Thread: Wood movement/stability question

Originally Posted by John Samuel

The question I have is, "how big could I make an end grain top like the above before running into trouble". I am imagining a kitchen table where the top is an end grain block such as those in the pics, but am I likely to run into wood movement problems at such a size? In my imagining, the top is held in place inside a frame by it's own weight, just like in the above pics. It is not glued or otherwise fastened into place.

Part of me thinks there could be issues ... but I recall some of the butcher's shops of my childhood. Some of those big butcher's chopping blocks were quite large.

I think that your childhood memory of butcher's shops may have missed that really big blocks were not framed so expansion / contraction was not constrained in any direction.

My own memory is of an iron hoop surrounding the block and saw dust (for the sausages) coating the floor.

I made a giant Jarrah one at my old work ages ago; 1400 x 750 x 70 (or maybe it was 90) if I remember correctly.
Definitely don't try gluing it down, but do have some support underneath it in the middle, not just cleats around the edges.

Sorry guys ... did not make myself clear.

It was always my intention to allow the top to flop around in the frame, as it does in the mobile butcher's blocks. Expansion and contraction will not be restricted. The top will be properly supported, as it is in the mobile butcher's blocks.

However, is the top likely to be stable in service; is it likely to want to twist or warp? I'm thinking of a top that will be about 1,600 X 1,000 mm and about 60 mm thick. Elanajacobs' experience suggests I should be fine.

Will depend on the timber And best look up the net for the expansion/ contraction expected -for that species -let alone if it's "dry" or not. Allowances must be made however or consequences shall have to be met.

More than anything, it'll depend on the 'cuts' of the blocks. Rift- plain- or quarter sawn.

Because tangential and radial movements differ so much (hence star-shakes) Quarter Sawn is fairly stable and any movement will leave the result in a more or less rectangular shape.

On t'other hand, Rift-sawn - or any timber cut with the grain more or less 45° to the faces - will move into a diamond shape and back again.

With plain sawn, it's all over the place depending on where the board is cut from. Usually it either wants to cup along it's length or becomes a 'butterfly' shape.

If you're using a mix of blocks, so long as they're relatively evenly distributed both in type of cut and direction of grain, you can make quite a large block.

But if you want to get fancy and align the end-grain into patterns, you need to be able to read the grain so that you're not introducing 'lines of stress.'

eg. let's say you want to use mostly quarter sawn, with rift -sawn in diagonals from the centre to each corner. Looks pretty, giving you the effect of concentric square grain around the table. But the way the rift sawn willl want to move is sorta like creasing a square of paper along the diagonals.

The likelihood is far greater that the table top will cup (whether up or down is any-one's guess) than if you'd made the same sized block using quarter-sawn in a checkerboard pattern.

1600 x 1000 will show the movement . Specially the 1600. It’s the same as having a 1600 wide top In normal 19 mm thick boards on a top that’s all glued together. It’ll move as one . Don’t glue them together and they would move as seperate 60 mm blocks , 27 of them , a lot less noticeable . I’d say the original butchers block tables were made that way . Hide glue wouldn’t have been a good idea on such a thing .

An end grain top looks great but why do such a heavy thing like that if your not pounding beef and bones apart and it’s just for looks . I’d press 60 x 60 x 5 mm end grain blocks down onto some good quality Plywood with Two pack glue or Poly Glue . Fix that down onto some sturdy bearers in the table to give it a solid feel and surround it by longer blocks to give it a thick as you want look . Impossible to pick it unless you look under . Feed it with some thinned oil finish for starters so it soaks down and drys first before rubbing in some thicker coats . Built like that the moisture that could move it is sealed out. The thin blocks don’t have the power to overcome the glue as well . And it can’t move at all .

Originally Posted by John Samuel

It was always my intention to allow the top to flop around in the frame, as it does in the mobile butcher's blocks. Expansion and contraction will not be restricted.

If you want to make it a dining table, maybe it would be a good idea to line the frame with a soft self-adhesive foam strip to keep crumbs from falling in the gap while still allowing it to move?

However, is the top likely to be stable in service; is it likely to want to twist or warp? I'm thinking of a top that will be about 1,600 X 1,000 mm and about 60 mm thick. Elanajacobs' experience suggests I should be fine.

I can't comment on the long term stability, we just made it and sent it out the door. Never heard from them afterwards though, so I suppose nothing went horribly wrong.

The hardest thing is going to be flattening it; we had 50hp (30 on head 1, 20 on head 2) worth of wide-belt sander to do all the hard work for us, I imagine doing it by hand would be...unpleasant.

A friend made a checkerboard endgrain chopping board out of e.pilularis and e.saligna as a present for my wife.
It ended up blowing the epoxy glue joints apart, because the two timbers appear to have different expansion
and contraction properties. (or maybe because, as I read, some gum and epoxy don't bond all that well).
But if you stick to one timber, I can't see any problems arising.

John , What does your Son do to level his tops down ?

