Changing your lead screws from a tight to a lose lead will definitely make your machine move faster as long as your stepper motors can handle the new torque that the lead screws will impose.
Here is an example of a speed change from one lead screw to another:
- Existing constants in the example: Stepper Motor steps 200, microstepping 1/8 making the total steps 200 * 8 = 1600.
- Old lead screw: 1/2" allthread = 13 threads per inch (UNC)
- New Lead Screw: 1/2" 5 starts, 10 TPI = 10 / 5 = 2 turns per inch
Old lead screw would achieve a steps per inch of:
1600 / (1 inch / 13 turns) = 20,800 steps per inch (You can also express the calculation as 1600 * 13 = 20,800 steps/inch)
New lead screw would achieve a steps per inch of:
1600 / (1 inch / 2 turns) = 3200 steps per inch
You can see that the new lead screw requires far fewer steps to get to the same length of travel. If you maintained the same velocity for both examples, the new lead screw would travel the same distance 13/2 = 6.5 times faster. So, if your velocity was say 10 ipm, your new velocity would be 65 ipm. That would translate to far fewer burned edges and longer end mill life!
Just remember, confirm that your motors will be able to handle the new lead screw. You will need to reduce the steps/inch causing the motor torque to increase quite a bit, so you should be fine.
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Can I increase the travel speed of my machine with different lead screws?