So here is my rough scribble when I was figuring out the front dogs. The front dogs need to be adjustable in three directions, the length of the bunk for different diameter logs, height adjustable for the same reason, and clamp adjustment to clamp the log or lumber to the back stops. The last two are easy enough, the bunk clamp required a little more thought. When I made this sketch I figured I could cut some 2 1/2" angle and 1 1/2" angle to make the bunk clamp. Turned out I didn't have any 2 1/2" angle.
After thinking about it for a while, 2 1/2" heavy wall tubing came to mind and it turned out to be much less work. Here I have cut two 2" lengths and then cut them lengthwise to make four bunk clamps. The piece of 5/8" thick steel will be used as a bending guide on the vise.
So here I clamped the fitting and the bend guide in the vise and using my trusty 5 lb. hammer bent it over. I then turned the fitting and guide upside down in the vise and closed the vise to complete the bend. Don't try this with a Chinese import vise, I have broken two doing this kind of work. My two tough older imports that I have mounted on stands just keep taking it.
Next I drilled it 7/16" and welded a 3/8" nut to it. Took a 2 1/2" X 3/8" bolt and welded a T handle to it. Done.
Here clamped to the bunk. The small bottom bend is important to keep the clamp from turning out when pressure is applied.
So thats one direction, Now for the vertical. I welded a 2" long piece of 2" tubing to the bunk clamp and drilled and welded a nut for a 5/16" wing nut. In the picture with a long vertical piece in place. Not a lot of press required here so wing nut is fine.
In this picture is a short vertical piece in place.
So here is the completed short piece. The third direction of movement is a 5/8" X 8" piece of ready rod operating through a nut welded to the top of the vertical piece, to provide clamping pressure.
Here the long vertical piece has been completed in a similar manner, except that the end of the clamp screw has been ground to a point. In the picture is also the short vertical fitting with its clamp screw. The long vertical with pointed screw is meant for clamping the raw log to the back dog. The point insures a good bite into the log to prevent rolling or movement. The short vertical has half a nut welded to the end and rounded on the disk grinder, to clamp squared logs or lumber to the back dogs, without damaging sawed surfaces, like the ground point would.
So here they are in use. You can see how low the short clamp can be set here. The bottom of the screw clamp face is actually half below the bottom of the wood.
Poor picture but you can see the bite the pointed clamp will get into a raw log. You wouldn't use this on a sawed surface
So three more to go, probably tomorrow morning.