Hall effect proximity sensors

[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

[magicniner]

An Acronym is a set of letters pronounced as a word, if the individual letters are voiced as in VCR or TLA it is an Initialism thus, somewhat amusingly, TLA is not a TLA :D

[cropwell]

To get back on topic....

I do not use work offsets very often, which I presume depends on the accuracy of determining machine zero by homing all axes (axises ?). Most of what I do is one-offs and for that I zeroise locally when the piece is bolted down. If I have to do two or more, then I use a simple jig and, as I said before, leave the machine in a known position if I have to switch off and return to it next day.

It would be interesting to determine the increased accuracy with a dual sensor set. I would guess that it would not be significant for most home built machines.

What do the big boys, like HAAS, do?

[cropwell]

an acronym is a set of letters pronounced as a word, if the individual letters are voiced as in vcr or tla it is an initialism thus, somewhat amusingly, tla is not a tla :d

this forum is changing case - wtf !!!

[magicniner]

Hey, if you don't need it or want it don't do it! :D

With decent screws and nuts I think a repeatability of 5 microns isn't out of reach, or even difficult, that's where I'm aiming with my next build, machining accuracy is likely to be closer to 15 but if you aim low you're bound to achieve shite results! :D

[cropwell]

Hey, if you don't need it or want it don't do it! :D

With decent screws and nuts I think a repeatability of 5 microns isn't out of reach, or even difficult, that's where I'm aiming with my next build, machining accuracy is likely to be closer to 15 but if you aim low you're bound to achieve shite results! :D

I work to an accuracy measured in Angstroms +/- a foot.



This is good enough for me, it is only woodwork

[routercnc]

I’ve just skim read this thread (funny in places !) so my answer to the first question which I think was essentially can I use Hall effect sensors instead of proximity sensors for homing -

They require a magnet to get close to the target to trigger and so like all magnets in the workshop will grow metal hairs and become unreliable. I have one to play with on my new E-kart foot throttle. Great if the magnet and sensor can be sealed in a box but I think one part must ride on the gantry for CNC machines if they are the sole sensor so they can’t be protected.

However for the auxiliary use as discussed they can be enclosed on the end of the stepper shaft at the rear of the motor or off the ballscrew and be sealed off. (Like the twist throttle of an electric bike).