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

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Prep Before Gluing

Contributor: @Sooner Boomer

When doing glue-ups, especially epoxy, I borrow a technique from cooking. Merriam Webster: mise en place - a culinary process in which ingredients are prepared and organized before cooking. Have an organized workspace, free of clutter. Lay out the parts/pieces to be glued. Have ready the glue(s), the mixing container (and scales if used), stirring stick, applicator, clamps or tape (if used), several loose paper towels, and a trash can. This way, you don't get halfway through and realize you need another tool (or something to clean up the big blob that just fell out). Have loose paper towels ready so you don't have to pull them off of a roll.

This tip can help prevent glue disasters from occurring while you search for that one item you forget or think you might not need.

 

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Keep your propellant dry.

Contributor: @cwbullet, @caveduck, @SolarYellow

This issue is not a massive problem if you live in a dry environment or use it soon after making or buying it. But if you store it for more extended periods, some of the propellants (Cough: whites and sugar motors) ate relatively hydroscopic and would absorb water from the air and might even oxidize.

I live in a very humid environment. Like @SolarYellow recommended, I store all of my rocket motors in surplus ammo cans. They come in a variety of sizes so you can probably find one hold most of your motors. They are sealed with a rubber gasket (check it before purchase because the crack with age). They are also design to hold flammable items.



As @caveduck suggested, if you have a bag sealer and the motor may have to wait a while before use, seal the motor in a bag with minimal air and some desiccant. This is really important for hygroscopic propellants like WL. I also use a Foodsaver to vacuum seal opened motors that I intended to fly but did not for one reason or another (weather). I often add a desigant pouch to absorb as much air humidity as possible.



I have also seen people use air tight containers such as plastic marine boxes or storage bin/containers with gasket such as those made by Sterilite.

Expert advice on buying a food vacuum device: don't use the one from the kitchen if you are married or in a relationship. That will not end well. Also, buy a good one with a vacuum tube. It will allow you to test your altimeters.

@prfesser added that Horrible Fright (Harbor Freight) has metal and plastic ammo cans, brand new with good rubber seals. And 'crystal cat litter' is an inexpensive silica gel, a very good desiccant. I fill several small holes in a peanut butter jar with the litter. Easy to remove and replace, neater than scattering desiccant in the bottom of the ammo can. Got one in each of my buckets of AP to keep them nice and free-flowing.

 

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Use umbrella bags to protect your rockets.

Contributor: @KenECoyote

Some stores, such as Target, have free umbrella bags at the entrance when it rains. Use them to protect your rockets in storage and transportation!

The Target ones are good for up to 4" in diameter...



If you have a rocket longer than the bag, just cut the bottom off a second bag and tape them together! Two bags were perfect for the full length of this 4" diameter Patriot (up to where the fins start).



Cost: Free

When arrested for taking the whole dispenser at the front of Target, please do not tell the police that Ken from Rocketryforum told me to do it.

 

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Yellow or White Glue?

Contributor: @cwbullet

Choosing the suitable adhesive for joining parts is often a challenge, and if you ask 100 people which one to use, you will get 150 opinions. Two common glues used in rocketry are white and yellow glue. Both glues dry fairly quickly. Both can be cleaned up easily with water.

White glue is one of the most common adhesive used for constructing model rockets. In fact, white glue is an indispensable household adhesive. Its formal name is polyvinyl acetate. And, as it says on the plastic squeeze bottle, you can use it to fasten paper, fabrics, leather, wood and most porous or semiporous materials, like ceramics. White glue is also low odor and cleans up with water. Under optimal conditions, it forms such a strong joint on wood that the wood will fail before the adhesive does. It is beneficial with porous surfaces such as paper. It works well for joining the most commonly used materials for model rockets, such as cardboard, paper, and balsa wood. It doesn't stick to non-porous materials such as metal or plastic. White glue can be more userful with gluing in couplers.

White glue has a few minor drawbacks. One is clamping time. To be sure that the glue has set, you generally have to leave the clamps on a workpiece for a couple of hours. Second, white glue isn't moisture resistant, but as long as your rocket does not take a swim in a body of water or hang in a tree for months, this is a perfectly good adhesive for wood, paper, and cardboard. White glue is simply a strong and inexpensive product.

