When error is greater than the sum of its parts

[Bruce Seidner]

I was hoping for the Salt Flats but ended up with the Black Hills for a wall supported work bench. It is framed by 2x4 studs that seemed straight enough and all was level as I fitted the composite sheet material between the 2' sections. But as I prepare the surface to be covered with a top of glued up 1" thick Ash boards it is like a Six Flags roller coaster, plus and minus a half inch up and down over the surface of this L shaped bench.

I have seen how one can set up a router sled jig to plane and level the surface but I am unsure how well the sub-floor material I used will plane. An electric plane does an ok job on it without the tear out I feared but this seems quite a lot of work for what is almost 20'x3' of surface. I have not ruled this out and it seems the responsible adult thing to do.

Then I had the cave man inspiration to "mud" the top with a half inch of concrete or some epoxy/adhesive/linoleum glue/etc. And then floating a sheet of 1/4" ply on top to create a flat and level surface to have as a base for the Ash boards. The squeeze out would make an Eclair blush but this might be quicker than planing the surface. Not all that original, I have seen it done when an old floor is to be tiled.

I am unlikely to make the cover of any of the Woodworking magazines in any event. This is not to be confused with elegant craftsmanship. It is more like being the first responder at an auto wreck. Triage advise would be most welcome.

[Bob Riefer]

Can you unscrew the mdf and shim it?

[Lex Boegen]

Several things come to mind--you could plane off the high spots and fill in the remaining low spots; or install tee-nuts in the low spots and insert bolts from underneath to provide leveling "legs" for the new top, or use 1/4-inch ply and glue & shim the low spots to bring the ply up level. Any way you do it, it won't be pretty.

[Jim Rimmer]

What about the self leveling stuff they put down under wood floors?

[glenn bradley]

Probably not the solution you want but, building a flat platform from square lumber is a lot less work that trying to make an uneven platform flat afterward IMHO. If I am understanding that the sub-surface is the one that is uneven, not the ash, I would remove the skin and correct the frame. I think in the end this will be a lot less work.

[Don Jarvie]

If I understand correct this is attached to the wall? If its going to be attached to a wall then you need to take it apart and build it off the wall.

Since my floor in the shop is unlevel I build the top frame 1st and attach it to the wall so it is level. Then I drop down each leg to the floor so the bench is supported. This way if one leg is slightly shorter than the other it's not a big deal.

It's a bit more tedious building benches this way but the are dead level and very strong.

[Jon van der Linden]

Not sure what "composite sheet" material is, but it is likely that it won't create a flat surface if it's resting over 2' gaps.

2x4s "that seemed straight enough" - either they're straight or they're not. If they're not perfectly straight this part needs to be done over.

As for the suggestions of "self leveling" epoxy or whatever, that's very expensive and won't solve the problem. Self leveling doesn't mean it will create a level surface, it means that it will flow sufficiently to create a somewhat even coat.

[Chris Padilla]

To get 2x4s to work, they must be dried like any other wood. They're often in the 20% range from the BORG and need dried to 8% or so. In that process, you hope they don't twist too much (so they need stacked/stickered w/weight). Also, select 2x4s that do not have the core (center of the tree) included.

Once they are dry, you can then joint/plane them flat and they should be okay.

[Don Alexander]

basically if you want straight , flat wood and don't want a ton of work to get it that way DO NOT use 2x framing lumber of any size it just isn't intended for furniture (a woodworking bench is furniture btw)


if you must use 2x's then drying them down as suggested is key otherwise theres a whole lot of twisting and warping going on when it starts drying out

the proper material for the intended use goes along way toward reducing aggravation and dissatisfaction with the end result

just my half a cent

[Don Alexander]

another thought occurs to me as well ........................... have you noticed any warpage in the ash top?

typical construction of a workbench top would be to glue it up face grain to face grain (boards standing on edge) rather than edge grain to edge grain (boards laying flat).

this is because the top is more stable in that configuration less likely to warp /cup and also its stronger in that configuration

HTH

[Bruce Seidner]

I truly underestimated the change and morphing that occurs with home center studs. These cheap sticks have been twisting on me over the month that they have been in my 50% de-humidified basement. It was level and square when I attached the 2x4's to the wall and built the frame for the top. And yes, the legs went on last. In fact I don't have the "good" Ash legs on yet. The top material is an OSB, 7/8" Weyerhauser Structure-WD for sub flooring. It seems pretty innocent and largely inert. It weighs a bloody ton and appears mostly glue. I did not want to build the top much higher than 36" and because of features in my basement, 36" was as low as I could go with the framing without taking a jack-hammer to an uneven and crude concrete ledge along the block wall. That is why I fit the OSB between the framing studs instead of on top of them.

I will try using a plane to knock down the high spots. This OSB does not chip and tear out as bad as I thought it might. I have a little electric Bosch planer that uses blades that they seem to encourage users to view as disposable. They might or might not be but they are not expensive and they are quite easy to change. So, keeping a sharp plane won't be such a chore. It may not be pretty when I am done but I will then epoxy a sheet of Luan over this sordid and warped top. The good news it is very stable and strong.

I will look into borrowing or purchasing a wood moisture measuring gizmo. At what point will these peri-pubertal studs settle into a normative and predictable life style. I will stop playing rock and roll and expose it to ambient sounds or play only elevator music to quell the squirming. When will this adolescence be done and how will it be measured?

[Don Alexander]

unless your space is pretty steady humidity wise they probably will never stop moving entirely

alot of 2x4 material these days is made from relatively young growth trees
simply because its a cheap and easily renewable source for boards not intended for making things that need to be dead-on straight and flat

obviously the younger the tree the less stable the lumber (comparing like species of tree)

fast growth timber is also less stable than slow growth stuff (again comparing like species)

2x4's are by and large stamped SPF which simply indicates that its either Spruce,Pine or Fir , all of which are relatively fast growing species


you can easily make the connection i'm sure

FWIW the lumber from smaller/younger/ fast growth trees is not nearly as strong as older/larger/ slower growth stuff

[Steve Peterson]

I agree that it is usually more convenient to buy 2x4s at the borg for bases of shop built cabinets. On the west coast, they have 1 rack of kiln dried 8' hemlock 2x4s. These are slightly softer than douglas fir, but they should not warp. Another advantage is that they do not bleed sap like the green DF. Cost is only 10-15 cents more than DF.

Steve

[Bruce Seidner]

To get 2x4s to work, they must be dried like any other wood. They're often in the 20% range from the BORG and need dried to 8% or so. In that process, you hope they don't twist too much (so they need stacked/stickered w/weight). Also, select 2x4s that do not have the core (center of the tree) included.

Once they are dry, you can then joint/plane them flat and they should be okay.

There really is no free lunch. I will have this engraved on my bench after the cosmetic and structural surgeries to correct the birth defects.

This is all considered and valuable advice. Thank you.

Bruce