I’m building a workbench out of Beech and have spread the work out over months now due to other obligations. In that time, the wood has moved (cupped) and I need to flatten the top.
I plan to use the router sled and rails method to accomplish this with a #7 cleanup and a scraper plane to finish.
My question is what are people seeing as far as “out-of-flat” measurements when they build their benches?
Mine is out 3/16″ across 32″…is this really bad or is this in the “within expectations” range?
Thanks,
erik.
Replies
erik,
There are no "specs" regarding workbench top flatness. Your bench needs to be flat enough to allow you to build whatever you're buliding to an acceptable degree of flatness (for you).
That is, your workpiece can only be as accurate as the surface on which you are building it. A chair set on the workbench top should have as flat a surface as possible to check the legs for accuracy and to trim the "long one." A panel glued up on the workbench will have any out-of-flatness measure that the top has. You have to decide what's acceptable.
Using the "Tage Frid router method" you should realize an over all flatness, easily, of plus or minus 1/64 (or better) for the entire surface. That's a pretty flat top.
Rich
It depends on what you plan to use your bench for. If you are primarily a handtool user and plan on using your bench as a reference surface for checking for highs spots on boards when dimensioning stock, then you'll want to get it as flat as possible. If, on the other hand, you're primarily a power tool user and plan to use your bench as a place to secure items that you will be drilling, sanding, routering, etc. then flatness won't be paramount and 3/16 over 32" isn't so far out of flat that I'd worry about very much.
I certainly don't think that you need to go through the hassle of making a router sled get-up. You have a #7. Add a pair of winding sticks and a straightedge (which can be made out of scrap) and you're in business. Even if you feel unsure about flattening such a large surface by hand, leave the router where it is and give you're #7 a try. It is surprisingly easy. All you have to do is plane off the high spots so they are the same level as the low spots and you have a flat surface. Plus, I'd be hate to have a router mishap in the middle of my new workbench top.
Houston,
I disagree with your advice about the router sled method. Have you ever tried it? It's very quick, it's extremely accurate. Far beyond hand planing.
The chance of a "router mishap" in the middle of a workbench top is nil.
Except for his preference to make the pins first for dovetail joints, I have found Tage Frid's methods of work great examples of expediency and accuracy. No one could ever accuse him of being a stranger to hand tools. But he never advocated a hand tool method when a power tool setup did the job better and faster. I like that.
Rich
Far beyond hand planing.
your router can level a surface to within a couple of thou..?? a surface big enough to call a bench top using a jig that negates Young's Modulus?? That I'd love to see...Mike Wallace
Stay safe....Have fun
A couple of thou? Where did I say that?
A couple of thou? Where did I say that?
you didn't.. but that's what can be achieved with a hand plane..Mike Wallace
Stay safe....Have fun
Mike, I must inform you that just about any router will flatten a surface such as a bench top absolutely as accurately as the reference/jig/sled that it rides on has been made....
Not that I advocate the use of routers & sleds to flatten benches- unless I made a vocation out of it. Just another lifeless jig gathering dust.
Youngs Modulus? Please explain....Philip Marcou
Edited 3/23/2007 3:59 am by philip
hello stranger.. where you been hiding??
absolutely as accurately as the reference/jig/sled that it rides on has been made....
that's exactly what I was hinting at, and what Youngs Modulus has to take into account..
What is it?? Calcs to determine the ability of a stressed member to resist a bending moment... deflection under load in other words. Most rigs I've seen to enable a router to do this kinda task simply aren't beefy enough to resist the mass of the router the rig to sag at mid-span.. net result is a dished surface; no use to man nor beast...Mike Wallace
Stay safe....Have fun
Thanks Mike- I have been here all the time....amongst the ugly and esoteric (elite inner circle privy to select knowledge) (:).
To answer the questions of the original poster I feel that any thick topped bench that maintains an over all tolerance of 1/32nd of an inch or so from one season to the next is living in a kind climate indeed and the wood itself very stable.Minor intolerances like should be easily and quickly dealt with by hand planing .In fact I would not be too worried by anything up to around 1/16th- as long as one knows where it is "out" it is easy to compensate for this when planing, for example. As for reference surfaces there are other surfaces more reliable-such as table saw tops, which are now approaching aircraft carrier proportions in North American home workshops from what I can see, not to mention jointers as long as rail tracks.Philip Marcou
Philip
Aircraft carrier proportions is an image that describes to perfection the North American fixation with bigger is better. I will remember that line for sure. JL
jean,
Heard on the news today, that the John F Kennedy is being decommissioned after only 40 yrs. A little retrofitting, and the deck would make a fine jointer bed. The aircraft elevators can be modified into an adjustable infeed table...
Ray
Ray
Who will manufacturer the knives? Maybe Philip will be interested? JL
I'd hate to be on the outfeed side when the steam cats get hold of a board...Mike Wallace
Stay safe....Have fun
Mike,
That would be a kickback.
Ray
Well, now that would handle a might big board.
Esoteric: Intended for or likely to be understood by only a small number of people with a specialized knowledge or interest.
