What is the correct position of the frog? Should it make a straight line with the rear angled portion of the throat? Are there instances where it should be forward/or behind the back of the throat (I figure it's adjustable for some reason, right)?
My assumption is that the blade should be sharpened flat (and square)across its full length. Is this correct or is there any reason for contour?
Maximum support of the blade from a conventional frog is obtained when the frog forms a straight line with the plane bed. Moving futher forward will effectively close up the mouth and with all things being equal such as super sharp blade finely tuned cap iron close fitted to the edge and a flat bottom with no hollows especially in front of the mouth you will be able to get the best finish on the finest set blade with the least amount of tearout on difficult grained wood.
Moving the frog back will allow you to take coarse shavings to knock a piece of wood down to dimension without clogging up the throat and having to continually clear it.
It is debatable whether moving the frog out of line either way has any deleterious effect on support causing the blade to chatter... at least that is Dano's view when I questioned the benefits of the "Bedrock" frog design
I usually have my planes set quite fine as these days I rarely dimension wood..preferring the tailed beasts of jointer or planer.
Some people have a couple of set ups on two separate planes.
Crowning the blade is a common practice on a plane set for "scrubbing " or removing wood quickly with deep cuts from a rough board ...it is easier to take coarse shavings with little risk that the blade will dig in.
For smoothing operations, leaving the corners of the blade sharp will cause perceptible tram lines to appear which would then need to be dealt with by a card scraper or abrasive paper. Just wiping the corners off with the stone will be enough to stop this happening.
My teacher from the middle ages would argue that all planes benefit from at least having an imperceptible crown on them and if you sharpen entirely by hand this is easy enough to do...I use jigs for ease of use...herecy I know.... and will then just knock back the corners of the blade.
Limey said, "My teacher from the middle ages would argue that all planes benefit from at least having an imperceptible crown . . . "
Sometimes I wonder if that is not an excuse made up after using a hollowed out stone for sharpening. Actually, some of the old timers even created that slight camber (maybe .002" on either side) on their jointer creating a slight hollow on the jointed edges which easily crushed when the boards were glued up and clamped covering up a small imperfections and createing a nearly invisible seam.
As to sliding the frog back past the tapered edge of the mouth, I would be concerned with the iron being bent slightly when the lever cap is locked down forcing the iron out of a coplanar situation. My Jack Rabbet plane is particularly susceptible to that, and I think that may have been the cause of the outside ends of the iron being slightly bent upward. At maximum mouth opening on that, it had a fairly narrow mouth, and now, with the thicker Hock blade, I may end up having to enlarge the mouth more than the sliver allowed now since you generally want to take a bit larger bite when cutting rabbets than the couple thousandths I'm able to get through that mouth now.
I think crowned blades and a large mouth are the better solution when "scrubbing" down a rough board. The scallop type cut produced can remove timber visibly and more easily with less effort ...the shaving only being very thick in the centre.. I think that the concerns you have with the cap lever are unfounded the blade and the cap iron are rigid enough to withstand any deformation that is applied when the lever lock is clicked shut.
With your hock blade have you tried opening the angle on the inside of the mouth. I have used the combination of the thicker Hock blade and the thicker detachable Clifton style cap iron and it was good at giving me a closed mouth but the shavings jammed. Filing the mouth opening to relieve the gap at the top without enlarging the mouth itself did the trick. With just the Hock blade and moving the frog back a tad if necessary is something I'd try first.
If you're saying to file the front of the mouth at an angle, that is what I've been thinking as opposed to really opening it up. Just a smidge oughta do the trick. This is one of the earlier ones with the lateral adjustment lever, but no frog adjusting screw, so I don't want to alter it any more than absolutely necessary to get it working well.
However, I don't mean to be simple here, but if the bed is flat will the thickness of the material removed be a simple matter of the blade depth and not any anterior/posterior displacement of the frog?
You are correct....
But moving the frog forward means that the fibres of the wood are supported far closer to the point at which the cutting edge of the blade starts to cut and "lift" them from the surface so that they are not able to so easily pluck out the grain and cause tearout.. The front edge of the mouth has the fbres trapped from lifting up, why it's important to have no hollow spot in this area...less advantageous these days is to set the mouth wide and take a deeper chunk with the blade set deep when it is advantageous to let the fibres have a greater degree of flexibility to be able to lift.
Jerry ...you were correct in your assumption that's what I was trying (badly) to get to. :)
Hey, sometimes you just slip out of American and back into English, but you are getting better (or worse as the case may very well be). Course, maybe you're practicing for your trip. Have a great one and hurry back. We'll miss you.
Just yesterday, we used clamps after glue simply to take the bow out of the wood we were using, and it straightened everything out for us. Usually though, any time you lay up a project the clamps are...