Tube supporting sleeves

[AdmiralDonSnider]

Looking for some input on how to make supporting sleeves (for pressing rockets mainly). I´ve seen a nice wooden one made by pyro09, but I´d love to hear other ideas, preferably with a pic.

 

I thought about using a metal tube, but I guess the driver won´t be easy to remove once pressed.

[Pretty green flame]

Looking for some input on how to make supporting sleeves (for pressing rockets mainly). I´ve seen a nice wooden one made by pyro09, but I´d love to hear other ideas, preferably with a pic.

 

I thought about using a metal tube, but I guess the driver won´t be easy to remove once pressed.

 

Split water pipe.

http://www.wichitabuggywhip.com/fireworks/rockets/extras.html

[Arthur]

Get a piece of plastic water main pipe, wrap you favourite size of tube in polythene, fill the gap with a polyester resin with 50% sharp sand as filler. (OK a bit more prep work is involved!) you get a mould just oversize for your tube (thickness of the polythene!) Make sure the sand is DRY in the winter make sure the sand is warm and dry!

 

Alternatively get a pair of alloy bars and machine out a tubular hole centrally across the joint, Use bolts, screws or clamps to bold it together and release when ready.

[dagabu]

Looking for some input on how to make supporting sleeves (for pressing rockets mainly). I´ve seen a nice wooden one made by pyro09, but I´d love to hear other ideas, preferably with a pic.

 

I thought about using a metal tube, but I guess the driver won´t be easy to remove once pressed.

 

PGF has Danny Creagan's link to the double wall sleeve. You cant go wrong to start with these. The next step is to have a custom Al support made for the tube you stay with.

[Col]

Looking for some input on how to make supporting sleeves (for pressing rockets mainly). I´ve seen a nice wooden one made by pyro09, but I´d love to hear other ideas, preferably with a pic.

 

I thought about using a metal tube, but I guess the driver won´t be easy to remove once pressed.

 

 

Antenna hardware suppliers may be worth a go..

Resin clamping blocks to fit most common sizes of aluminum tube? http://www.dxengineering.com/ProductDetail.asp?ID=24&SecID=1&DeptID=39

They seem reasonably priced upto 1.5" OD, the downside is you`d need quite a few to make up the length.

Bolt together (pressed steel) mast couplers could be yet another possibility, i haven`t come across any that accept tubes smaller than 1.5" od but they may exist.

[AdmiralDonSnider]

Thanks everyone for the inputs!

 

PGF has Danny Creagan's link to the double wall sleeve. You cant go wrong to start with these. The next step is to have a custom Al support made for the tube you stay with.

 

Did you mean this design? http://www.wichitabuggywhip.com/fireworks/rockets/extras.html

 

Hope I´ll find the appropriate pvc tubes. These have to be fit to the motor OD by heating, is that right?

Edited September 21, 2010 by AdmiralDonSnider

[dagabu]

Yes, you can use any close enough tube size to make the support. When hot, the PVC bends like taffy and can be shaped into sheets if you would like.

 

I make my double wall support by making two sleeves that fit one in the other and they are separated by two turns of kraft. I also separate the tube I am forming the supports around by three turns of kraft. Thai makes it so there is some spring in the cooled PVC so that the tube can easily be removed after the clamps are released.

[dagabu]

Just in case there are some new rocket people here, I am resurrecting this thread from the dead!

 

I know this was 4 years ago but the basics still apply. Also think about using the Forester Method using brass shim stock, HERE is a roll for about $25.00. Its about $6.00 for STEEL but rust is always a concern. Stainless steel is more expensive but it has twice the burst strength.

 

dag

[schroedinger]

@dag what do you mean by the forester methoo?

[Maserface]

Kentish mentions using solid pipe, with a single turn of paper on the outside of the tube, this allows the motor to be removed more easily than a solid pipe just.

[MrB]

I went and had a stainless steel tube split down the length, and then stuck it to the inside of a slightly larger pipe thats about a third of the length of the support. (Longer is better, just leave a gap in the middle) Did this for both the half's, and now i can slide em together to make a whole tube again. After pressing the half's just needs to be pushed in opposite directions to split the support, and free paper tube. This is where i made my mistake with the first version. The outer tubes cant meed in the middle, you need something to "hold on to", to be able to pull them apart. Sometimes it's freaking difficult to split the support. Only covering a third on each end lets me access the edges. I simply lay it on the vice, and open it up, and it splits the support open quite easily.

