bad element in the heat bed?

[DiamondMox]

So I have been having an issue with this printer since I've owned it and I'm thinking I may have finally figured it out, but wanted to run it by everyone here. Whenever I try and printer larger items on my V1, I have terrible lifting on my ABS prints. I though there may be a draft, bad leveling and the usual suspects, but after fixing all those issues, I think a ring on the heat bed may no longer be heating. I don't have an ir thermometer to test with, but by flipping my prints around, it's always the same corner of the print in relation to the printer. The lift doesn't follow the flip, it's always at the same spot on the bed. Is this an issue that I just didn't find on the forum or is this something new?

[nitewatchman]

Could be, the temperature on my bed varied considerably from inside to out and across the bed. I added a copper heat spreader plate under the Boro Glass and the temperature is now very consistent.

If the same corner is consistently lifting it could also indicate that this corner is low relative to the plane of the nozzle and the first pass is not being seated to the bed. Does it look ropey or rounded in that area? As the first perimeter is being applied can you rub it loose if you run you finger over it. The uniformity of the first pass cannot be over emphasized.

[forrie]

Tricklaser sell heat spreaders for the max. Get one, they work good.

[nitewatchman]

Tricklaser sell heat spreaders for the max. Get one, they work good.

I use a 1/16" copper plate from OnLine Metals.

[DiamondMox]

The heat spreader sounds like an idea. I didn't think of that. I might have a got at that.

As for uniformity, I haven't tried just printing a single layer and checking it. I have done the calibration and got it very zeroed at each of the towers and consistently hitting the right spacing. I even tried con caving it ever so slightly with the radius once, no dice.