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Background

I am looking to increase the versatility of a desk by allowing the monitor to raise and lower, using a manual mechanical solution (i.e., no electric motors). I am trying to make adjusting the monitor height be as quick and effortless as possible, while eliminating the risk of "dropping" the monitor.

The situation is depicted here:

Monitor Stand

The items involved in this problem include:

  • a monitor of ~12kg, with dimensions of 449.6mm x 690.2mm x 83mm;
  • a single post of 10cm in diameter, made from 5mm thick steel; and
  • an arm of ~3.1kg, with a maximum extent of 37cm.

The extensible arm provides a great deal of motion. The post is notched at the bottom, resting on a type of halved joint, and secured at the back of the desk by thick wood slats.

The monitor needs to have about two feet of motion so that I can stand while working. (Lifting the entire desk would be much [$10k] too costly!)

Problem

As described in this physics answer, the compressive force and the moment conveyed to the post are fairly significant. I'm looking for a solution that would allow the monitor to raise and lower and lock, even if it meant having to retract the monitor close to the post while adjusting the height.

To raise the monitor with the current situation requires unscrewing the post, hoisting it, and reattaching the screws. This is both dangerous (for the monitor) and time-consuming.

Post and Track

The faceplate welded to the post has 10 threaded holes drilled into it (barely visible in the above photograph). I think I need a two-piece sliding track mechanism. One piece attaches to the post and the other attaches to the extensible arm. The logistics resemble:

Sliding Track Mechanism

Question

What type of sliding track mechanism would allow the monitor to raise and lower without much effort, time, or potential for accidentally dropping the monitor onto the desk?

share|improve this question
    
-1 because I believe that building adjustable height desks and computer monitor stands should be off topic here (computer desk isn't really part of the home), even though a prior question on this topic was very highly rated. –  BMitch Aug 28 '13 at 11:54
    
-1 because not only do I think this is borderline off topic, but also because it's been asked before, twice, and there was another similar question focused specifically on the driving mechanism. I also think this type of question is too broad, since everybody that reads it could potentially offer up there own valid design. However, the question was presented in a very nice way, so good job on that. –  Tester101 Aug 28 '13 at 12:27
    
Spend $15.68 USD: monoprice.com/products/… –  Jason Aug 28 '13 at 14:38
1  
@Tester101: With respect to valid designs, don't most questions asked here receive multiple valid solutions? Isn't that even the point of this style of forum? ;-) –  Dave Jarvis Aug 28 '13 at 15:24
1  
The opinions of our star moderator may not reflect the collective opinions for the DIY.StackExchange.com site. Feel free to come by the chat room to express YOUR take on what the site is, should or could be. –  HerrBag Aug 28 '13 at 16:34

2 Answers 2

up vote 1 down vote accepted

Start by attaching two rack gears to the post.

enter image description here

Next fabricate a halved trolley.

enter image description here
Rear Trolley
enter image description here
Front Trolley

You'll need a couple pinion gears that can mesh with the rack gears.

enter image description here

And a couple pins to allow the gears to spin.

enter image description here

Next assemble the trolley. You can use cotter pins through the gear pins to hold everything together You'll probably want to use 4 cotter pins for each gear pin. One on the front of the front plate, one on the back of the front plate, one on the front of the rear plate, and one on the back of the rear plate.

enter image description here
Cotter pins not pictured

Finally, install a spring loaded release pin (held in place using a C-clip), that will lock the trolley in place.

enter image description here
Spring not pictured

When you want to raise/lower the monitor, pull out the release pin, move the monitor, then let the release pin spring back locking the monitor in place.


For a simpler design. Go take a walk through your local hardware store, and pay close attention to the mechanisms used to raise and lower the table on drill presses.

share|improve this answer
    
@DaveJarvis Wheels would probably work. I used a rack and pinion, because I thought then you would be able to add in a hand crank of some type. The hand crank would allow you to crank the unit up and down, which would be less effort than lifting the entire weight of the monitor to move it. I just didn't add the crank in the model because I'm lazy. –  Tester101 Aug 29 '13 at 12:02

This is a bit out there and seemingly off track, but please bear with me.

We have a premium shower system which includes a shower head holder on a vertical bar: Hansgrohe Croma E 75 3-Jet Wallbar Set, 24" Except our showerhead is much more substantial than in this photo and exerts fair bit of torque on the slider assembly. So much so that we barely have to tighten the slider.

As a result, we tend to leave it fairly loose so we can adjust it with one hand and only a little force by providing relief of the showerhead torque. It then slides easily up and down.

Perhaps that adding a single ring to glide closely around your post could use the same principle. It would be about 10.2 cm interior diameter, probably 5 mm thickness, and about 2 cm high. Weld to one side of the ring a vertical bracket to attach bolts to fasten the monitor arm. Diagram of collar around post with bracket to attach to monitor arm
I don't expect any artistry awards, but maybe this is clearer?

share|improve this answer
    
Wally, I was with you up to the part about the existing sliding arm. The system doesn't currently have a sliding arm. A sketch would be handy indeed! Thank you. –  Dave Jarvis Aug 28 '13 at 3:04

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