Really interested ? Google up "Angle of Repose" and click on the obvious .
the angle of repose.
The difference in the angles of slope of the pile are partly related to the difference between the dynamic friction angles which are relevant to the grain falling on the pile and the static friction angles which are relevant to the pile at the rest. The static friction is related in practical terms to the angle of internal friction which is the angle at which a block moves on a plane surface (Embleton and Thornes, 1979). It is denoted by the symbole Ø and usually associated with the Mohr-Coulomb failure criterion:
tf = c + sn tanØ .
tf is the shear strength of the substance at failure.
c is the cohesion (measured in Nm-2) which is the molecular attraction that binds particle together.
sn is the normal stress (in Nm-2).
Sorry Gordon..it didn't help me.. :lol:
With my experience in centrefire reloading I know that if I dump my powder scale pan in one lump into the case funnel, it can easily bridge. If I pour it slowly, no problem. I suppose if one was to slide the charge bar slower it may help prevent bridging as it would allow powder to slowly drop down the tube, rather than in one lump...
I rub the outside of my powder bottle and drop tube with an anti-static cloth, but don't add any to the powder itself. I have not personaly had a problem with powder bridging, but I have had shot bridging. The anti-static cloth dosen't help for this.
I have added a touch of graphite to shot I've poured in a bucket, and then mixed well. This seems to lessen the problem.
It probably wouldn't hurt if you could polish the inside of your drop tube, perhaps with a drill and a small piece of dowling, with a rag and a little car wax. :idea: