Radical solution for Z zero issue

I am thinking about using a microswitch for the Z axis as used for the bed.

I would position it near the extruder but on a higher position (so does not interfere with printing) and "click" it having the head move over the screws and the for corners of the bed (obv changing them with 4 taller ones).

What do you think? SHould be quite simple to implement

Yes, many people have modified their Ormerods to get a Z-axis microswitch working. See [forums.reprap.org] for example.

The danger would come when printing near the corners or homing the head if it's not lifted high enough to clear the screws??

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

The alternative is a better IR sensor, such as the one I sell (see [forums.reprap.org]).

Or, if you have the original Ormerod 1 sensor then you can substitute the Ormerod 2 sensor and loom, or hack the old one to add modulation as I did originally. Either of these solution works a lot better than the original Ormerod 1 unmodulated sensor (e.g. much less sensitive to ambient IR), although not as well as my differential IR sensor.

Edited 3 time(s). Last edit at 12/23/2014 09:09AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I use Microswitches for all my Homing Functions, and they are 99.9% reliable.
On the Z axis I use the Tilting of the Extruder to trigger the switch.
If you look on my ThingyVerse pages you will find the wiring diagram and right angled printed bracket I use on my BigBlue Fan Duct.
(I'm hoping over the cricklemas period to get some free designing time to produce a New Big Blue Design.

I have seen other peoples designs where they use a Microswitch that the X axis lowers down on to, which is fine provided you use the same
size glass all the time. But it makes no allowance for a different glass thickness.

If I disassemble the Extruder assembly then the Homing Z file then has to be reset as the position of the switch will be different.
But this only takes 3 or 4 minutes, and then once done can be forgotten about.

Only thing to remember about doing it using my method is that you must remember to Home Z HOT.... Else you end up zeroing the Z axis to
the ooze on the end of the Nozzle.

I've been very happy with the results. It works reliably even with my machine being transported to a lot of different locations and clocking up
1500 miles a month...

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete

I did use one for a while and it gave quite good results, you can see a picture of mine here. However I am now using one of DC's sensor boards, and it does seem more reliable.

Regards,

Les

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Pointy's Things
Pointy's Blog

Dc42's board is a very good solution as it is reliable and can measure all over the bed.

I got good results using the hacked modulated scheme. So I took it a stage further to avoid being limited to the corner reflector papers.

I spray my glass with 'appliance' paint which then gives good uniform reflection over the whole area. This is really only a viable method if using kapton tape on top as the printing surface. This should be applied using 'wet' method as otherwise the paint will pull off the glass while putting the tape on.

Using this I can zero and check uniformity over the plate and the measurements seem to be good to as good as 0.05mm