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End Stops?

Posted by Rlewisrlou666 
End Stops?
October 20, 2016 08:47PM
Hi Guys and Girls,

I'm still decided what electronics to go with and I'm just thinking about end stops.

Ok so my question is. Can I use the same proximity sensors that are used for Auto Bed Levelling for my end stops?

I'm just thinking of building this without the need for upgrades at a later stage and I'll be using them in my CNC build so I would like to get some experience with them.

Thanks in advance.

Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: End Stops?
December 19, 2016 01:17AM
I am an expert in this field, but I don't see why not as long as you have a small flat surface at the other end to reflect the signals. However, I don't see the advantage of using them over a simple switch!
I find the switch to be much cheaper, easier to diagnose and more flexible when your motor overshoots for some reason.

But I am not an expert so I might be missing something here.
Re: End Stops?
March 22, 2017 05:16PM
A latecomer to this thread but it rang a bell for me. It took me a while to realise that the reason for the three end stop switches on the i3 printer was not primarily to prevent over-run - if it were then surely there would be end stops on both ends of travel? No, it is a simple matter of ensuring that X0, Y0 and Z0 are found consistently when the home command is given. Simple and reliable. No need for complex proximity devices.

Nelson Kennedy
Rolleston, NZ
Re: End Stops?
March 23, 2017 09:33AM
A friend makes interactive displays for a children's museum and found that some of the snap action switches he was using were unreliable. He built a device to test such switches so he could figure out which brands were going to work for a long time and which were going to fail. See: [rasterweb.net]

I have used mostly snap-action switches for endstops but occasionally use optical interruptors. I suspect the opto interruptors are the most reliable in the long term, but quality snap switches work fine, too. They aren't likely to experience millions of cycles as end stops in a 3D printer.

My latest z=0 switch design uses a lever and cam to allow finer adjustment of the zero position. In previous designs, using a 32 TPI screw to bump the switch directly, one full turn of the screw would move the bed 800 um. Making fine adjustments with that coarse thread was difficult. The lever and cam reduce the sensitivity so that a full turn of the screw moves the bed about 100 um. The lever pivots on a bearing taken from a HDD so the result is very high precision.

Edited 3 time(s). Last edit at 03/23/2017 09:45AM by the_digital_dentist.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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