Make A Column With Your Bridge Saw

by Mark McMunn

Let us consider the versatility of the backbone of any fabrication shop; the bridgesaw. The bridgesaw is the most effective cutting tool in any shop, and new comers into the industry need to become aware of the many different things that the bridgesaw can do. All the bridgesaw can really do is cut, but how you place the workpiece under the saw blade, and the type of cutting tool used can make a huge difference in your production capability.

Today let's consider how to turn a bridgesaw into a lathe to produce turned work. This article will describe how to make a simple 3" diameter straight column.

First, make your workpiece, and your fixture. For the purpose of this article I will make a 12" long workpiece from three pieces of 3cm granite 3 3/4" X 12” glued together with epoxy to make our blank piece. After it is glued drill the ends and glue a 3/8' diameter support rod centered into the ends of the workpiece. Make sure that one of the rods is long enough to extend through the end of the fixture, and into the drive. During final shaping and polishing we will use a variable speed drill to rotate the workpiece after rough shaping is complete. Also, when placing the work piece on the fixture make sure to place a metal sleeve around the support rods to act as bearings between the rods and the travertine fixture. Metal conduit or copper tubing works well for this application. Make your fixture from a strong stone like travertine, and put it together with epoxy. Make the fixture similar to the photo with the base platform extending out to one side so that the fixture can be clamped down. Be sure to make the ends of the fixture high enough so that the work piece can turn without hitting the base of the fixture. Do not cut your grooves for the support rods yet!

Secondly, place your fixture under the bridgesaw. You may not have enough clearance to cut your workpiece if you place the fixture on top of the saw table. In that case you build a wood base in the front of the bridgesaw, and then raise it to the appropriate level, and then secure it with clamps and wedges. Now, with just your eye, and the blade, line up your fixture parallel as you can to the travel of the blade, and then secure the fixture. Now using the saw blade cut your grooves to accommodate the support rods and metal sleeve bearings. Simply use trial and error until the workpiece fits. Using this technique will ensure that the lathe/fixture, and workpiece are in perfect alignment with the the saw blade.

Thirdly, set the depth of your blade to achieve the desired diameter and begin cutting. To keep the workpiece from rotating while being cut simply place wedges under the workpiece from both sides to keep it from rotating. You will need different size wedges to do this as the size, and shape of the piece changes throughout the working process. Make your cuts slowly with the blade entering the piece and then returning through the same cut. Rotate the piece about a 1/4" each after each cut until you have gone all the way around the workpiece. After this process is done you can look at the end of the workpiece, and you will see what looks like many fins in a spoke pattern around the column. At this point our work with the bridgesaw is done, and the next step is to break away the fins and begin finish shaping and polishing by hand.