Glue Blocks
From WikiWOOD
Glue Blocks have been a way of life for turners to mount wood since glue was first used. Glue blocks can be turned with a tenon (spigot) to fit your scroll chuck. They can be mounted to a faceplate. They can be made from wood, without a faceplate.
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Contents |
Faceplate Mounted Glue Blocks
The turner needs one or more faceplates to dedicate to glue blocks. If you are turning items over 12 inches, use steel faceplates. If you are turning items under 12 inches, some turners opt for aluminum faceplates, since they cost less.
Mount a piece of wood to the faceplate and turn it round. You may use softwood, construction grade. You may use hardwood.
Use the self tapping metal screws either a #12 or 14. Do not use Drywall Screws as the are brittle and will not take the side forces of turning; and the threads are not that thick.
The turner now have a glue block.
Glue Joints
Turners use a variety of glue joints to mount work to a glue block.
- Hot melt glue,
- CA or Superglue (Cyanoacrylate)
- Wood glue with a paper joint
- Hide glue with a paper joint
When the glue block gets two thin (close to the screws) then mount a new piece of wood. The turner may glue another board to the glue block. Use a similar type wood. Use a good wood glue, not one of the temporary glue joints discussed above. Align the grain, so the movement of the wood does not distort your glue block.
Mounting Work
The work can be mounted with a glue joint or a jamb chuck method.
The turner rough turns the item (bowl, candlestick etc) between centers or on a face plate. Then a tenon (spigot) is turned on one end of the item and it is parted off, or the faceplate is removed The turner then chooses one of the glue joints above to mount the item on the glue block.
The turner rough turns the item (bowl, candlestick etc) between centers or on a face plate. Then a tenon (spigot) is turned on one end of the item and it is parted off, or the faceplate is removed. The turner takes a glue block, made previously, and cuts a recess to match the tenon (spigot). This is one one form of a jamb chuck. Matching the tenon and recess means the tenon should go into the recess with a tight friction fit. The joint must be tight for drive purposes; it must be tight to hold the work steady. If you miss the size, you can wet the tenon, causing it to swell, and tighten the fit. You can place a piece of paper towel over the recess and fit the tenon, with the paper towel tightening the fit. You can also mount the tenon with glue on the glue block without cutting a recess. Use your choice of wood glue joints.
Safety considerations cause most turners to bring up the tailstock after mounting a piece on a glue block. The tailstock is left in place until it must be removed to turn that area. The longer the tail stock is in place, the safer this operation will be.
Shop Built Wooden Faceplates
A turner can make glue blocks with out buying a faceplate for each one. A drill bit and a thread tap to fit the lathe spindle are needed.
- For a 1 inch by 8 tpi spindle; the turner needs a 7/8 inch bit and a 1x8 tap. Using a bit 1/8 inch less than the spindle size allows for the proper size of the threads.
The turner then mounts the wood in the lathe and uses the bit, with a Jacobs Chuck, in the tail stock to drill the hole. Then the tap is used to cut the threads.
Safety in mounting a faceplate or chuck to the spindle includes a firm butting of the faceplate against the back ledge of the spindle. To accomplish this with a wooden faceplate, the turner cuts a slight recess to match. The faceplate is then placed on the spindle. Tthe lathe is turned on and the wooden faceplate - glueblock is turned to round. Two or three pieces of thinner wood together to make a thicker wooden faceplate. The optimum thickness should be the length of the spindle plus 3/4 - 1 inch. As the surface of the faceplate and glue block is extended farther from your spindle, the chances are increased of wobble (runout).
The image shows a small 5 inch maple crotch glued to a wooden face plate. The face plate is 8/4 ash. The glue is yellow wood glue with a brown paper joint. While turning the outside, the turner realized the crotch piece was too thin to allow a spigot for a scroll chuck. Thus the decision to use a glue block for turning. This work piece was started between centers.
As the gluing surface is used and turned off, the turner can glue another piece of wood to the faceplate, extending the life of the threaded portion of the wooden faceplate. Do not use one of the glue joints mentioned above. Use a good wood glue and solid joint.
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