First, this new forum software SUUUUUCKS! I made this post earlier, and it just disappeared into the ether - not an uncommon occurrence since the "upgrade". And the forums hang frequently, and go completely off-line pretty much daily since the change. NOT an upgrade from this users POV. I sure hope they get it sorted out soon.
Anyway, my new mill (Novakon Torus Pro) uses inductive proximity sensors for homing/limits. These are great - they're cheap, and can be easily used on pretty much any machine. They're really good for benchtop machines, because some of them are quite small, and very easy to mount. But, I discovered one "gotcha" - they can be triggered by aluminum chips! On my machine, the Y axis sensors are exposed at some table positions, allowing chips to spill off the table, and land on the sensor, causing false limit triggers. I didn't expect this, but it makes perfect sense once you understand how the sensors work.
Today I took about an hour and a half and did something about the problem. The range of a prox sensor is about 40% less for aluminum than it is for steel or iron, so it seemed reasonable to me that if I could prevent the chips from getting too close to the sensor, it would prevent false trips, but still work properly with the steel limit "flags". A little testing determined that about 0.100" space worked well. So, I machined a couple of covers out of some scrap UHMW, and screwed them over the sensors. Works perfectly! I can pile 6061 chips 1" deep on top of the cover, with no false trips, but when the limit flag approaches, it triggers perfectly.
These covers were only needed on the two Y axis sensors, as the X axis sensor is always covered, and the Z axis sensor is out of range of any chips.
The bottom side:
Attachment 181519
The top side:
Attachment 181520
And installed over the sensor:
Attachment 181521
Regards,
Ray L.
Anyway, my new mill (Novakon Torus Pro) uses inductive proximity sensors for homing/limits. These are great - they're cheap, and can be easily used on pretty much any machine. They're really good for benchtop machines, because some of them are quite small, and very easy to mount. But, I discovered one "gotcha" - they can be triggered by aluminum chips! On my machine, the Y axis sensors are exposed at some table positions, allowing chips to spill off the table, and land on the sensor, causing false limit triggers. I didn't expect this, but it makes perfect sense once you understand how the sensors work.
Today I took about an hour and a half and did something about the problem. The range of a prox sensor is about 40% less for aluminum than it is for steel or iron, so it seemed reasonable to me that if I could prevent the chips from getting too close to the sensor, it would prevent false trips, but still work properly with the steel limit "flags". A little testing determined that about 0.100" space worked well. So, I machined a couple of covers out of some scrap UHMW, and screwed them over the sensors. Works perfectly! I can pile 6061 chips 1" deep on top of the cover, with no false trips, but when the limit flag approaches, it triggers perfectly.
These covers were only needed on the two Y axis sensors, as the X axis sensor is always covered, and the Z axis sensor is out of range of any chips.
The bottom side:
Attachment 181519
The top side:
Attachment 181520
And installed over the sensor:
Attachment 181521
Regards,
Ray L.