mabuse00 Posted December 30, 2020 Posted December 30, 2020 My stash of betonite i've been using since I started with this hobby is now quite depleted.I came from a pyro dealer and i never asked for details.Locking for new raw material i came across sodium- and calcium betonite.Sodium betonite is noted for having a greater swelling ability, but we dont want any swelling. We dont want the stuff to be water attracting at all.Which one would you chose, what is more suitable for our needs, so in 90% of cases, nozzle mixes?(I usually use the mix Ned featured in the skylighter article, just with a little more wax)
a_bab Posted December 30, 2020 Posted December 30, 2020 (edited) I would simply go for cheap kitty litter in granulated form (about 2 eur for a 5kg bag).Obviously not the silicagel-based one (doh...)Go for the white-colored one with colorful grains in it; it's usually cleaner than the "earth" colored one.The granules compact very well out of the bag. BUT it may contain small pebbles and sand, making the drilling operation very risky !So you may want to mill, sieve and use the dust. Edited December 30, 2020 by a_bab
davidh Posted December 30, 2020 Posted December 30, 2020 Cheap kitty litter works fine. Never heard of anyone having any problems with it, and it gets used a lot. I prefer fireclay. It's quite cheap and doesn't absorb water like bentonite, although it is a bit more difficult to source.
mabuse00 Posted January 1, 2021 Author Posted January 1, 2021 (edited) Kitty litter is the usual answer, but I like to know what is actually in there, what chemical compounds ect.Also, when one considers what the costs of the whole equipment amounts to, personally I dont care if a bag of nozzle/plug material costs 2€ or 20€. fireclayCan you be more precise with "fireclay", what specific variant, Kaoline? edit:seems like this question was answered a long time ago:https://www.amateurpyro.com/forums/topic/6876-nozzle-mixes/?p=90546 So, according to WSM calcium betonite and white china clay should be my next test materials. Edited January 1, 2021 by mabuse00
SharkWhisperer Posted January 1, 2021 Posted January 1, 2021 Kitty litter is the usual answer, but I like to know what is actually in there, what chemical compounds ect.Also, when one considers what the costs of the whole equipment amounts to, personally I dont care if a bag of nozzle/plug material costs 2€ or 20€. Can you be more precise with "fireclay", what specific variant, Kaoline?Cat litter works fine for most applications. When I blow up a rocket motor with a ground cat litter nozzle, it is a rarity that it suffered nozzle failure or the endcap blew out. FIreclay is easy to source from any pottery supplier--they'll have many options to confuse you. Some pyro sites sell fireclay. I have Hawthorne Fire Clay from Pyrochemsource that cost a whopping $2 pound (probably triple what he paid for it from his pottery supplier). Closest supplier here is 40miles away, but they often have other chems (oxides etc) that have dual use in pyro/pottery,and are often cheaper than from pyro chem dealers (especially if shipping not required). Grog I don't use but it's simple to make and cheap to buy, and pottery suppliers sell various mesh ranges. If in Europe, well, they do ceramics/pottery there, and you should have no problem finding what you're looking for. Dirt, aka clay, are not really controlled substances. Biggest problem at pottery supplier is probably going to be deciding between 20+ types of clay available. All are rated to different kiln temperature uses (called "cones" in pottery firing), so study up on that or just call and discuss with anybody at the shop. They'd probably be happy to share their knowledge and assist your selection if you told them your needs. I learned (and forgot) a lot of details between various clays, but the hobby is popular enough that plenty of information of clays/fireclays and their individual benefits (in ceramics) are easily located. And there's plenty of nozzle material threads here and on other pyro sites, too. If you have no nozzle erosion for your application, then why not stay with cat litter for pennies? Only for rocket motors, especially bigger ones (or huge gerbs that might slag up), do I consider changing from cat litter to another mix, which usually ends up being simply substituted with Hawthorne fire clay straight up, or mixed 50/50 Hawthorne with cat litter/bentonite. Never bothered adding wax or grog as some do, but hey, you do what works for you. No outlet erosion? No problem. Nothing to fix. A little erosion but no performance change? No problem. Nothing to fix. Erosion causing performance variability? Ok, small problem and easy fix. Many simply fail to make their nozzles long enough (at least 1 ID in length).
