RCBS Chargemaster Overthrow

[Rootshot]

This may be repetitive, but I've noticed some behavior in my RCBS Chargemaster I would like to correct.

In a minority of charges there will be a clump of stick powder at the end of the trickler tube. As it trickles to the final charge level, I can see the clump of granules fall out. The trickler stops immediately and registers an on-the-money charge at whatever charge weight that was set. This made me suspicious.

After a visible "clump dump" I lift up the scale pan and put it back down and it reads anywhere from +.1 to +.4gr over the target charge weight. I've now gotten into the habit of lifting and replacing the pan after each charge to verify charge weight before pouring into the case. This is slow and annoying.

Is there a way to re-program the Chargemaster to at least reliably indicate an overthrow condition?

--Rootshot

 

[memilanuk]

Mine does a similar thing as far as trickling up and then a 'clump' falls out. Mine beeps,its set to auto-dispense), displays the correct weight, shows the count, then goes back to display the charge weight... which by then,couple seconds) has registered 0.1 to 0.4gr heavier, as you mentioned. It is somewhat annoying to have to either toss the charge back, or pinch off a few kernels,after a while the ole thumb-n-forefinger get pretty well 'calibrated' as to how much powder is about a tenth or two), but either way, it doesn't take very long.

It would be disturbing for it to do that and *not* display the extra weight.

 

[mikecr]

Mine does the same, Rootshot. You are doing the only thing I know of to do -reset the pan for a real weight reading.
Mine will not read actual weight without disturbing the pan.

There is currently no easy solution for this, or for 'overtrickles'.
When someone comes up with a 'Fine Trickler' or 'Granule Dispensor', I'll buy the heck out of it.

 

[GLC]

I too have the same problem, my solution was to verify every charge on my Mx123, this takes seconds and you then get results to the nearest hundredth of a grain, usually 6 out of 10 charges I will either have to remove powder or add powder.

The charge-master is good for swift dispense but I think you def need another set of scales to avoid the final "lump" and be 100% certain of an accurate reading.

 

[Travelor]

Do you guys have the "new" model with the automatic dispense function? I have gone through what appears to be at least 3 generations of software in four different units and experienced this problem with the first two generations.

My last machine, with the auto dispense function, did not do this. The dispense function works in three stages: First stage is the actual dispense function and the display ALWAYS displays the requested charge; the second stage is a count function and displays the number of charges that have been dispensed; and, the third stage is a weight check of the actual powder charge thrown - this is the check stage and should be giving you the correct weight of powder in the pan. If it is not, then you should contact RCBS.

You may have noted that I stated my last machine DID not .... - it too has become defective. The center number keys and function key of the keyboard have become defective i.e. if I typed the key for the number 2, a 3 was displayed and a similar incorrect display was noted in the 5 and 8 keys. The key for 0 would cancel out all other requested numbers.

So............. my ChargeMaster number 4 is back at RCBS for repair/replacement. If it were not for this last machine working so wonderfully,before the keyboard problem) I would have gone somewhere else. But I truely enjoy the ChargeMaster when it works.

Good luck with your machines. Do a search as there as an old thread that I believe had the project engineer's phone number and name to contact.

George

 

[Rootshot]

Thanks for the replies. Glad to know I'm not the only one.

Yes, I have the newer model that is set to automatically dispense a charge when the scale pan stabilizes at zero. I realize that the mechanical aspect of the over-throw is hard to fix, but I would love to see something draw my attention to an over-charge such as a quick triple beep so that I know that I have to redo the charge or pick out a few granules.

I will call RCBS. If someone has a contact phone number, it would be appreciated.

--Rootshot

 

[BJILEG]

There was a great fix listed in the past on adding a variable resistor to the motor,I added the resistor and was able to slow down the third speed, that caused the error over weight to be reduced 99%

 

[smallblockfuelie]

I would love to hear what RCBS has to say about this.

 

[BJILEG]

The fix was posted on 8/27/05 by micker Mcrawford@ec.rr.com

 

[smallblockfuelie]

Thanks. Yes, I saw that right after I posted my response.

 

[mikecr]

I was an early adopter, so mine is not automatic in dispensing.
The potentiometer mod has worked really well.
I can instantly dial in for best possible operation with any given powder.
Every now & then I'll get an extra granule or two anyway, which equates to ~.03 to .08gr depending on the powder.
So just in case, I disturb the pan after the 'count' is displayed, and see that the scale re-settles to the correct weight. The scale rounds the numbers.

 

[Kevin]

I had approximately 50% overthrows,shows good until after the beep, then shows overweight). I have now got it down to about 1 in 15 overthrows.

My solution,and this has worked for another user as well) is to cut off a drinking straw about 3/4" long and heat one end quickly with a lighter to curl the end so it fits snugly into the threads of the dispenser tube. I leave it sticking out about 1/8 to 1/4". That's it, no wires, no potentiometers, nothing complicated at all.

Trickle time is reduced a little bit, but, the timing works great for me to dispense while I press the bullet, measure length and do a final press to length.

If need be, I can take a picture and post.

 

[Rootshot]

Does anyone have a link to the modification instructions?

RCBS called me on Thursday, but missed me / left a voicemail and will call back on Monday. I'm curious to hear what they say about this.

--Rootshot

 

[gunsandgunsmithing]

I have found that if you cut six notches around the end of the dispenser tube about 1/16" deep with a triangle file that you will have alot less of the clumps to trickle out as you describe.It made mine much more consistant.---Mike

 

[Rootshot]

Well, the gentleman from RCBS didn't call me back, so I did a little hacking on the unit.

