thebionicman, post: 396532, member: 8136 wrote: I'm with Mark. Sanding is for woodworking, not repair prep. If you have to remove old finish use wood stripper. Seal it with something that repels water, but avoid anything varnish like.
This isn't my first rodeo. Done it both ways - Sand and paint...also strip and paint.
Either way you end up with a set of tripod legs that look and function like new and can be used in foul weather without too many problems.
A quality oil based paint worked the best.
Didn't have the "throw away" mentality back then.
I want to say that my dad used the same set of tripod legs for 20+ years.
They were Topcon branded (I think) and very heavy.
Sure you could probably buy a set of cheap legs for the amount of time it took to re-paint the old ones. Had nothing but trouble with light weight wooden legs. Nearly totaled the gun once due to a warped dowel.
These new composite legs are really nice, you just have to be aware of potential errors they can introduce depending on what type of work you are doing.
The weight / durability / stability issues are all important factors. The stability factor is critical which lead me to wondering what the best material would be. Checked for thermal expansion of materials since we work in a variety of weather. The very best material would be Invar by far which has a coefficient of only .0000015" /inch per 1å¡F change. The next best choice is Douglas Fir with a close coefficient of .0000021" /inch per 1å¡F change. For comparison aluminum has .0000121" /inch per 1å¡F.
Amount a continuous 10' length of material would expand/contract with a 20å¡F change (assuming homogeneous temperature throughout) by my computation:
Invar = 0.004"
Douglas Fir = 0.005"
Aluminum = 0.030"
To compare: 1mm = 0.040"
Usually set the tripod below 6' height. Which means actual expansion/contraction variation would be 60% or less than that shown above. Once the material has acclimated to the atmospheric temperatures than the amount of displacement would be nominal. To think that aluminum could be suitable for most applications kind of blows my mind. Control work would still require the Douglas Fir type material.
Don't know what the weight of Invar is, but it is made from 36% Nickle and 64% Iron. Both sound like heavy materials. Not something I'd like to lug around all day.
Thanks for the ideas.
