>you really believe that all the bekants, after assembly, are perfectly identical so that the only remaining variable is the observer's subjectivity?
They may not be identical but I think subjective detection/annoyance of a wobble is the most likely difference because of the physics of how the desk is assembled.
If you're not familiar with the BEKANT desk, this video[0] shows what the underside looks like. (Please note this is showing the BEKANT version that is motorized to adjust the standing positions.)
You'll see there's not enough support mass, nor enough surface area of metal cross bracing, etc to prevent it from wobbling -- especially at extended heights of 39+ inches. Also notice that the braces are attached to the table top using plastic push pins and not metal lag bolts.
To eliminate perceivable wobble would require increasing the 2 'T' posts to 4 corner posts -- or keeping 2 posts but make them more massive, etc.
But IKEA didn't have to do any of those more expensive engineering designs because a significant number of buyers already praise it as having "no wobble." This makes sense to me.
Some other possibilities for the conflicting observations:
(1) It's possible that some self-reports of "no wobble" are mainly using the desk at sitting height instead of standing height.
(2) Maybe some users have it extended at standing desk but put in a corner so there are 2 walls that stabilize it.
(3) They may be using the BEKANT version that's non-motorized and sitting-height only. (That one has a different underside bracing geometry and also more mass for more rigidity. I wouldn't expect this desk to wobble.)
This thread happens to be about "standing desks" and the comment people are replying to is also talking about "standing desks". Therefore, I discounted the 3rd possibility.
ok, but the facts you present don't really isolate the cause (i.e., rule out other possibilities) of (the perception of) wobble.
you'd need to prove that all desks, when assembled by random people, have largely similar wobble characteristics (or the much harder proof that wobble varies with the perceptive tolerances of the observer). however, as you allude, the engineers were constrained by ikea's affordability (cheap), assembly (easy), and distribution (flat-pack) goals rather than precision around wobble.
as for the engineering, it's not support mass or surface area you need (read up on i-beams if this doesn't make immediate sense), but torsional rigidity at the joints, particularly tighter tolerances around the connectors when assembled by random people. torsional rigiditity in the spanning members is needed too, but that's less likely to be the issue since it's a steel frame.
this is a simpler explanation for the observed phenomena (apply occam's razor here). certainly more than one explanation might conjointly apply, but yours is the more complicated explanation and thus implores more observation and measurement.
>this is a simpler explanation for the observed phenomena (apply occam's razor here). certainly more than one explanation might conjointly apply, but yours is the more complicated explanation and thus implores more observation and measurement.
And I thought Occam's Razor as guidance made the basic physics of the joints making wobbling unavoidable was the simpler explanation. I think we have different exposure to this product. I actually examined this desk at the store. If you look at the pdf[0] of the assembly, you'll notice 2 bolts that attach the pedestal to the posts. It doesn't matter how much one tightens the bolts because when you extend the desk past 40 inches with a heavy weight on the top (20+ pounds), that T joint will flex and deform. (See 1st video I cited for example).
One doesn't need to examine 1000 different cars towing a heavy weight on the back to determine that it's unstable and will fishtail. The basic physics of the configuration will make it fishtail. That's the type of Occam's Razor I'm using. Yes, there will be variances in how the trailer hitches were installed to the vehicle, and also variances in the trailer ball diameter -- but those are not the dominant factors. To continue the analogy, some drivers with misconfigured weight distribution may not notice any fishtailing because they drove slower than 40 mph, or they didn't make any sudden steering overcorrections etc. Same situation with some desk users reporting no wobble by using it a shorter height, or placing it against the wall, or just not subjectively noticing it.
If one makes a desk that lets people put 20+ pounds at the end of a 40-inch extended pole that's attached to 2 bolts -- without triangle stiffeners, or welds, or cross-bracing, or whatever, ...it's going to wobble at least little bit. Based on hands-on experience with the desk, I contend the underlying physics of the assembly design overwhelms any deviations in manufacturing tolerances. Or put another way, if we consider the entire Gaussian distribution of manufacturing variances, all of the desk samples will still exhibit wobble to some degree as shown in the 1st Youtube video. Some may wobble less; some may wobble more. E.g. the telescoping cylinders (not CNC milled) that the users do not assemble may have variances that add to the total wobble.
I noticed others in this thread mentioned that the newer IKEA model IDASEN "solves" the wobble. (Or minimizes it.) If we look at its alternative design[1], lo and behold, we see that desk has added diagonal bars on the legs for extra support. Yes, it makes sense that structural triangles are stronger and stiffer than just 2 bolts fastening a T joint of the BEKANT.
They may not be identical but I think subjective detection/annoyance of a wobble is the most likely difference because of the physics of how the desk is assembled.
If you're not familiar with the BEKANT desk, this video[0] shows what the underside looks like. (Please note this is showing the BEKANT version that is motorized to adjust the standing positions.)
You'll see there's not enough support mass, nor enough surface area of metal cross bracing, etc to prevent it from wobbling -- especially at extended heights of 39+ inches. Also notice that the braces are attached to the table top using plastic push pins and not metal lag bolts.
To eliminate perceivable wobble would require increasing the 2 'T' posts to 4 corner posts -- or keeping 2 posts but make them more massive, etc.
But IKEA didn't have to do any of those more expensive engineering designs because a significant number of buyers already praise it as having "no wobble." This makes sense to me.
Some other possibilities for the conflicting observations:
(1) It's possible that some self-reports of "no wobble" are mainly using the desk at sitting height instead of standing height.
(2) Maybe some users have it extended at standing desk but put in a corner so there are 2 walls that stabilize it.
(3) They may be using the BEKANT version that's non-motorized and sitting-height only. (That one has a different underside bracing geometry and also more mass for more rigidity. I wouldn't expect this desk to wobble.)
This thread happens to be about "standing desks" and the comment people are replying to is also talking about "standing desks". Therefore, I discounted the 3rd possibility.
[0] deep link: https://youtu.be/lZ9VmpyXk6g?t=187