Lee Auto Drum innaccuracy: fast vs. slow

[jmac2112]

Having trouble with a Lee Auto Drum powder measure.  Essentially, the amount of powder I get depends on the speed with which I work the handle.  This is on a Dillon XL 650, which I usually use with the Dillon powder measure; I'm just experimenting with a Lee Auto Drum that I happen to have lying around.  Anyway, the charge is spot on if I go very slow, but the more I speed up, the less powder I get.  For instance, I'm currently aiming for 4.1 grains of Sport Pistol, but I will get as little as 3.9 if I run the press fast.  The hopper is half full; I haven't tried adding more powder.  Is this just the nature of the beast?  Or could it be static electricity?  I'm thinking of grounding my press, even though there doesn't seem to be any extreme amount of static.  Any help appreciated!

 

Thanks,

 

John

[LHshooter]

I'm new to the Auto Drum but before I recently purchased it I read several posts where people said that if you operated the handle to quickly all the powder would not drop into the case. I have not loaded too much yet, but I operate the ram slowly and pause at the top of the stroke before lowering it. I have had very good success so far with very consistent loads.

I have been using N320 and Titegroup, FYI.

[Miranda]

speed does have an effect of any automatic powder dispenser.

the lee auto-drum... is timed such that there is little open/dump time

at the top of the stroke.

If the dispenser had an over run area where the dump opened sooner

and then stayed open, that would create more time in the stroke for the drop.

I pulled the handle to the bottom and counted one-onethousand

because it took that long to fill the 223 case.

 

If speed of reloading is important, use a different powder drop.

the gears and slides and stops were not designed to take what

a 650 can pound out. I had two extenders on the drop and I like it.

The auto drum came out of the rifle side of reloading,

that works is often done on a single die press

I loaded 223 at more than 400 RPM so the drop is not a slouch.

 

some one here had drum with what I believe was

a broken gear set and I wanted to get a hold of it and try

some ideas.  when I restart my loading I may order a victim to tinker.

 

I have not had any powder cross check fail from the dispenser

the weights are more consistent than with the auto-disk and the dillon

(I did not test 223 dispensing, just pistol)

 

so you can have a benefit if you can stay within design limits.

 

miranda

 

 

 

 

 

 

[jmac2112]

Thanks for the replies!  I should have specified, however, that what really matters is how fast the powder measure is activated, NOT how much time I allow for the powder to drop once it is fully activated.  In other words, if the drum begins its clockwise motion too quickly, that's what causes a light charge.  To me, that doesn't seem to make sense, because the cavity in the drum has had plenty of time to fill.  The only thing I can imagine is that centrifugal force could be flinging the powder upward into the hopper, but that seems pretty far-fetched.  

 

None of this would matter if it weren't for the fact that I have to actuate the drum REALLY, REALLY slowly in order to get the full charge.  "Gingerly" might be the best word for it.  Bizarre.

 

 

[LHshooter]

3 hours ago, jmac2112 said:

 

None of this would matter if it weren't for the fact that I have to actuate the drum REALLY, REALLY slowly in order to get the full charge.  "Gingerly" might be the best word for it.  Bizarre.

 

 

I certainly don't have to operate it that slowly. I'm using a Lee single stage press and I just pull the handle down, pause,  and bring it back up.

A few things I did before running powder was to wash the drum in Dawn detergent and let it air dry. Then I ran about 1 hopper of powder thru the measure. I also read where some people rubbed everything down with dryer sheets to eliminate static. You might try those tips if you haven't already. 

Good luck.

[Farmer]

I did some testing with mine to see if it would vary under different conditions and so far it works fine. I tried shaking it, activating it fast, slow, running the shell up quickly and so far it stays within .1 of what I want. Don’t know if a different powder would change that or not. Was going to try some SP in it so I guess I’ll have to watch it. 