justvisiting Posted January 1, 2021 Posted January 1, 2021 I think the nozzle material becomes most important when pressing end burners or hand ramming core burners. If you are hand ramming an unsupported tube, the nozzle material is critical. So is the tube material. If you use cheap, hard kitty litter, you will split your tube before you get proper consolidation of the bottom of the nozzle. Poor consolidation can cause erratic flights. With proper tooling, the nozzle could be rammed in 2 increments to try to overcome the hardness of the litter. One thing I've done is to mix the cheap hard litter with soft granulated bentonite used for filling well holes. The hard chunks bite into the tube, and the soft stuff flows nicely to fill the gaps and make a nice solid nozzle. Also, taking about a cup of granular nozzle mix and shaking it with a teaspoon of graphite powder helps release the nozzle from the spindle. Most rocket makers agree that you can't go wrong with Dr. Elseys Precious Cat litter, a bentonite-based product. It's the stuff with the blue label. It's good enough for Estes I've actually taken clay from the bank of Lake Erie and processed it to form nozzle mix and modelling clay. Bit of a PITA but it worked well.
SharkWhisperer Posted January 1, 2021 Posted January 1, 2021 I think the nozzle material becomes most important when pressing end burners or hand ramming core burners. If you are hand ramming an unsupported tube, the nozzle material is critical. So is the tube material. If you use cheap, hard kitty litter, you will split your tube before you get proper consolidation of the bottom of the nozzle. Poor consolidation can cause erratic flights. With proper tooling, the nozzle could be rammed in 2 increments to try to overcome the hardness of the litter. One thing I've done is to mix the cheap hard litter with soft granulated bentonite used for filling well holes. The hard chunks bite into the tube, and the soft stuff flows nicely to fill the gaps and make a nice solid nozzle. Also, taking about a cup of granular nozzle mix and shaking it with a teaspoon of graphite powder helps release the nozzle from the spindle. Most rocket makers agree that you can't go wrong with Dr. Elseys Precious Cat litter, a bentonite-based product. It's the stuff with the blue label. It's good enough for Estes I've actually taken clay from the bank of Lake Erie and processed it to form nozzle mix and modelling clay. Bit of a PITA but it worked well.I first tried hand ramming cat litter from the bag. Big granules. Nozzles "seemed" tough, but would erode badly and occasionally blow out. A few seconds in a coffee grinder has it a pretty find powder, which I've never yet blown out on it's own. But have had some erosion issues with bigger motors. Never tried the powdered and chunk together for more bite. If erosion, then I substitute or add in (depending on mood and what's at hand) Hawthorne fireclay. Mine's a fine dust. Others swear by adding wax or oil to aid consolidation, but not sure I want fuel in my nozzle mixes, so haven't tried it. Can't see where adding graphite would hurt anything, so long as nozzle retention under firing pressures isn't compromised, and always nice to have an easy motor release from spindles, especially long core-burners. I usually just spray my spindle with Pam cooking spray (or generic similar), when I think of it, to assist in easy grain release from spindle. And while I make the occasional core-burner, most of my motors are modified endburners (longer spindle/core as size increases, just like Estes does) for use in finned rockets. So spindles aren't all that long anyways. Seems to work ok for me. Never needed grog to gain "bite" and don't want my spindles/rammers scratched all to hell. Think I'd rather just dust my spindle with graphite than include it in the nozzle mix. A bad fuel, but flammable nonetheless. But I'd consider JV's approach and try a mix of powdered and chunk cat litter to get a little "bite", although bentonite cat litter is pretty soft stuff, even the granules, vs sand and grog. If you are having nozzle issues, it's usually an easy fix. And once you find a mix that works well for your needs, well, just stick with it.
mabuse00 Posted January 2, 2021 Author Posted January 2, 2021 Thank you for your opinions.In fact I'm into Endburners again.Scratching or at least dulling the spindle does happen, especially when grog is added.But since my grog is very fine, it does not rip large wounds, it's more like very fine sandpaper.With EBs I find a dull spindle is not a big problem.But it allways hurts when your toolmaker has made you a nice shiny tool and you start using it With coreburners I went all nozzleless some time ago... here I agree, a dull spindle will definitely not help whith releasing the motors.Betonite alone, and also some catlitter I tried some years ago did indeed erode, in a way that it affected performance at least with EBs.With added fine grog ("chamotte") - no more erosion.I'll swap the betonite for kaoline ("china-clay") and see what happens, maybe I can omit the grog.
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