 

Quite easy to make to any size tube, and it should be possible to do with PVC, just as well. Longer tubes might take a very big vice, or some creativity to make it open enough. I'm thinking roman candles, gerbs, fountains, flares, such. Once it gets moving it seams to be easier to keep going, then to get started. I don't recommend splitting it by hand, since that quite easily sends the pressed unit flying when the half's of the support release from one and other.

B!

[dagabu]

Yup, Kentish has lots of good ideas but some are not as safe as you would like. The solid tube is great IF you have a paper tube that is the right OD, the pipe is not being rammed but pressed and you have a robust shield to hide behind.

 

Over the years, we have moved onto less lethal supports, PVC and now coiled shim stock do not pose the same risk as the mass is much less.

[MrB]

My version of tube over tube, should be easy enough to make yourself, at home, out of PVC. Fitting to the tube isn't really an issue for me, i'm making my own tubes so i pretty much have a chart for how long sheets i want to make the tubes with for them to fit my different applications, and hence the different supports. It would suck to have to start over making a new chart due to paper thickness changes, as in, lets say the paper manufacturer made some changes, or the retailer started carrying a different brand. That sort of thing.

I'm sure there is math to figure it out, but for me it's pretty much trial and error.

 

And while i agree, soft supports might to some extent be safer then hard, but the tube clamps used is some bad shrapnel of those PVC supports... Pressing should always be done with a shield. Not that i have one on "my" press. I walk away so i have a wall shielding me instead, but that does mean i don't have visual feedback on whats going on....

B!

[dagabu]

My take away is first hand experience with rocket motors going off at my work area at PGI where the motors were outside of the press. The hose clamp that hit one of the guys only caused a shallow cut in his stomach and was healed up by the end of convention.

 

When I was pressing rockets, I had a USB camera looking at the rocket and ram while was behind a steel post.

[MrB]

Never thought about using a sacrificial USB cam, and a laptop. That would make it very portable, which menas i'd actually use it. Nice tip, thanks.

B!

[mabuse00]

less lethal supports

That's a question I wanted to ask for some time.

 

If you have a rather massive tube support around your motor and the worst case materialises - what happens?

I've heard stories of rammers shot into the ceiling while ramming rockets. Hopefully not in the forehead. The pressure will escape that way.

 

But if your motor sits in a press, even with the hydraulics fail or the teeth of the arbor press stripping I expect a hell of a pressure - maybe even DDT?

 

 

I tried the hose clamp method on my little BP and whistle motors, and I hate it.

 

My solutions right now is

-not to use a sleeve at all, using rather high quality tubes

-I made a sleeve out of 2 pieces of medium density fibreboard and copied what's normally made out aluminium.

Besides of the screws this wont create shrapnell, but of course the material is to soft, it will give slightly.

 

The PVC/hose clamp thing has the same problem. When I press small rockets in a vice, this disturbs your feeling of the composition compacting. You think you're compacting the fuel, but in fact you only create a bulge in the tube. I'd rather leave the sleeve away and see the bulge.

 

It's like turning a screw in pastic, hard to feel when to stop turning, you know what I mean?

 

Since I only have an improvised metal shield I feel an urge to constantly look behind it and see what's happening while pressing

 

 

Something inflexible is needed - I have the "two halfs of aluminium" thing in mind...

 

[dagabu]

That's a question I wanted to ask for some time.

 

If you have a rather massive tube support around your motor and the worst case materialises - what happens?

I've heard stories of rammers shot into the ceiling while ramming rockets. Hopefully not in the forehead. The pressure will escape that way.

 

But if your motor sits in a press, even with the hydraulics fail or the teeth of the arbor press stripping I expect a hell of a pressure - maybe even DDT?

 

Great question and one that I have been asking as well for some time now. About five years ago, I proposed a test with my old press, a PVC support, hose clamps, rammer etc. be E-matched through the side for ignition and blow the motor up using some tag-board sheets for witness boards since they have the approximate breaking strength as skin (give or take a few lbs of pressure).

