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.

Ellipse shaped windows

Parallelogram type windows

Three window gate fuller

Pipe Fullers

Recently I have been making several components from structural round tube which required fullering to isolate the various segments.  I hadn’t had to do this operation in quite a while so it took some time to gather a collection of tools which I recalled using for one project or another and testing them to see which would work best.  I was a bit surprised to discover I could come up with so many.

As I looked at the results I felt I was getting a fresh educational experience and was now paying more attention to the finer details than when I last used them.  Several clearly needed some improving of the blade edges with a die grinder or flap disc or polishing wheel.  Some others needed some mechanical improvement of the hinge or other parts.

I believe after a couple of days of fiddling and observation I have a better perspective of how all the variables work to achieve the desired result and decided to write down some of my ideas before they slip away.

First there is a choice of the poser source.  Will the work be done by hammer in hand or the power hammer?  The treadle hammer works well with my smithing magician but the spare tire power hammer requires less effort on my part and is much faster if it can be controlled well enough.  In the days when I did demonstrations I used a gate fuller in the anvil hardy quite a bit.  I haven’t used the fly press much for this work.  The hydraulic forging press seems too powerful to control.   Probably it would work with a  series of stops.  Perhaps if I could spin the hot pipe really fast...

Next, what style of fullering tool to use.  I use gate fullers the most and guillotine fullers a little less often. Some people don’t make a distinction but, for me, gate fullers are hinged and close on the bias and guillotine fullers close in a parallel manner whether hinged with a four bar linkage or are independent.  Spring fullers haven’t worked very well in my hands at least for the tube  jobs I usually do but I used one for making a specific size grape a few years ago.

The heat is important so I have to pay attention to which incandescent color heat works best at each successive stage.  Going slow at first works for me.  Keeping the heat localized to just the working area and getting a perfect start without any buckling takes careful attention and control.  Sometimes torch heat is just the right  thing.  Each narrowing seems a bit less tricky.

There are a number of other critical technical details to consider.  The blade throat angle is said to work best on pipe and tube between 100º and 140º and the throat opening should give “four-point” contact to squeeze the wall toward the centerline at pairs of opposing points.

The blade throat shape can be curved or straight - an ellipse or a “V”.  I can’t speak to the “V” shape but I may try it in the future.  The symmetry between the two blades should be close but rotating the workpiece tends to eliminate most of the error.

Blade width needs to be considered.  If too narrow the tool works like a severing tool, not being able to pull enough mass into the elongating zone.  If too wide the blades will have more tendency to crush and buckle the tube - similar to working too cold.  I’d guess that for most of my work the blade width is about .25 x the tube outside diameter.  Probably some experimentation would determine what is best for thin wall tube versus schedule 40 and 80 pipe.

It seems like the blade edge radius should be about a half circle or a bit more acutely ellipsoid, symmetrical and well polished.

The blade depth needs to be .5 x the tube outside diameter or a slight bit less if the fullering groove isn’t going to be very deep.

Straight blades aren’t generally used for hollow stock but if they are used some type of stop needs to be installed if each groove is to be the same depth.  Using dies with an ellipse or “V” opening allows the die pair itself to be the stop mechanism.

The spring 2010 Hammer’s Blow is a reference worth reviewing.

http://www.persimmonforge.com/