Cracking legs

[Gerwyn]

Hi all
I’ve started making an table for myself with a centre turned leg approximately 200mm x 200mm x 760mm and I have tried beech,sapele,poplar and pva and polyurethane glue but I’m having movement after a week or so after they are turned. Can anyone suggest where I’m going wrong I just cannot get them stable enough

 

[sawtooth-9]

A pic showing the problem ( movement ? ) might help.
If you are doing this from a piece of 200 x 200, it may not be seasoned fully.
If you are making up the 200 x 200 from smaller sizes ( laminating ) I would glue these using epoxy resin

 

[Gerwyn]

A pic showing the problem ( movement ? ) might help.
If you are doing this from a piece of 200 x 200, it may not be seasoned fully.
If you are making up the 200 x 200 from smaller sizes ( laminating ) I would glue these using epoxy resin

I’ve tried laminating 50 x 50 to make a 200mm x 50mm slab then glue 2 of them together to give 200mm x 200mm block. I’ve added photos of the last one I did in sapele the beech and poplar are in the burner. The timber moister content is around 18% so seems quite dry the workshop isn’t central heated?

 

[Hornbeam]

!8% is not that dry. You really need to be around 10%
Also think very carefully about the growth ring orientation as wood moves twice as much tangentially as radially ( and almost not at all along the grain)

 

[Gerwyn]

!8% is not that dry. You really need to be around 10%
Also think very carefully about the growth ring orientation as wood moves twice as much tangentially as radially ( and almost not at all along the grain)

I’ll can’t get the timber much dryer than that from the timber merchant. I’ll store the rest of the timber in the house to try and reduce the moisture content

 

[sawtooth-9]

I would not suggest you use sapele for this. The grain strength is not good, especially if it's not REALLY seasoned.
Beech would be a much better choice.
The photos seem to indicate that the turning may have been a little "harsh" and it's easy to "shock" a stress into the timber - which can result in "splitting"
You could "recover your turnings by filling the "cracks" with epoxy resin and fine sanding in the lathe

 

[Phil Pascoe]

Those two pictures seem to me to show timber defects rather than any faults in the turning or lamination.

 

[Gerwyn]

Those two pictures seem to me to show timber defects rather than any faults in the turning or lamination.

I agree some of this leg is defect that was not visible when laminating but the other legs I turned split mainly on glue lines but also on the timber it’s self. I’ve tried using resin w pva and polyurethane glue but the same problem accrues a day or so after the turn.

 

[Gerwyn]

I would not suggest you use sapele for this. The grain strength is not good, especially if it's not REALLY seasoned.
Beech would be a much better choice.
The photos seem to indicate that the turning may have been a little "harsh" and it's easy to "shock" a stress into the timber - which can result in "splitting"
You could "recover your turnings by filling the "cracks" with epoxy resin and fine sanding in the lathe

I tried Beech at the beginning but the movement was extreme then I used poplar not so bad and now sapele which is not as bad but still frustrating. Yes I think I could save this leg as you mentioned in your reply

 

[Phil Pascoe]

For laminations, try
https://www.maragon.co.uk/glue.html#Init

 

[Gerwyn]

For laminations, try
https://www.maragon.co.uk/glue.html#Init

Thankyou I’ll give it a go

 

[Argus]

From what's been said about Sapele - which I agree with....... it can be a pig to turn if you find bits of silicate mid-grain. Not my favourite wood.
As with many 'exotic' woods, the dust can be troublesome, too.

Fully dry stuff of any size for turning can be expensive and rare because someone has taken the time and effort to dry it........
Partly-seasoned timber or larger sections, may have a differing moisture content from the outer layers to the core, which can take some time to even out - so turning to a true round is often a two-stage process with a delay mid-stage for drying.

This is especially true of larger, thicker items such as bowls from basic, sawn stock and wider, larger leg sections. Many turners often turn blanks to a rough shape and store.

This can work in your favour if you have time, because fresh-cut wood can be cheaper to get and easier to turn when wet
Turn your piece from square stock to a rough shape and leave it over-sized, allow it to dry over time and observe any potential changes in its dimensions from round to slightly ovoid as it dries.

When all this slows down to a stable piece and you can be sure that any latent defects, splits etc., are showing themselves, put it back on the lathe and finish the turning to shape.

 

[recipio]

Better to use 200 mm planks - they are more stable than 50 x 50 mm pieces. Bring them indoors for about a month to get them down to 10 - 14 % ( You can actually a digital scales to measure moisture loss if you don't have a meter ) The glue is not the problem. I use plain PVA for laminated pedestals and never had a problem.

 

[Gerwyn]

From what's been said about Sapele - which I agree with....... it can be a pig to turn if you find bits of silicate mid-grain. Not my favourite wood.
As with many 'exotic' woods, the dust can be troublesome, too.

Partly-seasoned timber or larger sections, may have a differing moisture content from the outer layers to the core, so turning to a true round is a two-stage process with a delay mid-stage for drying.

This is especially true of larger, thicker items such as bowls from basic, sawn stock and wider, larger leg sections.

This can work in your favour if you have time, because fresh-cut wood can be cheaper to get and easier to turn when wet
Turn your piece from square stock to a rough shape and leave it over-sized, allow it to dry over time and observe any potential changes in its dimensions from round to slightly ovoid as it dries.

When all this slows down to a stable piece and you can be sure that any latent defects, splits etc., are showing themselves, put it back on the lathe and finish the turning to shape.

Ye I think the issue is the dryness of the timber. No matter what glue I use if the timber wants to move it’s going to move. I did try beech and poplar but they was less stable than the sapele. The beech leg tested a 16-18% and even with multi laminated ie 2x2 and 4x2 still move quit a bit.