IR probe playing up

Corexy

Hi All,

My Duet wifi machine (converted Zortrax) has worked for a couple of years with a few hiccups, but generally just keeps smashing out excellent prints.

I am still absolutely useless at programming, and just left the firmware as is and just use it. I see there's even a new wifi 2 now?

Today my machine must have had a major incident on a big PLA print, and even yanked the bed off its pins and knocked itself around.

I've gone over it a bit, and reset the nozzle height with the G92Z0/G30S1 procedure, and the nozzle trigger height was all still the same as what was already in my config file. The bed is still level.

The problem I'm having is that on starting each print now, I'm hard down on the build surface, it can't even extrude.

I use a bit of offset in my Z axis G code, which has always worked brilliantly for my first layer. I even tried to print a gcode file I'd printed successfully the day before just to isolate whether it was the file or the printer...same thing. I tried using some z micro steps or whatever just to get it to work, but no response.

My thoughts are that my IR sensor may have been damaged by impact or fouled with debris, but it is working during the nozzle height procedure. It's an absolute hassle to get to as well, but obviously if it has to be done so be it.

I've literally NEVER had an issue with the IR sensor on my printbite bed. It has been rock solid bulletproof, and repeats the same height over and over.

Any check or whatever I can do to confirm what's going on before I pull the machine down?

Cheers in advance for your help.

Phaedrux

Clean the sensor lens with some isopropyl alcohol?

Corexy

I have thought about doing that, and will.

Just seems so odd that the nozzle height setting procedure works perfectly.

Thanks for the reply.

dc42

Which version of the IR sensor do you have? The older version used through-hole phototransistor and IR LEDs. These could get knocked out of place, causing the trigger height to change. The newer version uses SMD optical components, so the trigger height should remain constant unless the optical components get contaminated (for example, with filament), or the sensor position relative to the rest of the hot end changes, or you switch to a different build surface.

Corexy

@dc42

Hi David,

I would certainly have the older version, as I bought some of the first of your Duet Wifi boards.

I do have another new probe here, so obviously that's where I'll go first. It's just a pain, because I've got it tucked right up back of a fairly intricate hot end with dual fans etc, but that's how it goes.

It's most likely due to impact, as there was a hell of a crash when the hot end snagged on this print.

My only doubt about it is why does the nozzle height setting procedure work and not the print first layer height? That seems a bit odd.

Is the new IR probe a big step up? I've had an absolutely bulletproof run out of this one. I remember when I fit it thinking this little thing looks like a fail point, but absolutely not.

DocTrucker

Is the old probe still triggering, but just at a different height? If you run multiple probes is the trigger height consistant to around a few microsteps in z?

Forgive me if I'm stating the obvious but to save a rebuild I would home all then move the nozzle to 1mm above the bed (or higher if needed to avoid a collision) as close as possible to the co-ordinate that you home z at, but keeping the nozzle over printable surface. Manually reset the build height to 10mm so you don't hit any minimum z axis limit issues with:

G92 Z10

Then move the nozzle down in small steps until it just grabs a piece of paper. Reset z height to zero with:

G92 Z0

Move nozzle back up 5mm. Probe at the current locatuon but do not reset z with:

G30 S-1

The reported value is what you need to set your probe trigger height to in G31

If you find that you are always needing to baby step to move the nozzle closer to the bed for the first layer (extruded material is not adhering to the bed, or fill lines are not touching each other) then reduce the trigger height slightly. If too close to the bed for the first layer (extruded tracks very fat, extruder may be skipping or stuttering) raise the trigger height.

Corexy

Thanks very much for taking the time to type all that.

I did pull it down, and there was a sign of impact on the probe.

As it goes, the spare I had on hand was the new type. I bolted it up, set the nozzle height (which was exactly the same as the old one), and it's away and printing.

I'm very much out of my depth with the programming on this thing, but my wiring and build has been solid, as this thing's been an absolute workhorse for almost 3 years.

I actually bought 2 sets of gear (I have 3 more dead Zortrax's sitting there), and have never bothered fitting up the second.

I'm going to have to bite the bullet and try and update the firmware though I guess...take a deep breath David! We know how that's gone every time, lol.