New problem (I think)

[David Da Costa]

I am getting ready to do my first cuts on my NM0135 now that my enclosure is finished.

However, I am running into a problem.

I am using a TTS tool holder with a 1/4" end mill in it protruding about 1.5", I am going to be cutting a 0.125" sheet of aluminum clamped down to the mill table with a 0.25" sheet of sacrificial MDF underneath.

The problem is that the Z-axis limit switch is triggered with the tip of the tool about 1" above the table so I cannot cut it.

If the NM-135 used different pins for each axis limit switches I could just turn of the z axis limit in Mach3, but they all share the same limit (I tried it anyway and it still triggers).

My other options is it raise up the work piece which is not really practical and neither do I want to have to do this for all work.

Finally and I guess what I will have to do is to either lower or remove the actual metal trigger for the - Z which is going to be a big pain as I will have to dismantle some of the enclosure.

Is there normally a Z- limit switch and if so where is the "standard" position for it to be triggered?

David

[slatronic]

What about the soft limits? Mine was set on the cautious side. Too bad you may need to pull apart the enclosure. Makes me want to use it for some time and test it out before boxing it in. I've been thinking about making the back of the mill accessible for just this reason. I feel your pain.

[David Da Costa]

No it is not the soft limits, I turned them off.

Getting to the Z- limit is awkward as it is behind the spindle driver board.

What I have done for now is turn all the limit switches off and just use soft limits.

I have to take the back of the enclosure apart on Wednesday as I am replacing the black coreplast with clear acrylic so I will see if i can get at the limit trigger then.

I have two coolant leaks on my enclosure, one that is my cause and I will try to seal that with silicone and one that is caused because the front left pocket that the bolt that holds the mill to the stand was malformed and rather than being a sealed "cup" had a big hole in it. Initially it was leaking into the inside of the stand, but I sealed that with silicone and then epoxied a cup onto it. Now it is finding its way out from underneath the stands tray, between the tray and the stand.

I have now sealed all the way around the join of the metal tray and the stand so hopefully that will stop it.

David

[MichaelHenry]

I have a different make mill so am not familiar with the Novakon models.

Do you have both upper and lower Z limit switches? If so, you could simply disconnect or disable the lower switch and rely on the soft limit to prevent you from plunging a cutter into the table. On my mill, the limit switches are used to establish home position on startup. I find that really handy and would not want to lose the feature. A better solution would be to find a way to implement the lower Z limit at a different position.

Mike

[David Da Costa]

I have turned the limits switches off (for now) and even with the soft limits off it appears that the lowest you can get the z axis to go is about 4.7" from the bottom of the spindle to the top of the mill table before it hits a hard (mechanical) stop. With a 1/4" end mill in a TTS tool holder this means that the lowest you can get the tip is about 3/8" from the table top.

Not sure if this is a design feature or a problem, but I will not be able to cut the 1/8" aluminum sheet which I have on sacrificial piece of 1/4" MDF all clamped to the table top.


David

[Teyber12]

can you just take off the actual z limit?

[David Da Costa]

It's appears to be the physical end of the axis travel, nothing that you can take off.

[kvom]

You could add some additionnal thickness of MDF (or some other material) under the sacrificial piece to raise it uop.

[Frogblender]

On my rev2.1 nm135, the distance from:

Bottom of HEAD to tabletop = 5.56". (By "head" I mean the grey cast iron part to which the spindle bolts. I include this because the spindle length, judging by pictures, is different for different revs of the nm135).

Bottom of empty spindle to tabletop = 2.25"


The only time I've had a problem with Z depth is if I put a small bit directly into an R8 collet; with TTS there is never a problem.

If your distance is substantially smaller than 5.56", then my guess is you are hitting something (I did that once after I'd absent-mindedly used too-long screws to attach something to the sheetmetal column cover)