Yellow or carpenter's glue (AKA "wood glue") works similarly to white glue. As written in Popular Mechanics many years ago, “Yellow glue is a more muscular version of its familiar cousin white glue“. Like white glue, yellow glue bonds a variety of porous materials. There are several reasons for this. First, it withstands moisture better than white glue, and outdoor formulations of yellow glue offer even more moisture resistance than interior formulations. The advantage is that shortly after applying the glue to the workpiece you can stick parts together, and they will stay in position as you place the clamps. This also reduces the tendency of the glue to run down the workpiece. The converse is also true, however. You have to work more quickly with yellow glue than with white glue. It usually dries to a yellow color and isn't much more challenging to clean up than white glue. It is not as useful to glue in couplers because it might catch while gluing.

Joining parts made of non-porous material, such as plastic or metal, requires a different type fo glue. For these types of objects, you will not be able to use yellow or white glue. Metals and plastics require a more specialized glue such as a plastic bonder or epoxy. Be careful and do your research before gluing these items.

 

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Buy an Aluminum Angle:

Contributor: @cwbullet

I own several different sizes. My favorite size is the 3/4" x 3/4" that is 1/16" thick. I bought a 72" long piece and cut it into one and two-foot lengths. I use it for Three primary purposes, but I am sure you will find more.

Uses:

1. Mark body tubes: When you have to draw lines along the body tube to mark for fins and launch lugs, a trick is to use a piece of angle aluminum as a guide. Estes first mentioned this in 1965; aluminum angles are very useful for making a straight line on rocket body tubes.
2. Check Launch Lug Alignment: As described by Chris Michielssen in his blog, you can use the edge of the aluminum angle in the same manner as we use it to make a straight line, but this time we use it to check the alignment of the launch lug as being parallel to the body tube.
3. Fin attachment guide: A simple and effective means to keep your fins perpendicular to the body tube. If you have a bandsaw or Dremel, cut a slot and the body tube, and now you have a cheap and effective fin attachment guide. This method has been widely published by NAR and Estes,

Addition: aluminum angle uses; small tubes (say, up to an inch or so) use 3/4" angle; 1 1/2" for larger tubes up to 3-4" diameter. Small angle on a large tube tends to "wiggle" a bit, the larger angle straddles a wider portion of the tube for better accuracy.

Yes, you might need to adjust the size for smaller and larger tubes.

 

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This is index #4 for the tip-of-the-day thread.

List of Techniques (Index 4)

Page 1		Link to page 1 index
Page 2		Link to page 2 Index
Page 3		Link to page 3 index
91	2 May 2023	Masking Tape Spout
92	3 May 2023	Better Aligator Clips
93	4 Apr 2023	Better Paper Wraps
94	5 Apr 2023	Use reusable zip-ties
95	6 Apr 2023	Origami Black Powder Funnel/Trickler/Scoop
96	7 Apr 2023	Paper Weighing Boat
97	8 Apr 2023	Weld Nut Tip for Rail Buttons:
98	9 May 2023	Secure shock cord ends
99	10 May 2023	Ear Plug Zipper Protector
100	11 May 2023	Get a good sanding block
101	12 May 2023	Smoother Tube Cuts
102	13 May 2023	Don't forget pressure vents
103	14 May 2023	Tight gaps are better
104	15 May 2023	Cutting Motor Tubes
105	16 May 2023	Coin Bottles can organize your range box
106	17 May 2023	QuickLink Reminder
107	18 May 2023	Remove the safety lock from Spray Paint.
108	19 May 2023	Use the rail or rod as a guide
109	20 May 2023	A few balsa wood facts
110	21 May 2023	Priming 3d Prints (Plastics)
111	22 May 2023	Knots or not in rocketry
112	23 May 2023	Protect Your Scale
113	24 May 2023	Left Over Greatstuf?
114	25 May 2023	3D Printed Parts: Sand or not?
115	26 May 2023	Bundling Shock Cords
116	27 May 2023	Vinyl Decal Application
117	28 May 2023	Clean the surface before gluing
118	29 May 2023	Acetone Smoothing
119	30 May 2023	Stronger Shock Cord Attachments
120	31 May 2023	Light Reflection Alignment Tool
Page 5		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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Masking Tape Spout:

Contributor: @Tobor

This tip is similar to Swap Out the Spout. It is proof that there is more than one solution to the same problem.

W working on my Estes Shuttle, I came up with a better way to dispense Titebond III onto Estes parts...

I used masking tape to close off most of the tip, leaving just a ~18 gauge-sized hole (Blue speck on the left end of the tip).



