Math geeks- HELP!

[Bret4207]

Okay all you edjakated types, help me out. Lee makes their lovely little powder dipper sets and inlcudes a slide rule type load chart. Now, I also have a B+M Visible powder measure with micrometer drop tubes. Other than actually weighing out powder charges, is there a way to interpolate the Lee chart to the B+M tubes? Or rather, how would I go about it? It seems to me that since both work on a volume basis, I should be able to find a formula to do this.

Where do I start?

[lathesmith]

I am not familiar with the B+M powder measure, but the Lee measures include a powder/volume chart. As long as you know the volume of the B+M setup it should be no problem to convert grains per volume.
lathesmith

[45 2.1]

Current Lee dippers (the yellow ones) are measured in cubic centimeters. Your B+M drop tube needs to be measured: find its internal diameter accurately in centimeters (1 centimeter = 10 millimeters). Divide that by two and multiply that number by itself then times 3.142. That will give the area in square centimeters of the inside of the drop tube. To duplicate the Lee dipper volume or charge: Divide the Lee dipper volume (its number on the handle) by the area obtained above. This will give the depth in centimeters to set your drop tube to.

[Scrounger]

I thought of a couple of ways to do that but just trying to explain them would be a real bear. I personally don't think it's worth getting into but YMMV.... I would simply use the tried and true method of recording the meter setting when I found a load that I wanted to repeat. After X number of loads you will start getting a feel for setting the micrometer for whatever key point you want. Unless you simply have too much time on your hands and you want to turn a simple operation into a project. I'm glad I'm lazy...

[mooman76]

What Scrounger said. Plus the fact that Lees chart is inaccurate. I have used the dippers and the charges always weight lighter than the chart says. I believe it is a saftey factor for people that use the dippers but don't have scales.

[44man]

Use the measure to throw a close charge and the Lee dipper to dribble to the weight you want. I would not use the dippers to load my rounds. There is no way to be consistant with them.

[MtGun44]

Bret,

My guess is you want to use the Lee chart to get you "in the ball park" with
a new setup on the B&M. If you measure the ID of the B&M tube, and the
total range of travel available and send them to me, I'll work you up a little
table of settings (distance or depth) on the B&M slide that represent the
Lee dippers. I will need a list of the Lee dipper volumes so I can calculate
each one, so you can set the B&M to the equivalent volume, and expect to
get somewhere close to the amount of powder in the Lee chart.

I'm out of town in Va on Thanksgiving holiday, but will work it in as I can find
the time.

So - ID of B&M tube, min and max travel of B&M slider, and a list of the
"cc" sizes of you Lee dippers. You can PM me if you want.

Bill

[Ricochet]

I would not use the dippers to load my rounds. There is no way to be consistant with them.

I disagree. You can get very consistent weights with the dippers, just as you can with a mechanical measure. You have to use consistent technique with both. The amount thrown by a dipper will vary considerably with the technique you use. So will an RCBS Uniflow, depending on how you work the handle. There are powders prone to clogging and bridging that scare me to use in the Uniflow I have. Takes great care to make sure charges don't get loaded up that are way light or heavy. And some simply won't measure reliably through it. But they work fine in the dippers with the level in the cup kept roughly constant, a uniform dip, and a uniform strikeoff with a knife blade after dipping. That doesn't shear stick powders like the Uniflow, either. The only powders I'm happy using in the Uniflow are Ball powders.

[Maineboy]

Use the measure to throw a close charge and the Lee dipper to dribble to the weight you want. I would not use the dippers to load my rounds. There is no way to be consistant with them.


Like Ricochet, I get very consistant results with dippers, however they are slow when you're charging alot of cases. With big stick powder like 5010, I get much better consistancy with a dipper than with a conventional powder measure.

[KCSO]

Dippers not consistant? That would be a surprise to several generations of old time reloaders. Dippers were about all that were used until 1900 or so. They just require developing a technique and sticking to it.

