Tweet
I just wrote this to another thread:
From tech point of view it is all logical that in precision mechanism built from different materials-it will be shift, it is clear and kosher. What about other manufacturers, they don't have that shift or they don't got caught? I would not believe any optics made by anybody will hold perfect zero sighted at -40 and then put +120 and it will be no shift. 7075 has expansion rate of 13.1 micro inches/1 degree Fahrenheit. Probably adjusting screws made of brass (9 micro inches/1F) or stainless steel (minimum 5.2 micro inches/1F), seems like any case dimensional change with temperature will be not significant and it is inside sight itself, but ones this dimensional change projected to MOA-start growing up crazy. I just don't see how other manufacturers have their design works differently. Unless internal adjusting mechanism made of Tungsten or some sort of Silicon Nitride ceramic, it must be shift. Now, beside different materials, let's say everything is made from the same material-it doesn't mean they will expend or shrink evenly. Longer parts expend/shrink more then shorter parts. That means some all part of sight will be changing mechanical dimensions at same rate, but in absolute value differently-this will drive shift as well. Probably theoretically it is possible to design parts for adjusting mechanism different length from different materials and try to compensate absolute value of expansion/shrinkage, but it is only theoretical, practically I think it is still will be shift.
Bigger concern is electrical components, those are tricky, most of the components rated to -20C and for anything lower then that is already not ordinary over the counter components. Seems like EOTech doesn't have electronic failure, just mechanical shift.
I think this issue is more mental then physical.
I am designing devices which are working in temperature range from -55C (at altitude 30000') up to 80C. Our requirements for mechanical tolerances are not that tight as it have to be on optics. We testing/qualifying or product to full Mils-Spec 810, RTCA DO160 and others.
And BTW, I got my RMA approved, and I am on the fence now to return it or to keep it. Really don't want to find out 6 month from now that other manufacturer admits their optics has similar shift (I am pretty sure now somebody will start digging) and all will start over.
From tech point of view it is all logical that in precision mechanism built from different materials-it will be shift, it is clear and kosher. What about other manufacturers, they don't have that shift or they don't got caught? I would not believe any optics made by anybody will hold perfect zero sighted at -40 and then put +120 and it will be no shift. 7075 has expansion rate of 13.1 micro inches/1 degree Fahrenheit. Probably adjusting screws made of brass (9 micro inches/1F) or stainless steel (minimum 5.2 micro inches/1F), seems like any case dimensional change with temperature will be not significant and it is inside sight itself, but ones this dimensional change projected to MOA-start growing up crazy. I just don't see how other manufacturers have their design works differently. Unless internal adjusting mechanism made of Tungsten or some sort of Silicon Nitride ceramic, it must be shift. Now, beside different materials, let's say everything is made from the same material-it doesn't mean they will expend or shrink evenly. Longer parts expend/shrink more then shorter parts. That means some all part of sight will be changing mechanical dimensions at same rate, but in absolute value differently-this will drive shift as well. Probably theoretically it is possible to design parts for adjusting mechanism different length from different materials and try to compensate absolute value of expansion/shrinkage, but it is only theoretical, practically I think it is still will be shift.
Bigger concern is electrical components, those are tricky, most of the components rated to -20C and for anything lower then that is already not ordinary over the counter components. Seems like EOTech doesn't have electronic failure, just mechanical shift.
I think this issue is more mental then physical.
I am designing devices which are working in temperature range from -55C (at altitude 30000') up to 80C. Our requirements for mechanical tolerances are not that tight as it have to be on optics. We testing/qualifying or product to full Mils-Spec 810, RTCA DO160 and others.
And BTW, I got my RMA approved, and I am on the fence now to return it or to keep it. Really don't want to find out 6 month from now that other manufacturer admits their optics has similar shift (I am pretty sure now somebody will start digging) and all will start over.
Comment