Educate Me on Glue Blocks

[Mike Goetzke]

I've been mostly turning larger bowls but on my last blank cutting I made some smaller blanks so I would get more practice. I have seen posts about using sacrificial "glue-blocks" to preserve the wood on the blank you are turning.

I would like to know what are the steps in turning a bowl if you use a glue block (i.e. do you turn the outside of the bowl with the bottom facing the tail stock - just don't provide a tenon and then reverse chuck it with a glue block to core it???).



Thanks,

Mike

[John Hart]

I bought a tap with the same threads as my spindle....then I cut blocks of wood...drill a 7/8ths hole.....tap the hole...glue the block to my blank with heavy duty 5 minute epoxy.
Then I turn the whole bowl from there...bottom toward the headstock.....outer first...then inner basically. The foot is done from right at the glue block and is considered expendible.
I'm able to make a nice foot, but if I'm interested in doing something fancy....I will part it off and turn it around just for foot cleanup

These little threaded glue blocks take about 30 minutes to make 10 or so. I really don't use a chuck much anymore.

[Mike Goetzke]

I bought a tap with the same threads as my spindle....then I cut blocks of wood...drill a 7/8ths hole.....tap the hole...glue the block to my blank with heavy duty 5 minute epoxy.
Then I turn the whole bowl from there...bottom toward the headstock.....outer first...then inner basically. The foot is done from right at the glue block and is considered expendible.
I'm able to make a nice foot, but if I'm interested in doing something fancy....I will part it off and turn it around just for foot cleanup

These little threaded glue blocks take about 30 minutes to make 10 or so. I really don't use a chuck much anymore.

Thanks John.

Oh boy, I just started getting good at forming the outside of the bowl from tail to head stock (now I have to do it the other way around?).

I made one block this weekend with a tap the size of the spindle as you suggest. Think I goofed though, I have some 4x4 x 8' ash bat blanks and I was going to use this for the blocks and in my rush to make one forgot to use side grain. I just sliced a piece off the log and drilled and tapped into end grain. Oh well have plenty more ash to play with. Anyway I glued it to my 7" diameter bowl blank and was wondering if I should have processed the blank first.

Mike

[John Hart]

heh heh...I did the same thing with the end grain my first time too. I learned quickly.

I don't see a reason to process anything first...as I'll glue to big ugly chunks as long as I can find a flat surface somewhere near the center. Works well unless the wood is really wet.

[John K Jordan]

I've been mostly turning larger bowls but on my last blank cutting I made some smaller blanks so I would get more practice. I have seen posts about using sacrificial "glue-blocks" to preserve the wood on the blank you are turning.

I would like to know what are the steps in turning a bowl if you use a glue block (i.e. do you turn the outside of the bowl with the bottom facing the tail stock - just don't provide a tenon and then reverse chuck it with a glue block to core it???).

The glue block can be used as a substitute tenon.

Using a glue block was once the primary means of holding for turning. Typically a round cross grain piece cut from a board was glued on the flattened bottom of the blank then a faceplate was screwed to the block. Turn the bowl with the top facing the tailstock, then part off the block, reverse and hold the piece "somehow" and flatten and detail the bottom.

(Trivia for young guys: before the days of Cole jaws and vacuum chucks it was common to glue green felt on the bottoms of bowls to disguise the flat bottom or even hide screw holes. Another "old" method of finishing the bottom was to part and saw or break off the glue block then use sanding disks to power sand a slight concavity in the bottom.)

I don't use faceplates much these days but I do occasionally use the glue blocks cut to fit in a chuck. This is, as you said, to keep from using up more of the wood. More often though, I hold the bowl with a recess to hold with an expanded chuck if I can make the finished bottom thick enough (it really doesn't take much of a recess, just 3/16" or so in good wood.)

I ALWAYS turn the outside first, preferably with the bottom towards the tailstock.

Whether I use a glueblock in a chuck, a recess, or a tenon, I still turn the same way: Flatten an area on the top if needed (perhaps working between centers), drill a hole in the top side and mount in a screw chuck (my favorite is the old Glaser but I will use a wormwood screw if needed) and support with the tailstock. I turn the outside and bottom, turn a tenon, recess, or round the glue block to fit the chuck, then reverse and turn the inside and rim. Then either mostly part off the glue block (saw the rest of the way) and/or reverse (with Cole jaws, jam chuck, or whatever) and clean up and finish the bottom. If I can, I'll glue on the block before turning the outside, otherwise, I flatten a spot while the block is on the lathe then glue on a block and clamp with the tailstock overnight (wood glue such as Titebond.)

I usually cut glue blocks from 3/4" oak boards, make a bunch at once a little bigger than final size.

Some people put a sheet of newspaper between the glue block and the piece so they can split off the block after turning but I never used that method.


A friend of mine uses a different method to both hold securely and avoid wasting wood - he covers a faceplate with double-sided tape (the good stuff), presses the flattened blank and holds pressure overnight, turns the bowl, then removes it from the faceplate. He as turned large bowls this way, 20" or so, and never had one come off unintentionally. In fact, getting the bowl off the faceplate is sometimes that hard part if you don't know how.

JKJ

[Dennis Ford]

I choose from a number of methods, including face-plates, tenon, recess, screw-chuck, hot-glue & double stick tape. Most (probably all) of these can be used with or without a glue block. A glue block can be a good choice if you have a reason to bother with one. Regular yellow glue works great on dry wood but will not work on wet wood. Polyurethane glues or CAs glue work on wet wood. Note: if you use a glue block to turn a wet blank into a rough-out, do NOT trust the same glue block to still be secure after the rough-out has dried.

[Peter Fabricius]

As has been said, try a simple approach. 1. Turn the blank round and flatten the to be bottom between centres. 2. Glue to glue block on to the flat (no paper between the pieces, you will be parting the project off the glue block on the glue block side to save all the exotic wood). 3. Turn the outside to final shape, hollow the bowl to finished shape, apply sealer or final finish. 4. Part off the bowl, 1/16" thin kerf and then saw it off. 5. Reverse turn on a Jam Chuck or Vacuum Chuck to finish shaping the bottom. Apply final finish to bottom and you are DONE.
Peter F.