It's nearly Summer... So I'm going Probeless

Yepp!, my probes GONE..... Retired to the Spares box, for use on a rainy day.....

I'm using 2 MicroSwitches, that retail at £1.75 or something like that from Maplins.
One microSwitch for the X-axis homing, which needs a mounting bracket....

Then another Bracket on my Big Blue with another MicroSwitch, that picks up the TILT!

(EDIT....BTW The Big Blue isn't at a crazy angle, it was the camera angle)...
I'm getting 100% success so far. Ok, I might one day have to clean the MicroSwitch roller,
and recalibrate it, but that's 2 minutes to do.

If any one is interested then I'll put the STL for the two brackets and sample Gcode on ThingyVerse...

Note... This it fitted to my Big Blue. Big Blue was always designed to be expanded.
I now have nothing other than the HotEnd to tangle in the Print or Skirt.
I print on Glass, and the way I get the Zhoming will probably tear Kapton tape if you use tape... But I'm happy with it. And it's working
everytime, and is 100% reliable. I've been checking it every time I 've used it to see if it works before telling people about it, and it's been
spot on every time. I'm thinking of progressing the design away from a roller to just a plain MicroSwitch, that isn't
in constant contact with the X-axis arm, but that's an idea for the future.

Kim...

Edited 1 time(s). Last edit at 05/08/2014 06:42PM by KimBrown.

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Looks nice, good idea mounting the Z endstop switch on the hotend. I think I'll modify my x carriage once more and add a mount for another switch, too

Really nice solution, what is accuracy of the switch?
/Joar

Joar, well the switch is setting the Zhoming height every time at the same spot.
The arce that the Nozzle moves in it a fraction less than the arce the MicroSwitch is on,
so the movement is magnified slightly. So far I've test about 100 times as I completed it a couple of days ago.
Then after it's set the Zhoming position, I've been checking it, and it's been good every time. I wanted to raise the switch more
but there's just to much junk in the way.
The homing Gcode I use is:-

M104 S215
G91
G1 Z15 F2000
G90
G1 X100 Y100 F2000
M109 S215
G1 Z-50 F150 S1
G92 Z-1.6
G1 Z0
G90

Once the nozzle touches the glass the Big Blue I use starts to tilt. I let it lower it more and more till the switch trips.
Setting up was easy. I set the Tripping point initialy to zero, then manualy raised the HotEnd till it was just touching the glass.
Did a GETPOS on PronterFace, and this then told me the height it had raised the head to get to the point it was just
touching the glass (in my case 1.6mm). Then I added G92 Z-1.6 to the HomingZ.g file, followed by a G1 Z0 to move to that point.
It's been setting my HotEnd to the correct height every time, ever since.

The X-axis MicroSwitch Bracket is already on ThingyVerse... Help your self. The MicroSwitch touches the X-carriage close to the bearing.
So if one day I decide to change from using the Big Blue, it will still work.

You must have M558 P0 either in the config.g file like me as I no longer use a probe for anything. Or in the homingx/z files.
You can enable the probe again if you wish, but what the point. I've even cut the probe fitting off the x-carriage to give me even more clearance now.

If there is interest in it, then I'll dismount my switch, measure the bracket holes height on Big Blue, and add the holes to the design.

Kim

PS If people are using Kapton tape and want to use this system, then just lay a sheet of paper under the HotEnd, and add 0.1mm to the setting height.

Having got rid of the probe has meant it can't pick up the Skirt or Print and wrap it around the HotEnd.....

Edited 1 time(s). Last edit at 05/09/2014 03:54AM by KimBrown.

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btw my latest firmware release (0.59-dc42) includes a change from zombiepantslol that allows you to set a G31 height value for probe type 0, i.e. a switch. In other words, you can tell it that when the switch trips you are e.g. 1.6mm below the bed. So you don't need to edit homez.g and homeall.g to adjust this value.

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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].

Nice idea Kim, my probe is not causing any issues right now and I am waiting to see what the boys come up with in the other thread. I did some googling last night and there are lots of designs for Z Probes using servos to swing a switch into position.

I thought about mounting a switch on the end of the X Axis, as I have a twin Y profile bed now, I could just bolt a printed plate onto the outside. This would be fine if I always used the same piece if glass or if the different pieces of glass I have are exactly the same thickness. (I haven't checked them yet), otherwise it would be useless.

Regards,

Les

PS. You got some serious colour clashing going on there, a real rainbow Ormerod.

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That's a pretty neat solution, Kim, a real "Eureka" moment! I don't think I'll go the whole hog with your Big Blue just yet, but the microswitch/tilting head technique sounds very simple and reliable, and I'll probably adopt it. It seems that it may be better to probe at an XY position that puts the microswitch close to the bed center rather than the nozzle? (Not that it makes any difference where you probe if the bed is perfectly flat & level). It sounds like you have around 1mm clearance between lowest switch height and nozzle height, so there's little chance of it catching on a print when the extruder rides over a bump - would that be correct?

Dave
(#106)

Hi Dave, Nope I think you miss understood. The HotEnd Nozzle is the only thing near the bed... The next is my cooling ports on the Big Blue which are 5mm higher.
In fact the heater cables are the next lowest thing actualy.... At the hight of the top of the Nozzle nut... So I have acres of clearance now....
Since fitting the Z-axis microswitch I am getting very reliable prints again... It's working great for me...

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Quote
KimBrown
Hi Dave, Nope I think you miss understood. The HotEnd Nozzle is the only thing near the bed... The next is my cooling ports on the Big Blue which are 5mm higher.

