Help me rescue this adjustable desk project

[Why Not Indeed]

The biggest problem is that you need to try to get a double lift, one for each side of the desk.

Could this be the root of the problem then, I'm trying to pull it from the centre rather than at each side?

 

[Lower]

I'd look at linear actuators. One on each side, floor mounted, powered by the same power supply, would move that up and down nicely.

 

[Old Salt]

Could this be the root of the problem then, I'm trying to pull it from the centre rather than at each side?

I think so. If you can get an even pull you will get on better.

 

[Harry Bloomfield]

I'd look at linear actuators. One on each side, floor mounted, powered by the same power supply, would move that up and down nicely.

Would they not get out of sync?

A garage roller door motor might be worth considering. They are tubular, with adjustable limits and drive at both ends.

 

[Lower]

Would they not get out of sync?

A garage roller door motor might be worth considering. They are tubular, with adjustable limits and drive at both ends.

In theory, no. In my experience, the same make and model are very consistent in their output.

 

[Why Not Indeed]

Right, linear actuators are looking like the way to go. Similar "format" to a hydraulic ram but no oil to leak out of them. Lots of different sizes available. Can pair them easily enough. I understand electronics more than hydraulics.
Just need to work out how many Newtons I need. I assume they're just a big threaded screw inside as the load and speed are proportional on all of them.

 

[Harry Bloomfield]

Right, linear actuators are looking like the way to go. Similar "format" to a hydraulic ram but no oil to leak out of them. Lots of different sizes available. Can pair them easily enough. I understand electronics more than hydraulics.
Just need to work out how many Newtons I need. I assume they're just a big threaded screw inside as the load and speed are proportional on all of them.

As often used on steerable satellite dishes. They can provide positional feedback.

 

[Lower]

Right, linear actuators are looking like the way to go. Similar "format" to a hydraulic ram but no oil to leak out of them. Lots of different sizes available. Can pair them easily enough. I understand electronics more than hydraulics.
Just need to work out how many Newtons I need. I assume they're just a big threaded screw inside as the load and speed are proportional on all of them.

10 Newtons = 1 KG

 

[Why Not Indeed]

Have you considered a long threaded bar, running on a bearing at the top, nut fixed to the work surface and a reverse-able motor to turn the rod?

I looked at lead screws and the associated bearings, blocks, etc but wasn't sure how to size them. However, it seems like a "linear actuator" is essentially all of that in a package.
From an Aliexpress listing:

 

[Why Not Indeed]

just buy a second hand sitting/standing desk.

I am looking into this, it would contain 2x linear actuators, control switch and power supply, so ideal really.

 

[freddiemercurystwin]

Some old architects drawing boards had a foot rest that you lifted with your foot and the whole desk top lifted/adjusted as necessary and will go horizontal too I recall, really quite clever, certainly faster to adjust than any other system available. Sometimes they turn up for not much or even free on Marketplace or ebay.

Bieffe drawing boards was one make, eg

or

 

[Gasguru]

Just buy an industry standard workbench (mine are 935mm high) and a draughtsman swivel chair.

 

[Why Not Indeed]

2x 450mm 1500Nm linear actuators have done the job. They don't track each other perfectly and they're a bit loud, but they work.

 

[freddiemercurystwin]

So it makes a racket and your pens roll off the desk, sounds like a resounding success!

 

[Why Not Indeed]

Should have expanded on that a bit...on the test bench they move at slightly different speeds and one is 15mm longer than the other at full extent. But the "carriage" I built that slides up and down is quite rigid in that axis, so it doesn't make any noticeable difference.