- from the Oxford American dictionary built in to the operating system of my small, compact, efficient American-designed Macintosh computer, said to be the most advanced personal computer operating system in the world and proven daily by the performance of "Vista."There is history there, for using the word "esoteric" for a thread on workbench flatness - there was a legendary thread in the past that went on for hundreds of posts. I wish there was a way to recall it - I have only seen a printed copy.
Let me rephrase the question:
For persons that have actual experience building benches, when you have finished the top, how much "out-of-flat" have you typically seen?
I plan to flatten the top, no doubt about it, but I want to know how does a typical top come out as a baseline.
Thanks,
Erik.
I think it really depends upon what kind of top you are making and how you make it. I did a typical face laminated 8/4 maple top on my bench. As with several bench building articles I've read, I made sure to orient the grain in the same direction and after hand planing the bottom of flat, ran 12 inch wide glued up sections through my bench planer so the only thing to worry about keeping flat when gluing the last two sections together was that single joint line. With cauls and careful gluing and prep, there was hardly anything to clean up. I was prepared to take the top to a local place with a very wide belt sander, but when I checked it with straight edges and winding sticks, I found it was flat to the best of my sense of perceiving/testing it. I may have run my belt sander with a shoe set to take next to nothing off as a final step, but little to no final flattening was required.
OK,
Now that you put it that way. I have two benches. One I bought, one I built. They're in storage, so I can't measure right now, but I know the commercial one was "out of flat" bad enough for a straight edge to rock badly. I've never bothered to true it up.
I built the other from beech (much less expensive than maple) in 2 sections, about 11.5" wide. After glue-up, each section was unuseable due to the gross uneveness of the tops of each board (far more than your 3/32 figure). I eventually ran each through a 13" thickness planer, making the tops of those 2 sections "perfectly" flat.
Then I glued the 2 sections together. The completed top was again unuseable due to the need for the one glue joint dressing and very large deviation from flatness over the whole top. Again, the deviation from flatness was much greater than your figure.
There was no way I could have run the glued-up top through a planer. So I used the router sled method with a 1/2" diam, straight, 1 flute cutter.
It went pretty fast. The surface needed a little hand sanding, but was flat to a straightedge test. I could have used some feeler gauges where some tiny slivers of light were visible under the straight edge, but didn't bother. They were maybe .01-.015"
I'm not sure at which point in my construction sequence you would have considered the top "completed," requiring flatening, but before the router sled it was "rough" and after, it was as flat as I could want.
Rich
Rich,
Thanks -- that is exactly the reponse type I was looking for!
Erik.
Well, I built my bench (out of 2X4s on edge, about 35 years ago now). I flattened it with a scrub plane and jack. Never bothered to measure it's flatness. I use it as a workbench, not as a reference surface. When I'm gluing up furniture, I usually do it on a low plywood platform -- I find the bench too high for this job anyway. The moral of the story is that it's flat enough when it works for what you are using it for. There is no universal spec for a "flat" bench.
Mike HennessyPittsburgh, PA
got a feeling that this thread is going to go ugly and esoteric fast, so I will get my answer in to your original question. I made a bench out of three inch thick quartersawn douglas fir. It is inside, in a part of the house that is heated and aircondtioned. I orignially got the top flat with handplanes. After about a year there was a little hump about a third of the way across the top that covered maybe 60 percent of the length of the top. If you put a straightedge across the top, it would rock a little bit - maybe a 1/64th inch gap. I reworked the top flat with handplanes so that there is nowhere where there is a gap that is detectable by a metal straightedge. It is part of my routine to resurface and flatten the top every year - takes maybe an hour or two. Good luck, Ed
Erik
In construction, the standard for top quality flatness is 1/8" on 10'- 0"...so the 1/64" on the bench overall that Rich mentioned is a fair number. JL
I finished mine (36x84 top) about three weeks ago. I ended up within 1/32 over its length and less accross its width. It is working great for my current door project and it is very helpful to use a gage when prepping stock. I wouldnt want mine more out of flat than this. I hand planed mine, after chatting with a few and it was very easy.
I've seen some really nice workbenches over the years - some of them pretty enough to be in the living room rather than a shop! I can't imagine actually having one, however, because my workbenches get used pretty hard. - lol
My "workbench" is actually a multi-functional piece of my total shop setup. The top is a workbench, assembly table, and table saw outfeed table. The shelf underneath stores some benchtop tools and there's room under that for a couple of dollies. The hardpiped sections of my DC system hang under the top.
It ain't real pretty, but it works quite well. The top is basically a torsion box. It's framed with KD 2x6 and 2x4 and has a piece of 3/4" ACX screwed to the frame.
I've needed to "tweak" it a couple of times over the past five years and I do that by stretching a string across diagonal corners and using shims between the frame and the plywood to get it flat. When that's done, I use the leveling feet to get the top in the same plane as the top of the table saw. Since I'm on a garage floor, neither my saw table or bench are "level", but they are flat and in the same plane.
When I use biscuits or pocket screws, I register the pieces face down on the bench and (if I've cut the pieces square), the joints are dead-on every time.
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