Drilling Chrome Vanadium steel

[Gilbertd]

Now I know we've got a few engineers on here and this, while not being LPG related, is definitely a general discussion question. I need to drill an 11mm hole through a 20mm lump of Chrome Vanadium steel and am failing dismally. I started small and managed to get a 3mm hole drilled using a decent quality HSS drill bit in a pillar drill and lots of oil. I then managed to enlarge it to 5mm. Unfortunately my drills going up larger than this appear to have seen better days and I'm getting nowhere. Nipped out to Wickes yesterday and got a couple of their 11mm bits which have managed 1mm or so before simply burning the oil and making horrible grating noises. Anyone got any idea what I can use? I know that I can't cut the stuff with a hacksaw but can with an aluminium oxide cutting disc in an angle grinder. Is there such a thing as an aluminium oxide drill bit? If so, where can I get one?

[Morat]

according to the internet, cobalt bits will just about do it but you really need tungsten carbide and lots of patience.

I'm no engineer, I look forward to hearing from people who actually know

http://answers.yahoo.com/question/index ... 051AA2ywZ0

[Tubbs]

Tungsten carbide, or a diamond tipped drill i think wira make one. Lots of cutting oil and a really low speed.

[Gilbertd]

A Google for Tungsten Carbide brings up lots of masonry bits...... I did consider trying one but thought better of it, I think the shank will probably melt. However, it seems that Toolstation do Cobalt drills, there's a branch about 4 miles away from me and they are open on a Sunday! They do individual sizes and a set so I think I'll get one and try it. If it does the job then I'll probably treat myself to a set if they'll drill anything.

[demonicwillow]

As Tubbs said, also with plenty of pressure so it cuts and doesnt just bounce about getting hot, if you know a small engineering firm it may well pay you to take it to them and get the holes punched instead of drilled, much cleaner, quicker and accurate, by the time you spent out on fuel, drill bits etc etc, well you know what I mean

[Gilbertd]

OK, so 8 miles worth of LPG and a Cobalt drill later, I can confirm that they won't do it. The cutting end burred over almost as quickly as a standard HSS drill bit did.

[demonicwillow]

Im tempted to and also but I wont, I do understand how you feel when there is summat you really want to get on with but cant do easily ... just serviced a Ford KA for a friend, took me 4 days to get the spark plugs out basically after drowning them with diesel, plus gas, super dooper ice crack it release spray that is supposed to freeze steel down to -45C, getting the head nice n warm, then spraying the plugs with the said super dooper ice crack it release spray and getting nowhere it basically come down to 2 options, head off and take it to a machine shop adding an extra £200+ to her bill or break the plugs pop out the plug core's and with the aid of a few junior hacksaw blades and some nicely grounded to shape pin chisels, get them out that way, very frustrating I can assure you, got there in the end but unfortunately my fingers are still suffering with frostbite from the -2C weather

Go get them punched out tomorrow if you can http://www.google.co.uk/search?hl=en&tb ... XiKIWCVAWw a stainless steel fabricator will probably have the right gear

[demonicwillow]

Or another way you could try if your still determined is to try a masonry drill, on the slowest speed you can, which it should be set too anyway, I have had success in the past drilling case hardened steel by drilling through the case hardening with a masonry drill bit then changing to hss for the softer stuff underneath

[mat_fenwick]

Is locally heating the area (to temper it back a little) an option? What is it that you're trying to drill? The fact it's a chrome vanadium steel doesn't itself affect the hardness - that's effectively down to the carbon content and the tempering temperature.

[Tubbs]

http://www.leofixings.com/fixings-produ ... 0-132.html
Kind of meant these. But cant see why a masonry drill wouldn't. Be interesting to see.

[demonicwillow]

Or Here

[Martec]

As an apprentice in the 60's I had to take over from the guy who drilled the chrome moly van headers for tubes to be welded in ........with a 1.5" HSS drill. The trick was to keep cutting and not let it slip as this surface hardened the steel header.

Slow speed and a steady feed is essential. I assume you have allowed the drill to skid and so surface hardened it, so you will need to cut through this initially and keep on cutting, not easy without a drill press. Ignore the noise and keep cutting.

The normal included cutting angle of the drill for steel is 115 degrees, but the ramp on the cutting face can be quite sharp, you could try making it alittle more shallow so that when it starts cutting it won't dig too deep.

Or use a burning torch if it doesn't have to be too accurate.

Best of luck
Brian

[mat_fenwick]

Wonder if this would do the job?

[Gilbertd]

As it's made by B&D I doubt it would have a hard time drilling through butter and, at that price, I'm not going to buy one to prove the theory!

I assume you have allowed the drill to skid and so surface hardened it, so you will need to cut through this initially and keep on cutting, not easy without a drill press.

I think what happened is when I wore out the Wickes drill bits I have surface hardened it. So much so that it wore out the end of the Cobalt bit before it managed to bite. I've been using a pillar drill on the lowest speed and lots of lube but failed. However, as I managed to get a smaller hole through, I've changed the fixing method. It should be strong enough for the job.....

[demonicwillow]

Wonder if this would do the job?

Black n Decker Black n Decker Black n Decker

I think what happened is when I wore out the Wickes drill bits

Now there's your problem, its got our name on it !!

[SimonHobson]

The most reliable method would be spark erosion - that'll cut anything. Finding someone who can do it might be a different matter though as it's not exactly the sort of thing that every workshop has.

[tom-madbiker]

use A masonary drill a decent one if you have a grinder sharpen it up a bit ideally use a gerrn grit wheel but you can use a normal one but it will wear th wheel considerably run fairly slow about 300rpm and use wd40 as a lube it will gothrough no problem we used to do this to get the holes in 60 rockwell steel prior to wire erosion when i was toolmaking you will need to use a fair bit of downward pressure on the drill

[demonicwillow]

How did you get on drilling your hole ??

[Gilbertd]

I gave up! I managed to get a 6mm hole before destroying every drill bit I tried as I think I surface hardened it. I just used a thinner pin through it. If I manage to break the pin then I'll have another go.