Now I have really fine control of the dispensed glue.

 

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Better Alligator Clips:

Contributor: @Grog6

On the ignition end of things, I've found that the gold-plated alligator clips aren't as susceptible to corrosion from the propellant. The silicone-insulated wire from Amazon is also impervious to heat. Digikey has gold-plated clips in two sizes.

I don't have much experience with the gold-plated (BU-30G are $0.72 and BU-60G are $1.02 a piece), but Copper and Stainless steel will also last longer.

 

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Better paper wraps:

Contributor: @Bravo52

One way to dress up any basic rocket is with paper wraps. I use them for Command Service Modules on the Estes Saturn kits that are my "flyers." Other kits, like the Dr. Zooch kits, were perfect for making realistic semi-scale rockets that fly really well.

The one problem I have with paper wraps is that the printing doesn't go completely through the paper. If you have a seam on a dark background, you might end up with a white paper line on the print.

To avoid this, one day at the bench, I took a break and snuck into my wife's scrapbooking stash and grabbed a black acid-free marker, and "edged" the paper wrap. It instantly disappeared against the dark background. The "acid-free" is important so it won't bleed over time and stain the rest of the paper wrap. Avoid using a regular "Sharpie" as they bleed through the paper. Sharpie does make an acid-free version. You just have to look out for it. I've upped my game a little by using the appropriate color when called for on the design. However, you can't go wrong with basic black. It tends to fade away into the rest of the design.

Here is an example of a marker from Amazon.

I'll warn you in advance...if it says; "scrapbooking" anywhere near it, it will be pricey

 

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Use reusable zip-ties:

Contributor: @KenECoyote

Use releasable ones if you use plastic zip ties for your altimeter bay (and not already doing so).

• You don't need to cut old ones and find new ones.
• Quickly change batteries even in the field without cutting tools and new ties.
• More ecological and sensible (no worries about taking bits of cut zip-tie trash off the field).

I found these at Walmart:

 

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ORIGAMI BLACK POWDER FUNNEL/ TRICKLER/ SCOOP

Contributor: @KenECoyote

Learn origami while working with explosives!

Material required: Index card.



Step 1: Fold the index card upwards in half lengthwise.



Step 2: Fold one corner upwards.



Step 3: Unfold the corner and open the card, then flip the corner in, and viola... you've learned origami!



Pour the BP into the card, and the crease allows precise pouring (this is actually my setup and method).



You can tap it with a finger to slowly trickle a bit in.

If you overshoot it, it's straightforward to just pour the extra bp out back into the card.



I made it one year ago for pouring bp on a scale, and I'm still using the same one!

The best part about this tip is that the measuring funnel can be burned later. It is much easier to dispose of than a plastic funnel.

 

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Paper Weighing Boat:

Contributor: @cwbullet



I found this a few years ago. I found this video, and it describes how to do it.

 

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Weld Nut Tip for Rail Buttons:

Contributor: @ONAWHIM

When mounting rail buttons using weld nuts, try this method I learned on TRF some time ago.

To find the predrilled rail button hole, I cut a piece of machine screw of the correct thread size so I have what is essentially a small threaded rod (all thread) to locate the hole with.


To reach inside the airframe when attaching a weld nut for the rail button, put a pea-sized ball of putty on the end of something you can get down the tube, here an aluminum angle.



Using a toothpick add epoxy or JB Weld. Mark the angle beforehand at a distance to the hole so you can find it easily.



Once the JB or epoxy sets up a bit, I swap out with temporary extra long screws so the weld nut thread is perfectly aligned with the center of the airframe and lined up with the other rail button nut. A parallax view, if you will.

 

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Secure shock cord ends:

Contributor: @cwbullet

I like to secure both loose ends of my shock cords with shrink tubing rather than have them flopping around. I have found that tape and stitch alone can come loose over time. It is not needed as much if you sew the ends, but I do it anyway because it makes me feel it is more secure. With knotted cords, shrink wrap is more critical to avoid loose ends from snagging on items or coming unraveled.

 

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Ear Plug Zipper Protector:

Contributor: @BlaineS

Although this is not novel, many have used ear plugs, pencil cushions, and pipe insulation for years; Blaine did a thread with great instructions. It was revived in the tips comments by @KenECoyote . Thank you both.



