From: gmk@falstaff.MAE.CWRU.EDU (Geoff Kotzar)
Subject: Re: Innacurate Powder Scale
Organization: Case Western Reserve University

In article <58755@mimsy.umd.edu> cash@convex.com (Peter Cash) writes:
##In article <58589@mimsy.umd.edu>, Ken_Ziolkowski@transarc.com writes:
###
###   1. My powder scale will not balance. It is a standard
###      model RCBS and no matter what I do, it will not
###      "zero". Any advice?
#
#Any large metal objects near the scale? If your scale has magnetic damping
#(my RCBS does), this could definitely affect zeroing--and the accuracy of
#your charge weights.


I believe this to be irrelevant. Powder scales use stationary magnets in the
frame and a copper plate attached to the beam (my Lyman uses copper, 25 yrs
old, haven't looked closely at newer ones). Damping is by eddy current. Any
large metallic objects may be attracted to the base but should not affect the
beam.

In the past my non-zero problem was due to the knife edges being damaged
and slightly rounded. If the problem is due to the knife edge-agate bearing
interface the problem could be dirt on the agate or worn or damaged knife
edges. This would show up as a repeatability failure. Displace the beam
from its rest position, if it does not return to the original postion then
I would look at the bearing-knife edge pairs. When you displace the beam
swing it to one side (up or down) several times to see where it stops, then
swing it to the other. If it catches to one side and tends to stop in the
same place you probably have dirt on the bearings. If it stops in different
places each time my vote would go to the knife edges being worn/damaged. They
can be dressed if you are careful and if you have a set of calibration weights
to verify that you did a sufficiently good job.

If the beam is sitting to one side of zero, and you cannot raise or lower the
base sufficiently to make the beam pointer coincide with the zero mark, then
you have probably lost one or more pieces of the bias weights (pieces of shot
in the bottom of the hanger). This only applies if the beam is pointing down
indicating the pan/hanger is light. If the beam is pointing up your pan and
hanger are too heavy and how that could happen I don't know.

Hope this helps.

geoff kotzar


From: gmk@falstaff.MAE.CWRU.EDU (Geoff Kotzar)
Subject: Re: Problems w/ Dillon Electronic Scale
Organization: /etc/organization



I purchased one of Dillon's D-Terminator scales before the end of the year
and after checking it out had to return it. The following is the cover
letter I sent which lists what I found. Hope this is of some help to any
one planning on buying these and would like to here comments from other
owners.


To: Mike Dillon

From: Geoffrey M Kotzar

Re: D-Terminator S/N 24241220295



I am returning this balance because it has some very serious problems.


First, the claimed capacity of 95 grams is wrong. The capacity that I measured
was only 70 grams; at 70.10 grams the unit returned an error message.

In the process of determining the capacity I checked the accuracy using an
Ohaus laboratory check weight set. As the unit was supplied the accuracy was
only slightly better than 1%; however, after running the calibration procedure
outlined in the instructions, I obtained the following results:

Applied Weight      Indicated Weight

    0.00                   0.00
    1.00                   0.99
    2.00                   1.99
    5.00                   4.98
   10.00                   9.98
   15.00                  14.99
   20.00                  19.98
   50.00                  49.97
   60.00                  59.98
   65.00                  64.99
   67.00                  66.99
   69.00                  68.97
   69.50                  69.48
   69.70                  69.68
   69.90                  69.88
   70.00                  69.98
   70.10                  ERROR

    0.00                  -0.02

As you can see from the above data the accuracy is close to the claimed level
but the zero shift is very disturbing since it occured in the "grain" mode as
well resulting in overlaods as large as 3 grains.

Second, in working up a load for a .375 H&H using 4350 I found that the zero
would shift as the final half grain of powder was dribbled into the pan. When
the charge was poured out and the pan returned to the tray, the indicated
weight would read some negative value. If the unit was turned off, then
restarted and the same charge returned to the pan it would weigh the original
indicated weight, in my case 76 grains, plus an additional amount equal to the
negative value as well. The largest charge that occurred in this manner was
78.8 grains for a desired "measured" weight of 76.0.

I talked to a technician named Bill a little over a week ago about this and
he said it was due to faulty software for the "tare" function and that if
the unit was started with the pan on the tray, the zero shift would not occur.
I ran a series of tests at two load levels, 1.0 and 76.0 grains of 4350,
following his suggestion and still got the zero shift and attendant overloads.
I reran my tests yesterday and have enclosed the data below. It appeared to
make no difference how the zero reading was established. Since in the previous
tests the actual load level was irrelevant, I have included only data for a
1.0 grain desired load. The negative value in each column is the value returned
after the charge was removed from the pan and the pan returned to the platform.
The device was turned off and restarted using the appropriate mode for the
test being run and the same charge was reweighed which is the second number
for each heading.


                                Condition On Start-Up
Desired Weight      pan off tray    pan on tray      pan off tray
     1.0 gr         "tare" zero      auto zero       "zero" zero

    Run 1           -1.8    2.8     -0.9    1.9      -1.1    2.2

        2           -1.2    2.2     -1.1    2.0      -1.5    2.5

        3           -0.3    1.4     -0.5    1.5      -0.5    1.4

        4           -0.4    1.3     -0.8    1.7      -0.9    2.0

        5           -1.4    2.5     -0.3    1.4      -0.4    1.4


As you can see, the errors appear to occur at random and the negative values
indicating the zero shift agree well with the excess charge weights. Also, the
method of establishing the scale zero had no effect upon the wandering zero.
I suspect that you have a lot of product development yet to do or you need
to improve your quality control.

It is a nice idea at a nice price and I wish you luck on working out the bugs.
However, I am not interested in locking up one of my rifles in the meantime
and would appreciate a refund on this item.



gmk

[MODERATOR:  Interesting indeed!!  Dillon offers a very strong guarantee
on all their products, and so in theory you should be well taken care of
by them.  Geoff, I hope you'll send along some followup reports here and
let us know how they treat you.]

[MODERATOR:  Later Geoff writes ... ]

The settling time for the unit I examined was exceedingly long. It took
4 seconds before the unit indicated a final value. My old beam balance
takes a lot less time especially when dribbling the final few tenths into
the pan. Does anyone know what the settling time is for the RCBS and
Lyman units?

Thanks for the help. gmk