drilling welds and cutting panels

[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:

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
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

[Bigbjorn]

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:

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
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.

[back_in]

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

[chazza]

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

[groucho]

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....






https://www.aulro.com/afvb/images/imported/2010/01/637.jpg

[Bigbjorn]

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.

[Tote]

mmmmm.....thermite :twisted:

[groucho]

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





https://www.aulro.com/afvb/images/imported/2010/01/636.jpg

[groucho]

don't go silly drilling right through
clean and easy




https://www.aulro.com/afvb/images/imported/2010/01/635.jpg

[groucho]

The new bracket with the holes plug welded back



https://www.aulro.com/afvb/images/imported/2010/01/634.jpg

[spudboy]

Nice welding Groucho! Very neat.

[groucho]

Nice welding Groucho! Very neat.

That was on one of my Good days......:D

[groucho]

Panel cutting
grinding discs a pain in the rear
tin snips ditto
Nibbler good expensive
Air saw cheap now days just buy a packet of Hacksaw blades
you can get about three out of one blade
wonderful little tool





https://www.aulro.com/afvb/images/imported/2010/01/630.jpg

[dreamin']

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,


Thanks Charlie. Not planning to weld. Thought I'd just keep the joins as straight and strong as possible and rivet them. I had thought I could rivet through the cut-out welds but too big.

When I cut the damaged panel out I want to leave the folded sections with the welds in place and then rivet the new section in against these double-thickness, strong edges.

Am hoping if I brace the tub in a couple of planes before I cut it will hold square and make snug fit.

Thanks for the advice - see how we go.

[dreamin']

Thanks everyone for your tips and pics

I'll go looking for a weld cutter and shop around for saws. Air saw looks nice, but not sure if my little compressor would handle it. What do they need?

Will post pics as I get into it.

Thanks again

D

[groucho]

Thanks everyone for your tips and pics

I'll go looking for a weld cutter and shop around for saws. Air saw looks nice, but not sure if my little compressor would handle it. What do they need?

Will post pics as I get into it.

Thanks again

D

Air saws are cheap that one is a tiwanese job dose all i want
A normal air comp 8/12 cu /Ft runs them easy.....

[slug_burner]

What is the difference between that weld cutter and a sheet metal drill?

[Bigbjorn]

What is the difference between that weld cutter and a sheet metal drill?

Are you thinking of the stub drills sold in sizes to suit pop riveting? These are just a conventional twist drill made short for rigidity in hand held drilling. They usually have a 135 degree cutting edge angle instead of 118 degrees. This is to allow most of the cutting edges to be engaged at point breakthrough to help ensure a round hole not the misshapen hole often produced by a 118 degree drill in thin material. The spot weld drills have two outer cutting points with a third in the centre where the chisel edge is in a normal drill. Spot weld drills start cutting on the circumference of the hole and continue to cut inwards. Normal twist drills start cutting from the centre outwards. The idea of the spot weld drill is to cut out the weld body just outside the area of the weld and leave the panel separated.

[slug_burner]

Are you thinking of the stub drills sold in sizes to suit pop riveting? No I think of them as jobbing drills (jobbers) and they usually are double ended. These are just a conventional twist drill made short for rigidity in hand held drilling. They usually have a 135 degree cutting edge angle instead of 118 degrees. This is to allow most of the cutting edges to be engaged at point breakthrough to help ensure a round hole not the misshapen hole often produced by a 118 degree drill in thin material. The spot weld drills have two outer cutting points with a third in the centre where the chisel edge is in a normal drill. Spot weld drills start cutting on the circumference of the hole and continue to cut inwards. Normal twist drills start cutting from the centre outwards. The idea of the spot weld drill is to cut out the weld body just outside the area of the weld and leave the panel separated.

The three pointed ones as you say two outer cutters with the central locating point, I thought they were sheet metal drills. I thought that it would prevent oval holes and the sudden grab as the break through on thin material. I guess I should refer to them as spot weld drills from now on (doesn't seam right as it sounds too specific)

[Bigbjorn]

The three pointed ones as you say two outer cutters with the central locating point, I thought they were sheet metal drills. I thought that it would prevent oval holes and the sudden grab as the break through on thin material. I guess I should refer to them as spot weld drills from now on (doesn't seam right as it sounds too specific)

They were specifically produced for drilling out spot welds and are called spot weld drills in manufacturer's catalogues. You should use a size that cuts just outside the area of weld. The whole idea of these drills being to leave the panels separated. No problem in using them as a general purpose drill in thin material but they are expensive. If you are constantly getting ovality when drilling thin material try starting with a heavy centre punch mark and using higher speed and lighter feed. You could regrind the drill to a flatter angle so most of the cutting edge is in contact at breakthrough.

Other possibilities to ensure circular holes are to use a pilot drill and finish to size with a ball nose slot drill, or, a pilot drill and finish to size with a repairman's taper reamer .


"Jobber" in drill speak refers to drills that follow a certain geometry developed by a Mr. Jobber. Catalogues refer to them as Jobber Length Drills. Stub drills are double ended to save time in production work. Worker doesn't have to down tools and look for another drill when he stuffs or blunts the one in use.

[dreamin']

Come in 8.0mm & 6.5mm diameter.

What is diameter of spot welds on our Landies? Are we trying to cut exact diameter of weld or just outside it?

[back_in]

Hi
the cutter has to cut a track just larger than the spot weld.
If too small you will leave some of the weld till attached
just cut through enough to allow the cut piece to come free.
do not cut too far into the back sheet, so not weaken it.
cheers
Ian

[chazza]

Use kerosene as a cutting fluid on aluminium. Stops chips welding to the cutting tool. Normal practice in machine shops.

I have used kerosene in the past but dislike it due to the smell and fire risk.

"Fitting and Machining", TAFE Publications, 2009, specifies kerosene or soluble oil.

I haven't had any adverse issues with soluble oil,

Cheers Charlie

[groucho]

The spot welds on the early Land Rovers are generaly
a bit bigger than todays welds.
25/64 or there abouts works well
I never use any coolant as it makes a mess.
Generaly you are only drilling through panel material and
is very quick so it don't generate mutch heat
It is very Quick so you have to be carefull or oops you go through
Easy to do.......Mark