Temperature sensitivity

[scott/r]

I got to thinking a little while ago about the sensitivity of my 505 scales to different temperatures in my gun room. It all came about from when the mrs made me a coffee and stuck on the bench near my scales. Obviously the temp from the coffee lifted the pan and changed the reading on the pointy end.
So this morning I got a chance to do a bit of an experiment before and after I put the aircon on. I set everything up as per normal, leveled the platform I have my scales on and then zeroed them. I checked the zero to make sure the air current from the a/c hadn't changed it. All good. I then set them to 45.1 and then turned the a/c on. Straight away I started charging the cases from my cheap electronic scales into the balance scales, as I do normally. Now the temperature was 26.5 deg when I first put the a/c on. By time I had 50 cases charged with powder the house was down to 24 deg. Then I rechecked my zero on the beam scales. It had changed from 45.1 to 44.9. And that puts me outside of the node I'm looking for.
So I then went back through all the cases and re weighed the powder. It was very interesting to watch as the powder weight differences coincided with the temperature dropping in the house. Now just to make sure it wasn't human error or equipment problems, I went through and re weighed about a dozen loads at random of the adjusted lots. All came in spot on.
I now have a bit of a problem of trying to talk the mrs into me turning the shed into a room with it's own atmospheric temperature control unit.

[John23]

I have never considered temperature effecting beam scales .
I will have to do the experiment myself.


I did however whiteness my beam scales erratically moving about .3-.5gr during a electrical storm when loading late last year .

I have had plans to do some testing on that also but am yet to get a good storm at a convenient time

[johnk]

Any possibility that it's a consequence of air circulation, not temperature?

[scott/r]

Possibly, but when I rechecked the last time they were still on. Granted they weren't working as hard, but they were going.

[johnk]

The craziest thing ever happened to me was one session, one of those tiny spiders, the ones you usually see floating outside decided to drop off the ceiling & parachuted on a thread right into the quartz seat of one of the pivots. totally screwed the response until I gave him a decent clean off.

[Longranger]

I suspect beam scales vary with temperature because the aluminium beam would grow slightly in length but I wouldn't have expected a change with only a few degrees. If the beam was equidistant either side of the pivot I guess it would cancel out. Most are not like that though.

[scott/r]

Yeh it surprised me as to how much difference there was, that's why I put this up. It is a very sensitive set of scales though. You can see the difference with 1 kernel of powder.

[clohne308]

Scott,
I am running a modified 505, and it is also acurate to 1 kernel. Like you, I have noticed changes in zero. It was quiet noticable last night where the zero was approximately 0.1gn different to this morning. The only diffrence could be temperature / Air density, as I dont have any air circulation in my reloading room. I have noticed this previously, but couldnt work out what was going on. Thanks for the post. Opened my eyes, to another variable to consider.....

[scott/r]

No worries. And to add to it, I run another 50 through last night after work . The mrs had the a/c on all day so the house was a constant 24 deg and I had no difference in weight from the first case load to the last. That made me happy.