There are at least two different basic types of guides that I know of used on stamp mills. You have the early wood guides that are nothing more than two timbers approximately 4” X 12” X 57” that are sandwiched together with bolts. There are also steel type guides. There are several different designs for the steel guides. Both types do the same thing and that is to hold the stamps in place so that they will be properly lifted by the cams as the camshaft rotates. I have worked with both wood and steel guides. The 3 ½” hole for the guides is a standard size for the 800 to 1,000 pound stamps that have stamp shafts between 3 1/8” and 31/4” so using the 3 ½” forstner bit gives a little space for the shafts in the guides.
Wooden Guides: The important thing about making new wooden guides is to cut and bolt the two pieces of wood together as soon as you purchase the wood. This will prevent the wood from warping. If you are replacing the guides only and are using the original cross members, you should set the guides in place on the cross members and use the drill holes in the cross members and drill though the new guide timbers. This will insure that the holes all line up when reinstallation is completed. There are generally (8) 7/8” bolts that hold the guides on the cross members for the mill. When you initially assemble the guide halves together after drilling the holes, you should use short pieces of all-thread to temporarily hold them together for the drying and the 3 ½” stamp guide drilling phase.
To mark the location of the 3 ½” guide hole you must install one half of each guide in place on the mill with the camshaft installed. We used a “test” stamp made of aluminum and PVC, since the actual stamps weigh over 850 pounds each and would be hard to position. The “test” stamp below is shown being used to mark the location of the stamp on the guide in relation to the cams. It is very important that you accurately mark the location of the guides so that when you drill the holes they will be in the exact location for proper stamp/cam interface.
Once you have properly marked the location to drill the 3 ½” holes, you should sandwich the guides back together and install the temporary bolts for the drilling process. The picture below shows the holes drilled in on guide. The top left corned shows the labeling.
NOTE: It is very important that you mark the guides to show the location and orientation of the guides to the cross members. This one is the lower guide to #6 upright and the arrow points towards the cross member.
Steel Guides There are several designs used for steel guides. The steel guides we used were based on Joshua Hendy type guides. The installation of the guides works about the same way as the wooden guides. We made our own steel guides patterned off of Joshua Hendy steel guides. The picture below shows the fabrication of the guides from 3 ½” split pipe attached to schedule (40) 2” box steel welded together.
Once we had the (20) individual guides fabricated we took them to the mill and started installing the guides. We used the famous “Test” stamp to get the exact location needed for each guide to be located. Once the position was determined we bolted the guide to the cross member. You can see below how each guide was installed. This was a long job, but the guide locations were exactly where they needed to be placed for proper orientation between the stamp and the cams.