RCBS Chargemaster 1500 - Inconsistencies

[lazyMlazyK]

I've been using an RCBS Chargemaster 1500 for the last 5 years or so, and it has treated me pretty well overall. I've tinkered with the speed settings , and had it very slowly trickle up the last 0.4gr or so of powder. Time consuming, but pretty accurate. Out of the blue, I started noticing the scale drifting here and there. It would throw to my desired charge, say, 40gr., but if I let it sit on the scale for maybe an hour, it might read 40.4gr when I come back. Then I dump the powder and it reads the pan at -0.3gr....I started verifying the loads from the Chargemaster on a 5-10 beam, and some were a bit off, +/- (usually within the 0.1gr tolerance of the CM).

I close the A/C vent in the room and only have LED lights. I haven't noticed any static buildup like powder sticking to the pan or hopper walls. I normally turn the Chargemaster on a day or two ahead of when I know I'll do some loading, so it has plenty of time to warm up. I've got some of those circular spirit/bubble levels coming in the mail to verify that the scale is level. I know I should probably get a line filter for the incoming power - might look into that today (any recommendations?).

I tweaked with some of the parameters last night to get a bit quicker throw with a shorter trickle time. After that, the powder throws seemed to be more accurate and much more consistent from the Chargemaster verified by the beam scale. I did get to a point last night where, after verifying many powder throws with the beam scale, that I could trust the throws from the Chargemaster, but I also don't want to have this nagging feeling in the back of my head every time that I should verify each load with the beam scale, just in case.

Has anyone else here seen these anomalies with the Chargemaster? Do the FX-120i scales have any sort of wonky issues like I described above?

 

[CharlieNC]

Leaving a charge on the scale for a long time, it may drift because it cannot auto zero as it does between loads when the empty pan is placed on the platen. When this happens try dumping the powder into something and place the empty pan back onto the scale, it should auto zero, then pour that powder back into it to get what should be the proper reading you desire. If not then there is a probem.

 

[lazyMlazyK]

There's no reason for it to auto zero, it's still supposed to measure something. The length of time that the load sits in the pan shouldn't matter. It should read, for example, 40gr. right after the charge was thrown, and 40gr. twenty days later, without having to touch or move the pan, assuming humidity hasn't changed the powder at all. In my mind, that's what a good scale is supposed to do.

 

[6.5 forever]

There's no reason for it to auto zero, it's still supposed to measure something. The length of time that the load sits in the pan shouldn't matter. It should read, for example, 40gr. right after the charge was thrown, and 40gr. twenty days later, without having to touch or move the pan, assuming humidity hasn't changed the powder at all. In my mind, that's what a good scale is supposed to do.

I believe humidity can affect the powder weight when left out.

 

[lazyMlazyK]

Right. My example was excluding the humidity factor.

 

[CharlieNC]

There's no reason for it to auto zero, it's still supposed to measure something. The length of time that the load sits in the pan shouldn't matter. It should read, for example, 40gr. right after the charge was thrown, and 40gr. twenty days later, without having to touch or move the pan, assuming humidity hasn't changed the powder at all. In my mind, that's what a good scale is supposed to do.

Maybe, but that is not the way the CM and other strain gauge scales which I have operate. At the zero and/or tare weight they will auto zero to offset drift. Leave a non-zero weight on them for a "long" time and they will drift, but auto zero again upon removal.

 

[lazyMlazyK]

Hm, interesting. Thanks Charlie.

 

[wkdickinson]

I have been using my CM1500 for about the same length of time as you. I too have reservations about it's "accuracy". I have seen the behavior you describe many times. I usually leave mine on if I intend to use it again within a day or two, but always remove the pan during that time (but don't "zero" it out. The pan I use weighs 138.4 gr., so when I remove it, the scale reads -138.4. When I come back in a day or two, it often reads +/- up to 1.0 gr.

I use both a good quality filtered power strip (Monster Power) and all LED lighting, with no HVAC ducts anywhere near the scale. I have also used it on battery power (probably as "clean" a power source as there is) while dispensing charges and can't see any difference. So I believe the issue is either the strain gauge or the measuring circuitry.

What I am really more concerned about is the "rounding" algorithm being used. I have done a number studies where I took 50 or so charges as thrown by the CM1500 and weighed it on my GemPro 500. They all always averaged within the 0.10 gr +/- spec. However, there were usually 10% to 15% of the individual charges that were outside that range.

I continue to use the CM1500 because I am unwilling to spend the time trickle up each charge and can't bring myself to spend the money for an A&D FX-120i.

