PyroAce Posted March 4, 2012 Posted March 4, 2012 I have recently found out just how important it is to have accurate scales for weighing ingredients for pyrotechnic compositions. I had been making 100 gram batches of black powder, I followed the very precise method of ball milling using a rock tumbler and the optimum milling process, e.g. rock tumbler was filled half full of grinding media, in this case hardened lead balls, the ingredients were then weighed out to make 100 grams of black powder 75 grams of potassium nitrate, 15 grams charcoal, 10 grams sulfur & 5 grams of dextrin. This mixture was then ball milled for 3 hours (the tumbler rotates at 65 RPM) thinking this would be enough, I did a test light of a small quantity of powder and it just didn't have any oompfff to it and it also left quite a bit of residue than the commercial black powder I had always been using. It was then wetted and granulated and again not enough kick to it (mind you it would still lift but just lacked power that I had seen other peoples powder perform at) I milled a few more different batches and even when milling one batch for 15 hours it still didn't perform as good as it should, I then began to suspect that perhaps the ingredients might be a bit impure, but they seemed fine to me and were from a reputable seller. I then did some more thinking and did recall that with the scales I was using they seemed to be a bit out when measuring, as in when I put a disposable plastic cup on the scales to weight the ingredients it didn't give any reading at all even though I know these cups weigh at least a few grams. Also when I added an ingredients to the cup it never seemed right. I then decided to get one of those smaller pocket scales to try out, and sure enough the plastic cup measures a 3.4 gram reading, so knew right then and there that the other scales were not as accurate as I would want, sure they might be good for cooking food which isn't a massive deal but when you are striving for precise measurements with pyrotechnic compositions you really do need a decent scale. I have since made a batch with the new scales and straight out of the tumbler barrel the black powder burns way faster! This is proper black powder speeds and just needs to be granulated for lift. It leaves hardly any residue at all and lights and burns exactly like these tests: http://www.creagan.net/fireworks/charcoal_tests.html I hope my experiences can help others out. What I would love to see is if everyone can measure some coins from there country and post the weights on here so that others can test the coins on their scales to see how accurate they are because I believe that coins when minted all weights are very very similar amounts if not to within a 0.1 gram for various banking and coin machine requirements. You can also search Google for coin weights if you wanted.
warthog Posted March 4, 2012 Posted March 4, 2012 (edited) I use calibration weights to make sure my scale isn't off. If it IS off, I calibrate it per the instructions. Edited March 4, 2012 by warthog
Arthur Posted March 4, 2012 Posted March 4, 2012 As you have found you really do need scales that are accurate! In the UK there are lots of scales available in the 100g x 0.1g range, all from China, all disposable, and ubiquitously refered to as drug dealer scales!
oldguy Posted March 4, 2012 Posted March 4, 2012 Weight measures are critical if you want optimal BP and/or composition performance. A shiny new uncirculated Lincoln Memorial Reverse USA penny (mid 1982 to present) weighs 2.5 grams.I use them to calibrate my electronic scales, as well as my Ohaus triple beam & other balance beam gold scales I own.
dagabu Posted March 4, 2012 Posted March 4, 2012 As you have found you really do need scales that are accurate! In the UK there are lots of scales available in the 100g x 0.1g range, all from China, all disposable, and ubiquitously refered to as drug dealer scales! I use this one from DealExtreeme LINK as it weighs out 1000g to 0.1g. It is nuts-on every time I have tested them and love them especially at $9.00 shipped. I have bought a dozen of them and gave them away to pyro buddies and have another two on their way as we speak for others to try. http://img.dxcdn.com/productimages/sku_1165_3_thumb.jpg -dag
nater Posted March 4, 2012 Posted March 4, 2012 I use this one from DealExtreeme LINK as it weighs out 1000g to 0.1g. It is nuts-on every time I have tested them and love them especially at $9.00 shipped. I have bought a dozen of them and gave them away to pyro buddies and have another two on their way as we speak for others to try. http://img.dxcdn.com/productimages/sku_1165_3_thumb.jpg -dag Thanks for the link, I might have to order one for a backup to take to PGI next time I order from DX. I looked through there before I ended up buying one elsewhere and couldn't find it.
Tanner808 Posted March 4, 2012 Posted March 4, 2012 (edited) If u had a scale that was off You would still get the same ratio right, it might be the wrong amount overall but it would still be the same ratio and that's all that matters. Just a thought. Edited March 4, 2012 by Tanner808
Mumbles Posted March 4, 2012 Posted March 4, 2012 That's usually not true at all tanner. A scale will rarely be off by just 3.4g every time. That would just be a tare issue. Rather they're off due to their response factor. It could be off by say 5% every time. You could end up with 78.8:15.8:10.5. While close it could cause lowered performance. It can also have repeatability issues. IE, if you put 5 coins on the scale, remove and then re-add them, it will not give the same reading every time. In any case decent scales are not expensive.
PyroAce Posted March 5, 2012 Author Posted March 5, 2012 The biggest problem was weighing the charcoal powder, because it was so light it barely registered with the scale.