[glicerin]

My B&M has a bore of 0.9525 cm.(.375inch). Divide by 2, square it, multiply by 3.1427, gives me an area of 0.7126 square cm. One cm of travel gives 0.7126 cubic cm. My total travel is 5.87 cm, so max volume should be 4.18 cubic cm. Sit me in the corner(no recess) if the math is wrong.

[rhead]

Set the B& M measure on (1) Throw a measure of a powder that measures consistantly and weigh it. Repeat 5 times to get an average. Get the yellow Lee dipper marked 1 and throw the same powder and weigh it. repeat this 5 times to get an average. The average weight from the Lee dipper divided by the average weight from the B&M measure will be the volume in CC of one unit of measure on the B&M scale. If you want toget closer repeat this at other larger and smaller settings to confirm a linerar scale.

[Scrounger]

Set the B& M measure on (1) Throw a measure of a powder that measures consistantly and weigh it. Repeat 5 times to get an average. Get the yellow Lee dipper marked 1 and throw the same powder and weigh it. repeat this 5 times to get an average. The average weight from the Lee dipper divided by the average weight from the B&M measure will be the volume in CC of one unit of measure on the B&M scale. If you want toget closer repeat this at other larger and smaller settings to confirm a linerar scale.

For every powder you use.

[Tom Myers]

My B&M powder tube does not have a micrometer adjustment but i did set out to try and make up an algorithm that would accurately calculate scale weights by the marks on the volume adjustment rod.

What I finally determined is that the weights are NOT linear with the volume when using any setup that increases the volume in a vertical fashion. The higher the powder column, the more the powder packs closer to the bottom of the column. I did manage to come up with a non-linear formula that required a different variable for each type of powder, and then set up a computer program that would print out a grain weight for each increment on the adjustment rod. However, for me, that was more trouble than just writing down the adjustments for the loads that I used the most.

What I did find was that the Lyman measure with the horizontal sliding bars and cylinder could utilize a set of formulas that would calculate accurate grain weights from the measure settings, but only if the specific gravity of each lot of powder was determined before hand.

All in all, after all the work and research, I now just write down my settings or use trial and error adjustments to get the charge that I want.

Tom Myers
Precision Ballistics and Records (http://www.tmtpages.com)

[joeb33050]

I disagree. You can get very consistent weights with the dippers, just as you can with a mechanical measure. You have to use consistent technique with both. The amount thrown by a dipper will vary considerably with the technique you use. So will an RCBS Uniflow, depending on how you work the handle. There are powders prone to clogging and bridging that scare me to use in the Uniflow I have. Takes great care to make sure charges don't get loaded up that are way light or heavy. And some simply won't measure reliably through it. But they work fine in the dippers with the level in the cup kept roughly constant, a uniform dip, and a uniform strikeoff with a knife blade after dipping. That doesn't shear stick powders like the Uniflow, either. The only powders I'm happy using in the Uniflow are Ball powders.

I disagree, during the Astounding Powder Measure Test I gave my Lee dippers a shot, more than a shot, a serious try. Did it two ways.
Here is the excerpt:
Dippers and repeatability
Hoping that the Lee dipper would dispense charges of SR4759 and similar powders accurately, I worked with the 1.9 cc dipper for a while, then threw thirty charges using each of three techniques.

Average Wt.(Gr.) STDEV (Gr.)
Dip and slightly shake 20.7 .259
Dip and tap on the container edge 20.6 .222
Dip and scrape with a business card 19.5 .260
The dipper method has a much larger STDEV than the measures-isn't the answer.

Powder measures had half or less the S.D.
I've used Lee dippers for XX years, lots with BP and COW etc.
I was surprised, but then, that's why the test was Astounding.
Dip and weigh and calculate and become astounded.
joe b.

