Two Filing Horses
Bob Smalser
>The first storm of the year with 4 inches of rain gave me an excuse to get under cover for a day and make a taller horse for saw filing. Either I�m getting taller or my eyes are getting worse, and the horse I copied from one of my uncle�s and have been using for almost 40 years now is a bit too short these days.
I�ve always been interested in trying the Cornish �saw grip� from the UK on Alice Frampton�s Cornish Workshop web site. The Pennsylvania Dutch birdsmouth design on the right is simple and lightweight for toting around, but once the saw is tapped home in the wedged vise jaws, it�s easier to pick the whole horse up and reverse it than it is to reverse the saw to change sides.
The softwood birdsmouth is cut 7 degrees from vertical and reinforced with a carriage bolt to prevent it from splitting, and the hardwood jaws are beveled to 8 degrees so the mouth bites high on the jaw taper, forcing the jaw edges tight on the sawblade above. The saw requires a mallet to install and remove, which over time is hard on the jaws.
This horse has a 50� working height, with 6 X 30 X 3/4� jaws set in uprights of 1 3/8 X 3 3/8 X 48� jointed by mortise and tenon to two �� rails cut to provide an overall frame width of 20�. This one is on its third set of jaws and is spruce and cherry with holly jaws.
The Cornish vise is more sophisticated with a hinged jaw bearing against a fixed jaw�.
�.secured by a loose bar riding in slots in the uprights and bearing on two hardwood wedges screwed to the bottom of levers which are in turn screwed to the moving jaw. Sweet. Here for weight I used a 7/8� steel bar salvaged from an old wrench, instead of a lighter hardwood dowel that would have to be tapped home a bit harder.
The specifics of the Cornish design allowed a carpenter to quickly fabricate one of these on a job site using the lumber and framing saws at hand. I used a bit more time and tools to reduce and refine the scantlings a bit, and will only mention the dimensions I changed from the original plan. The frame was got out of three VG Doug Fir 2 X 4�s I used last year for concrete forms, the uprights measuring 1 5/16 X 3 1/8 X 52 1/2� and tapered from the center rail to the feet, allowing an overall working height of 53 ��.
The two frame rails were planed down to 7/8� and cut to make the overall width of the frame 17�. I deepened the mortise for the lower rail over the original design to produce two feet less likely to rock on a patch of wet shavings than if the entire length of the rail was in contact with the floor. The rails were positioned for the horse to mount cleanly in any bench vise or Workmate.
I enlarged the vise jaws to 5 � X 30 X ��, and kerfed the frame to accommodate my largest saws. The jaws have to remain true, and the wider the board, the greater the chance for warp. My hardest wood for this application is Pacific Madrone, not the most stable wood, so I kept them narrow and kerfed the uprights to take a 7 ��-wide saw. An alternative is to make wider jaws, each laid up from three narrow boards, flipping the end-grain cups to make a more stable jaw than one got out of one board.
The inner faces of the vise jaws in both designs must be beveled or coved so only the top inch or so of the jaws bear on the saw. Such tapering leaves insufficient thread depth for the wood screws mounting the levers to the moveable jaw, so I used machine screws instead. I used flat-headed lags in oversize holes rather than wood screws to mount the fixed jaw, so as to provide some minor adjustment to align the two jaws.
Continued�.
