# Why I get these Lines on my Cuts?



## oskar (May 6, 2018)

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


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## markba633csi (May 6, 2018)

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


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## darkzero (May 6, 2018)

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.


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## Ray C (May 6, 2018)

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


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## chips&more (May 6, 2018)

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.


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## mikey (May 6, 2018)

darkzero said:


> 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.


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## dlane (May 7, 2018)

Bead blast then away


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## oskar (May 7, 2018)

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


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## machinejack (May 7, 2018)

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.


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## T Bredehoft (May 7, 2018)

oskar said:


> 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.


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## Janderso (May 7, 2018)

Wait a minute. What speed are you running for the diameter of your tool?
The last pass depth?
A good quality, sharp 4 flute end mill at the right speed on aluminum produces dang near a mirror finish on my Bridgeport.
By the way, nice job!


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## oskar (May 8, 2018)

T Bredehoft said:


> 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.



Thanks for the compliment and indeed it was a lot of work to make the tool holder (BTW it was a video / drawings I was following) but to my opinion the only way to learn, that’s to follow a project.

Regarding the speed I’m running I have a VS Sherline DC motor and I selected a speed which was comfortable to my beginner’s skills. Perhaps wrong but I don’t like to have the spindle running too fast right now. I would guess I was at about 1K RPM and the end mill is new 4 flute


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## Rooster (May 8, 2018)

I for one like the tool marks left on some projects, it leaves a nice pattern.


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## T Bredehoft (May 9, 2018)

oskar said:


> I would guess I was at about 1K RPM and the end mill is new 4 flute



1/4" tool in steel (drill or mill) should run at 900, in aluminum 3 or 4,000 should do well. I learned that 1/4-900 figure abut 40 years ago, it stuck with me.


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## Charcole (May 10, 2018)

Change in tool pressure.  Tools don't really cut.  Look at the shiney side then look at the backside.  The backside tells the story.The material is nearly molten.  Very little is actually being cut.  

I would take a indicator to the surface and measure for ridges.  Just because you do not feel anything doesn't mean the tool isn't deflecting.


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## 12bolts (May 27, 2018)

Charcole said:


> ....Tools don't really cut.  Look at the shiney side then look at the backside.  The backside tells the story.The material is nearly molten.  Very little is actually being cut......


What do tools do to remove material if they "dont really" cut? I'm at a loss here. Could you expand on this?

Cheers Phil


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## Mystery1 (May 27, 2018)

Great result for a first project.

Surprisingly, end mills are not generally intended to be used as you did. They work best by using the sides of the cutter.  Depending on how rigid the machine is you will still get artifacts from the cutting operation. 

Rubbing the part on some sandpaper (wet & dry) or emery cloth with some oil will get rid of the marks. Also using some WD40 as cutting fluid (for aluminum) helps the cutter do its work.


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## KBeitz (May 27, 2018)

If you don't like mark use cutters with rounded edge.


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