Thrust skid

Thrust skid—The thrust skid of the Mark III Alaskan Mill has a built-in design problem. It often loses contact with the log (1), which causes the riser post to touch the side of the log, and quite often, to get hung up. The heavy vibration and stress exerted on the riser posts, guide rails and mill handle can also re suit in parts breaking or bending, or in misalignment of the mill. 

Here s one simple solution to the problem. Mount another thrust-skid unit inboard. Purchase these Mark III parts (2) 790 clamping bracket (thrust-skid end) 788 clamping bracket (nose end) two 808 x carriage bolts two 684 yi6-in. hex nuts. Epoxy small strips of cloth-backed sandpaper (from a worn, coarse sanding belt) to the steel pads on the brackets to prevent the thrust skid from slipping on the bar. Bolt the unit on where needed (3). 

The extra length and curved end of this thrust skid ensure smooth mill travel over log irregularities. The photograph (5) shows the thrust skid in action. 

Hold the steel tube in a vise, heal the end and bend it, Hacksaw a curve for the nose and another for the shoe. Remove the waste, pound the shoe up around the nose and weld the nose and shoe together. Drill two A-in. holes, in alignment with the holes in the standard skid, to attach the new skid to the mill. 

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Bolt the bar to the riser posts through the -in. holes with 7,6" x %" bolts (2). Use an extra heavy, /z-in. flat washer under the bollhead for a good torquing base. On the thrust-skid end of the mill, insert Vie" x Vi" bolts and washers through the bar and into the holes. These bolts add support and compensate for the extra pressure the long thrust skid will put on the post. It s a good idea to use thread lubricant on all nuts and bolts. 

Now pass two %" X 4" bolts through the holes in the adjustment post on the thrust-skid end of the mill. Screw four %-in. nuts on each bolt and torque them down. Put the long thrust skid over the bolts and lock it with two more nuts. Torque the skid down with the first nut and use the second to lock the first. 

Once you ve mounted the mill, make one final modification. Drill a %-in. hole through the standard thrust skid in alignment with the chain-tension screw. With this modification, you can reach the screw easily with your screwdriver (3) and tension the chain while in the cut. 

Thread the chain through the space between the thrust skid and the bar (2). Place the chain between the chain-guide plates and feed it through the thrust-skid space (3). 

If you don t have access to a forge, you can make adequate end dogs from square steel, aluminum tube or even flatstock iron (2,3). You can also modify an extra set of thrust skids (4,5). Simply drill holes to accommodate lag bolts. Use %-in. diameter lags or, for the convenience of using the same lag driver, use lags of the same diameter as those used for guide-plank supports. 

Start the cut with the guide rails flat on the plank and the thrust skid against the side of the cant (1). Set the end dogs, mount the winch apparatus (2) and counterweight, and mill (3,4). 

For production milling, it s a good idea to have a smaller mill and bar as a companion to the 4-ft. mill. This 2-ft. Mark III (4) is modified for bolting to the bar, has standard thrust skids and a winching button. If you use the same saw engine for both mills, make sure to couple each new chain to a new sprocket to prolong the life of the chain. 

External forces applied to the structure, for example, thrust exerted on the hearth and skids by a pusher... 

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