Extra Tips

WARNING AND DISCLAIMER:  If you are underage, then consult with your parents or guardians before attempting any of this.  You are on your own - I'm not responsible for your actions or harm you may bring to others because of your actions.  Making the items described below  can result in injury or death to you or people in your vicinity. Some things mentioned here may be illegal to make in your city, county, state, or country so check the laws that apply to you before you attempt anything described here. These notes are not complete on purpose. If you are reading them and new to pyrotechnics, then you are making a mistake. Stop now - this page is not for you. Get a beginning book on fireworks (see Skylighter or American Fireworks News (very quick shipping)  for a start) and read up. You can't make any of this work without more information so read up or join a club or ask someone to help you.

Reinforcing the Rocket Tube

Caution: when hydraulic pressing with sleeves of any kind, even the PVC sleeves, the motor is confined in such a way that an ignition will result in a catastrophic failure of the sleeve - always shield yourself when hydraulic pressing with sleeves!


You might consider using a reinforcement tube for these things to prevent failure or weakening of the tube because of overzealous hammering. Bind it together with hose clamps - use as many hose clamps as will fit on the sleeve.  I've started using this system and now I can tamp the crap out of a tube and it won't split. 

Warming a couple of sleeves at 210 degrees (F).

Sliding a warmed sleeve onto a tube and sizing it.

Example of a 1 1/8" sleeve combo that uses two PVC pipes - both of which were cut from oversize and downsized to fit using the oven method. The inner pipe is a schedule 40 and the outer pipe is a schedule 80. That makes a tough sleeve!

If you can't find a PVC pipe that fits perfectly around your tubes, then select one that is slightly bigger and cut a groove in it to make up for the slack. Then warm it in a 210 degree oven for about 10 minutes and form it around your rocket tubes. Hold it in place until it cools and you will have a custom fitting PVC tube for very little cost. Don't use clamps on the warm pipe as it will smoosh - use tape or gloved hands to hold the tubing until it cools (dip it in cool water to hasten the cooling). Above is an example of a 1 1/8" x 11" sleeve made with two pieces of PVC  and the warming method.. When clamped tightly, the slits just close.

PVC reinforcement sleeves are great for pressures up to about 4,000 or 5,000 pounds - perhaps higher if you carefully construct the sleeve. They seem to be prone to failure if you over-press them so be careful when you use them on a hydraulic press. The most common failure modes are rupture at the bottom and 'leaning over' of the tamping tool at the top - which sometimes causes the whole sleeve to tilt over and ruin the spindle (ugh!).  For hand tamping, they can't be beat.

If you want a more robust sleeve, then you might want to go the metal route. The above picture is a sleeve made from an iron water pipe (the inside has a weld seam so it has to be smoothed out on a lathe or cut out with a hacksaw).  

David Sleeter, in his book "Amateur Rocket Motor Construction" explains how to build a strong steel sleeve by welding 'lips' onto a piece of iron water pipe. Above is an example that is slightly modified from David's version. This is a 5/8" I.D. sleeve with two pieces of 3/16" flat stock welded onto it. The two pieces of stock were separated about 1/8" before they were welded to allow a hacksaw blade to easily fit between them. After welding the lips onto the pipe, the pipe was cut with a hacksaw down the center - a job made much easier since the lips now guide it along its path. After cutting, the gap was sprung outward a little by driving a screwdriver into it. The gap was widened to allow the 5/8" motors to freely load into the sleeve. On both lips, four holes were drilled to tap size and one lip was finished out to 17/64s while the other was tapped to 1/4-20. This definitely needs a blast shield when loading!

As an update, I tested the above sleeve for strength by compressing kitty litter in it. It failed somewhere around 20,000 psi on the comp. The failure was graceful and started on the side of the tube at the bottom. The place it started was a spot where I had accidentally touched a welding rod while making it. Even with the flaw, 20,000 is plenty good enough and hard to get to by accident (your whole press will be complaining!). With such good results, I decided to make another for my "every day sleeve" - only this time I was careful where I struck arcs with the welding rod. ;-}

The sleeve below is for those with too much obsession with pyro (;-})... I own two....

Want to get the Cadillac of sleeves? Get a Wolter custom sleeve ( www.wolterpyrotools.com ). It has quick disconnects and works like a charm. It is custom made for your tubes - it is not meant for everyday rocket making but it sure is sweet.



Sometimes the hobby pyro dealers will sell you inferior tubes that are just too soft and punky. A way to reinforce the tube is by using Minwax wood hardener. Minwax isn't a replacement for a sleeve - it is for making the tube tougher for flight.  The stuff is pricey and will add to your cost per tube.  Don't soak the tubes in it, just dip them and dry.


A cheaper trick to reinforcing punky recycled paper tubes is to use wood lacquer. It won't be as good as the wood hardener but it still works and it is considerably cheaper. I use it for cake tubes - it protects them from moisture and stops them from fraying.


Making Stabilizing Sticks for Rockets

When I first started making rockets, I was amazed at what caused the most worries. One of the silliest was finding a good source for rocket sticks. There are worlds of disinformation out there on this... my solution is to look for a small but sturdy stick. It can be hard wood, softwood or unknown scrap as long as it does the job. Its length should put the CG of the rocket just behind the motor nozzle - but that isn't critical. If your rocket is unstable and you have a stick that is close to the right size, then look for other things - like slow fuel or chuffing of the motor. The stick should be knot free - if it has knots, it will break.

I've used bamboo planting sticks - available from a nursery - and those work great but they are a little quirky (they corkscrew and have a good old time going up) so if you are sending a flight of rockets up, you probably don't want to use them.  

Round dowel works fine and is really easy to use but it costs 25 cents or more a rocket - which is kind of silly since the whole rocket probably costs less than that. Also, there is debate about whether round dowels offer as much stability as square ones.

For 1/4" rockets, I've used food skewers - the long ones. And those are cheap and easy to use.

The best sticks for 3/8" motors and above are made by ripping those Asian garden stakes to the right size. Get them at the garden shops especially in the spring. They are a tad expensive but don't have knots and cut nicely. They don't break unless there is a CATO. Cost would be less than for comparable size dowels and they offer more stability because they are square instead of round. 

In a pinch, you can rip pine lath to the right size - although lath is weaker and has many knots -  there will be more waste.

You can use multiple sticks. Just put on two sticks (across from each other) and decrease the length of them proportionately. Your rocket will fly nicely - even if it doesn't look like it would. Above is a two stick one pounder - a slow red mag rocket. Click on the picture to see the launch. The sticks were about 15 inches long. I have heard of one and two pound rockets with four 8 inch sticks.