Oli Glaser wrote:
> I remember having a hard time finding them in the first place - just
> looked quickly now for a US source but no luck.
> We get them from Mega:
> https://www.megauk.com/through_hole_rivets.php
> The brand is Favorit, they are meant to be used with a special punch but
> we didn't get one, as they work well anyway for our purposes.
> I got some ideas from this page (very good in general for PCB making)
> Look under the Through-Plating header - some of the links may still work
> (I remember a couple being out of production though)
> http://www.electricstuff.co.uk/pcbs.html

Interesting. So how do you get the rivets in -- just push them in with the=
=20
tip of a tweezer?


> We use a UV light box (4 x 15W tubes, timer etc, bought on eBay, very
> good quality and cheaper than RS/Mega offerings. If anyone wants to know
> exactly which one let me know and I'll check)
> I imagine for hobby purposes the price will be more of a factor and some
> savings could be made, probably as you say about half the price of a
> board house for materials.
> However there is a free 2-layer service available here (UK, Spirit
> Circuits) although I think it is directed more at companies (they ask
> for company details, though it does not specifically mention that they
> will not deal with hobbyists)

What is the advantage of using UV over presensitized PCBs sensitive to=20
regular light?


> I use Ferric Chloride - have you had better results with Ammonium=20
> Sulphate?

We like Ammonium Sulphate because it's clear. FeCl is dirty, it stains=20
everything it comes in contact with and you can't see the board in the tank=
=20
as well.


> I do use Sodium Metasilicate rather than Sodium Hydroxide for developing
> as it's far easier to use (not as sensitive to timing, temperature etc)
> I made a small etch tank using nichrome wire for the heater driven by
> PWM/MOSFET with a PIC16F, and a DS18B20 with PID to control temperature.
> Used a fishtank pump for the agitation also.

Fancy! We use a glass tray and sodium hydroxide, because that's what the=20
manufacturer of our PCBs (MG Chemicals) recommends. It works fast and=20
definitely is time-sensitive (easy to overdevelop), but with practice it=20
stops being an issue.


> We could do with a proper drill press though (did have one but it was
> old and broken, so we gave it away), that's probably the most time
> consuming part currently, plus as you mention broken drill bits. I'm
> thinking it's worth spending the money to get another half decent one,
> as it will have plenty of other uses too. The Proxxon one looks nice and
> a decent price - are you happy with it?

We are happy with it. There are some minor things that could be better=20
(e.g., a universal chuck) and we use it with a variable transformer for=20
speed control, but it does the job very well, and has minimal vibration.

Vitaliy

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