Accurate Balance Construction

[X-Wulf]

Hi everyone,
I searched the forum for "balance" and got about 56 results, but none that I saw dealt with balance construction.
Now pyrotechnics, demolitions, etc. all revolve around being able to weigh chemicals accurately (or at least consistantly). Triple beam balance scales cost a fortune as do electronic scales, so I did an extensive internet search. From the several thousands of results, I sifted out this link http://www.gj.net/~regiaero/balance.html
It deals with the construction of a wooden balance for weighing indoor model airplanes, and is apparently accurate to one milligram. I'm planning to build one based on this, does anyone have any input which might help?

Thanks

P.S. if it works, I'll upload some decent, detailed construction plans on a web page and post the link here :-)

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Live Forever!

[J]

I have a homemade beam balance. It isn't as accurate as that one, but it works fine for measuring out pyro chems, and will go as low as 0.1g. It's basicly a beam pivoting on a greased bolt, secured to a stand. I use lengths of wire as weight.

I intend to make a more accurate one using a small electric motor as the pivot. I'll hopefully upload the design to my site when I update it later this week.

J

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[Teck]

Hey people, check out ebay. I got my tripple beam balance at ebay for $35.00.

[10fingers]

I got an Ohaus triple beam from a pawn shop for $50.00. They're fairly easy to find at a reasonable price. Even new they're only around $120.00.

[cutefix]

There is a description of precision balance construction in the Swedish Informania,titled:
scale_sa.zip How to construct a scale, operating in the microgram range. Check it out at :
http://swi.1av10.nu/dist/ it might improve your knowledge about weighing scale construction.
Good Luck!

[X-Wulf]

cutefix: thanks for the link, they've got some neat stuff there! (pity most of the specifically pyrotechnics stuff is in swedish)

track, 10fingers: unfortunately, where I live there aren't many available in pawn shops http://theforum.virtualave.net/ubb/smilies/frown.gif

my buddy used the plans and built a scale accurate to about 0,1 gram in an afternoon (I'm hoping to better that http://theforum.virtualave.net/ubb/smilies/smile.gif )

[atropine]

ive just started reloading ammo. I got a balance scale accurate to 20th of a grain. Im not entirely sure what that is in grammes but 1 grain is alot less. Its permenantly accurate till it breaks and it cost me $20
leeprecision.com

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all wize men have unwize fantasies < ^ >

[EventHorizon]

15.43 grains in a gram.

7000grains in a pound


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[X-Wulf]

thanks for the link, i'll check it out.
but first i'll try building the wooden one, i've assembled all of the stuff that i need and simply need to assemble the thing.
i'm using 2,5mm thick balsa wood for the beam, so hopefully it'll be pretty accurate (though this would probably decrease it's maximum load)

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Live Forever!

[PYREX]

Look for those old, heavy mechanical balances. In labs they're replaced by electronic ones. I got mine for free and its still in a very good shape. Its accurate to 0.1g but you can estimate 0.02g quite exactly.

[SofaKing]

I don't think balsa is a good idea, the weight of the wood shouldn't matter , provided it's a uniform density. And as you said balsa would really limit the loads.

At this http://www.ctel.net/~dwilliams/index.html Site there are plans for different scale http://www.ctel.net/~dwilliams/scale/scale.html

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With Knowledge we find Truth - With Truth we find Freedom

[Flying Dutchman]

Why not buy an electronic one from United Nuclear?
they are only 70$ US.
acurate till 1/10 gram.
I wouldn't need more acuracy.
I have another question: I'm working with an normal thermometer right now should I buy one that's for chemistry only?
I did search on this question,
one guy said there was a big difference another guy said he didn't saw the problem.

