Beam Scale Precison - Part 2 - video added

[orkan]

Some of you may have seen the thread where I use a webcam to zoom in on the needle on my beam scale, allowing me to get more precision out of it.

The first thing I noticed on my RCBS 5-0-5 was that the needle doesn't overlap the zero marker. There was a good 1/8" or so space between there. This made it quit difficult to see exactly where things were. I had to "eyeball" it to see if they were straight across.

I've solved that problem by extending the indicator on the scale. I took a standard sewing needle, and cut it to 0.45", and glued it on to the beam.

By adding more weight on the end of the beam, I had to add a little weight on the opposite side. The RCBS pan tray has a built in ballast. Just unscrew the tray, and underneath you'll find the ballast. I opened up a shotgun shell and dropped 3 pellets of 7 1/2 shot. That was all that was needed to get back to zero.

I then checked my work with my digital scale that has a resolution of 0.04gr. My charges were dead on.

This allows me to throw powder and level out a little faster, and I can see very plainly, every single granule of varget I drop in the pan. I would think this would be a good mod for you, even if you don't use the webcam approach.

 

[gunman_7]

Re: Beam Scale Precison - Part 2

I always wondered why no one has come out with a beam scale that would be like two feet long, wouldn't it make it much more sensitive, therefore more accurate? Or am I wrong in this assumption?

 

[orkan]

Re: Beam Scale Precison - Part 2

In the case of the 5-0-5 the problem wasn't the length of the scale, but the space between the needle and the level indicator. Making them overlap, gives you a contrasting background so you can easily detect the most minimal change.

With this setup, if I move my hands too fast within a few feet from the scale, it moves. I'd say that is precise and sensitive enough! I just couldn't see the movement before.

 

[Winchester 69]

Re: Beam Scale Precison - Part 2

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gunman_7</div><div class="ubbcode-body">I always wondered why no one has come out with a beam scale that would be like two feet long; wouldn't it make it much more sensitive, therefore more accurate? </div></div>
It wouldn't do anything for accuracy; that's in the trueness of the scale and the finish of the bearings. The damping might show variation. What it would achieve is <span style="font-style: italic">apparent</span> greater resolution, if you need something like 0.01 gr. delineation.

 

[orkan]

Re: Beam Scale Precison - Part 2

I shot a bit of video last night. I could have made the needle a little shorter.

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/ZCs0Y7HH2zA"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/ZCs0Y7HH2zA" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

 

[johngfoster]

Re: Beam Scale Precison - Part 2

Have you noticed variations with your scale while weighing the same charge? I've been having trouble with my 5-0-5 where I'll weigh a charge, trickle it to exact weight, then continue with more charges. I then will go back to weigh the 1st charge and it is off by a largely noticeable amount. I'll then re-zero with my 50gr weight, re-weigh the first charge, and it'll be off again. I then re-re-zero and I have to adjust the scale again to get it to read right on the line. Very frustrating. I've tried wiping everything down with an anti-static wipe, avoiding flourescent lighting, avoiding any other electrical equipment/motors/magnets in the area, but I'm still having trouble. I like your idea of the needle mod to increase precision.

 

[orkan]

Re: Beam Scale Precison - Part 2

I haven't noticed that at all. I have a My Weigh Gem Pro 250 digital jewelers scale that is rated to 0.04gr that I check my throws with. I'll double check every 10th or so. So far, since I made these mods I'm never off by more than 0.05, which if I take into account any possible error on the digital scale side of things, I couldn't be off by any more than 0.1gr max, which is what I was looking for when I started this whole process.

 

[Winchester 69]

Re: Beam Scale Precison - Part 2

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: johngfoster</div><div class="ubbcode-body"> I've been having trouble with my 5-0-5 where I'll weigh a charge, trickle it to exact weight, then continue with more charges. I then will go back to weigh the 1st charge and it is off by a largely noticeable amount. I'll then re-zero with my 50gr weight, re-weigh the first charge, and it'll be off again. I then re-re-zero and I have to adjust the scale again to get it to read right on the line. Very frustrating. I've tried wiping everything down with an anti-static wipe, avoiding flourescent lighting, avoiding any other electrical equipment/motors/magnets in the area, but I'm still having trouble. </div></div>
Have you tried cleaning the bearings and pivot with alcohol?

 

[C.K]

Re: Beam Scale Precison - Part 2

Give Scott Parker a call 661.364.1199, he'll tune it up.

 

[orkan]

Re: Beam Scale Precison - Part 2

What does scott do to them?

 

[C.K]

Re: Beam Scale Precison - Part 2

I quoted this from a different post, I bought a scale from scott a while ago (redding) after my tunned rcbs was given to a friend.
"Scott Parker can modify balance beam scales to enhance sensitivity and more importantly, repeatability. Scott tells us: "You can literally count kernels with these scales--after tuning, the scales typically gain a half order of magnitude in sensitivity and a full order of magnitude in repeatability. Outside of a $250+ laboratory scale, a tuned beam scale is the most accurate and precise balance you can buy. I have tuned several 10-10s. They all have turned out very sensitive, consistent and hold linearity like a dream. The sensitivity after tuning is such that one kernel of powder registers a poise beam deflection. For repeatability, I remove the pan and replace it for the zero 10 times. The zero line and the poise beam balance line must coincide for each of those 10 tries. I then set the poises to read 250.0 grains. I remove and replace the pan 10 times with the calibration weight. For repeatability, the poise beam balance line must return to that same balance point ten times. I then adjust the poises back to zero and recheck the zero. A report is generated detailing the initial inspection of the balance, the corrective actions performed and any remaining concerns. I sell Ohaus type 10-10 and model 5-10 scales for $70.00 + shipping. I can also modify your existing 5-10 or 10-10 scales for $20.00 + shipping. Email me at [email protected] or call (661) 364-1199."