View Full Version : Best place for hard stops?

23-11-2014, 07:00 PM
I'm trying to figure out where the hard stops should go for just in case things go haywire. I'm thinking of putting HDPE plastic blocks in-line with the ball skrews and just have the ballskrew housing crash into them. Please see drawing below, HDPE is red bits. Is this a workable plan or is it better to put the stops somewhere else?

23-11-2014, 09:52 PM
Do you really want these ? personally I enable soft limits in Mach3 and fit mechanical limit switches to prevent over-travel, homing is taken care of by using separate homing switches.

Robin Hewitt
24-11-2014, 11:58 AM
Before fitting hard stops, calculate the maximum force you are looking to handle.

eg: 3Nm on to 5mm pitch = 0.378 tons

Then make sure your soft stops are good :encouragement:

24-11-2014, 12:25 PM
If you envisage that the likelyhood of a nasty crash is high then supply your stepper PSU through a cut-off circuit with switches at the ends of travel, if you use a multi-pole, double throw relay you can E-Stop your spindle controller and E-stop your control software at the same time.
No matter how kind your hard stops are if your machine winds into them hard you're no better of than if you hadn't fitted them at all,
- Nick

25-11-2014, 05:39 AM
Thanks for the advice gents. I like the idea of avoiding running into any hard stops by using additional switches to disable the drivers or cut the power to the drivers and I'll look into that a bit more. I wanted a foolproof way in case something goes wrong and I run thru my limit switches and these additional switches you suggest will do exactly that.