Glass Grippers

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Rev. 12/16/01, 31 August 2003, 2007-05-29, 2008-10-18

There are many tools, often created in a studio or factory environment, which serve the purpose of handling glass more easily or quickly or reliably, replacing a punty or gloves. Some of these a simple forks covered with fiberglass or frax to carry a goblet, vase, or mug to the annealer. In an book on glass working at the turn of the century there is a picture of a padded punty that fits inside a vase to hold it as a foot is applied.  Some examples toolmakg.htm#SPPUN
One common tool designed in various sizes is a pronged gripper that is used, in the smallest form to hold a marble while reducing the last punty mark, in a medium size to hold the base of goblets as an alternative to a punty, and in a large size to hold a footed base vase or pitcher while handles are attached. Basically the design is a tube forming a handle that aligns thin curved spring hooks. Marble holders are commonly made with wire hooks, medium sized with flat spring stock. The hooks can be installed inside the tube or guided outside. arrow springs hot fingers Or [Right] as shown at 2003 G.A.S. Conference.] 2008-10-20

My project is to build a medium sized gripper for goblets and large marbles. My method is to use the flat spring steel sold for replacement "fish tapes" used for pulling electrical wires through walls. This metal is about 1/16" thick and 1/8" wide and a replace reel is 50 to 200 feet long, mine being 50 feet. http://www.nationalwholesaletools.com/50ftfishtape.aspx

My design is to use a threaded rod running down most of the length of the tube, with wing nut or large knurled nut at the back end to tighten the grip. The natural curve of the fish tape is used to spread the prongs and I will try to make it work with the careful placement of the prongs on the mount to the rod to hold alignment. I may have to add a guide head to keep the prongs at 120 degrees to each other. Placement of the prongs is critical because if they project (even slightly) different amounts, then they will not hold the piece in line with the center of rotation. My method of dealing with this is to carefully construct a disk with a center shaft quite perpendicular that will be held by the prongs while assembly is going on during which the alignment of the shaft with the tubing will be maintained.

Part of the alignment process will be simplified by using a thin wall brass tube as a connector between the prongs and the threaded rod. The prongs will hold themselves by their own tension in the tube as they are adjusted for concentric holding, and then solder (or epoxy) can be added to lock the location. 2007-05-29

The picture at right shows the first execution of the idea, which reveals several flaws and a few good ideas.  This is built of 3/8" NPT black iron pipe (which has rusted)
 A) shows the working end.  The connecter allows mounting a short nipple for carving and filing and disposal if errors occur rather than cutting off the 4' pipe and rethreading.  In this version, the end was notched to guide the 1/8" wide spring steel fish tape wire (above) in expectation that gripping the glass would bend the wires out into the notches.  Not really functional.  Although not clear in this image, the 3 wires do not come together evenly and require better alignment.
 B) shows the bottom end and the kind of cap that needs to be drilled and installed at the A end to guide the wires and mount a center disk (below)  The bottom cap is center drilled and the 1/4" rod in C extends through it with a tightening nut or handle.
 C) shows the wires pulled out to reveal the silver soldering into a connector nut threaded to a 1/4" threaded rod.  I don't recall if I had to drill out the nut to take the wires but I do recall it was difficult to position the 3 flat wires evenly as they kept slipping, which aggravates the alignment problems mentioned in A.  Using the nut and abandoning the brass tubing permits using hard silver solder and removal of the wire end with the cap for something else or reusing the rod.  Note that with a 4' pipe and a 3' rod, another connector nut would be needed to extend the rod through the lower cap. 2008-10-18
REVISED DESIGN
A cap would be drilled with 4 holes - 3 placed 120 degrees apart to guide the wires and a centered hole tapped for 1/4" rod to mount a disk.  Inspection would determine if these holes would fit in the 3/8" NPT cap without weakening the end.  The 1/8" holes might be drilled smaller and widened to hold the wires to leave more metal in the cap.  The disk would be mounted with several nuts to permit moving it closer and further and to permit replacing the disk for larger or smaller glass. [Received e-mail "visited Fenton Glass works in W.V. and seen them using a spring loaded device called a snap They are made from a black steel pipe cap on the end of 1/2 ips screwed into the center of the cap. then there is a rod thru the center that is spring loaded somehow to release a three prong holder machined from cast iron plate with a inner grove on outer rim."]