Milling problem

[Cogsy]

Thats correct cogsey but if the edge of the cutter passes over the centre
then that removes the raised area in the centre.Again a flat surface.As long as the endmill is slightly concave due to bottom clearance it will cut a flat surface
If the end mill is slightly convex IE a ball nosed mill then it wont

But Baz, with round stock as I described (such as is the problem here) when the cutter swings to the centre it is cutting air as it is not on the contact line of the part. So it leaves the centre untouched.

Think of plunging a slightly concave stationary end mill into a rotating round blank on the lathe - the centre will not be cut and the endmill becomes a form tool rather than making a straight cut. You can then rotate that endmill as much as you like but the cut will never be flat.

 

[bazmak]

Thanks cogsy i did grasp you talking of rotating the job while milling
the photos i saw showed milling the rectangle body from round My apologies
regards barry

 

[Jmccrack]

Hey guys
Thanks for all the help. I tried everything. Fly cutting,2 and 4 flute end mills and regrinding a end mill flat. Nothing will work by rotating the part under the cutter. Here we go again (I thought I knew everything). There is only one way to get close to doing what I am trying to do and that is to rough it out by rotating than feed longitudinally in 1 or 2 deg. Increments than file. But it was a great learning experience. Thanks again for all the input this is a great forum. This pic shows 3 deg rotation and longitude feed. It will work well

 

[mc_n_g]

End mills flex. A square end mill (90 degree) end mill will dig on the side it is cutting. A rounded corner radius end mill will help but not remove 'lines'. A carbide end mill will be stiffer but you will have 'lines'.
I am talking about slight corner radius end mill. The following is an example. I don't work for or endorse them.
http://www.the-carbide-end-mill-store.com/20m5/corner-radius-end-mills.html