clever
What small digital scale do you suggest?
- Thread starter Dimner
- Start date
Dimner
I do believe in Captain Crunch.
Last night i broke out my Frankford Arsenal® DS-750 and a scale I forgot I had purchased. As well as the el-cheapo PL-50 (on Amazon sold under multiple names. Mine is the $17 "Fuzion Milligram Scale 50g/0.001g,". Ran the two small scales through a series of tests.
Both matched perfectly with the trx-925 with the 2g weight. 30.86 grains. So then I did a test where I used the 2g weight on each scale every 60 seconds until I hit 5 minutes and then every 5 minutes for the next half hour. Had to keep the FA scale from timing out, so I nudged it every 2 minutes. I did not tare for this entire test.
Both scales passed with flying colors. Except the FA scale at 25 minutes read 30.6 grains for about 5 seconds and switched to 30.8 right before I picked up the 2gr weight.
So then I tried to force the two scales to drift.
I let the scales warm up for 3 minutes. Tared the scale, then weighed.my 2g weight every 5 seconds for another 3 minutes. Ran this test twice on each scale. One with pushing the tare button before weighing every 5 seconds. 2nd test without any tare button except the very first weigh.
And I tell you, it's hard to force a scale to drift. I know when I'm sorting cast bullets both of these scales drift alot. But my test had hardly any drift.
Test 2a - 5 second 2g weight test with no tare
Even with all of this, I'm still tempted to buy that GEM20
Both matched perfectly with the trx-925 with the 2g weight. 30.86 grains. So then I did a test where I used the 2g weight on each scale every 60 seconds until I hit 5 minutes and then every 5 minutes for the next half hour. Had to keep the FA scale from timing out, so I nudged it every 2 minutes. I did not tare for this entire test.
Both scales passed with flying colors. Except the FA scale at 25 minutes read 30.6 grains for about 5 seconds and switched to 30.8 right before I picked up the 2gr weight.
So then I tried to force the two scales to drift.
I let the scales warm up for 3 minutes. Tared the scale, then weighed.my 2g weight every 5 seconds for another 3 minutes. Ran this test twice on each scale. One with pushing the tare button before weighing every 5 seconds. 2nd test without any tare button except the very first weigh.
And I tell you, it's hard to force a scale to drift. I know when I'm sorting cast bullets both of these scales drift alot. But my test had hardly any drift.
Test 2a - 5 second 2g weight test with no tare
- FA DS-750 -- 9 out of 36 results were 0.1gr high. 1 out of 36 results were low.
- PL-50 - 3 out of 36 results were 0.08gr high. No results were low.
- FA DS-750 - 4 out of 36 results were 0.1gr high. No results were low.
- PL-50 - all 36 results were perfect.
Even with all of this, I'm still tempted to buy that GEM20
I have a scale that reads FAST and at even gram loads like 1.000, 2.000, 3.000 ALWAYS reads correct.
In fact, as long as the test weight is within about 4 counts it always reads x.000 grams.
0.997 grams through 1.003 grams always reads 1.000.
1.004 grams sometimes reads 1.000 or 1.004.
This also applies to Grain loads that are at or near the even gram.
It's not bad at in between loads doesn't seem to drift much.
A to D converter/software probably has missing data points but is strange that the problem exists @ 1, 2, 3 - - 20 grams. Like the scale has a 1 gram repeating LOOP.
ALWAYS test sensitivity to SMALL changes, maybe with a kernel or two of Varget.
In fact, as long as the test weight is within about 4 counts it always reads x.000 grams.
0.997 grams through 1.003 grams always reads 1.000.
1.004 grams sometimes reads 1.000 or 1.004.
This also applies to Grain loads that are at or near the even gram.
It's not bad at in between loads doesn't seem to drift much.
A to D converter/software probably has missing data points but is strange that the problem exists @ 1, 2, 3 - - 20 grams. Like the scale has a 1 gram repeating LOOP.
ALWAYS test sensitivity to SMALL changes, maybe with a kernel or two of Varget.
