[UpAllNight]

u are right if its concave it would require lapping the whole bottom...but if u do this with sand paper on a flat surface u will in most cases put pressure on the fron edge when pushing and on the back edge when pulling making it appear to be concave...i just bet if u check one after it has been done with sand paper on a flat surface that the edges will be rooled to a certain extent...i mean checking it with a .0001 indcator...well im leaving mine alone and see what happens...if it was out bad in the part that comntacts the core i would surface grind it instead of laping it...but that the advantage of having a surface grinder...all in alll im happy with my maze 3 for what it cost...if i made one it would be a better machining job but it would cost 5 times as much to sell it for a profit

My maze3 came in pretty good shape for a production part for 42 bucks...the top was not cracked but it didnot seat completely against the copper bottom either but that is because of to much compression on the oring...i think thats the problem is the depth and the width of the oring...but i can see DD way of thinking better to have to much compression than not enough...plus just how much experence do u think the person has puting those maze 3 together and inspecting them and shiping them...u can only do so much for 42 bucks