Persimmon Forge: Professional Blacksmithing: How I Make Gate Fullers

I seldom use set-type fullers. I have a few pairs in which there is a bottom tool which fits in the hardy hole and a handled top tool. I picked them up in antique stores here and there in the early days thinking they might come in handy.

Mostly I use fullers with some type of articulation. I like gate fullers which I have made made and I like my Smithing Magician guillotine tool. I notice that some people use the term guillotine fuller for both types but, to me, there is a clear difference in operation between the two types. The gate fuller swings on a pivot like a gate and the guillotine tool moves up and down in a track. Both can have flat, full contact, blades or blades with concave reliefs of various depths.

I have one remaining gate fuller which fits in an anvil hardy hole but all the others have been converted for use in a power hammer. The last hardy hole gate fuller is the first one I made. It was made specifically for marking transition points on bar stock. Today, I use the Smithing Magician set up in the treadle hammer to do that.

I wrote a bit about pipe fullers on December 29, 2012 so some of this may be redundant. Gate fullers are used when I want to neck down pipe or tube. Working with this stock is trickier than solid stock. It seems that the most difficult part is getting started slowly and exactly. If the tube collapses too much too fast it can wrinkle and it may not be possible to recover and make a nice symmetrical circumferential fullering groove.

Most of my gate fullers have a single pair of blades and two or three openings of slightly different sizes. I work with pipe and tube stock from about 2.5” down to around .5” so I have designed the tools to work with stock between those dimensions. Some of the fullers have nearly round windows and some have windows which are more elliptical or even rectangular. It is important for me to get the points of contact between the blades and the tube in proper orientation to work well.

Fullering solid stock is easier since it can’t collapse. A bar stock gate fuller can have flat blades. A pipe and tube fuller needs windows in the blades designed to close on the pipe at “all four corners” so it is getting squeezed toward the center from four points simultaneously.

Let’s say I want to make a ball-type object from some of the larger diameter stock. I’ll plan to neck the pipe down to a cutoff point in perhaps five steps. At each step a different, smaller, fuller window is used. The first step may make a fullered groove just 1/4” deep around the circumference. This is the slow start that avoids collapse. Each subsequent step deepens the groove by about the same amount until the desired depth is reached.

If it is important that each formed object be quite similar in size, I make a fuller with two parallel sets of blades. This produces a pair of fullered grooves and with each heat the workpiece can be advanced so it’s near groove fits in the far grove of the tool and a series of equally spaced grooves can be made. I think of this as “string of pearls” indexing.

Since I make my gate fullers to work under my main power hammer (a spare tire mechanical hammer) they have some rather specific dimensional restraints. For instance, any mounted tool has a maximum height or the ram is “choked” and can’t start moving. The top blade will probably have a “sweet spot” where the ram will strike at the most favorable point and I often weld some extra mass there. I try to design the tools to be self-opening. A bar stock handle can be welded to the top blade end beyond the pivot point so it counterbalances the blade and raises it like a teeter totter.

I have made some other gate tools which are swages to make tenons or stems of a particular diameter. The shape of the working areas of the swage blades is quite a bit different from fuller blades.

Blade design presents a number of things to consider and I’ll cover some of my ideas and the step by step process in a later post.