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For years I used a Dillon digital scale that I bought in the late 90s. Along the way, I've tried some of the RCBS and Lyman systems that would automatically trickle out the correct charge, but I always found that they tended to drift and loose their zero a LOT. A couple of years ago my Dillon scale died on me. I was in a pinch, so I bought a cheap 50gram digital scale from Amazon for around $20. It runs on a pair of AA batteries or off of a USB adapter, but I found that it's a lot more consistent when using the AA batteries. I suspect that's because the power coming in on the USB isn't very clean. It turned out to be the fastest and most accurate scale I've ever used. It's accurate to around +/-0.02gr. I took a sharpie and wrote the weight of one of my pans on the pan, and check the weight every time I pick the pan up off the scale. I'm not going to say that its on par with the expensive lab grade scales, but its far better than +/- 0.1gr that most digital powder scales are advertised to have. For the price, I decided to buy a 100gram version as a spare. I found similar issues with it with regards to using a USB adapter to power it. I also found that the accuracy was only half as good as the 50gram version which makes sense as I'm sure they are using the same 4-20ma or 0-10v analog signal for both applications. So my recommendation would be to go spend $30 on Amazon for a 50gram drug dealer scale 
Full bridge load cells used in many scales usually have an output of around 3mv per volt of excitation. To eliminate MOST temperature effects in the electronics a ratiometric measurement is used. A STABLE voltage source is used to control both bridge excitation and AtoD reference (not separate sources). Reference goes up, or down and the ratio is maintained.
Loads cells can be somewhat temperature compensated but the Zero state is the most effected zone. Many scales will have a good bit of preload with platens to get some load on the load cell. Temperature must be stable or the compensation is chasing a moving target Air temperature is not always the best indicator of actual load cell temperature.
Perform a zero and full scale will probably be long term stable.
Tilt and a change in geographic location will impact full scale calibration.
Loads cells can be somewhat temperature compensated but the Zero state is the most effected zone. Many scales will have a good bit of preload with platens to get some load on the load cell. Temperature must be stable or the compensation is chasing a moving target
Air temperature is not always the best indicator of actual load cell temperature.Perform a zero and full scale will probably be long term stable.
Tilt and a change in geographic location will impact full scale calibration.
Dimner
I do believe in Captain Crunch.
I'm learning a ton in this thread. Both from the wonderful information provided and the testing I'm doing.
I loaded some fire forming loads with the PL-50 last night. Man that scale is jumpy! Very fast and sensitive. The load weight I was going for was 36.00. To reach that weight was very difficult for the scale, I'm guessing due to rounding issues. Using Shooters World Precision, a smallish extruded like varget, I would pour and then trickle the powder. I would either end up on 35.98 or 36.02. I'd remove the pan and replace it to verify the weight. Doing this a couple times I would either add or subtract one granule or powder and then pour into the case.
After every 7th round loaded I would tare the scale, make sure the 2g check weight was 30.86 grains, place the pan and tare the scale, then place the check weight in the pan. Doing this made sub groups of the 25 rounds.
After 25 rounds, I checked the results with the TRX-925. I found the results really interesting.
Each sub group was very consistent +/-0.02gr between the 7 rounds. However when comparing the weights of subgroup A to Subgroup B, the powder weight was nearly .08gr different.
It seems as though, re-taring the scale made my powder weights vastly different. I have no idea why. I tried another 25 rounds and tared the pan before each single powder throw. Results were all over the place. I know this is a lot of detail and boring to most, but maybe someone can help explain what is going on?
I loaded some fire forming loads with the PL-50 last night. Man that scale is jumpy! Very fast and sensitive. The load weight I was going for was 36.00. To reach that weight was very difficult for the scale, I'm guessing due to rounding issues. Using Shooters World Precision, a smallish extruded like varget, I would pour and then trickle the powder. I would either end up on 35.98 or 36.02. I'd remove the pan and replace it to verify the weight. Doing this a couple times I would either add or subtract one granule or powder and then pour into the case.
