UM3Ex levelling issue or something else?

[tgreensmith28 0]

Hello all,

Serious newbie so apologies. I have a used UM3Ex which has never had a nozzle change, unsure how many hours of printing etc on it but looked quite well loved. I've printed several projects well with first spool of Ultimaker PLA. Changed to Polyterra PLA and partway through (I mean 17 hrs into) the build failed (stringing, nozzle not contacting the model anymore) and the build was generally very weak (was designed to be a hard case but fell apart when removing from base plate).

 

I figured maybe it was clogged nozzles, so did multiple hot and cold pulls, all came out clean but issue persisted - now though (as it was the start of a print) the nozzle touched the baseplate and looked like there was no room for extrusion to occur. Did manual levelling and then active levelling, and all seemed to be fine (i.e. no errors from the active levelling) but still no joy when trying to print - same issue, nozzle touching base plate. Decided to swap the nozzles incase something had gone bad, but still I can do the levelling procedures just fine, I can extrude material easily when I load it into the printcores, but ask the printer to print something and the nozzle touches to the baseplate (as an example, I tried to do the XY offset with a thin layer of glue, and I was able to actually measure the offset because of the voids left in the glue rather than an extruded model....).

 

I've seen some other threads on levelling issues but they all seem to be issues during the levelling process which mine passes fine. The gap (reoughly 14mm) between base plate and top of metal part of base plate appears roughly ok too. More ideas? Fingers crossed and thanks in advance,

T