Crossbar leveling: getting multi-monitor setups to line up

The problem

Our dual and triple crossbars let one monitor arm hold two or three monitors. The dual crossbar is one straight aluminum extrusion with two sliding monitors. The triple is three extrusions joined by hinges, so the side monitors can cockpit toward the user.

Both had a built-in angle. The mounting part on the arm has a draft angle that the die-casting tooling requires. When the arm's head is in line with the upper link, you do not see it. When the head is turned left or right, which is common for installs against a wall or a privacy panel, the angle shows up. On a single monitor you can rotate the display on its plate to fix it. On a crossbar, even after leveling, the top and bottom edges of neighboring monitors step against each other.

It was a known issue at launch and was judged acceptable. It stayed a common complaint from customers, sales and technicians.

The challenge

A large business customer finally made it a special order request. The adjustment needed very fine steps, effectively infinite, over a range of about 5 degrees either way. It also had to hold against a big lever arm: a wide crossbar with monitors mounted as far out as possible, and possibly unbalanced.

What I did

• Worked with the Monitor Arms and Ergo Products Lead, who proposed the first concept, to develop it into a product.
• Compared a ratchet, a worm-driven gear reduction and a friction design. We chose friction because it built on existing mounting parts and stayed compatible with every earlier arm, so it could go to installed bases as well as new sales.
• Tested rubbers and foams for the friction stack-up. We settled on an expanded polyethylene foam used in automotive applications for durability and tunability, and tried a range of densities, thicknesses and compressions.
• Prototyped with machined parts, then early off-tool parts, then low-volume in-house builds.
• Spent time on the factory floor with the rework and manufacturing teams to write work instructions for a repeatable in-house process.
• Wrote drawings, did the DFM, and handled supplier negotiations and sourcing for the off-tool parts.

How it came out

What started as one special order is now in the production offering, as an upcharge on new arms or as a rework option for existing customers.

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