Lyman m5 scale drifting

[MislMan]

Maybe place a weight (a quarter coin) on your powder pan and see if the heavier weight calms down the movement.

 

[Bc'z]

With every load: I tap my scale lightly on the beam with the open-end of tweezers like a tuning fork, just enough to make sure the balance is what it purports to be.

I blow on the pan

 

[Coyotefurharvester]

Can the shot in the pan support shift about and cause a shift/movement in the beam?

 

[Straightshooter1]

Well, I'm just about going crazy with this scale. I hope someone can help.

I recently picked up an lyman m5 scale for a great price. And woah, this scale really blown me away with how sensitive, well built, and designed it was. A huge improvement over my m500 rcbs, which you all know.

Anyway, this scale will drift up to a tenth up and down. (2 tenths)
It will be repeatable as long as you carefully lift the pan and set it back down, however, even the tiniest movement while moving the poise, it CAN read off. Not always, but often.

Say I zero the scale, then put a 20 grain check weight on it. That 20 grain check weight will weigh 20.1 grains, or 20.0. Just depends. Maybe 19.9.

Then when the zero is returned, it may read true zero or A tenth up or down.

As you can tell, this doesn't invite itself for accuracy .

I've read many the threads, and anything short of a scale tuner, I just don't know what to do.

Ive cleaned the agate bearings with achohol and took a tooth pick to clean the groove.

Looked at the knife edges under a microscope, used a ceramic rod to remove the fine burr, polished and burnished the edge with graphite.

put a piece of felt below the pointer to cushion drops.

Leved the pan so it reads zero when the beam is level.

Brought the knife edges perpendicular to the beam( they were slightly off).

Ensured the knife edges where centered on the bearings(not touching the retainers).

After all this, and many smaller failed attempts, nothing I tried cured my problem.

Any time the smallest, and i mean smallest amount of movement occurs in the knifes and bearings, it may read off. A little wiggle of the beam may bring in back to the previous zero, but maybe not..

Please help

When I first started using my RCBS M500, I was having same kind of issues after doing much the same thing in taking care of the knife edge and bearing. Over some time and trying various things, I found to get as consistent reading I had to place the pan in exactly the same way at the same start position with the same amount of oscillation. Then I'd trickle up with just a few grains as I watch each grain move the pointer that's under magnification. The process was a bit tedious and wasn't getting the chrono numbers I was after, which led me to go with electronic scales.

 

[thesteelguitarman]

UPDATE:

after hours or tinkering with it, I may be on to aomething.
I spoke with Boyd Allen on the forum. He recommended taking a few swipes off each side. Being sure to maintain the angle and light pressure. Then try.
I did this method for I don't know how many times, and I eventually had a completely resurfaced knife edge, but no difference in performance.

I took it to measure the knifes on my rcbs scale with a a fine tip calipers. The were consistent to the left and right and along the same edge down to the .0005.

I measured the lyman and found this to not be the case. It was .003 off from one side to another, and up to .003 thousands off on the same knife!

I made an illustration to show what they looked like.





I now have each side within .001 and each knife edge within .0005


I now have a total drift of 1/20, or half a tenth.


With a bit more work, I may be able to shrink that number by refining the edge even more. It's a tedious process for sure.

Again, I tried everything else... I think.

How this helps anyone with a scale that just reads all over the place