Steps:

1. I poke a hole through a new & clean (LOL) ear plug with an awl.
2. Insert a plastic "bar straw and stir stick" using the inserted awl.
3. Cut away the excess straw.
4. Thread the kevlar shock cord through a straw with the "big end" of the ear plug orientated to the top of the body tube.
5. Use plastic cement to glue the ear plug on the shock cord at the top of the body tube.

 

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Get a good sanding block​

Contributor: @cwbullet

A good sanding block is essential for building rockets. I own a lot of sanding blocks of multiple sizes and shapes. You will find that you often need it to shape fillets, fin shaping, square body tube ends, and reduce transition and nose cone shoulders. At times, you will need rounded blocks, but the flat ones will be the most useful one in rocketry.

I have used a bunch and prefer the old Great Planes Aluminum but they do not make them any more. Du-Bro Kwik Sand Block is probably equivalent. I do not own one of these. The new Estes sanding block looks promising once it is finally released. I also suggest the Warner sanding block (34436).

For larger projects, I use large drywall sanders with hand guards. In addition to being a comfortable sanding block, the guard protects your hands when you aggressively sand.

Could I make my own? Absolutely.



You can also 3d print them, but that will be fore another day.

 

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Smoother Tube Cuts:

Contributor: @cwbullet

We have all seen a jagged tube cute that did not come out as expected. When cutting a paper tube without a cutting guide, wrap the tube in painters masking tape several times around the tube at the point that the cut is to be made to provide a cutting guide and to reinforce the tube. I have found that it helps keep the tube cut straight and smoother.

 

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Don't forget a pressure release holes

Contributor: @cwbullet

I do this on most of my rockets, but it is most important on larger high flying rockets. The reason this is important is air expands as air pressure decreases (increasing altitude). We have all witnessed a rocket deploy early and spread the body tube because a flier forgot and did not know to put the little vent hole in the tubing. No one wants to suffer premature separation.

I use a pressure relief hole (vent) just below the couple or nose cone shoulder. In general, the larger the cavity, the larger the hole. Any sections which will slip apart for recovery should have a small hole to the outside to allow pressure to equalize in flight. I usually use an 1/8" hole in rockets of 3 - 4 inch diameter. Be careful not to drill them where they will be blocked by the nose cone or a coupler.

Ground test ejection charges to ensure the hole is not too large.

 

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Tight gaps are better:

Contributor: @cwbullet

When designing a part or rocket, always make the parts fit tightly as possible when joining materials. Do not expect glues to work properly with large gaps. The maximum strength of most glues occurs when the fit is close and a minimum amount of glue is used. Also do not expect glue to fill the gaps and maintain full strength.

I slowly and lightly sand with 150 to 180# sandpaper to increase the bond surface, dust them off and then glue them in place. If they slide in easily and have perpendicular play, you sanded too much. Hint: This is more important in High Power.

 

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Cutting Motor Tubes

Contributor: @BABAR

This method works at cutting cutting body tubes that are motor mounts (BT-5, 20, 50).

Steps:

1. Attach a dowel inside a used black powder motor casing that just fits inside the tube you are going to cut.
2. Mark your cut line on the outside of the tube with a pen or marker.
3. Place the dowel/casing parallel to tube with the casing midway crossing the cut line to calculate the insertion depth. Put a small piece of marker tape on the DOWEL where it reaches the end of the tube.
4. Insert the dowel/casing to the depth marked by the tape, you now have an internal backing for your cut.
5. Using Estes Tube Cutting guide, marker tape wrap, freehand, or technique of choice, and a sharp blade, make your cut, several shallow passes may work better.

The internal backing from the motor casing keeps the tube from collapsing inward when you cut. The dowel/motor casings also are useful as “handles” when painting rockets. I put hooks on the free end so I can paint the rocket and hang it up while it dries.

 

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Coin Bottles can organize your range box:

Contributor: @Sooner Boomer



Clear plastic coin tubes are useful for organizing small parts. They come in a variety of sizes. They're good for keeping the smalls organized at home, plus a good way to take a small amount of spares to the range. I also take several OTC meds in small amounts (allergy meds, tummy meds, etc.). Labeling is really important in all of the above.

This tip is one have have used for years. I also use pill bottles and film canisters.

 

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Quick Link Reminder

Contributor: @KenECoyote

How many of you have forgotten to attach a link before the flight? How many almost forgot? Recently?

Now, I attach a piece of streamer or flagging tape to one or both ends as a temporary reminder that they're NOT attached.



