Tips and Technique of the Day Thread (Twice a week).

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Bundling shock cords.

Contributor: @KenECoyote

I use small rubber bands to make bracelets to keep shock cords bundled nicely and quickly. You can get a pack of 600 for about $5-7.



t fits well over small and large bundles, it's quicker than tape or crochet, and it provides some shock absorption too.

Double it up on small cords. For big cords, it stretches plenty enough for bundles; however, you can double it on smaller bundles to keep it tighter and for more shock absorption.

As mentioned by others, you can use dental bands for low power.

 

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Consider the Perfection Loop:

Contirbutor: @SolarYellow

I've been using the "Perfection Loop," a better method for tying in place of a bowline.

I have used this knot; it is perfect for the end of a line.

 

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Vinyl Decal Application

Contributor: @John Kemker

Instead of buying Rapid Tac for cut vinyl decal application, you can make a less-expensive solution yourself by mixing distilled water with a surfacant, such as Ilfotol, Jet-Dry, etc. You only need a few drops per liter of water in order to be effective. If you'd like to add cleaning power, add some 90% Isopropyl Alcohol, about 10% by volume.

 

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Clean the surface before gluing:

Contributor: @cwbullet

Some adhesives are hindered by dirty surfaces. I will clean the surfaces with a little IPA prior to gluing them together. It will remove fingerprint oils and dust to improve the adhesion.

 

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Acetone Smoothing:

Contributor: @cwbullet

I love to print rocket parts out of ABS. It is much more heat stable. It requries an enclosure and can come out kind of rough (brand depending). I have found that is you buy a simple empty paint can and a bottle of acetone that you can make a simple acetone vapor bath to treat your parts and make them smoother and stronger.

 

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Stronger shock cord attachments:

Contributor: @cwbullet

The number one cause of failure for a flight centers on recovery. One cause is a shock cord failure. On a low power kits, especially Estes, the shock cord is the weakest part of the typical kit. In my opinion, the attachment point is often a place of failure followed closely by damage to the cord itself. I prefer to use a kevlar line for their shock cord anchor that is firmly attached to the engine block.

The below video goes over several shock cord attachment options:

 

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Light reflections alignment:

Contributor: @neil_w

Use the reflection from your overhead light as an alignment tool. Here I used it to assist with decal positioning, to keep things aligned with the vertical stabilizer at left (you have to adjust your head position to make sure you keep the reflection in the correct spot; it's a little bit off in this picture, slightly above the vertical stab.)

 

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Label Everything:

Contributor: @cwbullet

I use a labeler to identify everything quickly. I found that I needed to do this the hard way. Unfortunately, it took two hard knocks of learning lessons to teach me the need. The first was assembling motors the night before. The second was two black powders in jars. One was BP, and the other was not.



Now, I even label my chargers. I learned this need from @OverTheTop in this thread.

I suppose masking tape and a Sharpie would work just as well, but to me, labels last longer, and an ounce of prevention is worth it to prevent a mound of heartache. Many black-appearing chemicals are less energetic than black powder. Unfortunately, I chose one that was much more hot burning. That is another story! Just buy a good labeler.

 

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This is index #5 for the tip-of-the-day thread.

List of Techniques (Index 5)

Page 1		Link to page 1 index
Page 2		Link to page 2 Index
Page 3		Link to page 3 index
Page 4		Link to page 4 index
121	1 June 2023	Label Everything
122	2 June 2023	Add Nose Weight
123	3 June 2023	Add Buttons and Rod guides
124	4 June 2023	Parachute Construction
125	5 June 2023	Paint with a Brush
126	6 June 2023	Safety First, including during your build
127	7 June 2023	Consider Recycled Parts
128	8 June 2023	SAND THAT FIBERGLASS
129	9 June 2023	Cutting a Body Tube
130	10 June 2023	Cutting body tubes part 2.
131	11 June 2023	Glue-Techniques Tips
132	12 June 2023	Consider using tracking powder.
133	13 June 2023	Pay it forward
134	14 June 2023	Keeping Paint Out of the Launch Lugs
135	15 June 2023	Snap Ring Check
136	16 June 2023	Applying Decals
137	17 June 2023	Thread Your Shear Pin Holes:
138	18 June 2023	Filling the wood grain
139	19 June 2023	Hoard Excess Paper and Cardboard!
140	20 June 2023	Extra Centering Rings Technique
141	21 June 2023	Motivation Tip #1
142	22 June 2023	Test Tubes Make Good Ejection Charged Cannsiters:
143	23 June 2023	Tape your shock cord bundles
144	24 June 2023	Straw Ejection Shroud
145	25 June 2023	Clean your nozzle and hotend
146	26 June 2023	Vacuum Pack Your Filament.
147	27 June 2023	Staying Cool at The Launches
148	28 June 2023	Heatshrink eMatches
149	29 June 2023	Save your brass
150	30 June 2023	3D Printed Fin Slot Guide
Page 6		Link to the next index

If you have an idea, could you each please help me post tips? Send me any ideas, and I will add them to the list.

