A beginner tip for turning gummy steel

[Shawn]

Today I was turning a small shaft to act as a pivot for two bearings. I got the size roughed out but the finish wasn't very good at all. The material looked like hot rolled, mild steelbar and was tearing all over the place. I made sure I had a sharp and honed tool on center line, I tried a few different angles on the tool but only got a slight improvement. As I only needed room for two bearing to be pressed onto the shaft I marked out the two locations by plunging in with a parting tool. The plan being to reduce the shaft in these places so the bearing easily fit and then go back and bring the two high points down to a press fit with a file and emery cloth. After making the plunge cuts I went back to my original turning tool to cut down the unnecessary material. What do ya know, out of the blue I am getting the best finish I have ever got on this steel? I was in my lowest speed ( forgot to change the speed back from the boring bar operation) and the tool was working beautifully. I will see I can post a few photos tomorrow. 

I might be the only one who seems to equate speed with a nice surface finish but that's obviously not the case. 

Hope that might give someone a helping hand one day. 

Shawn

[EdK]

Here are some links to a vertical shear tool that's supposed to help with the problem of getting a decent finish on cold and hot rolled steel.

http://www.gadgetbuilder.com/VerticalShe...alShearBit


http://www.chaski.org/homemachinist/view...0524139b4b

http://bbs.homeshopmachinist.net/showthread.php?t=39894


Ed

[f350ca]

Thought I'd posted here about using one but can't find it. Yes Shawn they work wonders, they work on your shaper too. It was an article on shaper tooling that enlightened me.

I needed a good finish on some 2 inch sched 80 pipe here.



Another advantage of this tool seams to be how efficient it cuts. The pipe here was close to 4 feet long. With the shear the work only bowed enough to show 0.001 lager dia in the middle. Pretty sure any other cutter would push the work away a lot more with out a follow rest.

[EdK]

(09-27-2014, 11:00 AM)f350ca Wrote: Thought I'd posted here about using one but can't find it....

I thought so too but I couldn't find it with a search either.

Ed

[Shawn]

I have been using a shear tool on the lathe and my shaper for awhile now. I think the slowing the speed down was almost as big of an improvement. Now I need to give both of them a try at the same time. ?

Cheers
Shawn