to lap a plate it is placed on a flat stone and worked until it is totally flat, both sides. What is your mix of meat to fat? for a good sausage it should be in the 25-30% range.
I grind my meat semi frozen, add my spice mixture then regrind again. I then put it back in the freezer to get cold then mix then stuff.I use a stuffer





Mixing is a very important part. You must kneed the meat mixture until it binds. Once it binds it becomes a sticky mass it will only bind if just above freezing if you get to say 37 F you can work it and the fat, water and meat won't bind, the fat will just smear. If doing it by hand, your hands should be almost frozen and should take about 10 minutes of vigirous mixing. I use a hand crank mixer as it just gets too cold on the hands to mix properly.
Read the ingredients on your commercialspice mix to see how much if any bread crumbs are in the mix as this also makes for a loose texture. Really what you have to watch is your meat/fat/water ratio and any fillers that might be in the mix