Why I get these Lines on my Cuts?

[oskar]

Just finished my first project on my mini Taig Lathe but in all my cuts I get these lines as shown on the picture. Rubbing my finger on the surface I don’t feel anything, surface is smooth, but I was expecting a uniform looking surface.

The cuts are made with a 1/4” end mill and each pass is about 1/32” to 1/64” at very low feed rate

 

[markba633csi]

Those are perfectly normal "beauty lines"- the surface is not perfectly smooth at the microscopic level
Mark

 

[darkzero]

That is known as tooling marks. There are ways to improve surface finish but tooling marks will always be present. Even on high quality CNC machines you will still get tooling marks. To get rid of them (or should I say minimize) you'd have to tumble, surface grind, sand, polish, etc.

 

[Ray C]

Good question Oskar!

BTW, you get the same tooling marks on a lathe but they're harder to see. On a lathe, the tooling mark is a single line that makes spirals all the way around the part. No matter how fine the Inch Per Revolution setting is, the line is always there. When held in the correct angle, you get the same rainbow effect that you see on a milled part.

Ray

 

[chips&more]

I know a few machine shops that no longer need to grind any of their lathe parts if surface finish is critical. They can turn it just as good maybe better than grinding it.

 

[mikey]

That is known as tooling marks. There are ways to improve surface finish but tooling marks will always be present. Even on high quality CNC machines you will still get tooling marks. To get rid of them (or should I say minimize) you'd have to tumble, surface grind, sand, polish, etc.

+1. If you want it to have a uniform finish right off the mill, fly cut it.

 

[dlane]

Bead blast then away

 

[oskar]

Now I know what “beauty marks / tooling lines” are. They don’t bother me so no problem here. I thought I was doing something wrong.
Thanks

 

[machinejack]

My first part for NASA at my new job was a bracket for the space station. I worked hard at polishing the tool marks out made it look perfect. Boss comes by later and says nice job on that part BUT they want the tool marks left on. Go figure that one out. I personally like fine tool marks they show a bit of skill of quality of work when they are uniform. You would not be leave how many grades of aluminum for different components that is required. All work carried a packet of certification papers that follow the parts around the shop.

 

[T Bredehoft]

as shown on the picture

You are to be complemented on building your own tool holder for a Taig Lathe. I started out doing Hobby Work on a Taig lathe set up for milling and it's fun, but a very lot of work.