Thread: drilling welds and cutting panels

Originally Posted by dreamin'

Arfa's previous owner cut a section out of the front of the tub so he could remove it and fold down the front seats to roll out his swag for the night, camping in the Tassie Central Highlands. The rest of the time, the removable section was held loosely in place by a couple of pins through the capping.

This arrangement must have left his body much stiffer than Arfa's!

I have noticed some thin vertical cracks in the galvanised door striker bracing plates, and suspect it may have something to do with this.

So I have found a spare tub and am planning to remove the front section by drilling out the spot welds, cut out Arfa's butchered one leaving the welded tabs in place, then rivet the replacement panel to the tabs.

I would replace the whole tub but Arfa's is in much better nick overall.

Questions:

1. is there a knack or special tool for drilling out spot welds? - I have seen a special drill bit used in magazine articles, with mixed results
2. what's the best way of cutting panels to get a straight, flat edge? I'm thinking tin snips would leave a bent edge and cutting disk on a grinder would be hard to keep straight. Must be something I can run along a straight edge clamped to the panel - jigsaw with an aluminium cutting blade?

Any tips from those who have gone before greatly appreciated

Thanks

P&N/Suttons make special cobalt HSS spot weld drills for this purpose. They are relatively expensive and near impossible to sharpen without a tool and cutter grinder. Come in 8.0mm & 6.5mm diameter. They have a centre point to locate and stabilise the drill and two outer cutting points which should cut just outside the area of the spot weld and leave a neat hole and separated panels. A nibbler or body panel saw, either air or electric, would be best for cutting the thin sheet aluminium.

Hi
after cutting 100's of spot welds with a sharp very thin broad saw blade.
this works.
the best is a old broad high speed saw blade.
sharpen the end by grinding a thin sharp cutting edge on one side, leave the other as is, this make the chisel cut straight.
grind the other end flat.
use the flat side against the material you wish to keep, and use a big hammer.
otherwise buy a spot weld cutter and cut the spot weld out of the piece you do not want to keep and grind and dress up what is left
have fun
cheers
Ian

I bought a cheap cutter from a shop on Fleabay, which sounds much as Brian describes; do a search there. On aluminium I think a cheap one should do well but it would be wise to brush soluble oil onto the work, whether or not you have an expensive or cheap cutter.

Getting a perfect edge can be tedious but I have had good success recently by:
1. Scribing a line with a straight edge and sharp scriber.
2. Witness mark the line with a very sharp centre punch - this means to lightly punch on the line about every 25mm.
3. Cut with your weapon of choice - your idea of a jigsaw is a good one, I cut 5mm chequer-plate with one recently and it worked well, the blade was medium tooth and I used soluble oil.
4. Use an emery flap wheel in a 4" angle grinder and sand to the line; the witness marks should be sanded in half just as the scribed line disappears.

When you join the repair panel to the body will you weld it? I have a similar repair to do on one of my Rovers and I am tempted to use Sikaflex and rivets,

Cheers Charlie

A drill bit spot weld cutter is the fastest and eazy way to remove spot welds
As Brian say's they are expensive to buy.
My neighbour is an expert panel beater and makes his own out of old drill bits
they are hard to do on a grinding wheel (i can't master them properly)i get him to do them for me. fast and easy i get 30 or 40 before the have to be sharpened. Also makes a nice clean hole to plug weld the panel back....

Originally Posted by chazza

it would be wise to brush soluble oil onto the work, whether or not you have an expensive or cheap cutter.

Use kerosene as a cutting fluid on aluminium. Stops chips welding to the cutting tool. Normal practice in machine shops. Need to clean out the chip tray after use though as a hot chip from machining steel is likely to set the machine on fire.

mmmmm.....thermite

The brace off the 80" took just a few minutes to get off
Easy job

don't go silly drilling right through
clean and easy