Or after a tool change.

This is a brand new 1100 I’ve only had for a couple of months, and I haven’t had much time to spend learning all the ends and outs.

As I do spend more time cutting parts I am running into problems that have no straight forward answer. If something goes wrong every time you can figure it out, but my main problem is hit or miss.

The mill always seems to cut the first part just fine, BUT there is no telling what will happen after a tool change, or when you put another blank piece of material in the vise and hit start cycle for the second or fifth time.

I was having problems with a Z plunge after a tool change on what is going to be my main bread and butter part. I’m just learning G-code so I figured that was where the problem was and hoped to answers would come with time and experience. So I moved to cutting some one off Christmas gifts while studying G-code and cam programs. Everything went just fine but I was only cutting one piece and moving on.

Last night I engraved our old family business logo on a gift and it turned out great so I thought I’d make a few more while I had the program set up. I cut four in a row without a hitch but while returning to zero after the forth piece there was a audible thump and the bit stopped short of zero but the DRO read zero on all axis. I re-set everything and cut three more and thump the same thing happened again.

Now it occurred to me that I was sometimes hearing that thump when it went to tool change on that first part I was cutting. I didn’t know enough to know something was out of whack and parts were ruined and bits were broken as the Z plunged through my expensive parts. Also you’re not always (or shouldn’t need to be) right next to the mill to hear the thump.

No thump no problem as far as I know, I do know that when I heard the thump I did have problems. The DRO always stayed green and read zero on all axis.

The thump kind of sounds like the thump when to hit the stop but not nearly so pronounced.

Any ideas??? Thanks for any help.