[Miranda]

4 hours ago, jmac2112 said:

Thanks for the replies!  I should have specified, however, that what really matters is how fast the powder measure is activated, NOT how much time I allow for the powder to drop once it is fully activated.  In other words, if the drum begins its clockwise motion too quickly, that's what causes a light charge.  To me, that doesn't seem to make sense, because the cavity in the drum has had plenty of time to fill.  The only thing I can imagine is that centrifugal force could be flinging the powder upward into the hopper, but that seems pretty far-fetched.  

 

None of this would matter if it weren't for the fact that I have to actuate the drum REALLY, REALLY slowly in order to get the full charge.  "Gingerly" might be the best word for it.  Bizarre.

 

 

 

ok, my problem and that solution are not your problem.

 

you are about to start a "how do i flipping fix this problem device"

research project.

 

your problem is filling the measuring cup.

the speed of rotation can't fling powder out because the powder is

supposed to be weighing on the drum and once in motion

the side of the drum keeps the powder.  

To fling needs open space to toss the powder.

because I do not know what is before you,

here are some obvious ideas.

look for obstructions in the intake to the measure and down in the throat

look for the measure being in the correct stop

the mouth of the cup should be a straight shot in there.

your description is most consistant with

the drum not getting to open.  buuut it is possible to overshoot the opening

and you may have a tooth in the gears that is jammed somehow.

 

miranda

[Farmer]

To go along with what Miranda said, make sure you’re getting full stroke on it too. I noticed that the drum doesn’t dump straight down even when at the top of the stroke so it needs all the help it can get. Only other thing I could think of is to check for burrs on all the parts. Maybe there’s something (casting flash) in the mouth of the housing pushing powder out of the cavity when operating quickly. I took my hopper off and watched the operation of the rotor when I first got it to make sure I was getting a full stroke on it. Just an idea. 

[jmac2112]

Thanks for all of the ideas!  I'll apply your suggestions and see what happens.

[Miranda]

when on the press does the adjuster for the measure bump into anything?

 

another idea that crossed my mind.

[jmac2112]

Miranda:  The adjuster is not hitting anything.

 

I grounded the metal part of the powder measure last night (by running a wire to the part of an outlet that is grounded with the green screw), and that seems to have made a difference.  I say "seems" because the weather here has also recently gone from very cold and dry to warmer and more humid.  Whatever the reason is, I am now able to operate the powder measure more quickly without getting a light charge.  If I go nuts with it I can still get 2-3 tenths less than I want, but it's giving me the right charge as long as I go at a moderate pace.  

 

Thanks for all the suggestions, and I will provide an update as things progress!

[Miranda]

hmmmm.

 

only because you got me thinking...

grounding the press has gained you a large improvement.

and

if static is the cause, running the press fast generates enough static

to have the problem rise again.

 

this is what I'd do to test that idea.

use alu foil because it can be placed under the hopper lid

take a strip about 3/8 inch wide and have one end go into the powder

up over the top of the hopper and replace the lid

the other end set against a metal part of the press.

 

that should give the static in the powder a path to lose energy/static.

 

If static is the problem, that should get the last out.

most powder has a graphite coat to fight against a static build up.

 

I use aluminium tape for this, and I started it as a way to

keep the hopper lid a bit more firmly in place.

 

luck

miranda

 

 

 

[jmac2112]

Thanks, Miranda, I'll try that!  I ran across a similar idea recently, which is to take a strip of dryer sheet and put it under the lid so that it dangles down into the powder.  Your idea seems better in that it actually provides a pathway to ground now that I've got the metal part of the powder measure grounded.

 

I have several of these Lee powder measures that I used about five years ago when I first started reloading.  I really started to focus on the possibility of static electricity a couple of days ago when I noticed that one of them still had powder clinging to the inside of the "neck" of the powder measure.  I also ran across the fact that rubbing nylon against other materials (or against itself) is a great way to create static electricity.  Guess what those Lee drums are made out of....  That could explain why I have never noticed this problem with my Dillon powder measure.