Comments or suggestions should be posted here:
https://www.rocketryforum.com/threads/trf-tips-and-techniques-comments-thread.177678/

 

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Add Nose Weight:

Contibution: @cwbullet

Remember that there is such a thing as an optimum weight to attain a significantly higher altitude. If you building for altitude, light is not always better, even if it sims stable. Adding a little nose weight and shortening the rocket can attain more height.

 

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Add Buttons and Rod guides:

Contributor: @cwbullet

Nearly all of my rockets have rail buttons, but I have begun adding buttons and rod guides to some of my low-power and mid-power rockets. The weakness is losing a little altitude, but the plus is I can launch off multiple other pads when the one I want is occupied.

 

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Parachute Construction​

Contribution: @cwbullet

This tip applies to those low-power parachutes you assemble yourself. If the kit has a parachute you assemble, don’t use scissors to cut it. Use your straight edge and X-Acto knife—Lay one side of the chute on your cutting board or a piece of cardboard. Set your metal ruler (straight edge if you prefer) along the line you want to cut. Cut on the line, using the metal edge as a knife guide. Cutting parachute material takes very little pressure with the knife.

Don’t lift the pressure-sensitive tape disks with your fingers. The oil from your fingers will diminish the stickiness of the tape disks and can make the parachute fail prematurely. Instead, use the tip of your knife to lift and place the disks onto the string and chute material.

 

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Paint with a brush.

Contributor: @SolarYellow

I did my routine of white primer, grey filler-primer sanded, then white primer, then sanded. There were several little spots scattered around the rocket that needed a bit more filling but were smaller than anything you'd use "filler" or putty on. I didn't want to sand off another layer of filler primer, so I decanted some into a red plastic cup and painted it onto the small spots that needed it with an old hobby/model brush.

It made for a LOT less sanding to knock those spots down to level after it dried overnight, and I will need to add less white primer (weight and cost - I need to reorder white primer) to cover the grey and get a uniform base for a light color coat.

 

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Safety First including during your build:

Contributor: @cwbullet

Some forum users will roll their eyes at this tip, but it is important nonetheless.

Stop and think, no matter what you are doing, is this the safest way? This tip is essential with large and scratch builds.

Things to think about:

1. Are these fins big enough?
2. Is the shock cord and parachute the right size, and is the anchor sufficiently strong?
3. Is this the correct adhesive?
4. Do I have the right personal protective equipment for this build stage?

In medicine and the military, we do a safety time-out or debrief at the end of each stage, so consider this your personal safety timeout. I am sure you will agree your life, eyes, and fingers are too important to risk.

 

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Consider Recycled Parts:

Contributor: @cwbullet

Nothing makes me happier than to see come of the uses people have for parts that were not meant to be a part of rockets. We have a guy that launches in South Carolina that loves using Pringles cans to make rockets. Let's face it; it is better than adding to the landfill. I remember an old humorous statement on the forum that you know your rocketeer when you walk through the grocery store and say I can make that fly on every aisle.

Items to consider:

1. Paper towel, bathroom tissue, x-mas tree wrapping paper core, or mailing tubing: These can be used to build the basic airframe or fuselage of the rocket.
2. Scrap matte board, cardboard, or foam board: These can be used for centering rings to hold the rocket motor and for fins or fin parts.
3. Easter eggs, gumball machine hemisphere capsules, Leggs Sheer Energy pantyhose capsules, or just about any conical item: These can be used for nose cones.
4. Soda Straws, pen tubes, or any small tube: These can serve as part of the guidance system for launch (the "launch lug"). The new-fangled paper ones are better as launch lugs than straws.
5. File Folder Labels: You will need these to stick onto plastic parts where paper has to be glued onto them. The file folder labels can eliminate the need to use exotic CA or epoxy glue that requires mixing or putting up with toxic fumes.
6. Balsa sheeting and thin wood: This can be used for fins and other components like standoffs for the straws so that they are some distance from the wall of the paper tube.
7. Metal rods from windshield wipers: These can make great motor retainers when cut to length and bent to the suitable form.
8. Thin Cardboard: Thin cardboard is a good source of this material and can be found at your nearest art supply store. Ask for two-ply Bristol brand boards if they still make it. You use this to make transition shrouds for more advanced rocket designs. Other cardboard types can also be used as long as they are the thickness of a 2-ply Bristol board.
9. Mylar or Garbage Bags: Make your parachutes or streamers.
10. Gatorade bottles: Can be used as airframes and 29mm motor retainers.

