General appeal - need to do a windscreen

BX Tech talk
User avatar
cauchoiskev
BXpert
BXpert
Posts: 282
Joined: Mon Aug 15, 2005 11:36 am
Location: France

Post by cauchoiskev » Tue Oct 03, 2006 7:45 am

DavidRutherford wrote:I've sucessfully removed a bonded windscreen before now using both the "hot knife" technique and the bit-of-1mm-copper-cable-and-a-12v-battery hot-cheese-wire technique. The hot-wire method was definitely easier, as once the wire gets hot (150°C ish) then it just glides through the sealant.
That's a bloody good idea, David ! I would have thought that 1mm copper would empty your battery in double-quick time, though. More or less short-circuit it. Maybe ni-chrome resistance wire from an electric heater would be better ?

User avatar
DavidRutherford
BX Digit man!
Posts: 2704
Joined: Wed May 18, 2005 5:07 pm
Location: Placing comments on YouTube.

Post by DavidRutherford » Tue Oct 03, 2006 11:12 am

cauchoiskev wrote:I would have thought that 1mm copper would empty your battery in double-quick time, though. More or less short-circuit it.
Yes, it does. We used about a meter length of wire, which was barely 0.02 ohms of resistance (the connections to the battery were probably higher resistance) which meant we were trying to draw something like 600amps from the battery, which it can't do for very long!

The main problem was that the bit of cable that wasn't being used to cut the sealant gets very hot indeed, so you have to use a bit of a sawing action to make best use of the heat available, and welding gauntlets were definitely the order of the day!

The other problem of course is having enough fat cable to supply to both the inside and the outside of the car. We used about 3 sets of jump-cables in the end.

Got the screen out in about 10 mins though, and well before the battery went completely flat
this might be a signature