Problem with my scale.

[armyrat1970]

Several years back I bought a Lyman D-7 off evilbay to replace my Lee. Never had a problem with it until last night. I was weighing some boolits I had cast for the 357. They were averaging around 163grs. I got a boolit that was a little heavier. Now follow me on this. I had the large weight on the scale set at 160grs. The smaller weight (or poise) I adjusted as needed. With this boolit I adjusted the smaller poise to 5 (which is max) which should have given me 165grs. This boolit seemed to be just over 165grs. as I had to lift the pan slightly to get the beam to zero. I estimated around 165.2 or .3grs. I adjusted the large weight to 165grs. and adjusted the smaller poise to 0. When I placed the pan with boolit back on my scale, the boolit showed lighter as I had to push down on the pan to get the beam to zero. Estimated around 164.7 or .8grs. What's up with this? Never had a problem with this scale before but have never weighed anything right at say 150, 155, 160 or 165grs. graduations before. I also double checked the scale several times with a boolit that went right at 163.5grs. and everytime I checked it, it came out the same. I don't get it and it has me pulling my hair out right now.
Hell with it for now. I'm 'gonna go cast a few more boolits before it's bedtime for bonzo!

[303Guy]

Probably the nornal and acceptable error a scal of this design would give. It's only 0.12% of the boolit weight. That's more accurate than my electronic scale! Other than that, if the blade pivots and resting 'vee's are dry and maybe dusty, that could happen too. I fitted a vibrator onto my beam scale and I lubed the pivot blades with thin oil. Even so, it's not a laboritory beam balance. It does measure the difference a single granule of powder makes but I cannot put an accurate value on that difference.

[smith52]

I don't think it's abnormal as long as the scale reads consistantly each time. I'm not familiar with this Lyman scale but, if you question it and you still have your old Lee scale, compare the two.
Doesn't your Lyman scale read 1/10th grain increments?

[StarMetal]

I feel it's abnormal. That scale should be able to set to balance the weight of that bullet. First I would clean the pivots and the notches the the counter weights set in. In other words get all the dust off everything. On a few brands of scales that I have owned sometimes the counterweight doesn't exactly lock into the notch I set it at. You sound very knowledgeable so I'm positive you re-zeroed the scale. I have never in my life weighed anything on my scales that would not balance the pointer on zero. When I worked at the chemical plant I cleaned a nickle coin. I weighed it on a lab scale. I wanted to see how close my old Redding scale was. I was impressed.

Clean up the scale and report back. I'm interested in what you found.

One more thing. I found, sometimes, that if I have powder in the scale pan, that if I either touch the powder or the pan, the reading is different, even after I move the beam to let her swing a few times. Only thing I can figure is the powder/pan was picking up skin oil.

Joe

[JSnover]

Armyrat, I see you live on the Gulf Coast. Any chance your scale is on a wooden bench and the temp/humidity swings are throwing it? I only bring this up because it's been on my mind lately to build a levelling plate for my scale. Anybody else ever try this?

[doubs43]

I've owned and used a D-7 for at least 33 years and until I bought a Lyman electronic scale, it was the only scale I owned. Before each use, I zero the scale using the adjustable front foot. I also clean the scale beam's knife edge balance arms and the v-notches they sit in. Further, I try to keep the position of the balance arms in the v-notch consistent. It's been a good scale over the years.

For weighing bullets, I find that the electronic scale is much, much faster. It's also quicker when adjusting the powder measure on my L-n-L progressive press or loading only a few rounds on my single stage press. With the cost of electronic scales now, you may want to consider getting one.

[Rocky Raab]

The basics are that the scale works to balance based on the distance the poise weights are from the fulcrum. If the notches are not cut with perfect accuracy (or are dirty) that can throw off the calibration a tiny amount when you change notches. That's what the OP described.

In this instance, I wouldn't lose any sleep over it. The bullet was either a tenth or so over or a tenth or so under 165 grains. It doesn't much matter considering that bullet was already two grains off the average.

[armyrat1970]

The basics are that the scale works to balance based on the distance the poise weights are from the fulcrum. If the notches are not cut with perfect accuracy (or are dirty) that can throw off the calibration a tiny amount when you change notches. That's what the OP described.

In this instance, I wouldn't lose any sleep over it. The bullet was either a tenth or so over or a tenth or so under 165 grains. It doesn't much matter considering that bullet was already two grains off the average.

Rocky that's understood and it doesn't worry me much as I have never ever dropped boolits that weighed the same. I have measured commercial boolits that are supposed to have good quality control and have found huge variances in weight, length and diameter. My main concern is if I weigh a charge that is right at max and my scale may be off I may get an over pressure charge. Again I never ran into this problem until my small poise was set to max, being 5grs. If I set the main weight on my scale to 40 grs. and then set my small poise to the max of five, and trickle in a charge to get it just right, I may be going over or lighter.
JSnover. I really don't think it has anything to do with humidity. It works fine at other readings. It's just when I set the small poise to max or zero.
StarMetal and doubs43. Yeah I feel it's abnormal also. But you guys bring out a good point. I always clean my pivot points of the scale and balance beam before using but never gave a concern to clean the notches that the weights slide into. Gonna try that.
303Guy and smith52. I do feel it is abnormal. On one side I am showing a difference of .2 to .3 grs. higher and on the other side I am showing a difference of .2 to .3 grs. lower. I am going to clean the notches and everything on the balance beam ad see if it makes a difference. Not with boolits this time though. I will drop and trickle a charge with my large weight set at 165 and my smaller poise set to 0. I will then switch and set my large weight to 160 and my smaller poise set at 5. Should balance the same. I'll see.
Thanks for all the feedback.

[doubs43]

Armyrat, with regards to the weight of bullets, I've posted elsewhere my experience with a 240 grain .44 Mag 4 cavity Lyman mold that cast far too many bullets with weights outside of my 3 grain window. I was throwing 40-50% of the bullets back into the pot. Recently I bought a 6 cavity Lee mold for 240 grain .44 Mag bullets and even with a 2 grain window I'm only throwing back about 14% of the bullets.

Lee used to advertise that they cut all cavities using the same cherry and the consistency of the bullets from their molds may be due to that.

Why am I so particular about bullet weight? I shoot in a competition where only lever action rifles are allowed and the targets are set at 150 and 100 meters. My Puma 92 in 44 Mag is pretty accurate for a lever action and part of the reason is the tight window I keep on bullet weight. For casual shooting, a 5 or 6 grain window is OK but for best accuracy, half of that is better.