After every 7th round loaded I would tare the scale, make sure the 2g check weight was 30.86 grains, place the pan and tare the scale, then place the check weight in the pan. Doing this made sub groups of the 25 rounds.
After 25 rounds, I checked the results with the TRX-925. I found the results really interesting.
Each sub group was very consistent +/-0.02gr between the 7 rounds. However when comparing the weights of subgroup A to Subgroup B, the powder weight was nearly .08gr different.
It seems as though, re-taring the scale made my powder weights vastly different. I have no idea why. I tried another 25 rounds and tared the pan before each single powder throw. Results were all over the place. I know this is a lot of detail and boring to most, but maybe someone can help explain what is going on?
It is possible the ZERO is a band a couple counts wide.
Scale senses you are close to zero and displays, yup, you guessed it, ZERO.
Maybe don't zero at zero, but some small weight.
Tare pan, add the 30.86gn 2 gram weight, in the pan.
Should read 30.86gn.
Add 36gn of powder, hopefully reading 66.86gn.
Dump on the TRX.
It is also possible that pressing on the Tare button is felt inside or disturbing level.
The scale in the youtube video I posted had a +/- dead band on even gram loads.
Test some pennies or dimes between the little 4 button black scale and your TRX.
Scale senses you are close to zero and displays, yup, you guessed it, ZERO.
Maybe don't zero at zero, but some small weight.
Tare pan, add the 30.86gn 2 gram weight, in the pan.
Should read 30.86gn.
Add 36gn of powder, hopefully reading 66.86gn.
Dump on the TRX.
It is also possible that pressing on the Tare button is felt inside or disturbing level.
The scale in the youtube video I posted had a +/- dead band on even gram loads.
Test some pennies or dimes between the little 4 button black scale and your TRX.
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I have a scale that was advertised as 0.001 gram resolution.
Ha 0.002 in gram mode, 0.05 in grain mode, but does have 0.005 carat resolution which IS one milligram resolution.
0.02% per count @ 10 g---- 0.01% per count @10 g---- 0.032% per count @ 10 g
Ha 0.002 in gram mode, 0.05 in grain mode, but does have 0.005 carat resolution which IS one milligram resolution.
0.02% per count @ 10 g---- 0.01% per count @10 g---- 0.032% per count @ 10 g
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He says he is going to the cabin. Does this mean he is just going to pop off rounds in the woods? Save yourself $100 and reload at home before you go to the cabin. If you buy a cheap scale you will probably never use it again when you get home. You said you could reload at a friends house when at the cabin. I assume he has the equipment.The OP was gonna use this for a traveling scale, so a beam scale wouldn't be near as handy if you ask me -- which ya didn't. It doesn't seem to be a critical precision situation, and after all, everybody isn't Rocketvapor.
Lyman has a few basic electronics that I've got that are consistent for my purposes, and I believe I weigh +/- 0.1 quicker than I can with my beam scales.
Question??-- It seems like I've heard that the small scales are more accurate operating on the battery than with the power cord. Any truth to that?.. jd
Using a Good scale at home, or a Cheap scale at home it's always good to really evaluate your weighing process to see if errors are the scale, the weighing environment, or the Weigh Master. Some error SHOW, some DON'T.
I guess what you don't see is OK
Moving to another location adds even more uncertainty.
I guess what you don't see is OK
Moving to another location adds even more uncertainty.
One small Nerf Brick coming at ya
I don't know if it's so much of an obsession with exact weights but maybe an obsession KNOWING how your weighing process is performing.
Those that spend the money for a GOOD balance probably expect performance to specs. Buying a cheap scale is a crap shoot. Some might be good, some not.
I think proving performance has merit.
If you only need +/- 0.1 grain, then watch your target.
I don't know if it's so much of an obsession with exact weights but maybe an obsession KNOWING how your weighing process is performing.
Those that spend the money for a GOOD balance probably expect performance to specs. Buying a cheap scale is a crap shoot. Some might be good, some not.
I think proving performance has merit.
If you only need +/- 0.1 grain, then watch your target.
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Dimner
I do believe in Captain Crunch.
