strange pattern

[savarin]

As a rank newbie I only have odd bits of steel of sometime obscure origin to practice on.
Today I wanted a small boss that will be welded to a plate so chopped a chunk off an old drive shaft from a front wheel drive car of some kind.
It was really weird, facing it produced these bands through the metal and it had different chips and sounds on the separate bands.



but the real surprise was the spiral pattern that formed on the length when I took a skim to remove the rust.
Also how polished the result is. When I flipped the piece to do the same to the other end the spiral didnt appear but the finish was awesomely smooth with a superb polish.



I'm assuming the original shaft was forged which produced various layers of hardness throughout the bar giving the bands as shown at the end but how on earth did the spiral occur. Anyone have any knowledge of this?
Manual feed was used each time with carbide insert tools.

 

[Sandro]

Hello Charles

The shaft might have been case hardened or at least carburized, which means the outer surface is harder than the core. The spiral pattern on the outside is a form of chatter, and by the look it makes me think the surface is hard.

To machine it keep using carbide but slow way down, 2 or 3 times slower than your original spindle speed and see what happens.

Hope this helps.

Sandro Di Filippo

 

[Rbeckett]

The pattern on the top pic is chatter. If your bearings are not tight you will get that pretty easilly. I used to machine brake rotors and the Caddy rear rotors were notorious for producing a pattern just like that and we traced it to sloppy wheel bearings. For a mere 457.00 dollars each you could solve the issue of brake pulsing and squeel. Only sold one set in about ten years, and only because the bearing failed completely. Check you bearing preload in the spindle and see if they could use a litttle snugging up if they are cone and race style bearings. I think the pattern looks cool on a finished part if it is just a look at kind of piece. Have fun and show us some more pics of your projects when you have some time please.
Bob

 

[savarin]

The pattern on the top pic is chatter.
Check you bearing preload in the spindle and see if they could use a little snugging up if they are cone and race style bearings.

I believe the bearing preload is tight enough, the headstock does get warm after a while.
I did have some loosness appear in the gibs on both the cross and top slide and re-did those but that was after this part.

I think the pattern looks cool on a finished part if it is just a look at kind of piece.

Me too,it would be really cool if you could get this to order:LOL:

Have fun and show us some more pics of your projects when you have some time please.
Bob

I will when I have something worth while. At the moment all the projects are bits and bobs of other things. eg. this bush boss will be welded to a plate so I can weld a bicycle sprocket to it to get a chain drive for a rock tumbler. Nothing flash, real bush engineering.

 

[jgedde]

That sure looks like hardened steel to me... A really sharp carbide tool, slow feed and speed, and you should get through it.

John

 

[savarin]

That sure looks like hardened steel to me... A really sharp carbide tool, slow feed and speed, and you should get through it.

John

Thanks I will keep that in mind if I use any more of it. This bit is all I wanted at present and does not have to be flat. It might look cool when its turning driving the tumbler.:lmao:

 

[Pacer]

Probably a combination of both - chatter and hard stuff...

I picked up an axle out of a piece of heavy equipment - couldnt cut it (except to look like yours!) Was burning some brush in a nice bonfire and put the axle in it, when the axle had got nice and red I let the fire die over nite and next day tried cutting it again - and, well, well, nice stuff.

 

[savarin]

Probably a combination of both - chatter and hard stuff...

I picked up an axle out of a piece of heavy equipment - couldnt cut it (except to look like yours!) Was burning some brush in a nice bonfire and put the axle in it, when the axle had got nice and red I let the fire die over nite and next day tried cutting it again - and, well, well, nice stuff.

Thats great to hear. Next time I do some casting I will place the two I have in the furnace. I wondered if annealing them would work.

 

[llarson]

When I went to trade school in the mid '60's, several sawmills and vehicle repair shops [ I say "vehicle" to include trucks ] set aside axles for us to use. I often took some home and annealed them in the fireplace, they cut great then; torsion bars seemed to not anneal though, better mtl. The nice thing about using axle steel, it can be hardened and tempered quite easily, has a wide critical temperature range.