mike s
Established Member
hi
how do i drill a hole in high speed steel?
will carbide drill bits cut it?
thanks
how do i drill a hole in high speed steel?
will carbide drill bits cut it?
thanks
drilling HSS?
- Thread starter mike s
- Start date
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Knicked this from elsewhere but saves me writing it all out
Anneal the spot with a propane torch try marking the spot with a center punch to keep track of where you are.keep the inner blue flame tip ( the prettiest cone)on that spot for about ten minutes if the spot on the metal starts to change colors like to a dull red that enough, and then let it cool to the point where you can touch it bare handed. That will soften the area as much as trying to drill it with a diamond bit by all the heat generated from the friction. Then get a good drill one made from high speed steel it will probably cost as much as a set of the cheap ones and half the diamond. Make sure you use a coolant Blu Chill is good get that where you get the drill from, an industrial supply house Blu Chill is usually concentrated so dilute according to instructions in a spray bottle and keep the drill bit cool squirt it every time you see steam coming off.
Or get a diamond drill bit - very expensive
Anneal the spot with a propane torch try marking the spot with a center punch to keep track of where you are.keep the inner blue flame tip ( the prettiest cone)on that spot for about ten minutes if the spot on the metal starts to change colors like to a dull red that enough, and then let it cool to the point where you can touch it bare handed. That will soften the area as much as trying to drill it with a diamond bit by all the heat generated from the friction. Then get a good drill one made from high speed steel it will probably cost as much as a set of the cheap ones and half the diamond. Make sure you use a coolant Blu Chill is good get that where you get the drill from, an industrial supply house Blu Chill is usually concentrated so dilute according to instructions in a spray bottle and keep the drill bit cool squirt it every time you see steam coming off.
Or get a diamond drill bit - very expensive
My recollection is fuzzy Mike, but I think care is needed as a lot depends on the exact grade and state of heat treatment. I think there are some that can be drilled going slowly and with plenty of cooling (taking a lot of care to avoid heating and work hardening) using a solid carbide drill, and some that can't. It'd be worth asking a toolmaker.
Another route is to find a tool making outfit with EDM (spark erosion), and to have them do it. It won't put heat in, and won't disturb the condition of the steel...
Another route is to find a tool making outfit with EDM (spark erosion), and to have them do it. It won't put heat in, and won't disturb the condition of the steel...
NetBlindPaul
Established Member
You can soften HSS with heat treatment, you should not drill ferrous materials with diamond as diamond is carbon, ferrous materials contain carbon and they react together.
What ou may need is a Stellite (TM) drill bit.
What are you trying to drill, what size and for what purpose there maybe other options.
Stellite drills are what I use to drill metal cutting hand files.
What ou may need is a Stellite (TM) drill bit.
What are you trying to drill, what size and for what purpose there maybe other options.
Stellite drills are what I use to drill metal cutting hand files.
NetBlindPaul
Established Member
They are not that expensive Gareth, bearing in mind the cost of spark eroding it will be probably around 4 hrs say at a cheap rate £120.00
Depends on the size and how many holes you need to drill.
Depends on the size and how many holes you need to drill.
Fair point, hadn't realised spark eroding would cost that much. I agree once you have a few holes the cost does become easier to justify. I was just surprised to see the Stellite drills at 30 - 50 quid each.
NetBlindPaul
Established Member
My suppliers start at around £12!
The whole point of many types of HSS is that they are so heavily loaded with alloying elements that when used as cutting tools that experience a lot of heat they as well as being very tough and wear resistant also self harden...
CHJ
Established Member
In simplified terms, HSSteels dependant upon specific alloy will need to be heated somewhere in the range of 850-1250 degrees C to soften.
This however needs to be done in a controlled manner, the steel needs to be heated to just below its critical austenitizing temperature and held until uniform temp throughout and then raised to its critical temp. It may crack or even explode if you don't.
This final (austenitizing) temperature is critical for selecting the grain size/alloy constituents and ultimate hardness of the material, and temperature held for specific times to allow the even formation of structure.
To harden, quenching must take place from this temperature in a specific manner and time control, by air, brine, salt bath, water. dependant on alloy specifics.
Followed immediately by tempering if the resultant glass hard martensite is not to crack or even spontaneously shatter.
Tempering 'may', more likely 'will' need to be repeated several times because any remaining autensite may convert into brittle martensite.
The chances are that any attempt to soften and re-harden normal shop HSS tools will result in a finished piece significantly differing in characteristics from the original, especially in a home workshop.
This however needs to be done in a controlled manner, the steel needs to be heated to just below its critical austenitizing temperature and held until uniform temp throughout and then raised to its critical temp. It may crack or even explode if you don't.
This final (austenitizing) temperature is critical for selecting the grain size/alloy constituents and ultimate hardness of the material, and temperature held for specific times to allow the even formation of structure.
To harden, quenching must take place from this temperature in a specific manner and time control, by air, brine, salt bath, water. dependant on alloy specifics.
Followed immediately by tempering if the resultant glass hard martensite is not to crack or even spontaneously shatter.
Tempering 'may', more likely 'will' need to be repeated several times because any remaining autensite may convert into brittle martensite.
The chances are that any attempt to soften and re-harden normal shop HSS tools will result in a finished piece significantly differing in characteristics from the original, especially in a home workshop.
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