When I try to cut with a 1/4" bit it makes a loud high pitch sound and mach goes into e-stop.I can hit the reset and every thing works fine again until the bit touches the wood to cut.I just cut with a 1/2" bit with no problem. any thoughts??

Could be the switch contacts being affected by vibration.

Tweakie.

Thanks, Would the best way to check this be to put jumpers on the limit and estop switches ? They are all normally closed switches.

Yes, perhaps that would be the best way.
It is probably only just one switch that is causing the problem or possibly a loose connection to one switch.

Tweakie.

Thanks for your help! I went ahead and disabled all my limits in Mach3 conf. and was able to finish my cuts.Now I will go back and narrow down my problem. I love your quote,how appropriate for us that have built a CNC machine. Thanks again, Tommy