[NERV]

There are designs for a micro gram scale at Rhodium’s web page. Just go to chemistry. Then scroll down to Equipment & Lab Technique's it should be under there somewhere.
<a href="http://www.rhodium.ws/" target="_blank">Rhodium's page.</a>

[EP]

I bought the larger of the two scales United Nuclear sells (hasn't come yet), but looking at eBay, I got ripped. :(

eBay is DEFINETLY worth checking out for scales. Here is the cheaper of the two United Nuclear scales for $4.20 + shipping:

<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=956338798" target="_blank">http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=956338798</a>

The larger of the two UN scales for $2 + shipping:

<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1762723505" target="_blank">http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1762723505</a>

And many other scales that are very cheap...guess I should have thought of looking at eBay before I spent $90. :rolleyes: <img border="0" title="" alt="[Frown]" src="frown.gif" />

[Anthony]

EP - cancel the order if you don't want to pay the $90.

Distance selling laws allow you to change your mind about a purcahse and return it up to 7 days after you recieve it.

[X-Wulf]

EP, those are some sweet deals! One problem, I'm from SA, so my money doesn't hold much weight (no pun intented).
The scale itself is fine, but the shipping would be four times as much!!

[EP]

I probably should, but I'm trying to get nice and friendly with Bob to become a Desert Blast attendee. From the website:

"If even the video isn't enough....
Attend this year's Desert Blast...
( regular United Nuclear customers are automatically invited to attend via mail )."

I've asked Bob (Lazaar, started DB, owns United Nuclear) about attendance requirements, and they don't seem nearly as difficult as I was expecting, so maybe there is a chance of going. :) I ordered the video also, it's on VHS, maybe I'll try and find a way to convert it and upload it (I have a friend that might be able to, I dont have the equipment).

A few other things I was looking at on eBay were a 6 ton hydraulic press (for pressing rockets) for $50! <img border="0" title="" alt="[Eek!]" src="eek.gif" /> Too bad I'd have to pay shipping for 115lbs! It was pretty similar looking to this one (but this is a 40 ton thats massive overkill for rockets and costs more):

<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1762902322" target="_blank">http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1762902322</a>

I'll probably buy one locally eventually. I've also seen some good prices on rock tumblers (to be used as ball mills) like this one:

<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2137134720" target="_blank">http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2137134720</a>

I'm going to check around locally also, the Lortone website lists dealers around the US.

[megalomania]

Here is yet another set of plans for a balance at Lindsy Publications:
<a href="http://www.lindsaybks.com/arch/bal/index.html" target="_blank">http://www.lindsaybks.com/arch/bal/index.html</a>

I think this balance offers a good balance (no pun intended) between accuracy and capicity. A bit complex perhaps, but not so far fetched that it can't be done.

[Zach]

can one of you owners of a scale do me a favor? I'd like to find out the length of any gauge wire that is equivalent to one gram. length is fine in whatever units you want, I am only looking to build a very simple balance scale.
I would greatly appreciate the time one of you may take , if youve got the time.

[chemwarrior]

I seem to recall once in the past a very reliable scale being made on the Hive. I havent been there in a long time, but Ill try and see if I can find it.

[Anthony]

Wire specification table (inc weight):

<a href="http://www.zelax.ru/windows-1251/english/sprav/awg_multi.html" target="_blank">http://www.zelax.ru/windows-1251/english/sprav/awg_multi.html</a>

Everything from AWG 36 to 0000

[jimwig]

is that accurately constructing an accurate ballance???

no one needs a microgram balance (in this field)
1- it's overkill and unusable- a waste of time, energy and resources.
2-the top end will not be sufficient- it accurant for butterfly turds but not more than 2 grams

"sitting all nite weighing out 28 grams"

3- the accuracy you need is in the tenths not millionths of a gram
4-get a used analogue analytical scale - they're all over the place for
$20 or so and they are good to a ten-thousandths. way overkill still....
but the good think is that they will weigh out usable amounts of chems.
100-200 grams or so.

concentrate on not blowing yourself up by spending time researching

BUT if you really need micrograms (they didn't at Los Alamos) i would love
to see what you are doing. Wow-far out!!!
and knowing what is going on with that nitrated molecule.