+slotslopediag = sqrt(1 + slotslope*slotslope);
+slotwidthx = slotwidth * slotslopediag;
+
+slotxperlen = slotslope / slotslopediag;
+slotyperlen = 1 / slotslopediag;
+
+mainframeholex = backslotedgespace/2 + slotpluglongerlen * slotxperlen
+ + 0.5 * slotwidth * slotyperlen;