The iPad: Trade Offs

This entry is about a change I made to the design of my iPad stand and the reason for that change. As the project evolved so too did the set of design requirements. Change is all too often typical in most projects. The only two requirements at first were based on position and footprint. I wanted the stand to position the iPad at a certain height and angle above a workbench close to where I am doing something, and because of that placement on a workbench, it must share space with whatever I am working on. So in that case I wanted the footprint to be relatively small.

I got far enough along in the project to assemble the post assembly to the table. I like what I saw but I began to realize that the design might have a center of gravity issue because the table angles forward placing more weight on the front two legs.

I am not under pressure to get this project done, so I am starting over with a design change that corrects the potential balance issue. The post and two back legs will stay the same, but the front legs are now splayed out from the post at a greater angle. This insures that the design maintains a better center of gravity, and the stand will be less prone to tipping forward.

The stand will now take up more workbench space but is better balanced. There is a trade off in accomplishing that, and it is not unusual for design requirements to conflict with one another. I think this trade off is minimized by increasing the angle on the front legs while keeping that of the back legs the same. This results in a design that still meets position and space requirements while better protecting the iPad it holds.

The iPad: Hand Tooled

I didn't notice it until I applied the first coat of finish, but one lower corner of the iPad stand post had a significant chip. The defect could not be sanded or otherwise machined out at this point with the four legs glued on to make up the assembly. So I decided to experiment with some ideas that would transform the defect into a design feature, and decided that the best way to deal with it would be to add a slight bevel to each of the lower post corners.

At this point there would be no realistic method to machine each bevel so I brought out a set of chisels and went to work carving each. I was carving into oak, and upon the first try each bevel came out somewhat irregular. Which was just a perfect match for the organic shape of the CNC routed leg profile. I decided not to perfect them further.

It is interesting how the most basic of hand tool operations using a simple chisel could compliment the technically complex task of CNC routing. Maybe not though since I was the one who either guided the tool against wood or curved a profile on a computer screen to create each.

The iPad: CNC Contouring

My design of an iPad stand has four splayed legs mated to a central post using mortise and tenon joinery. I cut a b-spline profile through one side of each leg to add a sense of organic fluidity to an otherwise angular structure.

The b-spline profile is created in the zx-plane and projected parallel to the y-axis to control the emphasis of linear movement along the height of the stand.

To actually create the contoured profile, I export a computer model into a program called Cut3D by Vectric Software. Cut3D creates the toolpaths and machine code required by a CNC router to shape the surface profile.

Cut3D happens to be a well featured program for creating 3-axis CNC toolpaths. It generates both rough and finish toolpaths, and displays those in animated form for verification.

Also output is an estimation of the time it will take to machine each leg.

The iPad: Building A Stand

I recently purchased an iPad based on what I thought would be its usefulness to my work as a woodworker. It actually exceeded some expectations in that regard. There will be more on how it has in a future post.

Its primary use is in the workshop itself. I find that having a stand to hold it at a proper viewing height while placed on a workbench or table would be helpful. I therefore am going to build a stand for the iPad, and document its construction in the next series of posts.

The design of the iPad stand is almost completed. It has four splayed legs for stability that are attached to a central post. The central post contains a pivot joint that secures a small table for the iPad itself to rest on.

I decided to use my cnc router in interesting ways on this project, and my next post will start this series off with a topic related to that.