Over the past few days I've been working on some aluminum frames which are fairly large and don't fit on any tables (without stuff piled on them) I have. Now, my back is starting to hurt from being hunched over for so long. (How) can I work on things on the floor without causing myself much pain?
Don't spend more than 15 minutes in that position at a time. Get up, stretch your back, take a drink of water. Stretch forward, backwards, side-to-side, and twist both ways. Roll your shoulders forward and back. Stretch neck in a similar pattern. Be gentle to yourself.
Also, you can do some back-strengthening exercises (when you've recovered from this project) to get you ready for next time. See https://fitness.stackexchange.com/q/153/234
Generally, I find the following tips helpful, depending on the job:
- A mover's dolly makes a great seat
- Never kneel. Kneeling kills. Sit Cross legged.
- Go down and stay down. It's the transitions that kill.
- Don't lean and stretch. Move. See bullet #1
- There is a spot, about 8 inches from your "Plumber's cleavage" that will not be searched by any blind hand sweeping. This is where all the tools you put down will end up.
The easiest solution is where you're helping re-distribute the weight. You can find short height adjustable work stools that you can lean forward on.
There's also the idea of reducing the amount of work by upgrading to more task specific power tools. The less time you spend in that position the better for your back.
Make sure you're doing the more obvious things such as not working in the same position for an hour without a break.
Another might be to think about a solution that is similar what mechanics do lying flat on their back, except you want to be suspended above. You could also build a custom 'table' that you lay upon(maybe with 2x4s, a wood pallet, and a sheet of ply on top). It might worth building custom work tables that would hold the work to a height where you do not have to bend over.
If you don't mind sharing the exact purpose and circumstances of the project, people may be able to give more specific tips.