 

I was able to test a BP rocket (1#) in the press but didn't have witness boards and the video failed (I did get great shots of my feet before and after though). The hydraulic jack was just fine, no damage, the rammer was 2 feet from the press and just kind of "fell out" of the motor when the tube exploded. Nothing, including the hose clamps went more than 20 feet from the press. It was kind of disappointing actually.

 

I tried the hose clamp method on my little BP and whistle motors, and I hate it.

 

My solutions right now is

-not to use a sleeve at all, using rather high quality tubes

-I made a sleeve out of 2 pieces of medium density fibreboard and copied what's normally made out aluminium.

Besides of the screws this wont create shrapnell, but of course the material is to soft, it will give slightly.

 

The PVC/hose clamp thing has the same problem. When I press small rockets in a vice, this disturbs your feeling of the composition compacting. You think you're compacting the fuel, but in fact you only create a bulge in the tube. I'd rather leave the sleeve away and see the bulge.

 

It's like turning a screw in pastic, hard to feel when to stop turning, you know what I mean?

 

Since I only have an improvised metal shield I feel an urge to constantly look behind it and see what's happening while pressing

 

 

Something inflexible is needed - I have the "two halfs of aluminium" thing in mind...

 

For hand ramming, I cant see using a support unless you use mushy/handmade tubes, NEPT tubes had ram just fine.

 

[MrB]

While explosions never are a good thing, i don't really see shrapnel as a reason for not using a "hard" support.

"soft" stuff will allow the tube expansion, and rupture, a support needs to be as strong as possible.

Dagabu is on the right track, hand ramming shouldn't need supports, and pressing, should be done in a way that an accident isn't a "problem". It might damage the stuff around it, but everything around it should be the sort of stuff that doesn't really matter if it gets damaged. Shielding, walls, such things.

 

B!

[DavidF]

"The Forester method..." Ha ha, I like it! I use a sheet of .005" brass shim stock, rolled up, as a tube support. I have developed it to the point that it is the best tube support for 'me' to use for all my rockets. I have made hundreds using the shim stock. It can take incredible pressures without deformation. There are no clamps, only O-rings or rubber bands and a piece of strapping tape.

 

The method is finicky and takes a bit of getting used to. The support can be a PITA to make. It is easy to damage if one is careless. Those are the negatives.

 

On the positive side: it is cheap, and easily available to all. Tube OD variations do not matter. It can be adjusted. I have used the same support to press (long) 1# rockets and (short) 3# rockets. The support for that is 9 1/2" long. I use a shorter one for strobe rockets.

 

My initial problems with this support came from deformation of the delicate edge of the bottom of the coiled brass. This deformation made an inward 'burr' that made the motor difficult to remove. That problem was solved by putting a plastic washer underneath the rocket when pressing. Also, in the beginning I used a single clamp to hold the support tight while pressing. This contributed to the same problem by causing too much rigidity. It was a potential step backwards in safety, although no tests of any kind have been done in that regard. The clamp was replaced with 2 wraps of strapping tape.

 

Once the sleeve has been tightened to just large enough to insert the empty tube, the tube is inserted while being grabbed from the inside with a special tool I made up. Then it is wound tight. If it just spins and does not 'grab' the brass enough to roll it tight, I partially remove the tube, wipe it with a damp cloth or sponge, and try again. This always works. When the motor is pressed, the tape is removed and the motor/spindle assembly is turned backwards of the direction of tightening. It makes an audible click and can be gently twisted out in perfect condition. Most times, the sleeve has not opened enough to require any dampening of the next tube- and the dampening is very slight and easy.

 

Now that I use only waxed tubes the downward force on the support is greatly lessened. More of the pressing power goes to compacting the fuel grain, which is where we want it. There are no wrinkles in my motors.

 

Before I tried the brass I experimented with rolls of mylar that I purchased as off-cuts. I could press BP motors with no problem but they were not strong enough for whistle rockets. However, that was before I discovered waxing the tubes. Now that the waxing has lessened the friction between the fuel and the tube, pressing with only a mylar sleeve could possibly be done at lower pressures to produce whistle and strobe rockets.

 

These are some of my adventures into do-it-yourself tube supports and are still in the experimental stage. More work needs to be done but the concept has been proven to be highly effective. After July 5 I will get back to working on it.

