Spindle Encoders
20 Dec 2020 23:56 #192587
by Xnke
Spindle Encoders was created by Xnke
Working on the design and implementation of my spindle setup the last few weeks, I've realized I will need a spindle encoder of some kind. I will need to be able to index the spindle for tool changes, and also being able to index and track spindle position opens up a few advanced machining modes that I'd like to have available.
What I have for my spindle is a cleaned up, re-greased, deburred/internally sanitized Chinese BT30 spindle.
And here's an early model of how it'll be positioned in the Z-axis:
This model has since changed a bit but the idea is still the same.
Somehow, I need to get an encoder onto the spindle that can give me spindle position for tool changer indexing and synchonized motion moves like rigid tapping.
As far as I see it, I could turn off one of the two 20mm wide HTD 5M pulley sections smooth, and mount a magnetic ring type encoder on to the pulley, or I can use one of the two sections of pulley to drive a belt-driven encoder. I can't have anything that mounts over the top of the spindle, as the pneumatics for the ATC drawbar will be over the spindle.
Does anyone have any suggestions for encoders that would work in this situation? I can find very few ring-type encoders, and even fewer that are affordable.
Could grinding off one tooth of the bottom section of HTD 5M profile timing pulley and using a variable-reluctance sensor give enough information? That's how I do automotive engines-a trigger wheel of a known number of teeth, grind out one tooth to use as a once-per-rotation index, the remaining teeth give velocity information. In this case, 54 teeth, grind out 1, gives a 54 position encoder with index. (54 positions with a missed pulse indicating home position)
What I have for my spindle is a cleaned up, re-greased, deburred/internally sanitized Chinese BT30 spindle.
And here's an early model of how it'll be positioned in the Z-axis:
This model has since changed a bit but the idea is still the same.
Somehow, I need to get an encoder onto the spindle that can give me spindle position for tool changer indexing and synchonized motion moves like rigid tapping.
As far as I see it, I could turn off one of the two 20mm wide HTD 5M pulley sections smooth, and mount a magnetic ring type encoder on to the pulley, or I can use one of the two sections of pulley to drive a belt-driven encoder. I can't have anything that mounts over the top of the spindle, as the pneumatics for the ATC drawbar will be over the spindle.
Does anyone have any suggestions for encoders that would work in this situation? I can find very few ring-type encoders, and even fewer that are affordable.
Could grinding off one tooth of the bottom section of HTD 5M profile timing pulley and using a variable-reluctance sensor give enough information? That's how I do automotive engines-a trigger wheel of a known number of teeth, grind out one tooth to use as a once-per-rotation index, the remaining teeth give velocity information. In this case, 54 teeth, grind out 1, gives a 54 position encoder with index. (54 positions with a missed pulse indicating home position)
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