5 dumb questions on benchtop construction

[Alex Liebert]

I'm slowly pondering design for a new basic workbench and pricing materials. I have some naive questions but figure it's better to ask before than after!

1.) Most plans for benchtops call for face to face laminations as opposed to edge to edge- is this mostly to get more benchtop thickness from thinner boards and construction lumber, or is there a structural advantage? If wide thick boards (say, 8/4 x 6") are available cheap, whats the argument against gluing them edge to edge?

2.) If I construct a top by laminating strips glued face to face, such that the edges of the boards face up: does this mean that wood movement will be basically negligible across the width and length of the benchtop?

3.) If I were to make a 2" thick top, but wanted to mount a bench vise underneath with more clearance to the bars- I would use a shim between the vise and the bench. Are there are any considerations to make with how to attach the shim? (For instance, if I glue and screw a plywood shim to a solid wood laminated top, am I asking for trouble?)

4.) Similar question: let's say I glued a 3" wide x 60" long x 3/4" thick board immediately under the front edge of 60" long top to create a ledge (as opposed to what I usually see, which is a boards face glued to the front edge etc.) Are there structural / wood movement problems with this?

5.) Let's say a support that's part of the base runs perpindicular to the top across the depth of the bench. Best I understand it, these can be fixed in the center to allow movement of the top but not at the edges. Is that right?

Thanks for humoring me...

[Luke Dupont]

1.) Most plans for benchtops call for face to face laminations as opposed to edge to edge- is this mostly to get more benchtop thickness from thinner boards and construction lumber, or is there a structural advantage? If wide thick boards (say, 8/4 x 6") are available cheap, whats the argument against gluing them edge to edge?

Face to face laminations will be more stable than edge to edge (assuming we mean the pieces are oriented so that the edges comprise your benchtop) and offer you a thicker bench top, but there's nothing wrong with gluing 8/4 pieces edge to edge and going with a thinner bench-top. Just be aware of how the wood might warp, and try to find straight grained, stable pieces. Alternate the growth rings when edge gluing so they even out.

2.) If I construct a top by laminating strips glued face to face, such that the edges of the boards face up: does this mean that wood movement will be basically negligible across the width and length of the benchtop?

Yep.

3.) If I were to make a 2" thick top, but wanted to mount a bench vise underneath with more clearance to the bars- I would use a shim between the vise and the bench. Are there are any considerations to make with how to attach the shim? (For instance, if I glue and screw a plywood shim to a solid wood laminated top, am I asking for trouble?)

Nothing wrong with that. I've done the same. Though, I didn't use plywood -- just regular 3/4 pine or poplar.
Also, nothing wrong with a 2" benchtop, especially if you want to be able to actually move the bench. Some people will no doubt tell you that you need a thicker, heavier bench. That's nice to have (providing you will never move it), but absolutely not necessary. In my case, I needed a portable bench. Everyone attempted to convince me that I needed a several hundred pound monster. I built a small, light weight (60lbs or so) 2" thick bench out of pine which worked wonderfully. But, I'm also not doing lots of rough work or building large heavy furniture. I also built it higher than is conventional as I tend to do a lot of detail work and found that I was bending over too much to see my work and really hurting my back. Consider your personal needs first and foremost!

4.) Similar question: let's say I glued a 3" wide x 60" long x 3/4" thick board immediately under the front edge of 60" long top to create a ledge (as opposed to what I usually see, which is a boards face glued to the front edge etc.) Are there structural / wood movement problems with this?

I doubt there would be any problems. Is this just to get thickness for the vice (or holdfasts?). I think it would just potentially look a bit ugly is all. The Apron you see on English benches is there for clamping boards on their sides, but kind of necessitates dog holes or holdfasts for clamping pieces on the bench top.

5.) Let's say a support that's part of the base runs perpindicular to the top across the depth of the bench. Best I understand it, these can be fixed in the center to allow movement of the top but not at the edges. Is that right?

Not sure I understand what you're describing.

PS. Take everything I say with a grain of salt. I don't do things in the most conventional manner and what might be right for you might be different. Consider your own needs first and foremost, and weigh the pro's and con's of a given decision with what you're trying to accomplish.

[Robert Hazelwood]

1.) Most plans for benchtops call for face to face laminations as opposed to edge to edge- is this mostly to get more benchtop thickness from thinner boards and construction lumber, or is there a structural advantage? If wide thick boards (say, 8/4 x 6") are available cheap, whats the argument against gluing them edge to edge?