Small step to take to avoid a big disaster!

 

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Remove the safety lock from Spray Paint.

Contributor: @KenECoyote

Ever grab a can of paint to spray outside only to see that it requires a screwdriver, and you don't have one with you? Annoying, isn't it?



Here's a trick. After opening it, use something to cut a slit in the inside ring that holds the lid in place. Now you don't need a screwdriver!



Note to store safely away from children (small children, not grown children ).

 

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Use the rail or rod as a guide:

Contributor: @KenECoyote

Ever get to the launch lug/ rail button install at the end and realized that you forgot to mark it off (or painted over the markings) and there's stuff in the way of using your nifty angle stock tube marker?

Just tape on an Estes lp launch rod to the outside edge of the angle stock marker to extend it through narrow areas for marking!

 

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A few balsa wood facts:

Contributor: @cwbullet

I am adding this information, but it is a blast from the past. I believe this came from Dan French on Bomarc.com. I just added it as a PDF. Why is the type of balsa Important? If you buy a larger piece to make a nose cone, the type of balsa can reveal a lot about how it sand and cut.

 

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Priming 3D Prints:

Contributor: @cwbullet

I received a question through a PM about how I paint my 3D prints. I usually do not paint them, but if I were to do so or when I do so, I would use a high-quality primer that is plastic friendly. Although this is written as a Primer for priming 3d prints, it applies to all plastics.

Steps:

1. Always test the primer and pains on something useless. Not all brands and types of plastic are compatible with primers and pains. For example, I had a particular brand of PETG that I could only get to work with water-soluble primer. I usually make a 2x2 plastic swatch as a test for each primer and paint.
2. I always pre-sand to remove fur. 3D Printer fanatics will know what I mean by fur or hair on 3D prints.
3. Use a light coat of primer and allow it to dry.
4. Sand between coats with a very fine 400-600 grit sandpaper.
5. Repeat 3-4 until you are happy with the surface.
6. Paint it with your final color.

Which brands do I like? I am delighted with the results from Testor's and Tamiya primers. They come in a spray can, and they are easy to apply. The downside is they are expensive, so I always test them on plastic and with paint before I test them on a print. Nothing is more annoying than painting a large nose cone and finding out after drying that the plastic and primer are incompatible.

 

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Knots or Not.

Contributor: @cwbullet

This text is something I acquired from an old website years ago and a guy that went by Fatboab.

Knots form the link between the recovery system and the rocket. It doesn't matter if you are using a bungee cord, tubular nylon, or kernmantle climbing rope, the ability to tie a variety of knots is fundamental to recovering your rocket safely. Any knot used should be as strong as possible yet be small and neat, it should not come undone during normal use, and it should be appropriate to the situation. Knots are only temporary connections and have a worrying ability to work loose on their own and become untied; thus, they must be checked before each flight to ensure they are still secure. The stiffer the tape or rope used the more likely the knot is to come undone. All knots weaken the rope by 25-45 percent, depending on the knot itself and the size of the rope used. This weakening is due to the bends put into the rope by the knot; the tighter the turn, the weaker the knot. Knots that are used to form a permanent joint, such as when tying rope or tape to form a sling, should be tied as tightly as possible. Knots for all other situations are worked tight by pulling the individual strands forming them. These knots should be firm but not over tight so that if they are loaded they can tighten up further and thus absorb some of the energy of deployment.

Knots Useful to Rocketry

Not all knots are useful in rocket recovery systems, they are either not suitable for the application or weaken the rope too much. You should never use a Clove Hitch or an Overhand knot if your recovery system is using rope or bungee, they are far too weak compared to other knots. Ideally, you should use a Figure-of-eight on a bight knot as this weakens the rope the least, the table below shows how different knots affect the strength. Knot strengths (percentages) Unknotted rope 100 Figure-of-eight 75-80 Bowline 70-75 Double fisherman's knot 65-70 Fisherman's knot 60-65 Clove hitch 60-65 Overhand 60-65 As you can see it isn't really worth considering the Overhand or the Clove hitch when constructing recovery systems. Similarly, if you have to join two ropes together a simple Fisherman's knot is inferior to a Double fisherman's knot.

