Thursday, August 9, 2012

Harsh Easel Project Part 1

I was looking at some project pictures the other day and I came across an interesting design project I did for an artist friend of ours a few years ago. He is really a good friend and fine painter Harsh Paintings to boot that likes to work on a huge range of painting sizes. His problem was he needed a larger easel. Commercial units were not up to the job and his old one had some problems and did not suit his needs any more. He needed an easel that could expand from the smallest postage stamp panels up to canvases that you can barely fit through a garage door. This easel design problem was a exercise in counterbalancing and size expansion. 

The first step of a design problem is to get the customer requirements converted into a scope of work. I like to do a little preliminary design at this point as a kind of a feasibility study to get a good direction going. I talked with Bill for quite a while and took some measurements of his current easel and workspace. We discussed what he liked and didn't like about his current setup and the laundry list of features he wanted in the new easel. At this point I went away into my cave and did some thinking and sketching.

Any decent designer always surveys what has been done before. You have all heard, "lets not re-invent the wheel" right? I had to believe there was much to learn about what has already been done with easels and some of the methods that others have used to solve the design problems. Design is like a sifting process. You have your specialized set of customer requirements on one hand and you research how other designers solved, or didn't solve the specific details weighing the features against the requirements.

Fortunately for me Bill is an excellent communicator. If he cant tell you in words he can make a great sketch that is worth a thousand words.With shadowed wheels even, sketched on expensive heavy artist paper.

There were two distinct and equally challenging problems. The first was the requirement to raise and lower the easel frame with some kind of mechanical assistance. Commercial units were available with a mechanical lift but they were inconvenient and didn't satisfy one of Bill's requirements for rapid repositioning. Looking for commercial devices that would work I found a few things that I could have re-purposed for the easel. From transmission jacks to optical transit stands. The one that caught my eye was a tool used to lift drywall for placing on the ceiling. This was a cable operated lifting device with a large hand wheel to raise and lower the head.

It was close to what was needed for the easel. The only hangup was where to position the gigantic hand  wheel so it didn't interfere with all the other bells and whistles he wanted. At this point I really started to think about counterbalances. Once headed down the counterbalance road I found what I thought was the answer to my design problem.
This is a constant force spring counterbalance used as a replacement for double hung window sash weights. They were pretty inexpensive so I bought a couple of different force ratings for the easel project from my favorite industrial supplier  McMaster Carr.  After testing the units it was pretty obvious that they would not work the way I wanted for the easel. The action was not smooth enough, and the load bearing strip was designed to exit the housing at a very awkward angle. Remember they were meant to be used in pairs as replacement window sash weights which is the reason for the weird angle.

To be continued.....