I have a sort of apprentice: our tree surgeon, who wishes to supplement his income from his rather seasonal job with a spot of furniture making. I have been good and started him off with handtools, despite his eyeing up the Woodrat expectantly.
Anyway, after making picture frames, boxes and so forth in my shed he is ready to start making stuff at his shed (as well as some more larnin’ items in mine). So he needs a workbench to go with his chisels, saws and plane.
Naturally we are both “careful” when it comes to timber – we likes it for nuthin’! Happily, one of my wood fairies has supplied sapele and iroko planks and beams of various kinds which, although rough and screw-ridden, have planed up well for legs, stretchers, feet and all the bench underparts.
The tree surgeon has himself been foraging and found a “furniture” factory that foolishly slings out slightly damaged 19mm oak-veneer (both sides) chipboard sheets. They give them to a local farmer, who buries them in his fields, would you believe. (Scandalous varmints)!
These sheets have been cut into a number of 2ft X 6ft clean pieces and we hope to laminate them together (perhaps 3or 4) to make a benchtop.
My questions:
1) Is the chipboard good enough for a workbench or should the top lamination be some solid timber (we could rip 1/4 thick planks from various hardwoods I have in the woodstore, for instance)? It is weighty chipboard, not the crumbly kind.
2) if we PVA the surfaces to be joined, what sort of pressure do we need to stick 2ft X 6ft sheets togther effectively? Will the weight of the sheets themselves be enough (they are quite weighty – good quaity chipboard you see) or do we need to pile on mass or even screw them (temporarily)? Or will we be able to make a rubbed join?
They will be stuck together whilst lying on my dead flat shed floor, to ensure the resultant benchtop has no bulge or sag.
Thanks in anticipation.
Lataxe
Replies
Hi Lataxe,
I've been working for years with salvaged and found materials. Gotta agree "nuthin" is a very right cost! By chipboard do you mean MDF or OSB? I have been using 1/2" thick MDF for the top of one of my benches for over 6 years. Its three layers thick, with two layers glued with PVA, and the top layer is screwed down with recessed screws so when it gets too scratched and dinged I can just replace it. So far I've turned it over to expose the "fresh" side. These panels were 2ft x 5ft and weighted with bricks when glued. The edge joints are all PVA glued and splined with 3/16" X 3/4" hardwood (all offcuts and scrap, so different woods). If the base is heavy enough he shouldn't have any trouble.
Funny thing, I got started with salvage material while working as a tree climber and I,m still using some of the wood I slabbed out 20 years later. Ash and maple make wonderful guitar woods and store well after drying. So your " apprentice " should have great resources for his future projects.
Bottom line, I say go for it. after all the price is cheap and you'll probably pickup some new knowledge on the way.
Good Luck,
Thos "gittercritter" Soehnlin
Thos & Rick,
Thanks both for the replies and the info.
The boards in question are known as chipboard in Britain - an interior quality particle board made of wood chips that have been stirred up in a soup of glue, etc.. The particles are not oriented (hence are not OSB) but nor are they reduced to fibre (hence not MDF).
The chips vary in size and density so that the core chips are quite large but gradually reduce in size towards the outside faces (known as "graded density chipboard"). This makes a smoother surface for the veneer to go on. The ones we have seem to be heavier and denser than most (ie better than what you would find in IKEA-style stuff). The oak veneer (on both faces) is pretty thin at around 0.6mm, judged by eye.
Like all such boards, they will sag more than solid wood equivalents so they will be bordered with 4 inches of 3/4 solid oak to help keep the lamination stiff. In addition, the bench will be made like a table, so that the top sits on the four legs and four aprons. The ends of the top will overhang the bench's "undercarriage" about 1 foot either end, though.
Presumably 3 or 4 laminations in the top along with the oak borders will keep such overhangs from sagging....? Even with heavy vices attached (the main reason for having the overhangs)......?
I believe the density of the boards is such that the top one will not be dinged too easily. Nevertheless it seems a good idea to make the top board replaceable by just screwing it onto the rest, as you suggest. I'm slightly wary of a benchtop with hard metal bits in it, although I suppose in practice their countersinking will prevent any damage to workpieces or tools that get onto the bench........?
Perhaps the screws could go in from below?
Presumably any dog holes must be re-drilled via the holes in the bottom, through the new top if one is needed?
Thanks once more for the advice.
Lataxe
Hello again,
I think 4 layers should be enough to prevent any noticable sag.
I haven't run into graded density material yet, but, it strikes me that it would be lighter in weight than regular MDF.
I was also worried that the screw heads would catch and scratch my work so the screw heads are set approximately 2mm under the surface. They do fill up with sawdust, but are not so deep that they are difficult to brush out. I admit I should have thought seriously about screwing from the bottom, but, it didnt occur to me at the time.
I'm not using any bench dogs through this top as I don't have an end or side vise on it. I don't beliive that manufactured materials will stand up to repeated side pressure without breaking down and buckling. If the dogs were the large square (shop-made) type, it could distribute the load enough to prevent that. I tend to use scrap and clamps to provide stops for planing and fiddly work. I have, when frustrated, screwed jigs and cam holddowns on my work surface. Then when removing the jig I fill the hole with glue and sawdust to restore the surface. This may not work as well with your veneer on the top, or it just may be to unsightly to live with.
The oak base sounds fairly sturdy and with good stout legs should resist racking very well.
I neglected to ask if there was any finish on these panels. If so, it will have to be removed before glueing up the top. (I may be preaching to the choir here.)
Sounds like you're getting your apprentice off to a good start. I really wish I had a mentor when I started. I have helped a few others along the way and have enjoyed it every time.
Good Luck.
Thos
Thos,
Thanks for the further thoughts. Tomorrow we do the deed and put the top together!
Dogholes: personally I would find it difficult to manage without them so feel reluctant to leave the top un-holed. The chipboard (particle board) seems very tough stuff, though - hard and heavy with no obvious inclination to crumble like MDF or the cheap chipboard that is as friable as a sandcastle.
Perhaps we will try just two dog holes opposite the side vice, to see how they fare under use. If they do go bad, two will be easier to plug than 22. :-)
Happily the veneer is untreated so the boards should glue together, no problem. (Famous last words).
Lataxe.
Next time you mount something up; think about installing threaded inserts. Flanged ones coming up from the bottom work best, as they are harder to pull out.
This gives you a permanent location to mount jigs, fixtures, hold downs, or other "tooling", and plate mounted bench top machines.
Just a thought but it works for me.
I'm assuming you mean particle board, not MDF. Chip board would be considered OSB in my shop. Using proper terms makes communicating a lot easier.
Offsetting the joints and screwing them together would be the best way. Say a 1' x 6' mated with a 2' x 6' and alternate the joint.
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