This form or rocketry has been called trailer trash rocketry or garbage rocketry. No matter what you call it, it is better for the landfill and your pocket book.

 

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Sand that Fiberglass:

Contributor: @cwbullet

G10 and G12 fiberglass, used for centering rings, fins, nose cones, and tubing, is less porous than wood or paper. Since it does not have the pores of wood or paper, you cannot use wood glue to attach the fins to your rocket, and you should sand it when using epoxy. It's a good idea to use coarse sandpaper (220 grit is so) to roughen/scuff up the sides of the parts where adhesive will be applied. This will give the epoxy a better surface to hold on to instead of a very smooth surface. By giving it something to grab, you will create a better bond.

 

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Cutting a Body Tube:

Contributor: @cwbullet

This tip is applied to paper and cardboard low and mid-power tubes.

Cutting a body tube is difficult if you do not have the right tools. The first tool you need is a sharp knife. I often start with a new blade to ensure I have it right. The second item will help you get a smooth straight cut. This is often a guide such as the Estes Tube Cutting Guides or the Kuhn Tube Cutting Guide.

When cutting a paper tube without a cutting guide, wrap the tube in painter's masking tape several times around the tube when the cut is to be made to provide a cutting guide and reinforce the tube. You will be surprised how well this works at getting a clean-cut.

 

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Cutting body tubes (part 2):

Contributor: @prfesser

Holding the knife at a fairly high angle so that the tip does the work seems to work much better for me than a low angle, where the body of the blade cuts. It may make a slightly rougher cut, but that's why the Flying Spaghetti Monster created sandpaper.

Also, I use those big advertising cardstock "postcards" (junk mail) wrapped around the tube as a guide. With several turns around a body tube, they provide a thick edge against which the blade can rest. With my shaky hands, I need all the help I can get...

 

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Gluing-technique tips:

Contributor: @prfesser

For the strongest possible bond, especially with epoxy and porous surfaces (balsa, plywood, some 3D prints), consider adding a thin scrim of glue to both surfaces when practical. It's common to apply glue to one surface and expect it to wet the second surface adequately when assembled but that doesn't always occur.

As many others have pointed out...how often have you had the glue grab too quickly, leaving the coupler/engine block only partly inserted? Epoxy is slower but doesn't grab the way that most wood glues do, so gluing couplers, motor mounts etc. can be easier with epoxy than with wood glue. And with very thin body tubes (e.g. my Saturn V Skylab) epoxy may be heavier, but there's no solvent to evaporate so epoxy avoids distortions in the tube that can occur from water evaporation with wood glues.

(Yes, I'm an epoxy fan.)

 

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Consider Using Tracking Powder:

Contributor: @cwbullet

Use red, orange, or pink tracking powder for rockets expected to fly over 2,000'. These colors contrast best with bright blue skies and work reasonably well on overcast skies. The higher the flight, the more tracking powder should be used. The most commonly used materials are carpenters' chalk (available at building supply and large hardware stores) and tempura paint (available at art supply outlets).

Form a pocket for the tracking power instead of just pouring it into the tube body. Wrap a tissue around a spare tube or dowel of a smaller diameter than the tube body. Pour the tracking power into the packet but do not seal the top. Load the packet last when packing the tube body for launch.

 

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Pay It Forward

Contributor: @cwbullet

This tip is not a building or flying technique but a life technique. We all know those flyers that share everything. They love to mentor new flyers and add to their knowledge. I fight to do this at every corner but acknowledge that I am not always successful.

I see it every month at our launches. A new flyer comes to the field and knows nothing of high-power rocketry. One of our older flyers spends the time to teach and answer his questions. They may even loan them items to lower the financial burden of the hobby.

The fact is that sharing is essential to the future of our hobby. So, I recommend sharing that 3D print file, simulation files (ORK or RKT), and those techniques you have learned over the years. It will help make sure our hobby expands and thrives. Let's keep our hobby growing by paying it forward. It is much better than being the old curmudgeon that never shares anything, and you will have karma on your side.

 

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Keeping Paint Out of the Launch Lugs

Contributor: @SolarYellow

To prevent paint from getting into the launch lug, I cut chunks of the paper stick from a cotton swab and wrapped them in blue masking tape to fit the ID. I leave them in place as plugs from the first primer layer until the last sanding before color coats, when I punch them out and clean up the excess primer buildup around the ends of the lug dries. This has worked well on several rockets now, and the plugs are reusable for several rockets if you clean up the ends.