 

[lazyMlazyK]

...I continue to use the CM1500 because I am unwilling to spend the time trickle up each charge and can't bring myself to spend the money for an A&D FX-120i.

Thanks for the reply. This is currently where I'm at too....I have so many things in my arsenal that I'd like to upgrade right now, it would be easy to drop $10k on things that may or may not make big differences in my shooting and reloading process. Hard to justify that when what I have works, as long as I take the time to verify it all.

 

[CharlieNC]

I just finished loading another batch for an upcoming Fclass match, and this time reweighed each one from the CM on a finer resolution digital. Done this hundreds, and hundreds of times and this is my general takeaway-

1. The primary means to precision on the CM requires tuning the trickling. While it is easy to slow down via the parameters for improvement, it is also necessary to reduce the diameter of the discharge tube using inserts you can buy or improvise on your own. It doesn't matter if you can weigh precisely if youre trickling with a dump truck load vs a shovel! This comes at the expense of speed, but then you have time to seat a bullet while the CM does its work; just don't cause any vibration during trickling!

2. When trickling, the CM will continue trickling until its measurement first exceeds the desired charge. It doesn't round off. This resolution increment is finer than the 0.1 shown on the display. This ties in with the need to establish the finest mechanical trickling per dump. I compromised with a medium diameter insert, eventhough a smaller was somewhat better but too slow for my needs. If you observe a clump trickling out, good chance the load is on the heavy side.

With these guidelines I find around 80% of the charges are within .05gr spread, and very few outside a 0.1gr spread unless a clump falls through final trickling. For matches I will add/remove a tiny amount of powder to maintain less than 0.1 range (note this is more challenging with larger extruded powder). This doesn't take much time to accomplish.

 

[jepp2]

Has anyone else here seen these anomalies with the Chargemaster? Do the FX-120i scales have any sort of wonky issues like I described above?

If you haven't watched this, you may find it interesting. I ran mine like this for about 3 years. Finally I broke down and got the A&D fx120i. I now use my Chargemaster as my "auto throw" so I get to see on my A&D the weight of every single charge my Chargemaster disburses. Surprisingly, probably 50% are within the 0.02 grs, but some are way out.

 

[lazyMlazyK]

If you haven't watched this, you may find it interesting. I ran mine like this for about 3 years. Finally I broke down and got the A&D fx120i. I now use my Chargemaster as my "auto throw" so I get to see on my A&D the weight of every single charge my Chargemaster disburses. Surprisingly, probably 50% are within the 0.02 grs, but some are way out.

Ha! Yeah, I watched that the other night when I was tinkering with it. That's Cortina's vid, right? Has me thinking about maybe getting into an electric trickler.

 

[Fairchaser]

For $100 you can add a vibrating trickler to your Arsenal. Use the CM to get to within a .1 and then vibrate 5-6 kernels until it just moves to the next .1 grain. Or do like me and speed up the CM to run a low load and then use the trickler on a FX120I to get to your exact load. Either way you will get a very accurate load within 1 kernel of powder. The FX120i may be a little more consistent.

 

[gunsandgunsmithing]

I think that debating whether or not it should read accurately hours or days after throwing a charge is semantics, unless that's how you load your ammo.
Calibrate it and dump a charge, then check it against a different set of scales if you want to. If it's accurate, to your own needs, go with it. If not, then call rcbs. I wouldn't condemn anything as bad unless it's being used like it's intended. Can't please everybody all the time, I guess.

 

[ken158]

I use 2 ferrite chokes on my power cord which stabilized my scale readings.

 

[Jud96]

I’ve recently been battling issues with mine overthrowing a lot. I’ve done the straw mod and reprogrammed it. I’ve made sure it’s level and even slowed down the trickling to try and stop the overthrows. I’m not sure what the issue is.

 

[Liven The Dream]

I went the scale proof room route . Line regulator, LED lights No cell phone .
Never made things 100% ?

Have a FX-120 and V-3 set up.
It will have it's over and under with H-4350 ?? one or two grains .

I am retired just take my time.

 

[CharlieNC]

I’ve recently been battling issues with mine overthrowing a lot. I’ve done the straw mod and reprogrammed it. I’ve made sure it’s level and even slowed down the trickling to try and stop the overthrows. I’m not sure what the issue is.

Does the charge tube rotate too long, or do large clumps fall out to cause the overthrow? I'm betting clumps, which the straw didn't help for me but a small ID insert solved.