Ruger Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
297 Posts
Discussion Starter #1
I have the Frankford Arsenal digital scale that I have been using for about a year now and as of late I've started to notice that during the first five or six rounds it will randomly go out of zero and display a negative weight of -0.2 grains when the powder tray is sitting empty on the scale.

My usual procedure is to place the powder tray on the scale, then turn it on for about a minute, verify that the weight reading is 0.0 and switch to grams. I then use the 50g weight to check its accuracy. Once I verify that the scale reads the 50 gram weight correctly I switch over from grams to grains, once again zero the scale with the empty powder tray and begin weighing each powder charge.

Am I doing something wrong or is the scale on it's way out?

Amazon.com : Frankford Arsenal Reloading Scale : Gunsmithing Tools And Accessories : Sports & Outdoors
 

·
Registered
Joined
·
84 Posts
Have you tried calibrating it per the manual?
DS-750 Digital Reloading Scale |

There is a manual here if you don't have one. They are sensitive to interference, wind, fans, lighting, ect. Maybe close the lid to shield it from air flow and see if it still fluctuates? I have one that was missing the cal wt and they were very helpful and sent me the weight free. If calibration doesn't fix it, or ruling out any interference, I would call or send an email to them and see what they say?
 

·
Registered
Joined
·
3,560 Posts
FOr what it's worth:

Be sure to keep it away from vibration

Be sure to keep them away from florencent lights.

I have a few of those small pocket size scales and a larger RCBS too. The larger RCBS is hopeless if run on AC with the overhead florecent light. It has to be kept at normal room temp. It has to be on a separate table from the press. Other than that, it's a wonderful piece of equipment 8(.
 

·
Registered
Joined
·
1,137 Posts
FOr what it's worth:

Be sure to keep it away from vibration

Be sure to keep them away from florencent lights.

I have a few of those small pocket size scales and a larger RCBS too. The larger RCBS is hopeless if run on AC with the overhead florecent light. It has to be kept at normal room temp. It has to be on a separate table from the press. Other than that, it's a wonderful piece of equipment 8(.
Florecent light??? Why?? I have an RCBS that I run on AC and have overhead fluorescent lights and have noted no anomalities.....
 

·
Registered
Joined
·
407 Posts
Florecent light??? Why?? I have an RCBS that I run on AC and have overhead fluorescent lights and have noted no anomalities.....
Many fluorescent lights create RF noise which will affect strain gauge balance scales. Strain gauges are used in all digital scales priced up to ~$600. Magnetic force restoration and other techniques are available above that ~price point.

Either your fluorescents don't generate RF, or they are far enough away, or you haven't noticed the anomalies.
 

·
Retired Moderator & Gunsmith
Joined
·
16,671 Posts
Twoboxer, I had a Pact BBKII that would go nuts on my reloading bench when I used the AC adapter. The florescent light was the culprit that emanated undesired signals into the scale via the adapter cord. When I used this same scale with batteries (no AC adapter) it would operate normally. Another issue with this scale was a cordless phone. Quite by chance, I noticed when I was on my cordless phone and was within 5 or 6 feet of the scale, it would go nuts and it didn't matter if I was using the AC adapter or not.

I trashed the Pact and bought a gem stone scale that appears to be immune to florescent lights and cordless phones. I also have an older "Cabela's" brand scale that is not affected by florescent lights, however the digital display is too small for these old eyes so I rarely use it.
 

·
Registered
Joined
·
297 Posts
Discussion Starter #8
Sorry for being MIA. A medical problem with our ten year old daughter has occupied most of my mental and physical energy. So I have not had the energy to do much else other than what was deemed necessary such as work, try to sleep, eat, shower help our daughter and that was it. nyway, things are much..much..much better and she is doing well. As a result I did a bit of reloading last evening. I calibrated the scale before using it and it no longer acted erratic.

I did notice that at times my Lyman powder measure would throw more powder than necessary. As an example. For 9MM 124 grain bullets I'm using CFE pistol. My usual load is 5.2 to 5.3 grains. At times the powder measure would throw 5.5 to 5.6 grains (I weigh each and every charge). I found that the bottom slide was slightly open and that could be causing the extra heavy charges. Now that I corrected that I'm going to reload tonight and I'll report back.
 

·
Registered
Joined
·
1,793 Posts
I've had several people who said their digital scales are affected by electrical devices. I've stuck with manual scales for that reason.
 

