Lack Rack mobile enterprise edition.(pt2)

David White Projects

Summary

This post details some problems with construction, custom rack rail fabrication (welding), and constructing the frame under the mobile lack rack.

In the last part I listed a welder in the tools section. Now you may be wondering, what is this guy doing with a welder and Ikea furniture, I hope he has a fire extinguisher handy. I do take safety seriously and do keep a fire extinguisher nearby when welding.

Problems

The distance between the inside of the coffee table legs is 17.5 inches. The standard server rack has a distance of 17.75 inches between the vertical rails. The coffee table is just a little narrower than the standard server rack. The legs are hollow with a thin paper laminate covering a hardboard like material. This is enough to hold up lightweight gear and slightly heavier gear with extra hardware typically used for mounting heavy picture frames on drywall. I wouldn’t trust this construction to hold up a full sized 4U server. This is why the rack rails are used, to hold the weight and provide a more convenient method of mounting equipment.

The rack rails present another problem though. The rails need to be mounted to something and the distance between rails needs to be enough to allow for the server to slide between them.

Rails mounted normal.
Rails held in place as they would be in mounted like they would be in a cabinet. This leaves 16 inches of space between them.
Rails mounted flush to the legs.
Rails mounted flush to the legs. This give more space between 17.25 inches, but is still too narrow.
Rails mounted flush to the legs detial
Rails mounted flush to the legs doesn’t leave any room for equipment mounting screws.

If the rails are attached as labeled, it only leaves 16 inches between them. Turning the rails around and mounting them flush to the legs increases the distance between them to 17.25, but that is also to narrow and doesn’t leave room for equipment mounting screws. I could extend the base frame for the rails and build it around the coffee tables. Well if I did that then the coffee tables become pointless. I could scrap the whole thing and built it out of angle iron and flat steel, but the nearest metals wholesaler is at least an hour drive from me and what do I do with three Ikea coffee tables.

Eureka a Solution

The solution became apparent when I was deciding how to attach the coffee tables to each other. The table legs are designed to be weight bearing in one direction. If I could put the weight of the servers on top of the table legs, not the side it would hold up. I needed to make a bracket to hold the rails from the middle of where the two tables connect. Making that bracket and attaching it to the rails would solve this problem. Fortunately I also had a piece of 2 inch by 2 inch angle iron in my ‘scrap’ pile. What followed was a series of cuts and test fits that resulted in the following creation. Modified rack rails with 90 degree angle brackets welded in the middle for mounting purposes.

Custom welded rack rails front view.
Custom welded rack rails front view. It needs a little bit of clean up yet but over all not too bad.
Custom welded rack rails side view.
Custom welded rack rails side view. The part sticking out will go between the two coffee tables.
The top of one of the rail brackets.
The top of one of the rail brackets. This was a challenge to weld around the top in a continuous bead.

The bottom frame

This went as well as planed, follow the photos below.

Assembling the frame 1
Starting with the cut wood from the first post. I measured where the middle 2x4s would have to be attached. They were attached to one 2×6 then the other. Once the 4 pieces were assembled, screws not fully tightened. The assembly was placed over the top of the coffee table. I checked for fit then tightened then screws.
bottom frame assembly 2
Attaching the front and back 2x6s required the use of some bar clamps. The clamps allowed me to position the end piece and nudge it in before screwing it together.
bottom frame assembly 3
The wood frame is assembled and ready for casters. Its a very snug fit around the coffee table.
bottom frame assembly 4
The casters are attached with the lag bolts. The bolts are labeled as self drilling however I decided that pilot holes would be a good idea anyways. The pilot holes would decrease the chance of splitting the wood so close to the edge.
bottom frame assembly finished
The frame is finished and right side up. It creates a nice edge around the bottom and will hopefully help protect the coffee tables and mounted equipment from accidental bumps while it is moved from classroom to lab.