Milling mild steel

[dudz]

My Cnc mills aluminium very well I think although I have not mastered finishes yet.

I tried to create a small pocket in Mild steel the other day, with a single flute 6mm endmill. Spindle at 9,000rpm , feedrate 90 mm/pm and depth of cut 0.2mm. Don't know what happened, but it ended up snapping the endmill and making a mess. This is all obviously done wrong.
It was only a practice, but please can someone tell me what rates I should be using for cutting slots in 2.5mm mild steel ? This is not something I am going to be doing very often.

[mekanik]

Hi Dudz
Try a look @ these SLOT DRILLS
they are used for producing keyways

[Jonathan]

9000rpm is far too fast for a 6mm cutter in mild steel. For things to be easy you'd want around 1000-2000rpm, but that's not happening with the spindle you have so just see how low you can set the speed without the spindle tooling.

You'd also be better off using a cutter with more flutes, e.g. 3 or 4. Depending on the spindle speed you can use, you may need to use cutters with a special coating - e.g. the blue ones from cutwell tools.

Hi Dudz
Try a look @ these SLOT DRILLS
they are used for producing keyways

Doesn't say if they're HSS or carbide? I'm guessing from the price that they're HSS. Carbide is definitely needed here due to the high spindle speed.

[dudz]

Ah thx. Might be better to use a 4mm 4flute in the blue ones then ? and just do more passes.

[Robin Hewitt]

Don't do this to me, I am definitely a 20th century machinist. If you tell me you can cut soft wood with your milling machine, I try and persuade you to cut a square peg because I know it isn't going to work. If you tell me you have this magical tool bit that lets you cut mild steel using a woodworking router, I want to see one you did earlier because I don't believe you

[Jonathan]

If you tell me you have this magical tool bit that lets you cut mild steel using a woodworking router, I want to see one you did earlier because I don't believe you

See here...

I did that with a generic carbide endmill. Admittedly that machine is probably a little stronger than dudz's machine...

[Robin Hewitt]

I did that with a generic carbide endmill.

Did what? That's a machine build thread (Imagine I could find a bewildered smiley here - grin)

[Jonathan]

Did what? That's a machine build thread (Imagine I could find a bewildered smiley here - grin)

The last three images in the build log show some parts I cut with that machine from steel.

[JAZZCNC]

If you tell me you have this magical tool bit that lets you cut mild steel using a woodworking router, I want to see one you did earlier because I don't believe you

Cutting steel is easy enough with a router provided the machines stiff enough and you use the correct tool for the Job.!
Yes compared to a milling machine it's slow going and your not ripping more scratching away in comparison but most certainly possible and something I've done many times.

Cutwells X5070 Blue Nanograin carbide 4 flute cutters are the magical tool you'll be looking for Robin.!!

[Robin Hewitt]

The last three images in the build log show some parts I cut with that machine from steel.

Wow, you made a router that was heavier than your milling machine ? This is most excellent.
.
But even so, hand on your heart, would you really recommend it for cutting steel?