Classic cars forum & vehicle restoration.

[D4B]

Some advice please, I have just bought from the national chain of tool shops who shall of course remain nameless but are painted red and white, one of those spot weld drills with the sprung loaded pilot and removable reversible cutter piece.

It lasted precisely 30 seconds and was blunt and broken before I had even managed to remove one spot weld

Considering that the 1977 Honda I am using it on is predominantly made of cheese, this was a surprise!

Has any one had experience of these? Perhaps I did something wrong?

Thanks Steve

[ukdave2002]

I Have an SP one that must be 20 years old and still going....With all drill bits you do tend get what you pay for, some of the stuff from China is made from Mcdonalds leftovers...other stuff is ok..one other thing to check is that the drill is rotating true, one of my Dewalt cordless drill is useless with anything less than 6mm as deviates about 0.020" off centre snaps small drill bits and heats larger ones up, its relegated to wooden tasks and screws If I didn't know I'd blame the drill bits....

Dave

[D4B]

Thanks Dave, I think the type I bought is next to useless:

http://www.machinemart.co.uk/shop/product/details/cht468-516in-spot-weld-drill?da=1&TC=SRC-spot+weld

I shall try this type next:

http://www.ebay.co.uk/itm/8mm-COBALT-QUALITY-SPOT-WELD-DRILL-BIT-Made-in-England-/110532822156?pt=UK_Body_Shop_Supplies_Paint&hash=item19bc45048c

[ukdave2002]

It's so difficult to gauge the quality of some tools these days; my lathe, milling machine and others are made in China, there are some niggles and some corners cut for cost, but actually the important bits like the flatness of the bed are fine, and I would not have been able to afford an equivalent UK made lathe...other stuff is different I had an anvil from the same red and white store, again made in China, believe it or not it had filler in it , the store manager was so shocked he gave me a refund and offered me 25% off anything else in the store!

Spot weld drills do have a tough job as the steel round the spot is hardened, cobalt coated drills are recommended for harder stuff like stainless steel, so fingers crossed should do the job!

Dave

[D4B]

I have bought loads of great tools and equipment in this store, including my mig welder, which have all been fantastic and usually great value too. I think the only exceptions have been this nasty spot weld drill and their cheapest angle grinders of which I have just killed # 3.....

[Phil - Nottingham]

I bought one of those spring loaded versions 20 years ago - not from that shop - and it quickly blunted

I use a normal sharp twist drill now which removes enough to all metal to be peeled back by a thin cold or air chisel
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[D4B]

[MikeEdwards]

I use one like the second link you posted - just a normal 8mm cobalt drill with a different shaped end. I've got a link somewhere to instructions on how to sharpen them which could quite easily be used to get a "normal" 8mm drill bit and convert it into a spotweld drill.

The key thing I found made a difference is to remember that it's an 8mm drill bit, and use it slowly (in terms of rotational speed). First time I tried one, I just stuck it over the spotweld, pulled the trigger and went for it. After three or four spotwelds, it was blunt. With the second one, I used the drill much more slowly, and because it didn't heat up so much it lasted much longer.

[D4B]

Hi Mike,

I have just bought 10 x used 8mm cobalt spot weld drills which I plan to resharpen and use, so I will report back

Steve