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...

[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.!!

[AdCNC]

interesting convo chaps. :-) ive just watched a vid Jonathan's doing test cuts in aluminium on the second pass you can here what i class as pretty bad resonance of the cutter, that alone is mainly down to the rigidity and mass of the machine, now i to have use them blue coated cutters on jobs in the past, they are "OK" as chinese and korean cutters go but there are better out there but at a cost, personally for me using a router of any sort to cut steel is asking bit, especially when spindle plays a big role in the quality, and time it takes to machine a job in steel. i would convert a mill to cnc for use on steel any day and not rely on a cutter to be the saving grace. i can't see any router thats been made on this forum that could hold to a few microns. My machine at work does that but that way 6.5 ton.

[JAZZCNC]

i would convert a mill to cnc for use on steel any day and not rely on a cutter to be the saving grace. i can't see any router thats been made on this forum that could hold to a few microns. My machine at work does that but that way 6.5 ton.

You Bloody trouble causer starting this back up again. . .Lol

I agree 100% Addy but that doesn't mean router can't cut steel like was suggested they just don't do it as good or quick. For the Odd time you need to cut mild steel with a router then provided it's of good strength it's possible and can get jobs done, Yes not High accuracy Jobs but still profiles etc then it works.

Many moons ago the Windows Guru's said controlling a CNC machine with Windows was imposible So Art fennerty proved them wrong. . . . . . Never say never.!!

[CharlesJenkinson]

I landed on the calculation of specific cutting force (SCF) whilst researching the other day. I get the feeling that fiddling around with some of the parameters in the SCF equation via the use of fancier cutting tools like the blue nanograin, and speeds/feeds and DOC appropriate to routers, that the actual cutting force comes down, for cutting materials like steel. And this is what makes cutting harder materials possible on a router versus the traditional milling machine, i.e. It's a different process.