Yeah for me l, my testing and what not has to do with gaining confidence in the cheap scale for my purposes. Turns out the scale does heat when I do not use the tare function.
However, I got burned.by playing around with it too much. I found that the PL-50 has a calibration mode. So I ran it through that mode. It calls for a 50gram weight. I drop the weight on the platter and it says PASS. I got grains and try my 2 gram weight and it now shows. 31.96 grains. Dammit! So I try the 50 gram weight on the gram setting... 49.759 grams. Wait, what?
So all my readings are now skewed and not accurate. I think I trashed this scale.
Also @Webster , I'll reload at the cabin because it's something I like to do. I'll bring my stuff to my friends because all he has are lee dippers for powder measurement. Not sure why you assume my friends place is anywhere near the cabin. They are separate locations an hour between.
However, I got burned.by playing around with it too much. I found that the PL-50 has a calibration mode. So I ran it through that mode. It calls for a 50gram weight. I drop the weight on the platter and it says PASS. I got grains and try my 2 gram weight and it now shows. 31.96 grains. Dammit! So I try the 50 gram weight on the gram setting... 49.759 grams. Wait, what?
So all my readings are now skewed and not accurate. I think I trashed this scale.
Also @Webster , I'll reload at the cabin because it's something I like to do. I'll bring my stuff to my friends because all he has are lee dippers for powder measurement. Not sure why you assume my friends place is anywhere near the cabin. They are separate locations an hour between.
Dimner
I do believe in Captain Crunch.
Cuz it's raining outside and I'm procrastinating doing laundryAnd much of the obsession with exact weights borders on the ridiculous.
Ducking the bricks headed my way (weigh??)...
Good shootin' -Al
A milligram scale, even good ones will likely NEED calibration before first use.
Unless you have the same local gravity as Canada, Japan, or even China where it was first calibrated. If your scale does not have a bubble level how can you place it level? How do you monitor scale temperature?
Sounds like this scale may be a lost cause.
Unless you have the same local gravity as Canada, Japan, or even China where it was first calibrated. If your scale does not have a bubble level how can you place it level? How do you monitor scale temperature?
Sounds like this scale may be a lost cause.
For grins and giggles here is a test I ran on the GEM 20 when I first received it.
The test was to see what kind of repeatability the scale would have in two cases. One was zeroing the scale before each weighing and the other without zeroing before each weigh. The test test weight was a Nosler 60 gn Ballistic Tip.
Statistically the mean weight variation is statistically significant by Welchs T-Test but the standard deviation is not statistically significant by the F-Test. It is important to note that the mean difference is less than the scale resolution of 0.02 gn.
It is not possible to know what drift may occur in the scale when the drift is less than the display resolution. This is was to determine if this scale is subject to drift and if re-zeroing prior to each weigh would reduce the possible error. When the individual weigh points are plotted it appears that the weight in not zeroed case did decrease with time while the Zeroed case remained consistent as shown below. This is anecdotal evidence based on one test that the scale may be drifting. As a result I tare the scale before each weigh.
The test was to see what kind of repeatability the scale would have in two cases. One was zeroing the scale before each weighing and the other without zeroing before each weigh. The test test weight was a Nosler 60 gn Ballistic Tip.
Statistically the mean weight variation is statistically significant by Welchs T-Test but the standard deviation is not statistically significant by the F-Test. It is important to note that the mean difference is less than the scale resolution of 0.02 gn.
It is not possible to know what drift may occur in the scale when the drift is less than the display resolution. This is was to determine if this scale is subject to drift and if re-zeroing prior to each weigh would reduce the possible error. When the individual weigh points are plotted it appears that the weight in not zeroed case did decrease with time while the Zeroed case remained consistent as shown below. This is anecdotal evidence based on one test that the scale may be drifting. As a result I tare the scale before each weigh.
The low range (instead of 50 or 100grams) and the small load cell (low mass) for a milligram scale makes it good for trickling. Try your bullet and add 1, 2, 3, kernels of Varget to simulate final trickle to charge.
The "One Kernel of Varget" is the universal test of scale sensitivity.
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