Hall effect proximity sensors

[cropwell]

https://www.google.co.uk/url?sa=t&rc...DWNnAf7sglZ7fP

Page 64

But I personally would stick to Inductive sensors.

[magicniner]

2 inductive sensors in series on each axis, one sensing the linear position and one sensing a rotating tab or chopper on the ball screw or stepper would give you accurate, repeatable homing.

[Voicecoil]

2 inductive sensors in series on each axis, one sensing the linear position and one sensing a rotating tab or chopper on the ball screw or stepper would give you accurate, repeatable homing.

Having a rotating tab on the ballscrew is a good idea - essentially magnifies the resolution - I'll see if there's room to incorporate it.

[cropwell]

2 inductive sensors in series on each axis, one sensing the linear position and one sensing a rotating tab or chopper on the ball screw or stepper would give you accurate, repeatable homing.

I presume these would have to be the Normally Open types. I think it is over the top for woodwork, but probably OK for watchmaking.

[magicniner]

I presume these would have to be the Normally Open types. I think it is over the top for woodwork, but probably OK for watchmaking.

Series for NO, so the circuit only closes when both close.
Parallel for NC, so the circuit only opens when both open.
:D

I'm planning this with my Chester Mill CNC conversion, I've become accustomed to being able to shut down my X7 and know there will be no positional errors when I turn it on the next day, select the WCS and slot a part into a fixture, I can't imagine going back to having to indicate every time I fire a machine up, I don't think a homing system which requires you to re-indicate a fixture which hasn't been moved is acceptable, in fact I think that's the definition of Useless.

[cropwell]

Series for NO, so the circuit only closes when both close.
Parallel for NC, so the circuit only opens when both open.
:D

I'm planning this with my Chester Mill CNC conversion, I've become accustomed to being able to shut down my X7 and know there will be no positional errors when I turn it on the next day, select the WCS and slot a part into a fixture, I can't imagine going back to having to indicate every time I fire a machine up, I don't think a homing system which requires you to re-indicate a fixture which hasn't been moved is acceptable, in fact I think that's the definition of Useless.

Why not have 1 NC and 1 NO, then it wouldn't matter whether you wire in series or parallel

It took some time for me to understand the second part of the reply as I don't get what part the Wildlife Conservation Society play in CNC. If I am cutting a few parts and have to turn off the machine then I zeroise the Z and 'Ref All Home' to send the X and Y back to the zero point. That way, when I switch on the next day, I know here the machine is.

BTW, I love these things, Engineers Lego......

https://www.arceurotrade.co.uk/Catal...-Metric-Blocks

Cheers,

Rob

[johnsattuk]

Why not have 1 NC and 1 NO, then it wouldn't matter whether you wire in series or parallel

BTW, I love these things, Engineers Lego......

https://www.arceurotrade.co.uk/Catal...-Metric-Blocks

Cheers,

Rob

[magicniner]

If I am cutting a few parts and have to turn off the machine then I zeroise the Z and 'Ref All Home' to send the X and Y back to the zero point. That way, when I switch on the next day, I know here the machine is.

My point is that with a well designed and implemented system that shouldn't be, and in fact isn't necessary :D

Work Coordinate System BTW

[cropwell]

Work Coordinate System BTW

Hi Nick,

WCS - I looked it up on Google. I actually rejected the idea that it could be the wildlife thing, toyed with Workflow Control System, Warehousing Computer Systems and World Coordinate Systems (Getting close there - that was defined as something to do with CNC). I did not think that with this latter CNC TLA you needed to know the precise latitude and longitude to define the machines X,Y 0,0, but apparently there it is. Even more incomprehensible is the UCS (universal Coordinate System, which even takes into account the Space/Time Continuum.

Maybe it is time that we had some TLA control, such as an Acronym Registration System (ARS). Maybe I could become an Acronym Registration System Executive (ARSE), although a lot of people probably think I already am.

Rob-T

[johnsattuk]

2 inductive sensors in series on each axis, one sensing the linear position and one sensing a rotating tab or chopper on the ball screw or stepper would give you accurate, repeatable homing.

Generally I don't use N/O types for limit switches, they dont cover broken connections. Could use two N/C in parallel