Replies

1. 
   lat_axe | Oct 09, 2024 07:49am | #1

   Hi Lady,

   It can be difficult to give advice unless the question posed is very clear, specific and unambiguous about what the issue is. In this case, the term "butcher block" can be confusing as some define that as having the upward-facing work surface made of end grain-up blocks (the working surface presenting as end grain) whilst others seem to include long-grain tops made of glued up strips in the definition of "butcher block".

   Could you say which yours is?

   If it is end grain-up in composition, there's going to be significant shrinkage & expansion of the top as the moisture levels in which it lives change. Plywood is much more stable so if you glue an end grain-composed surface to a piece of plywood, there's very likely going to be splits between the blocks, as the expansion & contraction of the end grain blocks fights the plywood.

   However, an end grain-up butcher block glue up of 5/4" thickness will be very strong all by itself, as would a similar top made of long grain strips of that thickness glued together. It would have to have a very large area to show any sag when sat on the underpinning rails/aprons.

   Nevertheless, you can strengthen end-grain-up tops by wrapping them in aprons of their own. You'll then have the issue of differential expansion between the long grain aprons relative to the edges of the end grain-up blocks. Corner mitres of the aprons might open a little bit, for example.

   However, you can compensate to a degree by allowing this differential expansion via attaching the aprons to the end-grain-up chunk only at their centre points, with something like two long brass screws per apron. The mitred corners of the aprons can be wrapped with brass straps screwed to the corners with brass screws. (Brass is soft and will bend or stretch a little bit with the pressures of differential wood expansions).

   The attached pic is an example of such a butcher block. Its made of iroko cubes of 5/4 length edges, wrapped in some old-growth teak aprons salvaged from an Edwardian era lift (elevator) shaft. (Teak was used to reduce flaming if the building caught fire, as the elevator shafts became chimneys but teak will only smoulder rather than shoot big flames up to the higher floors - or so I read).

   The sides are attached to the end grain-up chunk with 3" long No. 12 brass screws and the corners wrapped in 1/16" thick brass strip, screwed in place with smaller brass screws.

   That chopping/bread board is now 13 years old and has been in use every day since made, for chopping wet stuff like veg, fruit, meat & fish as well as slicing big loaves with a huge bread knife. Its still very flat and, despite standing on four corner feet 1/8" high has no sag whatsoever. It's 2ft 3" X 1ft 5".

   Your top is larger but I think it'll still tend to the sag-less - depending on the timber used. If you're worried about potential sag, you can make the blocks thicker or add struts under the top but inside of the supporting aprons, attached to the top only in the middle parts of bot, to avoid the problem of differential expansion.

   
2. 
   Ladyloveswood | Oct 09, 2024 10:54am | #2

   Hi Lat axe, thank you for all the info. I’m fairly new and when I googled there was a lot on inconsistencies in the information I found. This is not end grain, it’s long strips of hardwoods. I was thinking of adding struts but I didn’t know to lea e them inside the apron. I was also worried about the areas outside the aprons. I’ll attach a picture of the sections I’m working on. There are four. Thanks again!