vacuum, so you're going to have even less pressure. I've
done a LOT with vacuum clamping over the years, and use 10-12 lbs per
square inch as a ROT (Rule Of Thumb<G>) I'm working near sea level.
So with a 2 x 4 inch board, we're gonna get 80 to 96 pounds of
pressure. I'm no "Arnold", but I can surely do that with an iron...
BUT, as I first mentioned, I like your idea. And I think that the
pressure attainable WILL be enough. But we CAN provide more with a
handheld iron, IMO.
Another similar idea which seems to have gotten lost in the mix when
it was posted; about using an electric frying pan, washcloth and a
lead brick instead of an iron.
Good heat control, accurate, repeatable even pressure (if your brick
of lead isn't flat you'll need something flat between it and the
washcloth). The only thing remaining is time, and that's easily
monitored/controlled.
Your setup duplicates this, and "could" provide equally repeatable
pressure. A brake bleeder tool--any Auto parts store-- will give you
a simple means of accurately repeating the vacuum.
Using an electric frypan/griddle (cheap new and even moreso at EVERY
salvation army/thrift store everywhere<G>) and a weight (doesn't have
to be lead, but diver's weights are resdily available, as are other
sources of lead or similar "heavy" things, like thick steel plate.)
is a simple effective way to avoid the need for a laminator, which
still seems to me to be the best overall answer.
But I DO like your idea!
Ballendo
--- In Homebrew_PCBs@yahoogroups.com, "Earl T. Hackett, Jr."
<hacketet@c...> wrote:
> If you have a vacuum pump (even a good shop vac or vacuum cleaner)
you can put the board and the artwork in a Reynolds Aluminum 'Bake 'n
Bag", pull a vacuum and set the iron on it. That should generate
much more force (and much more unifom force at that) than you could
ever generate by hand.
> ----- Original Message -----
> From: Bob Weiss
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Monday, October 18, 2004 11:24 PM
> Subject: [Homebrew_PCBs] Re: Questions about toner transfer
method.
>
>
>
> I just made another "test" board using Staples Picture Paper and
> this time used more pressure and time under the iron and I am
amazed
> at the quality you can achieve!! There is no going back to
the "old"
> way for me...this works great! Thanks for all your help.
>
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