PM-833 Maximum Z Travel with Limit Switches

[ahazi]

I finished installing the X and Z power feeders. They both work very well. The Z axis is a little tricky and the instructions can benefit from a rewrite...

I did not finish the limit switch installation on the Z axis as I realized that as recommended it actually reduces the travel range to 15.5" vs the 17.5" that the mill is capable of and spec'ed at. I might replace the fency stops with the springs (see pictures) with something smaller without a spring that does not consume so much vertical space, not sure why a spring is needed, the limit switches have springs inside and the X axis is not using such stops.

Am I the only one experiencing this or this was observed and corrected by others?

Ariel

 

[davidpbest]

You might consider using Item-northamerica.com Profile 10 50x20 E, T-slot aluminum extrusion with 50x20 grey end caps for limit-switch end-stops.

 

[parshal]

The way I mounted the accordion chip shield the head stops when it's flush with the top of the column. I'd used it before I installed the shield and ran the head higher than that point. How high can the head go and still retain rigidity?

I ask the above because the Z stop on mine stops the head as soon as it's flush with the column.

 

[ahazi]

The way I mounted the accordion chip shield the head stops when it's flush with the top of the column. I'd used it before I installed the shield and ran the head higher than that point. How high can the head go and still retain rigidity?

I ask the above because the Z stop on mine stops the head as soon as it's flush with the column.

The total (possible) movement of the Z axis is 17" which is exactly the spec from PM.
The head protrudes over the column by about 2.6" to achieve the full range.
The (vertical) size of the head that moves on the column is 9.5" so you still have a 7" engagement even when you go to the end of the travel. I would like to preserve the full travel range for the cases where I need to use the machine as a drill and in particular for large wood pieces so the rigidity is not really an issue.

 

[parshal]

Where did you mount the top of the chip shield on yours? Mine was not connected.

I would think we could simply get a longer bracket and run the stop above the column.

 

[davidcarmichael]

I finished installing the X and Z power feeders. They both work very well. The Z axis is a little tricky and the instructions can benefit from a rewrite...

I did not finish the limit switch installation on the Z axis as I realized that as recommended it actually reduces the travel range to 15.5" vs the 17.5" that the mill is capable of and spec'ed at. I might replace the fency stops with the springs (see pictures) with something smaller without a spring that does not consume so much vertical space, not sure why a spring is needed, the limit switches have springs inside and the X axis is not using such stops.

View attachment 319979 View attachment 319980

Am I the only one experiencing this or this was observed and corrected by others?

Ariel

The stops must be set to handle conflicting requirements. With a powered Z-axis using the fast traverse, you must allow extra space for the knee to stop before hitting the physical end stops. This means it must stop the motor well before the end is reached. Both the spring in the switch housing and the stop spring are fully compressed when the end of travel is reached.

If you then use the power feed at slow speed then you will lose quite a bit of feed length because the motor will stop much more quickly when the stop switch is pressed.

I have mine set for safe fast traverse feeding and use the handle if I need the last little bit of travel. I seldom do.

 

[aliva]

That's some clean mill

 

[RJSakowski]

The stop is easily removed for those cases where you need the extra travel. You can make a witness mark for ease of repositioning when putting the stop back in place.

 

[ahazi]

Where did you mount the top of the chip shield on yours? Mine was not connected.

I would think we could simply get a longer bracket and run the stop above the column.

Brian,

There was a metal bracket that came inside the blue toolbox that was removed during transportation. See pictures below:

Ariel

 

[parshal]

That's what that's for! LOL