| Gallery, Projects and General > How do I?? |
| Another daft idea, electronic lead screw. |
| << < (2/4) > >> |
| awemawson:
Most stepper systems are 'open loop' ie rely on motor turns and gear ratio to tell you where you are. Servo motors however invariably use an encoder in a feed back loop. So if you already have a 'nice stepper that might be suitable ...' perhaps you don't need an encoder ? |
| John Hill:
The stepper will be driving the lead screw so the software needs to know what the spindle is doing. Some on-line comments indicate just one index per revolution is sufficient. |
| awemawson:
When I 'CNC'd' a Denford ORAC lathe many years ago I fixed a slotted disk to the spindle with a single slot and simple forked opto sensor which was quite satisfactory for threading. That was in the days of TurboCNC rather than MACH or EMC, but no doubt the threading algorithms will be similar. Now on my Traub TND350G the spindle has a 36,000 line encoder that is geared up to something like 90,000 lies per rev but that is perhaps a bit of overkill for simple threading ! |
| John Stevenson:
--- Quote from: awemawson on March 16, 2014, 05:14:23 AM --- that is geared up to something like 90,000 lies per rev --- End quote --- You said it :ddb: |
| awemawson:
--- Quote from: John Stevenson on March 16, 2014, 08:44:12 AM --- --- Quote from: awemawson on March 16, 2014, 05:14:23 AM --- that is geared up to something like 90,000 lies per rev --- End quote --- You said it :ddb: --- End quote --- I obviously need longer fingers to reach the keys ! |
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