Am I kidding myself with this glue up?

[rtyuiop]

Hi folks,

So I started working on a turned coffee table in bits and pieces of jacaranda this week, and I'm suddenly having doubts about my plan. I wanted to join a couple of blanks together to add some mass and height to the base, and add some extra surface to hold onto a central leg, but the main piece is too large to go through my thicknesser.

I decided to get both pieces onto faceplates, roughed out, and flattened the surface I wanted to glue with a combination of careful scraping, followed by rough sanding with a reasonable length of sandpaper wrapped around a long flat offcut, and finally some very careful touch up work using the edge of a rule as a very long, very blunt scraper.

Once I thought I'd got both surfaces pretty flat I mounted the faceplates to both head and tailstock, applied some titebond, and then clamped them together with some tailstock pressure:



Once I had it together I got worried about how strong that glue up is going to be. Anyone have any thoughts? Have I basically just constructed a booby trap for myself that's going to fly apart when I go to turn the result?

Cheers,

Danny

[Chief Tiff]

Many people make blanks from laminated timbers; they call it segmented turning? If your surfaces are flat and the pressure is adequate when gluing then it will be strong enough to cope. The only issue you might have is if the balance is out because you didn't get both pieces concentric, so your initial cuts should be done at a lower speed until the whole blank is trued up and running without vibration.

A similar technique is gluing a false base onto the finished bottom of a bowl blank so the inside can be turned without having to cut a dovetailed recess into the bowl to allow it to be held in a chuck; it looks exactly like your picture. In this case however there is a disc of paper between the bowl and the base; when the bowl has been finished it is split off from the base with a chisel. The chisel actually splits the paper disc in half along its thickness; just needs some sanding to remove the paper and glue residue.

[Bob Wemm]

They say Titebond is stronger than the wood itself. I have never been able to separate a titebond joint once dry.
I cannot see a problem. Just my 20 cents worth.

Bob

[Mobyturns]

Jacaranda glues well, Titebond is a good product, so if your skills are up to producing a flat surface on both sides of the joint then there should be no issues. Allow the glue up to cure to full strength and to redistribute the moisture after gluing. A few days to cure should do it.

[rtyuiop]

Yeah, if it was a surface flattened by normal means I would be very confident (I've done a few bowls like that), it's whether or not I have managed to get the surfaces flat and mating properly...

It sounds like it's something a good turner should be able to pull off, time will tell if I can!

[turnerted]

There should be no problem . I have made a hollowform by glueing two hollowed out bowls together face to face and I only had about 10mm mateing surface .
Ted

[ian]

the only issue I can foresee is if one or both of the mating surfaces is slightly concave. If this is the case your glue join will be donut shaped and have a void in the middle.
If you are confident that the mating surfaces are flat then you shouldn't have a problem

[powderpost]

I have been known to glue a bit of wood together. I generally use exterior aquadhere. I have attacked the joint with mallet and chisel, and found the timber failed, not the glue joint. Follow the advise on the container closely. Please do not put paper in the glue joint, it will fail. I know this from experience. I would be happy to turn that job, even with only a 12mm joint glued together. Start with a speed fast enough that the lathe is not vibrating and increase speed as the piece becomes more balanced. Go for it.

Jim

[Nubsnstubs]

If you are concerned about flat surfaces not being a strong enough joint, why not in the future turn a groove on one surface and a tenon/rabbet on the other surface. That would assure both pieces being centered, plus it would allow more glue surface and a stronger joint. I've done that on several pieces that were too deep to hollow. I cut at a strategic location, hollowed, joined both halves, and finished the OD. ................ Jerry (in Tucson)

[rtyuiop]

Thanks folks! I'll be turning this tonight if things according to plan.

You have all given me a bit more confidence. Only thing I'm worried about is whether or not I ended up with a concave surface on either bit, as Ian mentioned. I'll be keeping well out of the line of fire regardless of my confidence level!

[Paul39]

Thanks folks! I'll be turning this tonight if things according to plan.

You have all given me a bit more confidence. Only thing I'm worried about is whether or not I ended up with a concave surface on either bit, as Ian mentioned. I'll be keeping well out of the line of fire regardless of my confidence level!

The next time you do this, put a ruler or the edge of a skew or scraper across the surface to see if it is flat. If a bit out, a piece of sandpaper wrapped around a known flat board applied against the whole rotating piece will flatten it nicely.

When making a rolling pin, sandpaper wrapped around a flat board and run back and forth across the rotating pin will even things out nicely.

Yes, I know many of you can do it with a skew, but I'm not that good.

[Picko]

I decided to get both pieces onto faceplates, roughed out, and flattened the surface I wanted to glue with a combination of careful scraping, followed by rough sanding with a reasonable length of sandpaper wrapped around a long flat offcut, and finally some very careful touch up work using the edge of a rule as a very long, very blunt scraper.

That's what he did.

[Paul39]

I decided to get both pieces onto faceplates, roughed out, and flattened the surface I wanted to glue with a combination of careful scraping, followed by rough sanding with a reasonable length of sandpaper wrapped around a long flat offcut, and finally some very careful touch up work using the edge of a rule as a very long, very blunt scraper.

Some how I missed that.

[rtyuiop]

Some how I missed that.

Your post actually reassured me my flattening technique was valid .

[rtyuiop]

Turned this today, no hint of problems with the join .

Of course I messed up something else and will have to figure out a plan B to join the leg to the base.

Danny