I agree with 'shellman'. Dirt buildup under any type bottom replacement will cause "humping". To solve this, cut 1" slits across and near bottom of feeder, first on the left then on the right, overlapping slightly in the middle. This will allow dust, dirt to fall out. I do lots of custom beans and replacing fdr bottom is an annual event. Best I've found is A.B. sheet metal. Steel suppy shears it for me. Tack-weld in just a few places on all sides. Works great and easy and quick to replace (about an hour)!