Diamond tipped drill-bits

This gets farther into the "defeating instructions" category than I'm comfortable with on an open newsgroup. If you have a legitimate need for information, work through industry channels.

So pick them. The typical UK "mortice" lock is trivial.

So why are you using a carbide drill bit ? These are insanely expensive and hard to find. Almost all those sold are actually masonry bits, which might be carbide, but they're no use for hard plate.

Use a cobalt bit instead. The ones you want are silver M42 HSS alloy and _NOT_ the ones with the blue or vari-coloured "cobalt" coating.

I really wouldn't think that "thin" hard plate would be that bid a deal with regard to using quality carbide bit. In any event diamond abrasive bits are easily available if you want them. Try a safe and vault tool supplier. The bits you are talking about are also used in other industry. Getting them from a non-specialized supplier shouldn't be a big deal. Try a Google search.

Pretty common item. Harbor Freight use to sell them up to 3/8". Probably still do. Google shows 80K+ results.

Not alot of levers.

No they are pretty easy to find you just have to know where to go to get the ones you want.

Cobalt alloy bits will not drill most hardened steel very well if at all. They will wear much longer than other bits and they are good for stainless etc. They are all I use for normal drilling operations. Well worth the extra cost but they have limitations.

As it was put to me by a machine shop. Carbide is carbide, the only real difference between a $2 masonry bit and a $10 safe drilling bit is the angle the bit was sharpened. I have yet to see a piece of hardplate I cant put a hole in with a regular masnory bit after I have changed the angle.

GH

I am assuming you are talking about this sort of bit:

Never used them myself, but I'd expect you would end up trashing them the same way. I'd suspect that what is doing the bits in is the drill-jolting impacts with the tumblers / gate /steel-brass boundaries etc. (i.e. after you have penetrated the plate) - unless you are hot enough to be able to drill the pivot point every time. Are you finding that carbide bits get chipped or just blunted? - If the later you can sharpen them a few times.....

"Coherers"

As with anything, there are different grades of carbide. If you're doing production wood machining, you start to care ("micrograin" carbides have a longer working life before they lose their edge). I've never seen the grade noted on drill bits though.

The shape of the insert varies too. Not a problem for thin hardplate, but swarf clearance isn't very good if you use a good masonry bit with a long insert and flutes intended for dust. When I have resharpened carbide bits for drilling steel, I've had more luck with cheaper poor quality masonry bits, than with the good ones.

Hardplate isn't really that hard to drill. It's an easy job compared to some engineering tasks, such as repair work on press tooling.

How do you price your time for regrinding though ? I don't have a drill sharpener jig that will do carbide, and the carbide-capable wheel I do have needs to be used freehand. Your carbide drill bits are much cheaper than mine (I'd pay about $30), but I'm buying from an engineering supplier, not locksmith's wholesale. For $10 bits I'd just buy the things.

I still haven't found much that can defeat M42 HSS.

As an aside, how hard _is_ modern "hardplate" ? What's it made of ?

depending on the company, you cant find that out, without investing a LOT of money in expensive tests.. Reslom comes to mind.. --Shiva--

I learned a new word

swarf

Best band in Brighton !

If you are a locksmith you can order hard plate bits from any locksmithing supplier. They go through BS locks no problem. regards from a very dull Oban.