Thread: Mixing timber species

I'm listening to/following this post intently, as I am sort of in the same position as you Mike!

Looks like too nice of a timber stash to make into a bench

I did just that a few weeks ago - I made a dining table from Baltic Pine and Merbau. The table top is 1.10 m wide and 45 mm thick. The upper half (~18 mm) is made from Merbau, the lower half from Pine, glued together with PVA glue. I did check the difference in wood movement on the The Wood Database page before I started (7.3% vs 4.8%). So far no problems, the table top is straight as it was on the first day. In my experience, most wood movements happen around the 15 to 25% moisture content. If you use well seasoned timber, the difference in movement will be negligible, because well seasoned means well below 15%. I assume your bench will be in a room with roughly constant climate though.


Spotted Gum | The Wood Database - Lumber Identification (Hardwood)
Radial: 6.3%, Tangential: 9.9%

Ironwood Australia - Technical Specifications - Blackbutt
Radial: 4-5%, Tangential: 7.3%

There is a diiference in shrinking, but I don't think it's substantial.

Cheers,
Andy

I'm thinking the differences between the two could be ignored safely for the carcase, but even so I'd still play it safe and try to make all the uprights, all the left/right beams and all the front/back beams from the same species.

That way you'd have consistency in movement in each of those directions, the differences would be most obvious in the joint sections. There the difference would be negligible, given the short distances involved and the simple fact that even timber of the same species has different movement rates between long-grain & cross-grain.

So long as you're smart about fixing the top, you shouldn't have any problems. Unless you try fitting a solid shelf between the legs, in which case you'd want to leave expansion gaps to minimise the risk of such a shelf racking the frame.

If I didn't have enough of each type of timber to do the 'all one way, etc.' I'd still try to make the heaviest elements in each direction from the same timbers and use t'other timber for the smaller pieces.

An ounce of prevention, yada yada yada.

Originally Posted by Siggykc

I'm listening to/following this post intently, as I am sort of in the same position as you Mike!

We will learn together. This forum is a font of knowledge and experience.

Originally Posted by barramonday

Looks like too nice of a timber stash to make into a bench

Most of it is "feature-grade" KD Spotted Gum (i.e. cheap), reclaimed SG (cheap), Blackbutt, Grey Ironbark, a bit of Jarrah and Rosewood (prob won't be used for the bench), some Hairy Oak and some Fiddleback Tassie Oak that I plan to use for the drawer fronts. It's about time I used some of it to free up some much needed wall space.

Originally Posted by AndyJ

I did just that a few weeks ago - I made a dining table from Baltic Pine and Merbau. The table top is 1.10 m wide and 45 mm thick. The upper half (~18 mm) is made from Merbau, the lower half from Pine, glued together with PVA glue. I did check the difference in wood movement on the The Wood Database page before I started (7.3% vs 4.8%). So far no problems, the table top is straight as it was on the first day. In my experience, most wood movements happen around the 15 to 25% moisture content. If you use well seasoned timber, the difference in movement will be negligible, because well seasoned means well below 15%. I assume your bench will be in a room with roughly constant climate though.



Spotted Gum | The Wood Database - Lumber Identification (Hardwood)
Radial: 6.3%, Tangential: 9.9%

Ironwood Australia - Technical Specifications - Blackbutt
Radial: 4-5%, Tangential: 7.3%

There is a diiference in shrinking, but I don't think it's substantial.

Cheers,
Andy

Thanks for sharing your experience, Andy. I knew that there was a difference in their shrinkage characteristics but I wasn't too sure what it meant in practical terms. Yes, the timber is well-seasoned. The BB I've had for about 3 years and it wasn't newly milled when I bought it. The SG is either reclaimed (20yr old pergola and I've had it for about 3 years) or kiln dried which I bought about 3~4 months ago. My "workshop" is the standard double car garage. It's a 2 story house and the garage is well insulated and shielded by mature trees on the western side so hopefully the temp and humidity fluctuations aren't too severe.

Originally Posted by Skew ChiDAMN!!

I'm thinking the differences between the two could be ignored safely for the carcase, but even so I'd still play it safe and try to make all the uprights, all the left/right beams and all the front/back beams from the same species.

That way you'd have consistency in movement in each of those directions, the differences would be most obvious in the joint sections. There the difference would be negligible, given the short distances involved and the simple fact that even timber of the same species has different movement rates between long-grain & cross-grain.

So long as you're smart about fixing the top, you shouldn't have any problems. Unless you try fitting a solid shelf between the legs, in which case you'd want to leave expansion gaps to minimise the risk of such a shelf racking the frame.

If I didn't have enough of each type of timber to do the 'all one way, etc.' I'd still try to make the heaviest elements in each direction from the same timbers and use t'other timber for the smaller pieces.

An ounce of prevention, yada yada yada.

Thanks Skew. You make some good suggestions which I'll be sure to follow. Your point about difference in shrinkage even when it comes to timbers from the same species is a good one and allays most of my concerns somewhat.

I've given some thought to allowing movement of the top. I plan to cap both ends and the right side will house a twin screw vice. One of the reasons why I've decided to go with the split-top is because I can fix the width of the top whilst allowing for movement towards the middle. It's going to be in the Shaker style so there won't be a shelf between the legs.

Thanks again.

Originally Posted by AndyJ

I did just that a few weeks ago - I made a dining table from Baltic Pine and Merbau. ...

Finally I found the time to put a few images of that table on the internet: My corona lock-down project

Cheers,
Andy