Beam scales accuracy

[BeemerMark]

This isn't about how accurate a given reloading beam scale is, the question is how accurately can it be read. I have a RCBS 505 that I've owned forever and (it's getting rather beat up) am looking for a new beam scale. One frustration I've always had is reading the pointer. 0.1 grains barely moves the pointer a hair breath from the scale center. So unless I hold my breath, squint with one eye and make sure my eyeball is level with the pointer (to avoid parallax) it's difficult to tell if the pointer is exactly in line with the scale center line. I'm looking at the classic Ohaus M-5 which has a vernier scale but what are the hash marks equal to? 1 grain? 0.1 grain? 10 grains?

I load pistol cartridges predominately and most loads are less than 10 grains. Another peeve of mine, if you have ever dealt with any type of instrumentation you know the most accurate (and easy to read) is an instrument where the maximum values read is equal to the maximum value you want to read. So except for maybe the 458 Lott or 50 BMG the maximum scale for any powder would not exceed a maximum scale of 100 grains not 500 or 1000 grains. For a pistol scale 25 grains would be enough.

[HangFireW8]

Sensitivity is the measure of how easily a scale moves. It needs to be less then the intended accuracy of the scale. On an older scale, sensitivity can be restored by sharpening the knives, and/or replacing the stones they sit on.

I have a 505. The 1/10 over/under markings are not spaced a hairs width apart on mine. Also it is 20 years old and still less than 1/10 sensitive. But then I dismount the beam after every use and store it in a purpose made box.

Scales that sit mounted will inevitably have something placed on top which will peen the knives. That happened to my previous scale, a Hornady. It was repaired for free, or at least for the cost of outbound shipping. That is when I got educated on beam scales.

[greenjoytj]

Ohaus M-5? A Google image search shows me that the Ohaus M-5 is the RCBS 1010 beam scale.
I knew that Ohaus made the 1010 for RCBS, but I did not known Ohaus sold it under their own name. The RCBS 1010/ Ohaus M-5 was a great scale and being such a nice all in one package/case design sold me on it many years ago. The current RCBS M1000 mechanical scale looks ungainly and I doubt it has a nice hard shell cover to enclose it for protection of its delicate parts.
I use a large hand held magnifying glass to zoom in to read the scale.
A beam scale is good to own, but for practical use I’ve moved on to digital scales.

Currently I’m using a twin set of RCBS 1500 digital scales, one on the dispenser the other as a stand alone to verify the dispenser scale.
Typically a dispensed charge won’t weight the same on both scales, one scale will read light.
Trickling in 2 to 3 individual granuals of powder will then make the pan with the charge read the same weight on both scales.

Maybe the knives on your scale just need a little touch up with a ceramic stone, clean out dust from the bearings. Be sure it’s used on a level surface with nothing that can make or hold a static electric charge. Use a magnifying glass.

[country gent]

I have used a piece of 6" metal machinist scales to make a new scale for the pointer to read against Most of these can be found that have 1/8,1/16 1/32 and 1/64 graduations. Or metric. My 5-10 and 304 only have 0 lines no graduations. Double faced tape does a fine job of holding the scale in place.
I have found some of the old oil dampened can be quite sensitive more so than the newer ones.
Some of the newer digitals are reading to .02 grns instead of the .1 grns now and can be quite accurate. Last are the old analytical balances that are as accurate as the weights used to set them.

One thing the more sensitive the scales the more suseptable to air currents vibrations and out side interference it is. My good digital scales is actually influenced by the furnace air conditioner if not place carefully. My old redding also.

[Mike W1]

To aid in both seeing and having a level surface I built this little contraption. Lead weighted and 4 adjustable legs along with the magnifying glass. Seems to work well as check weights are always right on.

[Catshooter]

I like that Mike, that's clever.


Cat

[jime444]

Used beam scales for years. I then worked in the digital scale industry. Buy a decent digital scale, leave it powered up, find a good place to store it(safe, no drafts, interference issues) calibrate/zero it before use, you’ll never use a slow, difficulty beam scale ever again....... technology is your friend.

[Tatume]

How much variation in charge does it take to show on target? I don't have my notes handy, but I was surprised at the magnitude my own experiments indicated. This was when I switched from weighing every charge for my match ammo to dispensing powder with a volumetric measure.

[NyFirefighter357]

These are easy to read

[Chev. William]

I have two RCBS Beam scales: the First one purchased is a "5-10" and has a capacity of ~500 grains; The second one purchased is a "10-10" and has a capacity of ~500 grains. Both have the 1/10 grain set with a threaded rotating Drum with ten marked divisions on it outer surface.
These graduations are spaced out enough so I can Interpolate between marks to set the two Scale to about +/- 0.02 grains repeatably.
The major difference is that the "10-10" incorporates a removable plastic storage cover to keep most dust off The components when stored.

Over the years I have tried buying a couple of Electronic Scales and even a traveling dual pan balance.

