Tim
Great to hear things are working well. Y slippage can happen. If your belt is tensioned it is not likely to be skipping teeth. It is more likely that if your bed is supported by 17mm ply (which it looks like from the photo) then it may be a bit on the heavy side for the stepper to accelerate without skipping steps occasionally. You can fix it by either tweaking stepper driver current or decreasing Y acceleration but for my money the real fix is to swap out the bed support plate for something much lighter - either thinner ply or aluminium, or cut a lot of large holes in your existing bed support plate. Even with a light weight bed, I occasionally have problems. My last large print job weighed 350g and it slipped a few mm near the end of the print. Fortunately I managed to salvage the print by taking to it with a chisel to separate it at the slip line, then using short lengths of 1.75mm filament pushed into the 30% hex infil holes to act as keys while I used a dremel to weld the parts back together (like this).
I have also seen slippage caused by strong daggy bits sticking up from the model (particularly after the first solid layer on top of a large area of sparse infil). The extruder nozzle can collide with these dags and the side force can either make the stepper skip or the bed move relative to the bed support (or even make the model break free from the bed). Tweaking extrusion temperatures and fan settings can minimize this risk. A spring loaded bed also helps here - allowing the bed to spring down rather than move sideways.
Pulley slippage on stepper motor shafts is another thing to look out for. It helps if your stepper shafts have flats on them.
Great to hear things are working well. Y slippage can happen. If your belt is tensioned it is not likely to be skipping teeth. It is more likely that if your bed is supported by 17mm ply (which it looks like from the photo) then it may be a bit on the heavy side for the stepper to accelerate without skipping steps occasionally. You can fix it by either tweaking stepper driver current or decreasing Y acceleration but for my money the real fix is to swap out the bed support plate for something much lighter - either thinner ply or aluminium, or cut a lot of large holes in your existing bed support plate. Even with a light weight bed, I occasionally have problems. My last large print job weighed 350g and it slipped a few mm near the end of the print. Fortunately I managed to salvage the print by taking to it with a chisel to separate it at the slip line, then using short lengths of 1.75mm filament pushed into the 30% hex infil holes to act as keys while I used a dremel to weld the parts back together (like this).
I have also seen slippage caused by strong daggy bits sticking up from the model (particularly after the first solid layer on top of a large area of sparse infil). The extruder nozzle can collide with these dags and the side force can either make the stepper skip or the bed move relative to the bed support (or even make the model break free from the bed). Tweaking extrusion temperatures and fan settings can minimize this risk. A spring loaded bed also helps here - allowing the bed to spring down rather than move sideways.
Pulley slippage on stepper motor shafts is another thing to look out for. It helps if your stepper shafts have flats on them.