Stanley Made a Butchers Block Plane.

Stanley No. 64 Butcher's Block Plane - Handplane Central

Stanley 64 bucher block plane

I have the Stanley 62 which is pretty much the same plane with some extra refinements, nice plane . Its not what I reach for first though when planing end grain . If I have a large amount to plane I go narrower with the blade, makes a huge difference to the push needed, much easier. For this I grab a cheap shoulder plane ( cost $90 ) that I added a wedged Tote Handle to. The blade has a radius to it so 1/3 is cutting. It works really well . It'd need a few sharpenings for a top that size.

You'd get a good finish just using a sharp no 3 or 4 bench plane with the radius though.

Rob

Thanks for all the feedback, guys. I appreciate it.


Rob, veneering is an option I am considering. Already done that once with the first mobile butchers block. The chopping block is solid, but the lower shelf is a veneer cut from the block as noted below.

Mobile Butcher's Block 2.jpg


Thought I'd make a block that was about a quarter the size of the table (400 X 250 mm) and then cut veneers off that. However, you surprised me with the notion of using 5 mm thick sections. The advice received from this board many years ago was not to allow veneers to be much more than 2 mm thick, or it wants to start behaving like wood again. Does using end grain veneers make a difference, or am I missing something ... again ... still?

Originally Posted by auscab

John , What does your Son do to level his tops down ?

Rob

Rob,

We glue the boards up in my U-Beaut clamp trolley, so things are pulled nice and flat. Here is the trolley, with a web frame in it.

IMAG0013.jpg

We clamp a piece of timber to either end to keep everything square and flush.

Then it goes through the drum sander with 40 or 60 grit paper. Done in a flash.

Even very irregular things like twisted slabs can be flattened on the drum sander. I rough it down with a plane, and then hot melt glue it to a lump of MDF, which acts as a sled and provides a flat reference surface as it goes through the sander.

Originally Posted by John Samuel

However, you surprised me with the notion of using 5 mm thick sections. The advice received from this board many years ago was not to allow veneers to be much more than 2 mm thick, or it wants to start behaving like wood again. Does using end grain veneers make a difference, or am I missing something ... again ... still?

No end grain doesn't make a difference.
1. You have to make sure its glued with Two pack or Poly glue . No water based glues .

2. Its got to be glued to good Plywood . Plywood is fixed, its as rigid as can be in its flat plane .

If you glue 5mm to it and The wood is moist , or water based glue is used , or it gets wet on top later before sealing. It'll do some moving . The 5mm will move and bend the ply .
If the ply is fixed down to a frame it wouldn't be very noticeable.

I had a disaster years ago and learned this the hard way glueing wet parquetry down with PVA or Titebond . I noticed my parquetry was cupping when I applied glue to one side . I moistened the other side to counter balance and it stopped cupping so I pressed them down . Not thinking that I had just enlarged each piece. The glue set . For a week or two it looked great . It was a draw leaf table so the tops on those are not fixed down . I went to finish it off a while later and the top had a BIG bend in it . All the Parq had shrunk back and I had a banana top table . It could no longer be a draw leaf extension and the two leaves were discarded and the top was pegged down to the base . It didn't take much to straighten it flat. I sold it and never saw it again.

If the 5mm wood is glued down with two pack or poly and left to dry . The ply is fixed to a frame, before glueing or after. Then leveled and sealed , polished. It would be fine . End grain at 5mm could be soaked and the open pores filled right through and never react to moisture again. Its a sort of re engineering process and you win over Mother nature which is a rare thing . As long as the table stays in a similar environment to which it was made, like indoors. You know, don't leave it in the Sun and rain for months !
Mother nature will always win in the end .

Ive been doing them like this for years and no problems . Pics of some are on my instagram page .
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Another thing is , fixing to a frame is good. Some of my tops are just fixed in a mitered frame around the outside and sit on flat bearers. Torsion box construction could also be a good option with ply on top and under. If I made a top like that I wouldn't want it sounding like a drum if it was tapped.
Torsion box construction - Google Search
Rob

Something I have saved on instagram . Looks like a heavy lift doesn't it . Not sure how its constructed . Its probably all solid. Heavy and weak . A solid top like that could easily snap in half if not lifted right .

I like that over head arm for sanding too .

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Rob

Thanks, Rob.

The comment that struck me was, "End grain at 5mm could be soaked and the open pores filled right through and never react to moisture again."

I always use PU glue for chopping boards and for veneering.

The only things I have ever oiled are chopping boards. Most of what I make is furniture. All the indoor stuff is lacquered and the outdoor stuff is finished in two pack poly. Until I read your comment it had not occurred to me that end grain veneers could be saturated with oil and that an frequent wipe with an oily rag would ensure moisture never got into the timber.

What oil do you use? On chopping boards I have been using paraffin oil, and it seems to work fine. I have had a couple of camphor laurel end grain boards in use in my kitchen for several years, and they are in great shape despite being used every day.