The Bantam uses proximity sensors for homing and limit switches. These are the yellow boxes in the photos. They are eddy current sensors, as opposed to magnetic sensors (a common misconception) ie they work with nonmagnetic materials such as stainless steel, aluminium and brass, as well as steel.
Another job I "never quite got round to" is shielding them from swarf. As they are positioned directly below the toolpost, it shouldn't be a surprise to find that they are prone to false triggering due to said swarf, usually at the most inconvenient moments.
Here's the underside of the saddle, showing the bracket that carries the sensors. FYI - the adjustable (sliding) black plastic bracket contains the home switch target, which is simply a stainless steel grub screw on the underside face.
You can see the problem illustrated here, where the far limit switch is located - although this isn't a proximity switch, there's evidently a lot of swarf flying about.
I'm imagining a shield, wrapped around the front corner of the saddle that hangs down from the underside of the saddle, sheltering the sensors from falling swarf. I'd like to be able to see the sensors from the front of the machine so I can see their LEDs, so this perhaps dictates how far the thing will extend down.
So first, I need to model the functional features of the saddle.
Make a test piece to check it fits the features - The Stupid Fat Bloke can usually be counted to fuck something up when tasked with something simple like measuring up features on a part.
Oof, looks as if that wasn't a cockup - that happens from time to time. On with the model creation....
Here's a skirt type shield that clears the ballscrew, encoder body and limit switch, while covering the proximity sensors, as best as I can tell. It's held on by the four 1/4" BSW threads on the side and the front, as well as locating in the hole where the cross slide leadscrew used to reside - this will also remove a path for dust to get into the area where the X axis (magnetic) encoder lives:
Export it into Orca slicer. This orientation should hopefully avoid layering and messy transitions where the rafts and supports join on the exterior visible surfaces, or where surfaces are at small angles to horizontal - the skirt is at 15 degrees to the vertical in this orientation, so should be fine:
Let's wait a mere 7.25 hours to find out how that looks / fits - let's call that tomorrow....
It was ready and waiting this morning. Looks like a good result.
And it fits very nicely.
We will call that a result.
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