Should I be concerned about building a workbench top using a 12/4 Ash?
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I have a few slabs of Ash that are 3 inches thick 10 feet long and maybe 15 inches wide
they have been air dried for the last three years. I’m curious if I should make strips and glue back together and use as the top or just throw the slab on the base and hope its not to hard to keep flat
Replies
I wouldn't even think of ripping it and gluing it back up. Nope, nope.
It would be best if you had a moisture meter and can monitor it for a while. For me, three years air drying for a three inch slab is the minimum, but it might not be ready still.
What will your finished width be? 15 inches is a little narrow.
I would be very tempted to make a split top Roubo style bench out of two of these 15" wide slabs. I would probably cut them down to about 12" wide; a 12" width would give you a bench width of 24" + whatever gap you leave in the middle.
Even if the wood turns out not to be totally dry, you can easily remove them if they cup and flatten them with a planer...or just use a hand plan to flatten them in situ.
My bench made of 12/4. It's been great. Low cost. I glued up to 7" wide boards. Been real flat. No issues.
My bench is made of 3 chunks of maple 12/4 by 12 inches wide. Two were squared off to make the top and the third cut in 4X4 to make the legs. The plan was that since the wood will inevitably shrink, there is a gap between the two top slabs where I loose my pencils but I have lived with it for 40 years so Now I know where to look for when I need a pencil.
How is the ash cut?
Through and through, so that the rings form a large arc on the end of each plank, might be problematic at 15 inches wide per plank. It might be a challenge to keep the bench top flat enough if it's in an environment with significant humidity changes over the year. It'll want to cup to some degree, at some times.
Quarter sawn will be a lot more stable.
Personally I'd rip the planks into 3" X 3" sections, make sure they really have dried out (leaving them for a bit if they haven't) then re-glue the bench top with the grain going here and there so that any overall cupping will be very slight.
In fact I did this with the workbench I made 15 years ago from hard maple. It lived in an unheated shed (albeit a well insulated one) for 13 years and remained flat within a few thou, planed away in 1o minutes a year after I made it, despite the humidity changes.
Lataxe
I agree with you mate! Instead of ripping monitor it with moisture meter and wait for a while.
If they are not in the shop yet bring them in and let them acclimate for a couple of months. If they don't move / cup they probably won't.
+1 on both moisture meter and bringing inside shop.
There is nothing wrong with ripping them down into 2x3’s you will have a more stable top. The issue with this is what will happen when you open up the wood? There could be stress resulting in twisted boards. At the very least you will lose up to 1/2” of dimension from milling. Check the cut, if there’s lots of quarter or rift sawn it won’t be as bad, but you still never know. If you go this route do it on a bandsaw!
If you go with slabs, you can plane to it as needed to flatten.
Kind of a toss up. I would go with the slabs and build it to allow for a lot of movement.
I would rather try it as one big slab (after measuring moisture relative to other ash in your shop you know is dry). If it causes you problems down the road you could always take it off then rip and glue up. In theory, leaving it as a slab would require less work the first time and there may not be a need for a second time.
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