Cold rolled finish stinks, I've had enough

[rockrat]

Why does cold rolled suck so bad now? I remember cutting cold rolled 10 years ago and it would finish fantastic. But now... well here's the story.

All I wanted to do was hit the garage, turn on the lathe, make a couple screw jacks, and be happy. But noooooo......rock the rat was not to have fun today.

After the project was finished, I must have sanded every part twice due to poor finish. Changed speeds and feeds more than I changed my mind. Fed by hand to see if I could find the sweet spot. Nada.

I tried carbide and HSS. Used cutting fluid, oil, bacon grease, snot, urin, cat turd and anything else that I could get my hands on. Except the cat. Probably best that he ran off when he saw me reach for him.

The bar would cut so nice, then it would tear for 1/2 a rev, then cut nice again. I ended up usng HSS and running it a bit slower than I thought and got a decnet finish. Sorta.

Then I started to chase the threads. I got 1/2 the depth and they were looking a bit shaggy so I grabbed the thread die to finish it up. And wouldnt ya know, it ended up drunken cause I held the handle my hand instead of using the die holder for the tailstock. Grrrrrr........

So what gives? Do you fellers have a trick you use when it just wont finish? Or should I just change over to 4140 and be done with it?

rock

[aametalmaster]

Wow! cat turds usually work for me, must be the cat breed. I quit using HR and CR for all the reasons you mentioned. I am hooked now on 4130 and P2 Mold steel. I can get unlimited 4130 from work out of the dumpster...Bob

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Bob Wright
Salem, Oh Birthplace of The Silver & Deming Drill

[bobw53]

When your saying cold rolled, I'm assuming 1018. Your getting that nasty grey, smeared finish? With 1018 the only thing I've learned you can do is go with a very high surface speed, up to and over 900 sfm(carbide), and a large depth of finish cut, .020-.030. A high feed wouldn't hurt either. You will probably get a better surface finish without coolant.

If your getting a crappy finish in your threads, again, run it faster, on a manual lathe that can be tough up against a shoulder. Run it Z+ from behind and spindle reverse, so that you don't have to worry about smashing the shoulder, though I'm sure you knew that.

[JRouche]

<font face="Verdana, Arial" size="2">Originally posted by rockrat:
Why does cold rolled suck so bad now? I remember cutting cold rolled 10 years ago and it would finish fantastic. But now...rock</font>

Oh man, I hope we are not seeing the start to a horrible chinese steel importation market.

Mild steel is not the cleanest cutting I agree. But you say you have seen a change in quality over the years so that stirs my thoughts of imported steel. JRouche

<font face="Verdana, Arial" size="2"> I can get unlimited 4130 from work out of the dumpster...Bob </font>

I also like 4140, if I could go dumpster divein for it I would also


[This message has been edited by JRouche (edited 01-28-2006).]

[rockrat]

Yup, 1018, bottom of the batch. With all of the crap they throw in the mix for it, most likely its tears when I hit that little chunk of engine block from a '76 Gremlin.

Will have to try running it a bit quicker. But yes, I think that I need to try a different grade of material. I have some 304L that truns great. Fantastic finish. Must be that little bit of lead in there.

rock-

[rsr911]

I've been having the opposite problem. CR has been hard to come by lately so I'm stuck with HR. Tears up carbide on the CNC cutting through the mill scale and leaves a bad finish on the lathes. Made my bullnose out of HR yesterday (see other post) and got a good finish with a TNMG insert and 1100 RPM with a deep finish cut (0.050") Run those postive rake inserts fast enough and they'll almost polish the metal any slower and the surface it rough than 80 grit sandpaper.

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-Christian D. Sokolowski

[torker]

Christian...a dummass question...as usual, But have you tried soaking the HR in vinegar overnight?
I've been doing it for awhile now and it sure makes life easy.
Russ

[rsr911]

Nope never tried that. I'll need a pretty big vat off vinegar though.

Does the acid attack the mill scale?

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-Christian D. Sokolowski

[torker]

Yes...over night it will remove most of it. I use a large Tupperware cake container to soak most things in.
The vinegar is cheap and lasts a long time.
Try a small piece...you'll like it!
Russ

[tattoomike68]

many times turning cold roll that gummy stuff tears and looks like hell,like a big long shaft that you dont want to spin too fast, I save .002 to file and if its for a seal surface I may save .005" to file then polish.

Cold rolled finish stinks is right , get the stressproof shaft if you can.

[radish1us]

Got to agree that the cold rolled is not what it used to be, even down under in Aust, it's the same horrible stuff. The metal dealers get their supplies from Korea and yep, it's sure crud to work with. Anything under about 1200 rpm just turns to SH*#, not nice stuff at all.

[mbensema]

Rockrat, 304L does not have any lead in it, the L means low carbon.

http://www.azom.com/details.asp?Arti...tainless_Steel

[HWooldridge]

Cold rolled is just hot rolled that has been finished between dies after the scale is removed - what you are seeing are hard and soft spots in the bar. Some of this stems from the fact that the carbon content has crept up over the years so the stuff will harden in places. Most of our steel is remelted cars so the '76 Gremlin is probably on the mark. I toured a "mini-mill" some years ago when they were melting shredded cars and making rebar. Inclusions were often seen in the rolled bar.

A well-known ornamental blacksmith (Robb Gunter) used to demonstrate making 'quickie' tools by heating a piece of A36 and quenching in a brine/soap solution - the piece would come out between 35-40 Rc. That tends to prove that 1018 ain't really that anymore - it's closer to 1030, which is approaching medium carbon steel.

[Dick Plasencia]

This may all be due to the source of the 1018. I wouldn't think there is a difference but the horror stories I read here have got to be true. My supplier gets his 1018 from Canada. It is also stamped or stenciled that way. It machines very nicely and I can get a bright finish on it without sanding or filing. So the question is how can there be different 1018? Seems to me that some supplier is not selling 1018 they are selling something else under that "name."

[amateur]

While were on the subject of steel grades I was wondering what is SPS shaft steel ? Is it a trade name.
Thanks