BJV Posted March 5, 2012 Posted March 5, 2012 The biggest problem was weighing the charcoal powder, because it was so light it barely registered with the scale. What?!?!
dagabu Posted March 5, 2012 Posted March 5, 2012 The biggest problem was weighing the charcoal powder, because it was so light it barely registered with the scale. It's 10g, it may take a lot of volume to get there but any pyro scale should be acceptable of measuring .1g. -dag
AdmiralDonSnider Posted March 5, 2012 Posted March 5, 2012 I´m using the MyWeigh i601. 600g max and .01(!) gram reading. About 130 Eur with AC adaptor, calibrateable etc. There´s also a 1kg version. Good scale.
oldguy Posted March 5, 2012 Posted March 5, 2012 For bulk weights up to 75lbs, I use a Ultraship Postal Scale. They are not expensive & good for heavy weights. Runs on batteries or AC adaptor. They are all over eBay.
starseeker Posted March 5, 2012 Posted March 5, 2012 I use a set of scales which weigh up to 200g and down to 0.01g,i find that these are a bit easier to get your measurments for small experiments bang on,they were about £20.
dagabu Posted March 5, 2012 Posted March 5, 2012 (edited) For bulk weights up to 75lbs, I use a Ultraship Postal Scale. They are not expensive & good for heavy weights. Runs on batteries or AC adaptor. They are all over eBay. I have a good scale for heavy weights as well but with a 2g resolution on the Ultraship line, you really have to be careful when weighing small batches. -dag Edited March 5, 2012 by dagabu
oldguy Posted March 6, 2012 Posted March 6, 2012 I have a good scale for heavy weights as well but with a 2g resolution on the Ultraship line, you really have to be careful when weighing small batches. -dag I only use the Ultraship for dividing raw chems to store in smaller containers or for shipping.Otherwise, I use a triple beam or 0.1 gram scale.
Zingy Posted March 6, 2012 Posted March 6, 2012 (edited) I have found antique candy scales the most convenient, because of the large stainless steel pouring bowls, that come with the scales. I realize they are not the most accurate, but are excellent for low density items like charcoal. Edited March 6, 2012 by Zingy
PyroAce Posted March 6, 2012 Author Posted March 6, 2012 What?!?! Think about if the scale didn't even pickup/register the disposible plastic cup how much trouble it would have with charcoal powder.
PyroAce Posted March 6, 2012 Author Posted March 6, 2012 It's 10g, it may take a lot of volume to get there but any pyro scale should be acceptable of measuring .1g. -dag Don't you mean 15 grams?
asilentbob Posted March 6, 2012 Posted March 6, 2012 You can somewhat get around low accuracy on only gram accurate scales, including ones that are off a bit more by measuring out larger amounts. The postal scale I have used in the past is only rated to 1g accuracy. When I measured out chems for BP and star compositions and such I'd measure out for 1Kg+ total composition. This way the ratio hopefully approaches what you are wanting and with the larger total mass of chems a few grams more or less of something has less effect than if your in the 10s or 100s of grams scale where a few grams more or less of something has a much larger effect on the ratio. This is applicable if the scale is truely accurate to the gram, or truely off by a small fixed mass. Obviously this is not always an option when testing small batches of composition before scaling up... but for instance with black powder, you know your going to need a lot of it to do just about anything, so there is almost no such thing as making too much. Since you only have a small rock tumbler, you could crudely mix a larger batch of chems in a different container (maybe gallon size) till its a rough "green" powder, then take out ~100g of that to mill as needed. If the scale is off by a varying percentage based on how much it has been loaded down... its trickier, but not impossible to get around if you don't care to be super precise. If its off because the mechanism is gummed up or something, then your screwed, if you can clean and fix it awesome, if not you need a new scale.
dagabu Posted March 6, 2012 Posted March 6, 2012 Don't you mean 15 grams? DOUGH! Sorry, got S and C mixed up.
nater Posted March 6, 2012 Posted March 6, 2012 ng Think about if the scale didn't even pickup/register the disposible plastic cup how much trouble it would have with charcoal powder. what weighs more, a pound of feathers or a pound of lead? or a pound's a pound the world around. the scale does not know what it is weighing. A low density object will weigh the same as something of high density.
Mumbles Posted March 6, 2012 Posted March 6, 2012 Agreed Nater. However, he could be saying that the increments of charcoal added may not be heavy enough to register a change, which is valid with low quality scales. That is easy enough to remedy. If you tap the scale to induce a change, it will often then register the weight change as the reading resets.
Algenco Posted March 6, 2012 Posted March 6, 2012 Agreed Nater. However, he could be saying that the increments of charcoal added may not be heavy enough to register a change, which is valid with low quality scales. That is easy enough to remedy. If you tap the scale to induce a change, it will often then register the weight change as the reading resets. yep, I've had that problem when weighing Paulownia char, if you add small amounts it won't register
PyroAce Posted March 7, 2012 Author Posted March 7, 2012 ng what weighs more, a pound of feathers or a pound of lead? or a pound's a pound the world around. the scale does not know what it is weighing. A low density object will weigh the same as something of high density. What Mumbles said is what was happening with the old scales, it wouldn't register a change.I used to love the old pound of feathers or pound of lead gag, it's suprising how many people think about it and then say the lead would weigh more!
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