Oh - even more clever! The microswitch is operated by hitting the X arm rather than the bed. Nice.

Dave
(#106)

Technically, you are not probe-less, you just switched to simpler probes.
Using a microswitch for Z detection would be ideal. Isn't there a risk that the internal circuitry of the switch moves about a mm or so after a day or a month?

michaelljunggren, well I haven't got an IR Probe I meant.... Technicaly the Nozzle is the probe, the switch is just the tripping device.
MicroSwitches are pretty good. They will do a few million change overs before failing, and by that time I think it will be more than just the switch I might have to replace. If it ever needs re-calibrating it only takes a minute to do.... But I don't have anything hanging down that can get caught on the print now.

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Quote
michaelljunggren
Technically, you are not probe-less, you just switched to simpler probes.
Using a microswitch for Z detection would be ideal. Isn't there a risk that the internal circuitry of the switch moves about a mm or so after a day or a month?

I hate to be a per nittengryn but I think the correct expression would be "..micro switched to simpler probes"

:-)

Erik

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Just had my first full on Bloked Nozzle..... It spat my tongue out..... So sorry if I'm typing with a lisp....
At least it made me realise I didn't have any spares, and it's just about holding in....
So printing 3 right now.
Now what blocked it was funny.... Clear threads of PTFE.....
So the filament must be giving these tubes a bashing....

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Quote
KimBrown

..a micro switch for Kim, a big step for Ormerod :-)

Erik

The Ormerod isn't happy about it....... It's saying....
Work...Work....Work....Work.....

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Hi Kim, do you have the model number of that micro switch you are using ? Trying to find the micro switch that fit into the existing holes on the x motor bracket.

I'm using a Cherry DC3 microswitch for the X axis, which even has a blade on top, so I don't need any extra mounts for the X motor bracket.

I really like this method Kim, thanks for sharing. I decided to make my own implementation of this after I had more problems with the probe catching prints and so far it seems to be working good. I just need to tweak a couple of bits and tidy up the wiring then I will post some pictures. I also made a probeless X Carriage, if anyone is interested, I'll post the stl once I have printed and verified it.

One little tip if you are using a micro switch for the X axis homing, is to mark the middle of your bed, home the X axis then move to the head to 100,100. Next move the head until it is over the middle and make a note of the X position. Then edit your homex.g file to suit, so that x100 is in the middle.

My X position was 113 after moving so I simple add a 13mm move after zeroing and then zero again. This is my homex.g code...

G91
G1 Z5 F200
G90
G1 X-240 F2000 S1
G92 X0
G1 X13 F200
G92 X0
G91
G1 Z-5 F200
G90

Regards,

Les

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Hi the X-axis microswitch was one from Rep-Rap, I ordered 6 from them some time ago.
But, after fitting it, I found I had to move it to a bracket to get it to be hit by the X-carriage.
The bracket is on Thingyverse.
The Z-axis micro switch was from Maplins, I picked it up on my way to work.
I am thinking of changing the microswitch for one of the button types with the idea been that
it won't be in contact with the X-axis arm all the time.
I'm also thinking of moving it high up the Big Blue, and maybe have operated by a block mounted on the X-axis.
Just thinking that the higher it is will make the levering moment great, i.e. magnify the movement.
Glad people are finding it interesting...
I have some other ideas cooking... But at the moment it's problem solved here.

Kim

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If you have a microswitch as a zprobe, it must hang lower than the extruder. Dont you risk dragging the microswitch into the bed?

As you can see from the picture the micro switch is attached to the fan mount, and connects with the X rib when the hotend is tilted.



Regards,

Les

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Glad to see it's catching on... I'm using a roller, but one day when I'm bored I might change it to a regular switch like Les above...

@michaelljunggren not sure your seeing what we are doing.....
We are letting the tilting action of the HotEnd assembly press a switch against the side of the x-axis...
It's working perfectly here for me, and I won't go back to a probe again..


Kim

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Can this somehow aid in auto bed-leveling?

@michaelljunggren No... It's aimed at getting a single point measured. It lowers the HotEnd untill it is past it's ZERO level, and continues to lower untill the switch trips.

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Yes, but if the firmware was aware of this, a quick 4 point sensing could auto generate the calibration information that the setbed.g contains. The head could jump between these points in a few seconds...

The firmware can do it - I've checked that already. But at the moment a major problem for me is the X rib, because the distance between the switch and the rib seems to vary depending on the current X position. I think this should work better with an alu X axis/rib, though.

Hmmmm yes I see what you mean... Maybe DC42 could add an offset entry to be read from the config.g file to use it for probing.... As each machine would be slightly different, and
so would require setting up, but that's possible I would have thought.

I prefer to use a level bed, so never even thought of using it that way..

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Heh, adding more compensation code is not a big deal, but I personally wouldn't be satisfied with that solution. Using the 623 bearing on the x carriage as a switch in combination with X axis alu replacement parts would be a much cleaner approach IMO.

My bed is completely level, too, but today I've noticed my nozzle is sagging a little during X movements - that's the next point on my never-ending TODO list

Another tip for anyone wanting to do this...

You can use the probe wires to save sending more up to the head. Leave the black and pink/red (Gnd, 3.3v) wires where they are connected in to the Duet and connect the blue wire to the pin directly next to the Z motor connector (Z_Stop_Conn). At the head end you will just need a male plug or pins to mate with the probe connector. (Black/Blue wires)

Regards,

Les

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