·
Registered
Joined
·
407 Posts
Twoboxer, I had a Pact BBKII that would go nuts on my reloading bench when I used the AC adapter. The florescent light was the culprit that emanated undesired signals into the scale via the adapter cord. When I used this same scale with batteries (no AC adapter) it would operate normally. Another issue with this scale was a cordless phone. Quite by chance, I noticed when I was on my cordless phone and was within 5 or 6 feet of the scale, it would go nuts and it didn't matter if I was using the AC adapter or not.

I trashed the Pact and bought a gem stone scale that appears to be immune to florescent lights and cordless phones. I also have an older "Cabela's" brand scale that is not affected by florescent lights, however the digital display is too small for these old eyes so I rarely use it.
It's so difficult to pinpoint what exactly is causing any one scale's reaction to its environment. Equally tough is to say or imply that all XYZ devices will disturb one's scale.

EG, (most) switching power supplies (the most common type, eg, wall-wart transformers) generate interference, yet the switching supplies from a PC (most often) do not. So it depends on the quality/composition of the device. And sometimes the rest of the environment.

As you say, fluorescents (particularly their transformers or ballasts), cordless phones, as well as bluetooth devices, cell phones, some audio/video equipment on the same circuit . . . anything that transmits or can feedback is a potential strain gauge scale assaulter. Instead of a flat, constant DC voltage, those signals appear in the power flow to the device. So continuously varying voltages are supplied to a device not capable of handling them.

I've also heard strain gauge scales sarcastically called "RF meters" rather than balances lol. The scale's programming can help a strain gauge somewhat, but sometimes that programming causes problems.

EG, my 4th (or maybe 5th) scale was a GemPro 250 that looked pretty good to me. Ran best on batteries like you said (but ate them like candy). Bought a lab grade power supply to feed it, and the scale looked more stable, ie it held "0" better than others I had.

But the scale didn't trickle well . . . small additions wouldn't register unless the pan was lifted and replaced. After a couple dozen rounds I found the contents were actually heavier (eg 25.5gr) than the scale reported (eg 25gr).

My own theory was that the programming would detect flutter around what should be "0" . . . and adjust itself to "0".

IF TRUE this could build in a cumulative error and explain what I was seeing, requiring re calibration. IF NOT TRUE, something else is needed to explain what I experienced.

Regardless, I bought a magnetic force restoration scale, and my other digital scales, lab grade power supply, etc are now gathering dust. They normally cost $600 and up . . . I believe it's called "buy once, cry once" lol.
 

·
Retired Moderator & Gunsmith
Joined
·
16,671 Posts
Twoboxer, I read a tech article about digital scales a few months ago. In it they discussed the two basic algorithms required to make them work. The cheaper scales typically used for reloading operate with a technique much like a frequency mixer; two frequencies are generated ... one from a fixed oscillator, another from a variable oscillator (platen). The unit then measures the difference of the two oscillators, calculates the weight, then displays it on a LCD. Because strain gauges aren't perfectly stable, the first type has software designed to take a reading, lock the reading in, then display the results. Using this algorithm, any further minor weight change (a couple tenths of a grain) won't change the display but a more significant change will. Digital scales that use this type of strain gauge and associated algorithm are pretty worthless for trickling. Further, if the weight is changed by a significant amount, the scale will likely go into an error mode, which describes my previous Pact BBKII to a tee.

The other type of strain gauge takes continuous readings and displays them WITHOUT locking in a reading. This type of strain gauge and algorithm rarely go into error, are not affected by external emanations, and are great for trickling. This describes my gem stone scale to a tee. The problem with this system is ... just sitting in one place, with or without a weight on the platen, and even with a wind shield, the display will drift a few digits in the right column. My gemstone scale has a resolution of .02 grains and will drift as much as +or- .04gr .... still way more accurate than a typical reloading scale with a +or-.1 gr resolution.

The first type noted above, drifts the same way as the second system only the algorithm locks in the reading to make it appear more stable. Both types are plenty accurate for weighing powder, bullets, or doing tare weights ... it's just a trade off ... apparent stability versus the ability to weigh a changing load. Of the two, I much prefer the second system that will allow trickling.

Magnetic force restoration scales use an algorithm much like the second type above .... except they are exceptionally stable. Prices are high but I suspect they will get more affordable as the manufacturing technology adapts. That said, even a hundred bucks is too much for a reloading scale when a higher quality gemstone (.02gr resolution) strain gauge scale costs a little over 50 bucks and is way more accurate than needed for any type of reloading.
 
1 - 12 of 12 Posts
Top