 

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Snap Ring Check:

Contributor: @John Kemker

When assembling a snap-ring motor, make sure the snap ring is in the groove by grabbing the "ears" of the snap ring with your snap-ring pliers and slightly compressing the snap ring. Give a gentle rotation to see if it moves freely and smoothly. If it does, the snap ring is properly seated. If you feel grit or resistance, you either have a grain of sand or are not properly seated.

(This is from a conversation with Scott Koremeier of Loki Research this afternoon.)

 

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Applying Decals:

Contributor: @cwbullet

The best way to put on pressure-sensitive vinyl decals is to put lukewarm water and TWO SMALL drops of dish detergent into a bowl. Then, take the decal off the backing and dip the side with the adhesive on it into the bowl (make sure not to let the adhesive touch the bowl). Now you can put it on the rocket and move it to where you want the decal. Set the rocket aside to dry, and you’re done.

 

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Thread Your Shear Pin Holes:

Contributor: @cwbullet

Some fliers have found getting those sheer pins in on the field challenging. I would recommend that you bring a drill and tap to the field. You can thread those holes and make them easier to place those plastic screws.

 

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Filling Wood Grain​

Contributor: @cwbullet, but they are originally from Chris Michielssen

I use a cheap 1″ utility brush with Elmer’s Carpenter’s Wood Filler (CWF). It is relatively cheap at your local home or hardware store. A brush used to apply CWF cleans up easily with water.

1. I start by sanding the surface lightly with 400-grit sandpaper.
2. It is easier to fill the grain before gluing them to the tube. It is near impossible to fill the grains after you attach them to the tubing.
3. Thin the CWF to the desired consistency. I prefer mine to be rather thin, but the thinner you make it, the longer it takes to dry. You think it with water.
4. Dip the brush about 1/4″ into your thinned CWF and paint the balsa with the grain, then against it. You are against the grain, forcing the filler into the open pores. Paint over one side of the fin for now, and let dry a few minutes before painting the other side. CWF or Sanding Sealer can warp thin balsa fins. Usually, when the other side of the balsa is painted with filler, it will flatten out again.
5. Let the CWF dry a few hours before sanding.
6. Sand the flat sides of the filled fins with 400-grit sandpaper on a block. Sand the rounded fin edges with a small piece of 400 grit sandpaper rolled over a fingertip. Ultimately, you’ll want the balsa surface to have a thin skin coating of the CWF.

 

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Hoard Excess Cardboard and Paper!

Contributor: @cwbullet

Cardboard and paper can help you protect your surfaces and floor. I save excess cardboard shipping boxes, cartons, newspapers, and brown paper bags.

1. Cardboard: It can help protect surfaces from glues and knives. I use them for cutting boards and backing boards for spraying small parts. Cut the cardboard boxes into smaller “flats.” A good, workable size board will be around 12″ x 18″. I cut balsa, shroud lines, shock cords, and parachutes on the cardboard sheets. It can also be used as a backing to protect your card table if you want to prime or paint fins.
2. Brown or newspaper: You can use it to mask off parts when you are painting. I also use them as tablecloths to prevent glue spills and protect the surfaces.

The best part about these types of recycling is that it is burnable when you are done. I incinerate it all. I can hear my wife huffing as I type.

 

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Extra Centering Rings Technique

Contributor: @techrat

I've started working with mid-power 3" and 4" rockets. Usually, a kit will come with two centering rings for the motor tube. Generally, I have been placing these between where the fins are supposed to go so I can also adhere the fins to the centering rings for added strength. However, that usually leaves a significant section of the motor mount tube past the fin area. I cut myself a third centering ring from foam core or corrugated cardboard and glued it to the top end of the motor mount tube and against the inside of the body tube. This adds almost no weight to the overall rocket.

This does two things: 1) It keeps the top end of the motor mount firmly centered and also stiffens the body tube a little bit more, and 2) it reduces the amount of volume that the ejection charge needs to pressurize so that popping the nose cone is no hassle.

 

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Motivation Tip #1:

Contributor: @jqavins

"The number one, single most important tip for getting rocket stuff done: get off the couch."

No truer words have been said. Excuse the crumugeonly sarcastic sense of humor and sue it as motivation to start building. Until you start, the most useful tip will not help. {/quote]

 

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Test Tubes Make Good Ejection Charged Cannsiters:

Contributor: @cwbullet

I usually buy them on eBay or get them as work when they expire. They come in many sizes so you can adjust them to the size of yoru rocket.



I drill a small hole in the bottom for the ematch wire. I feed the wire through so the match is at the middle of where the charge will be. I seal the bottom with a glue gun and add a wrap of electrical taep to secure it. Add the desired amout of BP and fill the rest with Dog Barf. Seal the top with tape. I toss the lids because they can cause projectile damage to paper tubes.

You can also use aquarium tubing!