However; I have NOT found any 'check weights' marked and calibrated in even 0.1 Grain increments, let alone 0.01 grain increments. The closest I seem to find are
1 grain and 1/10 GRAM increment 'check weights'.

Full scale verification is easy with the sets I have found but Low range is NOT, and I desire better than 1.0% accuracy in measuring 0.5 to 3.0 grain powder charges.

Not yet Economically available in my price ranges.

Chev. William

[jsizemore]

I've got a RCBS 304 scale. Built a wall hanging cabinet with various compartments. The space for the scale is at eye level. Since it's not on the bench it doesn't get influenced or jarred by the action of the press. Since it's at eye level there's no parallax. Cabinet is dadoed, glued and screwed. Items in the other cabinet compartments keep it damped. Sealed door over the scale keeps the dust out. Well, the biggest part anyway. I built it out of cabinet grade plywood 25+ years ago. Still doing it's job.

[beemer]

I was looking at scales a while back and most of what is offered looks to be cheaper made than the older ones, probably made in China. As far as I know Ohaus doesn't make beam scales for reloaders.

I believe the 505 you have is a 3 poise, that is what I prefer. The M5 is a 2 poise with the grain scale in 5 grain increments and the small poise up to 5 grains in .1 increments.

I found a RCBS 502 and a Ohaus Dial-O-Grain at an estate sale really cheap so I am set. The 502 doesn't have a scale for the pointer and I had to get used to the 2 poise beam but they work well. Mike W1 has set his up his at eye level, that really helps.

Lyman sells a set of check weights that start at .5 grain and go up. They might not be scientific quality but are good enough for my purpose. I use them to check new scales and myself till I get used to the lay out. I have checked 8-9 scales with these weights and very few are perfect through the entire range. Most were good at the low end with some being around .1 variation between scales.

I do like to keep 2 sets to check against each other. After looking at most of what is offered I would try to find a nice set of older scales. If your old scales are still functional maybe they can be cleaned up and recalibrated and kept for a spare.

Beemer

[kokomokid]

Get a cheap prism off e-bay and you can see level on the pointer from above it.

[Catshooter]

Chev,

The leveling screw of your 10-10 has a hollow top. That is there to hold a small weight that came with the scale when it was new. At the very end of the beam you'll notice a funny little stud poking out about 3/16ths. That's there to hang the weight off of. When you do your scale now weighs to 1,000 grains by doubling all the values.

Just FYI.


Cat

[Tatume]

Chev,

The leveling screw of your 10-10 has a hollow top. That is there to hold a small weight that came with the scale when it was new. At the very end of the beam you'll notice a funny little stud poking out about 3/16ths. That's there to hang the weight off of. When you do your scale now weighs to 1,000 grains by doubling all the values.Just FYI.

The last statement is incorrect. Using the weight adds 500 to the indicated values. Here is a PDF of the instruction sheet.

http://rcbs.com/RCBS/media/RCBSMedia...structions.pdf

[redhawk0]

To aid in both seeing and having a level surface I built this little contraption. Lead weighted and 4 adjustable legs along with the magnifying glass. Seems to work well as check weights are always right on.

Very clever...I like this idea.

I have a RCBS 505 (two of them actually)...mine will move almost full stop high or low when I move a 1/10 grain. I suggest you take a toothbrush and clean the dust out of the pivot point and make sure the triangle lever points are sharp.

If you are looking on Ebay for an Ohaus...just be aware that not all Ohaus scales are in grains...some are grams...so be sure to get the right one.

redhawk

[pworley1]

I have several beam scales and also several digital scales. After trying the digital scales I have now gone back to the M-5 scale. I guess I am just too old school to enjoy using the digital scales.

[Catshooter]

Thank you Tatume for catching my mistake. And here I thought I was perfect in every way!


Cat

[kungfustyle]

Look for relative distance. .01 grains off on a 49 grain charge of 4895 isn't going to affect the ballistics much. Heat and humidity can have more effect than .01 variance. Just look where the pointer is pointing and keep it there with each load. I got a Chargemaster lite and love the thing, however, I still use my beam scale to check the weight electric scales can be very finicky.

[country gent]

I have a few scales now and check them against each other occasionally, also several sets of check weights for this also. When setting a scales to a given charge ( especially the old redding that's 5 grn increments) I use the check weights like we did gage blocks in the shop. I get a "group of weights" that totals the charge or very close to it and then weigh them on the set scales, just to be sure of the setting and scales. On my digitals its nice to know they are reading an actual 42 grns as 42 grns.

The oil dampened scales sensitivity can be adjusted a little by the weight / amount of oil in the scales, but the lighter the fluid the longer it take to settle. SOme of the old herters scales had a little dampening lever that stopped the pan swinging and slowed ocilations a lot.

For check weights of a often used charge a weight can be fashioned from any soft metal or even epoxy and set to the weight desired. Lead is easiest it can be weighed in solid form slightly heavy and a small wood mould made. issue a flat ground drill bit to drill a hole deep enough to hold it all plus. Melt the lead and pour let cool and set to weight with a file on the bottom, then stamp weight in it.