How best and what tools to use to turn steel?

[alexccmeister]

Hi,

I have been trying to turn steel rod down for testing as and when I get my rolled ballscrew I will be planning to turn it down to fit some bearings and such. But its really tough to turn and I went tru 2 cutting tool before I managed to get a decent turn down of the diameter. But the surface is not smooth and it get so hot (Which is understandable for steel. How best to turn steel to get good result. I am talking about turning stainless steel here. Is rolled ballscrew softer? What type of tool material should I use? Carbide, HSS or something else? Thanks in advance.

Alex

[Cruiser]

you will want to use the best carbide you can get and the rolled screw will be hard probably to the high 50's or more in rock c and even carbide will have a hard time with the interuptions. this is why many grind off the hard surface to get into the soft core for the machine work. sure it will get hot, try to loose the heat with the chips, leave some stock for finish and let it cool before doing the fine finishing. coolant, mist, air jet, or jockish would help.

[alexccmeister]

Hi Cruiser,

Thanks for the reply. Is HSS harder than Carbide or vice versa? Littlemachineshop is selling indexable tips and HSS tips are twice the cost of Carbide. How do you suggest I grind the hard part off the ballscrew? I tried using files for grinding down the S.Steel rod and the steel just wore the file down. instead of the other way.

How fast should I turn the spindle? 1000RPM or max 3000RPM for steel? Thanks.

[Cruiser]

Carbide is much harder than HSS, for grinding you might do best to find a pedistal grinder to use or an angle grinder with a hard wheel. For how fast to run lathe, just stay in your comfort zone for now, actually carbide and the diameter of screw would put speed high, but it is going to be more important for you to get good finish and size's right on spot. So stay in comfort zone and if the speed you select feels noisy try another and try to keep speed up some. the rolled screw is going to be work hardened all along the ball race with the hardest part being the ridge or land at the outside diameter, this is where the material was rolled into itself. trying to cut this with a light machine, lacking rigidity will waste a lot of carbide, so measure it out and grind this ridge off, you will quickly see what i'm talking about when you start grinding, the bottom of the ball race is going to be hard too, but not as bad and it won't be as severe interuption so cutting it will depend on the grade and geometry's of the tools/carbide you select to cut with in your machine