1lb Rockets Failing - I Need Help

[AcEz03]

Just wish I was able to roll my own tubes lol.

[lloyd]

Ace,

Why would you not be able to roll your own tubes? It's a 'skill', sure, but one anyone can learn.

 

Lloyd

[OldMarine]

Phil has some nice tubes. They're spiral wound but I've had very good luck with them. Caleb made me some pvc sleeves to adapt them to my supports.

http://ihaveadotcom.com/cart/index.php?main_page=index&cPath=72_118&zenid=s68mntvvrs4vtmgn54f4tn2k12

 

Viking has a video of his tube rolling technique here somewhere.

Edited May 24, 2017 by OldMarine

[AcEz03]

Firebreather I tried making a tube roller which if I had to say I think failed pretty bad. It's a 3/4 aluminum rod that has a spring loaded board pressing against the rod. I don't think I'm using the right weight kraft paper just some I found at Walmart. I can't keep the paper from walking on the rod(tube becomes Longgated). Plus after rolling the first tube I tried putting the tooling I got from woodys in the tub the rammers wouldn't fit. Almost wish I could use pvc pipe with this tooling kit much cheaper and can get it local lol.

[calebkessinger]

I can ship those cheaper man.. I don't have a shipping calculator really... it's by weight. minimum shipping is suppose to be 12 bucks but I wave that sometimes if people are just getting 1 item and it ships for 8 bucks in a flat rate envelope.

 

oh.. you CAN roll your own tubes. the roller you wrap your tubes around needs to be at least 25 thousandths bigger than the desired size. You can do that with a couple wraps of paper on the long rammer or some tape on a dowel. Then roll away!

 

I Am Woody's.

 

and I'm glad to help any way I can. I struggled for years getting my rockets to work and sometimes still do.

[AcEz03]

Yea I kinda seen that after it was already posted lol. Not trying to call ya out at all no disrespect either bud. I completely understand u got to make money on stuff. I'm just a poor boy look for the cheapest way to make rockets lol. Might even holler at you when I go to vacation near Grove Oklahoma might be worth the trip there. If y'all do walk in sales that is. Awesome product on the tools by the way.

[calebkessinger]

I know all about it man.. I'm glad to help. Come on by sometime!

[MrB]

the roller you wrap your tubes around needs to be at least 25 thousandths bigger than the desired size.

 

Is that 0,0025mm?

Is there a upper limit, as in when do the tubes get to wide, and wont be usable?

[DavidF]

He means .025", or 6.35 mm. is what I said.

 

He means .025", or .635 mm. is what I meant.

Edited May 26, 2017 by DavidF

[lloyd]

Um, David? Wanna do that conversion again? <grin>

 

Lloyd

[MrB]

With 6.some mm slop in the fit between the rammer and tube, i'd get a face full of fuel mix when i try and fit the rammer in there so the press could do it's thing. But yeah, i stumbled on a zero. If he is indeed speaking inches, then it turns out to about 0.635mm. Some of the "oversize" will be eaten by the tube shrinkage when drying, It's also large enough that it could be reasonably accurately machined by "anyone with a metal lathe".

Sounds like a lot, but i guess it might be right.

Still, there is of course a "upper limit" for how much larger it can be. Question is, what is it.

[NeighborJ]

I roll some of my own tubes. There is not much extra diameter needed for rammer play IMO. I use dowel rods for the formers, chip board for the paper and Elmer's wood glue Max for the glue. They don't shrink much, if at all. My dowels are coated in a varnish to prevent any glue from sticking too much so they are slightly oversized, maybe .005 in. The rammers fit snugly and are easier to work than some of the inconsistently sized NEPT tubes.

I find that when a tube is oversized the comp squeezes out along the outside of the rammer and make spindle removal a challenge, it can also allow the tube to become cocked on the spindle forcing the upper rammers to wedge against the spindle during pressing. There are other solutions to this problem and most toolmakers craft their tooling to account for it.

As for the face full of fuel upon insertion of the rammer, most people use screen granulated, unbound fuel to which is added 1% water to help fuel consolidation and to prevent the dust poof. I find the extra granulation step to be unnecessary and simply add the 1% water to mill dust prior to pressing and have no instances of powder poof.

[lloyd]

Neighbor,

I designed and built a fully-automated gerb (and rocket) press for my last employer. The pressing rods were deliberately 'loose', so they'd go into and out-of tubes without interference. The difference, I think, was in granulation.

 

We always granulated all of our gerb compositions. They pressed with minimal-to-none 'squeeze-out', and without rammer jams. They also made supremely-reliable gerbs and rockets.

 

I (personally) think that granulation is one of the most important steps one can take in making gerb and rocket comps.

 

Lloyd

[OldMarine]

I may be wasting good powder but I've taken to making the fastest Paulownia BP I can and then I granulate it with naphtha /mineral oil for rockets. Slows the fuel a bit I imagine but I'm getting very consistent thrust and zero poofing or rising of the fuel around even my loosest rammer set. I've not perfected anything in pyro but I'm not ashamed of my rockets!

[lloyd]

Old Jarhead Marine sed,

"...and then I granulate it..."

 

----

Uh, huh!