It is basically done to get more thickness, since a lot of people like their benchtops to be 3 or more inches thick. Having lots of laminations should also make for a more stable top, and if the lams are all flat sawn then they'll result in an effectively quartersawn benchtop, which is more stable. The argument against using 8/4 edge-to-edge would be that 2" is on the thin side for a benchtop unless you are going to beef it up with a heavy apron or undercarriage of some kind. Also if the 8/4 boards are flatsawn they will tend to move with the seasons, cupping across their widths. This can be controlled with battens underneath.

2.) If I construct a top by laminating strips glued face to face, such that the edges of the boards face up: does this mean that wood movement will be basically negligible across the width and length of the benchtop?

You would have a quartersawn slab basically, so it will move across its width but less than if it were flatsawn (look up shrinkage for radial grain for the species you want to use). Movement along the length is always negligible regardless of grain orientation.

3.) If I were to make a 2" thick top, but wanted to mount a bench vise underneath with more clearance to the bars- I would use a shim between the vise and the bench. Are there are any considerations to make with how to attach the shim? (For instance, if I glue and screw a plywood shim to a solid wood laminated top, am I asking for trouble?)

No that sounds perfectly fine. The shim will not be large enough to present wood movement problems.

4.) Similar question: let's say I glued a 3" wide x 60" long x 3/4" thick board immediately under the front edge of 60" long top to create a ledge (as opposed to what I usually see, which is a boards face glued to the front edge etc.) Are there structural / wood movement problems with this?

No. I'm not sure whether you want to glue the face or the edge of the 3/4" board to the underside of the bench, but either way will work. The grain directions are aligned.

5.) Let's say a support that's part of the base runs perpindicular to the top across the depth of the bench. Best I understand it, these can be fixed in the center to allow movement of the top but not at the edges. Is that right?

You can fix it at the center or at one edge , but yes a benchtop will be wide enough that some allowance needs to be made for expansion and contraction. On my bench, a split top roubo, the two slabs are fixed at the outer edges (via the leg tenons) and the wood movement is directed towards the center. They are held down towards the center from underneath via a lag screw in an oversized hole.

[Prashun Patel]

1.) face glue up = less movement (in theory) + thicker = more stable. Still, take reasonable care to use straight grain. Also, align the grain in the same direction so that when you need to flatten, planing is a little easier.

2.) yes.

3.) I'm not sure why you need more clearance. However, the mounting plate will be bolted or lag screwed deeply into the bench, so the shim attachment method is moot.

4.) No, but beware this will affect your ability to use clamps on the front edge (if this is important to you.

5.) Correct. I have used oversized holes in the base rails for the perimeter attachments, and then attached lag screws with thick fender washers.

Thanks for humoring me...

[ken hatch]

I will respond to question #1: If you do not put stretchers under the slab it needs the strength of face to face glue-up. Think of putting two 2X4 boards across a 8' span. If you place them face down and stand in the middle the boards will bend but if you stand the boards on edge they will not. The reason English style benches can have slabs with boards face up is because of the multiple stretchers across the span.

ken

[Alex Liebert]

Also, nothing wrong with a 2" benchtop, especially if you want to be able to actually move the bench. Some people will no doubt tell you that you need a thicker, heavier bench. That's nice to have (providing you will never move it), but absolutely not necessary. In my case, I needed a portable bench. Everyone attempted to convince me that I needed a several hundred pound monster. I built a small, light weight (60lbs or so) 2" thick bench out of pine which worked wonderfully. But, I'm also not doing lots of rough work or building large heavy furniture.

Thank you. More or less in line with what I'm thinking. I've only completed one real woodworking project, but I designed it to be the largest thing I'd ever want to build out of solid wood and it's not that big. It did show me everything I wanted a bench to do and what the limitations of what I have are.

I doubt there would be any problems. Is this just to get thickness for the vice (or holdfasts?).

Yes exactly.

5.) Let's say a support that's part of the base runs perpindicular to the top across the depth of the bench. Best I understand it, these can be fixed in the center to allow movement of the top but not at the edges. Is that right?

Not sure I understand what you're describing.

Here's a sketch of what I mean. If we assume for a moment the top itself is an edge-to-edge lamination and thus movement across its width must be considered...I'm trying to make sure I understand the concerns for attaching cross braces like in this drawing. The grain of the top and the cross pieces would be perpindicular. Does that mean I can't glue them together that way or fasteners should be applied in a certain way only?

crossbars.jpg

[Alex Liebert]

I will respond to question #1: If you do not put stretchers under the slab it needs the strength of face to face glue-up. Think of putting two 2X4 boards across a 8' span. If you place them face down and stand in the middle the boards will bend but if you stand the boards on edge they will not. The reason English style benches can have slabs with boards face up is because of the multiple stretchers across the span.

ken

Thank you Ken. To clarify terminology, is a stretcher defined as something that goes with the grain of the top, perpindicular to it, or either?