I found the post about the potentiometer and I also saw a reply on how to enter the programming menu by pressing "Cancel/Stop" and "Enter".

This produces a number of variables that can be edited by the user:

HSP_A1 15.68
HSP_B1 3.42
BSP_C1 1.08

MSP_A2 39.20
MSP_B2 8.55
MSP_C2 2.25

SSP_A3 196.00
SSP_B3 42.75
SSP_C3 11.32

SEL 65
F_A 50
M_A 35
S_A 6
W_F 200
W_M 100
W_S 36

S_F 12
S_M 24
S_S 128

FR1 40
FS1 16
FR2 80
SR1 32
SS1 8
SR2 40
DEC 0
AT 0

I studied this, made a few guesses on what each does and started tweaking variables. I was observing how it throws 40.0gr of Varget,stick powder).

The HSP, MSP, and SSP groups of variables appear to set speed-weight thresholds for low weight, medium weight, and heavy weight loads respectively. The 40.0gr test load is manipulated by the HSP variable, so this is the one we play with.

The HSP_A1 defines at how many grains under the taget weight, the trickler slows down fro full speed to high speed. HSP_B1 defines how many grains under the target charge that the trickler slows down to slow speed. HSP_C1 defines howmany grains under the target charge the trickler slows down to the slowest final trickle speed. For example, if the target load is 40.0gr and HSP_C1 is set to 2.0, it will enter the slowest trickle speed when the measured charge weight is 38.0,40.0-2.0).

I increased HSP_B1 from 3.42 to 8.0 to increase the time spend on the slow trickle speed with the theory of evening out the powder level in the trickler tube. I also increased HSP_C1 from 1.08 to 1.25 to allow the slowest trickle speed to kick in slightly earlier.

I tweaked a few more variables that I am not positive of.

W_S was reduced from 36 to 12. I *believe* this reduces the rotation of the slowest trickle cycle to 1/3 of the factory. This is hard to measure, but it appears that that the tube rotates less now.

S_S was increased from 128 to 200. I believe this is a scale sensitivity/timout setting for the slowest trickle speed. I *believe* that by increasing this, it allows the scale more time to settle and read the charge before trickling more.

Soooo....after all this tweaking you have to be wondering what the results are. Well, dispensing is slower and the overcharge problem appears to be reduced somewhat. The problem is that "a clump at the end of the tube" is a "clump at the end of the tube" no matter how slowly or carefully your trickle. It still periodically throws heavy charges, but at a lower frequency than before.

Someone else posted a possible fix that involved using a small triangular file to put 6 notches in the end of the dispenser tube in the belief that this will break up clumps. I tried this in combination with the tweaks above. No love. I may but them deeper and try again.

Although hacking is fun, I will try to get some official documentation on these variables from RCBS.

Be careful what you do with this info. I take no liability for you breaking your equipment or yourself.

I may have to try the potentiometer modification next.

--Rootshot

 

[Kevin]

rootshot,
nobody has mentioned my drinking straw idea as a good idea. For that, I'm a little disapointed. At least nobody has knocked the idea. Additional benefits: it also serves to reduce the diameter of the dispenser tube and makes the tube "smooth" on the inside. These two properties inherently make fewer "clumps".

It's free, takes less than 5 minutes and is easily reversible. No permanent modification to software and/or hardware. You might try it.

 

[Rootshot]

Kevin,

I must have missed the drinking straw fix. I'll give that a try too. Given my observations, it sounds like reducing the clumping may be the best long-term fix.

Thanks.

--Rootshot

 

[Kevin]

Kevin,

I must have missed the drinking straw fix. I'll give that a try too. Given my observations, it sounds like reducing the clumping may be the best long-term fix.

Thanks.

--Rootshot

No problem. Let me know how it works for you. Also let me know if you need any pictures.

 

[Rootshot]

Kevin,

Well, I didn't have a straw handy, so I went through my range-brass collection and found that the neck of a fired 7mm Rem. Magnum fits perfectly in the end of the drop tube. I cut it at the shoulder body junction, polished the inside and outside, and stuck the shiny little funnel into the end of the drop tube.

There is definitely an improvement. Clumps don't form easily because of the constriction in the end of the drop tube and the polished inside surface.

Out of 40 charges I threw to test this, 5 were over. This is definitely an improvement, but still not perfect.

--Rootshot

 

[Rootshot]

I saw a similar message thread about the ChargeMaster on SnipersHide.com,http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=277899).

"Scott R" analyzed the problem as being too much powder in the trickler tube at any one time leading to clumps. His solution was to obstruct the powder inflow by using a cut off 308 bullet that he taped in the cutout of the trickler tube where the powder enters.

I replicatd this using a pencil eraser taped into the inlet cutout of the trickler tube. I adjusted the distance to the entry until I saw a noticeable reduction in powder flow. I would estimate the gap between the eraser and the entry point of the trickler tube being about .05-.1". This seems like a small distance, but has little effect on dispensing speed.

Out of 40 charges thrown, 39 were right on the target weight of 45.0 grains. One kept flickering between 45.0 and 45.1 and finally settled on 45.1.

This modification was combied with inserting the smooth brass cartridge neck into the end of the trickler tube as an anti-clump aid.

I reset the dispenser parameters back to factory settings to speed things up. This had no ill effect.

As far as I'm concerned, the ChargeMaster has been accurized / problem solved.

--Rootshot