Oak worktop on sit-stand frame?

Gary Frost · 13 Nov 2020 at 15:53

Hi all, I've noticed some great advice on here regarding DIY desks and recommendations to use worktop-express.co.uk. I've got space for a 2m desk, so am considering a 2000 x 720 x 40 oak worktop (https://www.worktop-express.co.uk/wood_worktops/oak_worktops.html). (Which would come in at 25kg)

However given I sit at this desk *a lot* I'm considering using a sit-stand frame. The ones I'm interested in is the EQ4 https://flexispot.co.uk/standing-desk-eq4.html as it's dual motor and can have a load of 125kg (and a few other reasons).

I was planning on having the legs inset about 200mm to 300mm, leaving a 1400-1600mm span between the legs. I'm wondering if this span would present a problem on this 40mm thick worktop. I'm factoring in 2x28" monitors, keyboard, speakers on the desk, with the computer itself on the floor, so probably only 15-20kg of weight on the desk. However if we also add a factor to that for all the other stuff I'll likely end up putting on there, then factor in me leaning on it, I could imagine we get to 50-60kg of load (do you agree, should I factor in more/less), so still easily under the 125kg limit on the sit-stand frame.

However, my biggest concern is the 1400-1600mm span between the legs, do you think this would be a problem with this type of setup? Anyone else used these (or other) sit-stand frames with a 2m worktop, any issues.

All thoughts/help greatly appreciated.

Kind regards
Gary

roy_g_biv · 14 Nov 2020 at 23:50

Gary Frost said:
Snip

I've never done this, but I've done some research on it - there are metal braces people buy to stop sag in these instances. You should be able to find them fairly easily

One thing to consider as well would be stability around max load - if it's too top-heavy it might sway and wobble, especially with a monitor stand

Abyss · 15 Nov 2020 at 12:56

If one of your concerns is about the desk sagging just put the details into the sagulator :

https://www.woodbin.com/calcs/sagulator/

Based on a 1600mm span, 720mm wide, 40mm deep your are looking at >200kg before you get any issues with the desk sagging.

roy_g_biv · 15 Nov 2020 at 13:53

Abyss said:
If one of your concerns is about the desk sagging just put the details into the sagulator :

https://www.woodbin.com/calcs/sagulator/

Based on a 1600mm span, 720mm wide, 40mm deep your are looking at >200kg before you get any issues with the desk sagging.

This is really useful

I do wonder how it applies to made of bonded smaller pieces like the OP's, since "The deflection calculations use average wood stiffness properties of clear, straight-grained samples"

Gary Frost · 15 Nov 2020 at 15:10

roy_g_biv said:
I've never done this, but I've done some research on it - there are metal braces people buy to stop sag in these instances. You should be able to find them fairly easily

One thing to consider as well would be stability around max load - if it's too top-heavy it might sway and wobble, especially with a monitor stand

Ok, thanks, yes I could put in some metal braces, or even route a grove under the desk and put in a decent metal bar along it perhaps

Gary Frost · 15 Nov 2020 at 15:12

roy_g_biv said:
This is really useful

I do wonder how it applies to made of bonded smaller pieces like the OP's, since "The deflection calculations use average wood stiffness properties of clear, straight-grained samples"

Indeed, +1, thanks Abyss

I do also wonder about the bonded pieces, though I'm imagining that if they use decent glue for the lamination then it could (potentially) be stronger than a solid piece

roy_g_biv · 15 Nov 2020 at 15:16

Gary Frost said:
Indeed, +1, thanks Abyss

I do also wonder about the bonded pieces, though I'm imagining that if they use decent glue for the lamination then it could (potentially) be stronger than a solid piece

I guess you still have plenty of headroom even if it halves the threshold for sag

Abyss · 15 Nov 2020 at 19:53

No problem

Glue is usually stronger than the wood itself so I wouldn't expect the oak worktop to be any weaker being made from 40mm staves. Given you are talking about 50kg of weight you are nowhere near the limit so I wouldn't worry about.

pp111 · 16 Nov 2020 at 10:55

I have used this stuff for desks. Mostly you are fine but you will find an issue with monitor stands, they apply a twisting force that can separate the pieces of oak. If you are at all worried then use a 9mm hardwood plywood to reinforce the area. Ordinary wood glue is good enough. Completely coat one side of the plywood before you attach it so that it bonds all the pieces of oak.

Gary Frost · 16 Nov 2020 at 14:22

pp111 said:
I have used this stuff for desks. Mostly you are fine but you will find an issue with monitor stands, they apply a twisting force that can separate the pieces of oak. If you are at all worried then use a 9mm hardwood plywood to reinforce the area. Ordinary wood glue is good enough. Completely coat one side of the plywood before you attach it so that it bonds all the pieces of oak.

Interesting, so glue (and screw) some 9mm ply on the underside of the desk where the monitor stand/arms will sit?

jpaul · 16 Nov 2020 at 14:32

I had specced 25mm box section steel, not so expensive, to use as a support - there's an earlier thread.

the eq4 stand, linked, has a cross-member - no ?
so I wasn't sure why you might need an additional support, but it's telescopic nature would make it a bit weaker.

Gary Frost · 16 Nov 2020 at 15:31

jpaul said:
I had specced 25mm box section steel, not so expensive, to use as a support - there's an earlier thread.

the eq4 stand, linked, has a cross-member - no ?
so I wasn't sure why you might need an additional support, but it's telescopic nature would make it a bit weaker.

It does, but as you say with the telescopic nature it looks a bit weak tbh

pp111 · 16 Nov 2020 at 17:04

Gary Frost said:
Interesting, so glue (and screw) some 9mm ply on the underside of the desk where the monitor stand/arms will sit?

Yes. Use the largest piece of plywood you can get away with to spread the forces out as far as possible. The screws just need to hold until the glue sets and it will be as solid as concrete!

joelk2 · 27 Sep 2021 at 20:55

Did you ever go ahead with this?

mice just built a new desk but was considering adding stand functionality with one of these frames.
I have the 2m x 620mm x 40mm oak worktop but it’s certainly heavier than the 25kg quoted above.

easily double I would have though.

thenewoc · 27 Sep 2021 at 21:29

My sit stand frame was about £100 cheaper than the one mentioned above and has metal bars between the legs. These are directly beneath the desktop so no problem with sag. The motors are housed between these bars too. My desktop is a bit smaller, 1.5m X 70cm X 30mm, plywood which I bonded Formica to. I have an ergotron hx monitor stand clamped to the ply, holding my 34" ultra wide.

joelk2 · 28 Sep 2021 at 10:32

I’ve found some around the £200 mark which I’m looking at getting (hopefully can put it on expenses with work as I WFH 9 out of 10 days)

joelk2 · 28 Sep 2021 at 10:39

Hoping to do something like this
(ps ignore the screens being at different heights)

thenewoc · 28 Sep 2021 at 19:52

joelk2 said:
Hoping to do something like this
(ps ignore the screens being at different heights)

My one is made by Devaise which I got from Amazon. It expands between 105 - 160 cm and is rated at a 120kg load capacity. I think you could do what you've suggested but the overhang on each side may sag a bit if heavy items are placed there. It might be better to place the PC on the floor or move the monitors off centre so the PC can sit over one of the legs. There may be other frames that expand more than the ones I have though.