Ignoramus408 wrote:
On Sun, 13 Nov 2005 01:25:46 +0000 (UTC), Christopher Tidy wrote:

David Billington wrote:

You can get add on rectifier/ smoother boxes as well as add on HF unit.
For some years I used this set-up with a Max-arc rectifier and Max-arc
HF unit connected to a Pickhill (like Oxford) 180A oil cooled welder. It
worked well but no current control for ramping. Both units were
purchased in the UK 2nd hand. I think Max-arc themselves are long gone.
The rectifier also contained a choke to smooth the DC.

Thanks for advice. I'll keep an eye out for a used rectifier unit. Any
idea what they're worth in decent condition?


You can make your own rectifier from diodes, or buy a fully made
rectifier bridge. They sell a lot of them on ebay.

Lot of 4 Diode 1N3267 - 400 Volt 160 Amp

http://cgi.ebay.com/Lot-of-4-Diode-1...cmdZ ViewItem

You can make a rectifier bridge out of SCRs, as well:


SCR Stud Mounted 300 Amp Heavy Duty 250051 High Volt

http://cgi.ebay.com/SCR-Stud-Mounted...cm dZViewItem

these SCRs could get you weld at under 180A.
http://cgi.ebay.com/6-Eupec-SCR-Rect...c mdZViewItem

2 Huge SCRs, SCR diode
http://cgi.ebay.com/2-Huge-SCRs-SCR-...c mdZViewItem


I have two more SCRs that I can give you, good for 300A each, free
except you pay shipping to UK.

http://igor.chudov.com/tmp/TT170N-SCR.pdf

Note that besides a rectifier, it would be good to have something to
smooth your DC voltage. That usually includes some capacitors. I can
give you three 19,000 uF 75V capacitors that are already paralleled
and have discharge resistors on them already, for free, if you pay
shipping to UK.

If you look for SCR on ebay, also type thyristor in the search box.

http://cgi.ebay.com/10-IR-620-Amp-SC...QQcmdZViewItem


i

Thanks for all the kind offers! I'll think about building an add-on and
get back to you if I do, but I was hoping I might find a ready built
unit this time. Otherwise every tool becomes a project, as I'm sure
you've discovered :-). That said, postage from the US to the UK is
usually much cheaper than the other way around. USPS seem to do work as
opposed to sitting behind their desks in trendy hi-vis vests chewing gum
and listening to rock (this was what I found when I visited our local
sorting office recently).

Sadly I daren't do any welding right now. I spilt a gallon of diesel on
the workshop floor and soaked it up with sawdust, so now I'm giving it
some time to evaporate to reduce the fire risk!

Chris