we have installed a new floor in my house .its a 2 floors new house built on the the old basement .we used the sub floor from the old house . we installed an oak floor and paint it cherry color .after 3 coats the floor shown lines going across the rooms all over the house . they are especially bad in one of the room. I searched the site and saw that they are called chatter marks.my installer saw the problem and resend the house the lines appear again . we are both frustrated and dont know what to do now . I saw a case from 2006 in which they used some sort of a disk to resolve the issue . my installer checked his machine and says that its ok

Waves are similar to chatter and can happen when new wood is sanded .This assumes that the milling is not good and there is over wood .This means that two boards placed end to end do not meet perfectly even or flat.

Then the big sander jumps up over the high spot and creates a wave. Also , the machine's wheels follow these bumps. Chatter usually looks like narrower and more closely spaced "waves"

If he can't sand the floor without getting chatter ,it is likely his machine and or technique but resolving this issue when his machine may need maintenance means you will have to use something like a disc buffer with hard plate and sand paper to take out the chatter.

I have sanded chatter and waves out of floors from previous contractors so I know it is possible to correct the issue.

the waves are at almost even one from the other they are more pronounced in one of the rooms in the first floor where we the floor is not even with the rest of the first floor .is it possible that it has something to do with the stain or the color that we choose ?
someone told me that we need to sand in an angel what does it mean ?

Sanding on an angle means that the drum sander is moved across the flooring at a 45 degree angle in relation to the board direction. I do this when I sand a floor that I think has problems because sanding at a 45 degree angle helps prevent the sanding machine from following the old chatter or weaves and making them worse.

Once the floor is cut on a 45 , you then need to do a final straight cut. However, if your contractor has a machine that is not maintained or set up properly, it will simply put new chatter marks in the floor .

As for your other question, stain color has nothing to do with chatter at all.Chatter shows up in a natural floor as obviously as it does in a stained floor.

after sanding at a 45 degree it looks like the marks are gone .than he stain and the lines were back there . it cant be the machine since the family room which is a larger room came out ok . I am ready to give up . Is it possible that it has something to do with the sub floor ?

Sub floors don't usually have much to do with chatter.