 

Another (expensive) way to skin the cat might be adjustable shaft clamps. I have only drooled over pictures of those...

[dagabu]

Dave,

 

​Thanks so much for posting, I also found stainless steel shim stock, it is such a dry metal, I bet a single piece of Scotch tape would hold it closed! Could post a few pictures of your tools and the support?

 

MrB, it does matter a lot if you are not adequately shielded, others are around you, which way the support is facing, fuel used and the actual mass of the support.

 

What Dave is doing is changing the the whole rocket thing into a holistic approach for pressing rockets. I am looking forward to his next ideas on spindle removal, I know I have the best design ever for spindle removal due to its simplicity, no tools needed and almost zero friction. 100% brass materials and readily available ACME screw and nuts make it a reality for anyone with the ability to solder and turn a couple handles.

[nater]

Dag, does your spindle removal design work with any type of spindle / base design?

[MrB]

MrB, it does matter a lot if you are not adequately shielded, others are around you, which way the support is facing, fuel used and the actual mass of the support.

I hope you know i love and respect your opinion, but, working under the circumstances above is just a no go to start with. How you guys get anything done at all in a PGI event is beyond me. I couldn't work like that, or rather, i wouldn't. Doing what we do, we know, or should know, that while we might be able to stack the odds in our favor by a crapload of measures, it just means the accident is less likely to happen at any given moment. Anyone who did a bit of probability calculations in school knows that means it can still happen at any moment. For that reason, tube support could be made out of hardened steel, with WW2 grenade pattern cut in to it. Nobody is going to be anywhere near it when ever it blows up.

 

I am looking forward to his next ideas on spindle removal, I know I have the best design ever for spindle removal due to its simplicity, no tools needed and almost zero friction. 100% brass materials and readily available ACME screw and nuts make it a reality for anyone with the ability to solder and turn a couple handles.

Sounds interesting. I generally let the same vice that does my tube support splitting, pull the spindle lose by the same principle, before splitting the support, but since it's pushing on one side only it's been known to cause out of line forces, sometimes knocking a edge of the clay plug...I've been meaning to simply add a tread on it, and use a large nut to push it straight out, but never got around to it. Sloppy, but i blame it on not really doing much cored rockets.

 

I don't intend to disrespect anyone, or their work. I just cant relate to working around people, hell, i can hardly even TELL most people what i do for a hobby, much less include them in the process.

B!

[dagabu]

Dag, does your spindle removal design work with any type of spindle / base design?

 

No, it's not an add on but all part of one mechanism. Simply turn the nuts away from each other and the nozzle pushes the rocket off the spindle.

 

[Bobosan]

So you had the ACME thread welded on? or was it turned from solid bar stock?

[dagabu]

I hope you know i love and respect your opinion, but, working under the circumstances above is just a no go to start with. How you guys get anything done at all in a PGI event is beyond me. I couldn't work like that, or rather, i wouldn't. Doing what we do, we know, or should know, that while we might be able to stack the odds in our favor by a crapload of measures, it just means the accident is less likely to happen at any given moment. Anyone who did a bit of probability calculations in school knows that means it can still happen at any moment. For that reason, tube support could be made out of hardened steel, with WW2 grenade pattern cut in to it. Nobody is going to be anywhere near it when ever it blows up.

 

Sounds interesting. I generally let the same vice that does my tube support splitting, pull the spindle lose by the same principle, before splitting the support, but since it's pushing on one side only it's been known to cause out of line forces, sometimes knocking a edge of the clay plug...I've been meaning to simply add a tread on it, and use a large nut to push it straight out, but never got around to it. Sloppy, but i blame it on not really doing much cored rockets.

 

I don't intend to disrespect anyone, or their work. I just cant relate to working around people, hell, i can hardly even TELL most people what i do for a hobby, much less include them in the process.

B!

 

No offence taken and I actually dont disagree with your hypothesis but after two separate incidents, testing and having to live with the guilt of two people, a year apart, pop rockets, we just cant take the chance at PGI to allow for a run away burn so distances, press locations and a blow-out area are essential. As far as productivity goes, you are right, I spend all day every day teaching others to make and then go with them to shoot their rockets. I got NOTHING done all day long!

 

This year Ill be standing all day in manufacturing as a living reminder of what can happen, tell me this wont be a sober convention for some?