 

Lloyd

[OldMarine]

I tried pressing them with mill dust and I ended up wearing as much as was in the tube it seemed. Even with the o-ring around the rammers it was a mess. For gerbs i just use 95% isopropyl alcohol to granulate and it takes care of the dust and rise around my rammers. The air can squoosh out of the grains without carrying fuel up with it. Another good thing about alcohol granulation is that you can toss it back in the mill if adjustments are needed. No binder so it goes back to dust easily. I've done this many times trying to keep nozzled core burners from CATOing. MANY TIMES!

[lloyd]

FWIW, I like harder granulates. I use dextrin, and screen-granulate to -12 mesh for pressed items. It's always worked, makes NO mess, and except for a few 'special experiments', no CATOs.

 

Also, for what it's worth, SOME comp does 'squish up' around the bottoms of my rods, because most of them have sufficient wear that they're slightly rounded-over on the ends -- not a lot, but some (I re-dress them when they get too rounded). But it never causes problems, either with the pressing or with their functioning properly.

 

Lloyd

[MrB]

I'm not sure, but i think the thread got on a left turn, and sidetracked after i said that a to lose fit in the tube might be an issue... I'm very thankful for the enthusiasm shown in sharing ones experience, but lets try and remember that 6.some mm is quite a lot. .6some+ mm is probably what Caleb was suggesting, and should be fine.

 

I re-dress them when they get too rounded.

Now that is more interesting. How? Turn them down, add a sleve, and start over, or what?

I sort of expected to have to replace the rammers completely eventually.

[OldMarine]

I wonder if waxing my tubes helps prevent the rise of the fuel around the rammers?

[NeighborJ]

Lloyd when you say you use dextrin, what percent? I've tried 4-3-2% granulated and have still had consolidation issues due to the hard grains,even when jacking up the pressure hence the controversial non-granulated method. For me it's produced the most reliable motors. I'll still use granulated fuel with waxed tubes but haven't needed wax either for mill dust motors.

[lloyd]

MrB asked,

"

I re-dress them when they get too rounded.

Now that is more interesting. How? Turn them down, add a sleve, and start over, or what?

I sort of expected to have to replace the rammers completely eventually."

 

Originally, I resorted to re-turning the ends of tools on the lathe. As we evolved to the point of wearing out tools with some regularity (on the automated press), I re-designed all the pressing tools. For cost and weight, their main shafts and mounting bosses were made of 6061 aluminum. But, then, they were 'footed' (like a footed arrow) with a stainless steel tip, which was threaded on, and held with a heat-removable thread-locker liquid.

 

We then resorted to always keeping a spare 'foot' for each tool in stock. When a tip wore out (and the SS wears MUCH more-slowly than Al) we'd simply heat the union, remove the old tip, and lock a new tip on the end. Then we could repair or re-make the worn foot at out leisure.

 

Part of the reason for that is that on the machine, ALL the rods had to be of the same length, to minimize stroke distance (and thus, time of run). Repairing individual tools by re-turning would compromise that relationship, unless they were ALL repaired at the same time.

 

-----------------------

Neighbor,

I use 5.88% dex (+1oz / lb of powder) in pretty much anything BP-based and water-bound. The secret is how much water you use to granulate. Less water and quicker drying result in a softer grain. As you note, TOO hard of a grain can require extreme pressure to re-compact to a solid.

 

Lloyd

[MrB]

Originally, I resorted to re-turning the ends of tools on the lathe. As we evolved to the point of wearing out tools with some regularity (on the automated press), I re-designed all the pressing tools. For cost and weight, their main shafts and mounting bosses were made of 6061 aluminum. But, then, they were 'footed' (like a footed arrow) with a stainless steel tip, which was threaded on, and held with a heat-removable thread-locker liquid.

 

We then resorted to always keeping a spare 'foot' for each tool in stock. When a tip wore out (and the SS wears MUCH more-slowly than Al) we'd simply heat the union, remove the old tip, and lock a new tip on the end. Then we could repair or re-make the worn foot at out leisure.

 

Part of the reason for that is that on the machine, ALL the rods had to be of the same length, to minimize stroke distance (and thus, time of run). Repairing individual tools by re-turning would compromise that relationship, unless they were ALL repaired at the same time.

 

Makes sense. Non sparking SS, threaded on, and just keep spares. Thanks for sharing.

[DavidF]

Heh heh, loading mill dust into rocket tubes SUCKS! One thing I accidentally learned during recent experiments was how to make it free-flowing. I like to make up words, so I call it 'micro-granulating'

The first powder I handle in the video is straight mill dust. The second powder is the same stuff after micro-granulating. It sure makes producing end burners way easier and faster. Here's a little clip that shows what I mean. The details are in the description.

 

https://www.youtube.com/watch?v=N5GG7Hk_TKw

[NeighborJ]

Oh come on now, that was rigged. It will clog a funnel when it's dry. I suppose using mill dust needs clarification. When the water is added, it clumps a bit. The clumps are broken up into granuals but not dried, this easily passes a funnel.

 

I don't usually use a funnel anyway, my scoops are slightly smaller in dia than the tube and deep enough to hold one full increment. When I do use dried unbound grains they have the same flow characteristics after the water is added so I really don't see the big deal with skipping the drying and rewetting process.

 

I didn't want to go divert the subject matter of this thread but it seems to be what people want to talk about.

Edited May 27, 2017 by NeighborJ

[DavidF]

Ha ha, rigged, whaaat? I wasn't comparing it to your method NJ. I was unfairly comparing it to dry mill dust, yes