I stand at the crossroad, patchwork Duetto

[cjheath]

Anybody have a recommendation for drill bits (type/brand) that won't go blunt straight away?

I can't see any trace of a cutting oil. Use some, even WD-40 is fine. Also, you need to go slow enough that you can feel the drill bit biting. It also takes a fair amount of pressure, don't be afraid to push too hard, as long as you're going slow. It's no use if it's just running in circles making heat and blunting itself. A sharp bit should last quite a long time if you don't abuse it.

[LaStregaNera]

Cobalt / Carbide will last longer - use some lubricant and slower is better      Are you using the spot weld drills ?  they have a smaller pilot on the tip, then a wider flat edged area like a milling bit that cuts the spot weld  - that way you end up with only a small hole on the back sheet.     There's also some expensive ones that are like a mini-holesaw

Amazing work C !

Never had any luck with the mini holesaw ones - much better off learning to sharpen a normal 8mm sutton to work as per the spot weld drills - the extra length is very usefull too!

[Craig_m67]

I wasn't using any lubricant. Didn't think about that at all. 
Will have a look on the weekend when I get back to it.
Any type I should be looking for?

I have two spot weld bits I bought from RS but they need a pilot hole of sorts pre drilled otherwise they wander about. Easier just to use a std drill bit so far.

Found more rust (LH inner wheel well) too, yay!!

[AikenDrum105]

A good hit with a sharp centrepunch usually gives the pilot something to hang onto. 

I've seen someone using a grease stick to smear a weld before drilling it.  But I'd just run the drill as slow as you can,  keep a tin of WD40 or similar handy and give it a squirt now and then - it also helps keep the bit cool which will make it last longer.

I use a tin of sticky spray lubricant called Trefolex which works brilliantly for drilling and tapping. 

This one http://www.ebay.com.au/itm/TREFOLEX-CDT-SPRAY-300G-/230884331168?pt=LH_DefaultDomain_15&hash=item35c1c74ea0&_uhb=1

most engineering supply stores would carry it,  Blackwoods, Hare and Forbes, Bearing Supply stores etc.

I'll have another tin too, while you're at it

[Craig_m67]

Cheers Scott,
I've been centre punching, the two spot weld bits I have don't have nib or pilot.
I was running the drill flat out too, so obviously to fast

There's been several years (decades) since metalwork class in yr10

Found some very ugly repairs today underneath more mastic/bitumen crap..not sure I want to post a pic.  I suspect the other side is similar 



Mind you, once your in (it's fine) and all that .. no repo repairs panels for this bit I'm aware off.  On a lighter note.. That undercoating stuff, once chipped off wipes away nicely with some 18mth cellared petrol.  And for those of you playing at home it goes rust, creamy primer, red paint, under sealer .. So yes, was painted body colour underneath at the factory.

[cjheath]

I was running the drill flat out too, so obviously too fast

A drill is ground to have certain angles, and so when working right it'll cut maybe 0.2mm on each and every revolution. As soon as it stops cutting, it's just making heat instead. Learn to recognise the feel of when it's cutting (biting in) and when it's not, and simply don't let it spin - make sure it always has enough force behind it to cut instead. You should see nice spirals coming from both sides. If that requires too much force, it needs sharpening (that's something you can learn to do, too - I even do it by hand on a wheel).

That said, if you use a drill whose angles have been ground to be suitable for wood, or brass, you'll have a hard time with steel. You can usually re-grind them, but you have to know what to aim for. There is no one-size-fits-all.

Any cutting oil is better than none, and WD-40 not much worse than the purpose-made stuff. Just spray the target and/or the drill tip before each hole, and repeat if it's a deep hole.

[Craig_m67]

Had a surge of motivation on the weekend, most of the passenger floor is now out, will clean it up later and trial fit new.  Really hate undoing patches, on patches on rust on mastic

[AikenDrum105]

Awesome ! 

Some of those patches were lovingly applied... ;P

[Craig_m67]

*L* made me laugh, cheers

it's all part of her history. Digging out the multiple layers of floor in the inner sills was the most challenging



Recv. a twinspark AFM to go with my ECU an loom today.
All i need now is wiring diagram and a test stand

[colcol]

For drilling out spot welds, you can make up a sheet metal drill or buy some stub drills or panel drills that panel beaters use, they are short little 'throw away' drills, Colin.

[LaStregaNera]

For drilling out spot welds, you can make up a sheet metal drill or buy some stub drills or panel drills that panel beaters use, they are short little 'throw away' drills, Colin.

Learning to make a spot drill out of a normal drill is about 1000 times cheaper than the "throwaway" stub drills. You can sharpen a normal 8mm sutton in spot weld form about 30 or so times before it's as short as the brand new spot weld drills that cost the same...

[colcol]

Learning to make a sheet metal drill is a fine art, but when you do, they work like a treat and you only need to drill the top panel to make the weld separate and they don't distort the panel either, Colin.

[LaStregaNera]

It's not rocket science.

[AikenDrum105]

[colcol]

The sheet metal drill that i am talking about has a flat bottom and a spike or centre in the middle of the drill.
If you just use a flat bottom drill, there is nothing to steady it and it will just take off, when you start to drill, put a steady in the centre of the drill and it stabilizes it.
An old tradesman taught me how to grind one up years ago when i was an apprentice, great for drilling out spot welds, Colin.