Is there a formula or method for roughly calculating the deflection based on size / thickness / grain orientation / species etc?

(In Chris Schwarz' "Weekend workbench" video, he face laminates two 1.5" thick pre-made laminated countertops together into a 3" thick top, then mounts them on two legs pieces roubo style. He also mounts a vise cantilevered off one end. How does one roughly determine the thickness or construction that top must have to survive before it needs more support structure?)

[Don Dorn]

I made the Schwarz two day bench in May. It's heavy and stable but my concern is whether it would stay flat outside the legs. I chose to put a tail vice on as well as the front vice being just to the left of the left leg as opposed to inside. For that reason, I thought it might sway and while it could over time, it has remained perfectly flat so far.

While my last one was face to face, this one seems perfectly fine and so far, no regret in not spending that amount of time doing another FTF (last one was just too short).

[Patrick McCarthy]

Alex, re your sketch: you will have more rigidity if you rotate the stretchers 90 degrees so they are on end; same as Ken pointed out with standing on the 2x4’s.

[Alex Liebert]

Alex, re your sketch: you will have more rigidity if you rotate the stretchers 90 degrees so they are on end; same as Ken pointed out with standing on the 2x4’s.

Understood! I want to make sure I grasp the wood movement considerations in the abstract though. If I build something like the drawing, I assume the top of the bench would grow and shrink in depth, while those cross braces would not. Does that mean I should not / cannot construct something like in the drawing?

[ken hatch]

Thank you Ken. To clarify terminology, is a stretcher defined as something that goes with the grain of the top, perpindicular to it, or either?

Is there a formula or method for roughly calculating the deflection based on size / thickness / grain orientation / species etc?

(In Chris Schwarz' "Weekend workbench" video, he face laminates two 1.5" thick pre-made laminated countertops together into a 3" thick top, then mounts them on two legs pieces roubo style. He also mounts a vise cantilevered off one end. How does one roughly determine the thickness or construction that top must have to survive before it needs more support structure?)

Alex,

I'm not familiar with the "Weekend Workbench" so not a clue how or if it works.

There are publications that give formulas for figuring span strength, I've never bothered, I just use the "it looks about right" and if a "little is good a lot more is better" method.

A stretcher connects the legs of the base and can go in either direction, with or cross grain. Stretchers can also support the slab, see English workbenches.

Patrick is correct on the best orientation. I would say you are obsessing about the wrong aspect of a workbench, wood movement isn't usually much of a problem. just build a simple, heavy workbench with few bells and whistles and build it quickly and cheap. Then go to work making things other than a workbench. After you have build a few, changing the things that drive you howling at the moon crazy with each new build you will end up with a bench that works for you. BTW, that is the only way I know that works, books and articles on building benches don't.

ken

[Matt Lau]

Those aren't dumb questions at all.


1.) Most plans for benchtops call for face to face laminations as opposed to edge to edge- is this mostly to get more benchtop thickness from thinner boards and construction lumber, or is there a structural advantage? If wide thick boards (say, 8/4 x 6") are available cheap, whats the argument against gluing them edge to edge?
-- structural. Most boards aren't available quartersawn.

2.) If I construct a top by laminating strips glued face to face, such that the edges of the boards face up: does this mean that wood movement will be basically negligible across the width and length of the benchtop?
- minimized, not negligable

3.) If I were to make a 2" thick top, but wanted to mount a bench vise underneath with more clearance to the bars- I would use a shim between the vise and the bench. Are there are any considerations to make with how to attach the shim? (For instance, if I glue and screw a plywood shim to a solid wood laminated top, am I asking for trouble?)
- I'll have someone else answer that

4.) Similar question: let's say I glued a 3" wide x 60" long x 3/4" thick board immediately under the front edge of 60" long top to create a ledge (as opposed to what I usually see, which is a boards face glued to the front edge etc.) Are there structural / wood movement problems with this?
-ditto

5.) Let's say a support that's part of the base runs perpindicular to the top across the depth of the bench. Best I understand it, these can be fixed in the center to allow movement of the top but not at the edges. Is that right?


Do you have a bench?

You may want to just try the solid core door on a frame. Works really well, and is fast and cheap.
You can use it to make a bigger bench.

[lowell holmes]

OR, you might consider a bench top made from 3 2X8 boards. It's not furniture, but it sure is effective.