Nozzle Dragging on Parts

[Schnupp]

The thin circuit board heaters aren't all that flat or rigid. Placing a piece of glass (with corners cut off) onto the heater and using binder clips to attach the glass to the heater should straighten things out. You then adjust bed leveling and nozzle clearance to the glass.

That is exactly what I was doing but I took my glass off to inspect its flatness and then I inspected the heat be as well. I am using 2 binder clips on each side of the bed.

[printbus]

Ah. I read stuff into your picture I shouldn't have. Well, don't worry about how flat the heat bed by itself is. The clips will straighten it. FWIW, I prefer to use the smaller, mini binder clips, and if I had a 12-inch bed I'd consider using at least 3 on each side. Just because those heat beds are so flexible.

[Schnupp]

Ah good call Printbus ill throw some more clips on there. After some more tinkering its starting to look like the problem is being caused by a couple of small things. I noticed my X carriage assembly was a bit wobbly so I tightened some loose screws which helped a bit. My bed is still a bit off and I think im going to ditch the nylon spacer and replace it with a spring. I think I read that you did this in your build Printbus?

[printbus]

Yes, I ditched the fixed spacer before I had a more reasonable way to adjust the Z endstop. Having all four corners adjustable allowed me to just get close with the Z endstop switch position and it's original hokey mount, and all four corners were then adjusted to set the nozzle clearance around the bed.

When I adopted clough42's enhanced Z endstop mount for the i3v-8, I just left the bed the way it was. Some people prefer to keep one corner fixed, otherwise you could I guess end up going around in circles never getting the bed leveled. I haven't had much of a problem. Each corner has a thumbwheel to adjust with. As it turns out, the thumbwheels I ended up with have 10 notches on them. I can sort of manage how much I'm rotating the thumbwheels by realizing each notch I turn it adjusts that corner by about 0.05mm in height (0.5mm pitch for M3 screw / 10 notches per rotation of the thumbwheel). As long as I don't overadjust a corner too bad, I can get the clearance set fairly quick. I usually get there in about two passes around the bed. With no tools required, that's often within a minute or two for a minor tweak.

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After thinking about the clips, I'd definitely have more than two on each side. I'd put one on each end near the corner. These will help tie the glass to the adjustment height on the corners. Then add at least one more in the middle or where you see the heat bed dropping away from the glass.

Again, I highly recommend the mini binder clips. Their size is a lot more suited for this application than the small binder clips typically used.

For reference, the BED LEVELING post in my build thread has info on the corner hardware stackup I use and HEAT BED CLIPS has a picture comparing the size of the mini and small binder clips.