[44man]

If anyone can get to 1 or 2/10 of a grain consistantly with a dipper, they are a genius. No thanks, I will always throw with the measure and trickle to the charge. I only trust my Redding BR measure with ball powders, never with stick powders.
How many times has it been posted that some of you work loads by 1/10 gr increments because it makes a big difference? Now I am told a dipper is accurate! [smilie=1: It is fine for reduced, run of the mill loads but don't tell me that BR shooters use them. The time and effort it takes to get all charges the same with them is a lot more then throwing and trickling loads.
When I load, I want every charge exactly the same. Even if I used a dipper, each charge will go on the scale. I do use a dipper a lot for the first dump into the scale pan and no matter how careful I am, none are the same.

[joeb33050]

The higher the powder column, the more the powder packs closer to the bottom of the column. Tom Myers
Precision Ballistics and Records (http://www.tmtpages.com)

Nay nay, see the Astounding Powder Measure Test"..See "Head". I was astounded, you will be too.
joe b.

[grumpy one]

Many long years ago when I started to load (for 38 Special target work, initially) a guru told me that the inconsistent part of using dippers is thrusting them into the cup of powder. He said the answer was to pour powder into the dipper, then strike the top across level. This closely matches the process a powder measure uses.

[montana_charlie]

Because of experience that have nothing to do with gunpowder, I have a feeling grumpy one speaks the truth.

But, about the Belding & Mull calibration thing...
I've never examined a B & M measure, so I have some questions.

As I understand it, the B & M has different charge tubes that can be used. The large one is suitable for 0 to 100 grain charges.

Is this correct, so far?

Are the marks on the stem equally spaced?

Is there (for instance) a '35' mark that is supposed to mean '35 grains'?

Does the slider fit closely enough in the tube to hold water?
CM

[Scrounger]

My B&M powder tube does not have a micrometer adjustment but i did set out to try and make up an algorithm that would accurately calculate scale weights by the marks on the volume adjustment rod.

What I finally determined is that the weights are NOT linear with the volume when using any setup that increases the volume in a vertical fashion. The higher the powder column, the more the powder packs closer to the bottom of the column. I did manage to come up with a non-linear formula that required a different variable for each type of powder, and then set up a computer program that would print out a grain weight for each increment on the adjustment rod. However, for me, that was more trouble than just writing down the adjustments for the loads that I used the most.

What I did find was that the Lyman measure with the horizontal sliding bars and cylinder could utilize a set of formulas that would calculate accurate grain weights from the measure settings, but only if the specific gravity of each lot of powder was determined before hand.

All in all, after all the work and research, I now just write down my settings or use trial and error adjustments to get the charge that I want.

Tom Myers
Precision Ballistics and Records (http://www.tmtpages.com)

Which is what I said 8 or 9 hours ago... Must be a lot of masochists here... I know, I'll find them an auction for a hair shirt so they'll run off chasing that for awhile...:veryconfu

[45 2.1]

My B&M has a bore of 0.9525 cm.(.375inch). Divide by 2, square it, multiply by 3.1427, gives me an area of 0.7126 square cm. One cm of travel gives 0.7126 cubic cm. My total travel is 5.87 cm, so max volume should be 4.18 cubic cm. Sit me in the corner(no recess) if the math is wrong.

Math is basically correct except that isn't Pi. Pi to 5 places is 3.14159 usually rounded to 3.142. Your answer is correct as it is to two places, so you get to go to recess.

[jhrosier]

Bret
If you can use it, I have an Excel spreadsheet that can calculate the correct dipper size for a powder charge and the setting for a B&M tube also. It uses VMD data from Lee for 167 different powders.

Jack

ETA: email me from my profile page in case I forget to check back here.

[Bret4207]

Holy crap! This is way beyond me so far. I need this in laymans terms, think Homer Simpson as far as me and math go. Or grammar as that last sentence shows. As one of the posters said, I'm just trying to get in the ball park with the tube settings. I do a lot of loading where there are 10 of this and 10 of that, but the overall count will be 150-200 rounds,. The B+M seems handy for this.