Figure-of-Eight

The figure-of-eight is a very versatile knot, it's used predominantly by climbers for tying into the rope for safety. It has a distinctive shape, is easy to tie, is strong, and is fairly easy to untie after it's been loaded. Also if it's been tied wrongly with either one turn too many or too few, it will still produce a usable knot, an overhand loop, or a figure-of-nine. It is advisable to tie this knot with the main rope lying along the outside of the first bend. A figure-of-eight can be tied anywhere in the rope, but if tied in the rope end the tail should be secured with a stopper knot which is then worked up close to the main knot. Although this stopper knot does not make the main knot any more substantial, it does ensure that a sufficiently long tail has been left. Too short a tail could work itself loose.

Bowline

The bowline is a strong knot that is easy to adjust and easy to untie after it's been loaded. It is a popular choice for securing a recovery system. However, if it is tied wrongly it can be unsafe, it can work loose reasonably easily and it doesn't function well if subject to a three-way loading, when it can slip or even invert. It should be secured with a stopper knot tied around the rope in the loop. A bowline can be tied anywhere in the rope by doubling it and tying a bowline in this bight of rope. However, this isn't recommended for the parachute attachment point due to the three-way loading this leads to. You can reinforce the bowline by lying a second loop on top of the initial turn and then completing the standard bowline. This double-knotted bowline is stronger than the basic bowline and less prone to inverting.

Tape Knot

The tape knot is the most suitable for joining tapes. An overhand knot is tied in one end and the other end then follows it through. This knot can work loose very easily and long tail ends must be left (approximately five times the tape width). Load with at least body weight to tighten, check every time you fly, and re-tie if the ends become too short.

Alpine Butterfly

A useful mid-rope knot, the Alpine butterfly's main advantage is the ease with which it can be untied after it has been loaded. It can be loaded along either of the main strands or by the loop, this makes it an ideal parachute attachment knot. In this method of tying the knot, a bight is twisted to give three loops, then the top loop is taken behind and up through the bottom loop and the knot is finished by firming it up.

Conclusion

As you can see that are only a few knots that are useful to rocket recovery systems. The overhand knot and the clove hitch are too weak to use and in my opinion the bowline is too complicated and the risk of it being tied wrongly is too high. This just leaves the figure-of-eight, which is a really easy knot to tie and still safe if tied with one loop too many or too few. The figure-of-eight also just happens to be the strongest of the bunch and if climbers trust their lives to it then we can safely trust it in our rockets. The parachute attachment point is a little trickier, the bowline should definitely not be used due to its weakness under three-way loading. The figure-of-eight can be used, but it's not ideal in this situation, however, it is really easy to tie. The ideal knot for this application is the Alpine butterfly as it can be loaded quite happily in all three directions and still be very easy to untie if the attachment point needs moved. If you are using tape of any kind then you should use the tape knot. This is the safest knot for use with tape and again climbers trust it to tie slings to protect their climbs. It's easy to tie and when loaded can be pretty difficult to untie. Finally, always check your knots before each flight. There is no point tying the perfect knots if they are loose and lead to a recovery failure. Check and doublecheck and if in doubt, retie the knot.

 

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Protect Your Scale

Contributor: @prfesser

If your scale for weighing liquids/powders has a protective cover for the scale or platform that can be turned upside down...use it! If not, use the bottom or side cut from a milk jug or other suitable container. Epoxy dripping onto the platform makes quite a mess. Even powders can be challenging to clean entirely without damaging the scale. Oxidizers are incredibly corrosive. (Spent 42 years watching students ruin expensive scales in chem labs...)

 

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Left Over Greatstuf?

Contributor: @prfesser

No use for Greatstuf in rocketry? Well, this is a use.....

A different sort of rocket stand if you have a bit of GreatStuf left over that must be used. Either a 1/2" dowel in a used 18mm motor case, or a 3/4" dowel in a 24mm case. Spray the foam indiscriminately; it'll look fine. Paint if you wish, but it looks pretty good without paint. A heavier base was needed for this, I used a plastic disc from SWMBO's bin of painting stuff.

 

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3D Printed Parts: Sand or not?

Contributor: @cwbullet

Recently, I received this question by private message.



Sanding should not be needed to glue 3d printed parts together because of the nature of 3d printed parts. 3d printed parts are layer down in layers 0.15mm to 0.8mm thick so they have ample voids and roughness for glue to grasp as long you you choose the right adhesive.



Do I sand parts? Yes. I sand parts when they do not have the right fit or if the surface is rough and I want a better finish. The biggest reason to sand an 3d printed part is to remove surface imperfections such as furries and blovers. Outside of that, sanding is not needed.