# Milling HSS?



## Twmaster (Apr 5, 2011)

What sort of cutter to mill an HSS bit? Carbide?

I need to make a fairly accurate form tool for for a job in my workshop. I am not steady enough with a Dremel to get the kind of shape I need. The tool is too small for me to attempt on my bench grinder.

A small endmill would be perfect to get the shape I need.


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## Ken I (Apr 5, 2011)

I'm assuming you want to grind a profile onto an endmill (A'la router bit profile) ? In either HSS or Carbide.

Grinding is the only practical way and for carbide it would need to be via a diamond wheel or at the very least CBN.

You would also need to do this on a tool and cutter grinder equipped with wheel profiling gear (like a Diaform).

Pretty much beyond the realms of hobbyist.

Having said that you can make something out of silver steel and harden it (what are you going to machine - material - quantity - is this a "production" run ?) What profile are you trying to achieve ?

As a complete Heath Robinson approach I have ground some cutters freehand on a bench grinder using a cordless drill run in reverse to drive the cutter - the trailing edge of the cutter touches the wheel first and tends to receive more attention from the wheel giving a natural relief.

Below - this method to repoint a broken tap - illustrative












You can accomplish much the same thing by putting the cutter in a lathe and freehand grind using a Dremmel and suitable grinding and slitting wheels to shape your cutter.

As stated - this is a very Heath Robinson approach and not to be considered for accurate profiles.

Also please be careful - safety glasses etc. Also if done in a lathe - cover the bed - you don't want grinding dust there.

TC router bits in various profiles are cheaply available - these are not really meant for metalwork but work quite well on non-ferrous metals. Use on steels is limited to very light cuts and are easilly broken.

Ken


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## gbritnell (Apr 5, 2011)

As Ken has stated why not go with drill rod/silver steel. I have made some quite intricate cutters from this material and they have held up quite well. 
It sure beats trying to grind small shapes into a rod of high speed steel by hand.
gbritnell


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## Ned Ludd (Apr 5, 2011)

Hi Guys,
Contrary to popular opinion you *can* mill HSS with a solid carbide end mill. One of our club members did so recently. I seem to recall him saying it was fairly easy but obviously care was taken to avoid too many shock loads which would have broken the end mill. The old timers at the club thought he was milling annealed HSS but it was a fully hard piece of 5/16 lathe tool.
Hope this helps.
Ned


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## Ken I (Apr 5, 2011)

Following from Ned's coment I may have interpreted your request incorrectly - are you trying to make a turning tool profile from a carbide cutter - ie making a radius forming tool for a lathe using the milling cutter to generate the form ?

I must admit I've never tried to use a TC cutter on HSS - wouldn't want to risk an expensive TC cutter and I really don't think it will work anyway.

Anyone else out there tried it ?

Ken


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## mu38&Bg# (Apr 5, 2011)

I tried milling HSS with a carbide endmill and got a 1/2" linear cut before the endmill was done. Cutting looked promising initially. The endmill was something that was in my toolbox when I bought it, but it was a good brand. I'm sure that if you bought a tool specifically for hardened steel it could be done with a reasonable tool life. General use carbide endmills won't get far.

I have also made turning tools from drill rod.


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## BillTodd (Apr 5, 2011)

I've turned HSS with a carbide insert. You'll probably need a substantial milling machine to mill the stuff without breaking an end mill with vibration (they can shatter with a bang so watch out) .

Bill


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## Twmaster (Apr 6, 2011)

Duh. Make a cutter from drill rod..... Harden...

That is a much better solution than trying to mill HSS.

Thanks for the insights gang.


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