[Fastest1]

I was scared you were going to say that. Though i do understand these benchtop machines are smaller and theoretically less dangerous. I dont think that is the best way to approach safety. In fact if it was mine, something (A BIG RED BUTTON) would be wired to the relay or contactor that killed power to all 3. Kind of like your pulling the power just safer and more obvious. Me being only a hobby machinist and not trained might be where my ignorance comes in but at times I freeze in absolute disbelief when the cutter starts going the wrong way after 4000 correct lines or so. At those moments the Estop is never close enough. In fact I am still trying to figure out how guys in the youtube videos never have torn up clamps LOL. Anyway I know the machines can take stalling as I have done about everything wrong you can do with a Sherline and it still works! I am sure if it was a BP or such it would be broken, or the table would have milling grooves, or drill marks, or a broken screw, the list would go on!

There is a power switch on the controller box, and a power switch on the spindle motor, and a power switch on the outlet strip everything is plugged into. This is apparently adequate for a small benchtop machine. For instance, the mechanical travel stops will stall the steppers on a Sherline.

The same would not be adequate for a larger mill. The Bridgeport I'm currently reworking had an eStop button with the original BOSS computer, and will have the same eStop button, at a minimum, after I finish configuring it to run on a PC. In addition, power to the computer and drivers comes through an air conditioning contactor, and power to the VFD for the spindle comes through a second air conditioning contactor. I've got a convenient wall switch which will kill the 24 volts to the contactors, which will make the mill get real quiet, real quick.

Tom

[TarHeelTom]

I was scared you were going to say that. Though i do understand these benchtop machines are smaller and theoretically less dangerous. I dont think that is the best way to approach safety. In fact if it was mine, something (A BIG RED BUTTON) would be wired to the relay or contactor that killed power to all 3. Kind of like your pulling the power just safer and more obvious. Me being only a hobby machinist and not trained might be where my ignorance comes in but at times I freeze in absolute disbelief when the cutter starts going the wrong way after 4000 correct lines or so. At those moments the Estop is never close enough. In fact I am still trying to figure out how guys in the youtube videos never have torn up clamps LOL. Anyway I know the machines can take stalling as I have done about everything wrong you can do with a Sherline and it still works! I am sure if it was a BP or such it would be broken, or the table would have milling grooves, or drill marks, or a broken screw, the list would go on!

Well, there is an eStop button on the screen with EMC2, and of course the escape key works as an eStop button also. But since I didn't design and build the Sherline, I can't take responsibility for their design.

But both my Sherline mill, and my BP have some minor gouges in the table. Those on the Sherline were not caused by being out of control, and the ones on the BP got there in its previous life in a commercial shop, so can't comment on how they got there, as I just don't know.

But, I do spend a fair amount of time running simulations before I actually power up the mill itself. And I'm still looking for a nice rubber pencil or such that I can use as a cutter simulator so that I can actually run the steppers and watch the cutter path in real life before starting to spin the spindle.

And, knock on wood, I've not yet broken an end mill, and I've worn out several of them.

Tom