Nozzle height

Hi,

I may have missed this in the build instructions, and a quick search on the forum didn't yield the answer, however I apologise if this has already been covered or is blindingly obvious! Once the mendel is setup and calibrated, how high above the printbed should the tip of the nozzle sit?

Milly

Hi Milly

The tip of the nozzle should be 0.1mm above print bed when setting the Z height, this is from what I have read on here and experienced with a BFB3000 machine. However I am trying to calibrate my Mendel and not having much luck.

Hope this works out for you

A good way is to level the bed first using a round rod like a drill or an extra piece of the smooth rod for the axis. Set the z equal to the diameter of the rod, then adjust the screws on the bed so that you can just roll the rod under the extruder tip. This avoids the danger of dragging the tip accross the bed. After that, set the and y and z to home and set x=100 and slide a piece of paper or post-it under the tip. Most paper are around .1 mm thick. You can check this with a caliper. It should just clear the tip with some resistance. If not, adjust the height of the z end stop, then home the z again and check with the paper. Then move the head at the four corners and verify/adjust the height using the paper.

Ideally, the nozzle should be one layer height above the bed for the first layer, otherwise the first layer will be have either too little or too much plastic. When using PLA on blue tape it needs to be a little lower to make it stick, but not much, otherwise the nozzle will start ploughing through the plastic and start rucking it up. However, if the extruder uses a plastic insulator it may expand 0.25mm when it heats up, so it has to be calibrated hot.

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True. That was the method I use for heated glass. For blue tape at room temp, maybe it's better to set the z to the first layer height (probably 0.4 mm) and set the clearance with two sheets of paper (0.2 mm).