cutting circles

[woodguy7777]

i have been cutting some 1.5 inch circles in 1/2 ply  using a .375 bit
the problem i am having is that the circle in not coming out completly round.
the problem seem to happen where the bit enter the material.
there is a small teardrop in that area.
its in that area where the circle is not completly round.
can anyone help
paul

[BR549]

It could be backlash loose play or loose motor connection to the screw.

[Hood]

If its where you are entering then it is likely tool flex or spindle flex, if it happens at  the 4 quadrants then its backlash.
Hood

[kf2qd]

A suggestion - Use a leadin/leadout like the plasma folks do. If you are trying to cut a disk, start and finish with a move that takes you outside the toolpath for the disk. If you are cutting holes, start on the inside and have starting and ending moves that take you to the inside of the finish hole. You might still come up with a slight mark where the cuts overlap, but if you play with how much under/over cut you do at that point you can minimize it.

[woodguy7777]

thanks for all the help.
got the problem solved  turned out to be just play in the axis
re tighten and verything is ok now
thanks again
paul