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

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Tape Your Shock Cord Bundles:

Contributor: @cwbullet but original answer by @jahall4

A fouled chute or shock cord can ruin your day. Like rubber bands, you can use masking tape to organize it in bundles or pucks. The beauty of rocketry is there is more than one way to accomplish the same task. See the link below for the technique.

https://www.rocketryforum.com/threa...-shock-cord-entanglement.179146/#post-2414357

 

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Straw Ejection Shrouds:

Contributor: @prfesser

I haven't used this for a long time, but I found that the soda straws in my cupboard were a perfect, snug fit for the plastic e-match protective shield. Cut a piece of soda straw, slide a match head/shield in one end, and wrap tape to hold it in place. Scoop BP into the straw---if memory serves, a bit over 1" of BP was one gram, but test to make sure. Trim the straw to length if necessary. Wrap of tape around the other end and pinch the tape closed.



This shroud (straw) is slightly larger than my other batch of matches. Press the edge of the shroud against a hard surface and rotate it before inserting. The straw will stretch just a bit.



After filling with BP, wrap of masking tape and pinch closed.

 

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Clean your nozzle and hotend:

Contributor: @John Kemker

Another 3D Printing tip: Clean your nozzle and hotend regularly. You'll get less messy prints in the long run.

The more burned-on mess you have on it, the stickier it gets, and the more you have issues with black burn marks on your prints.

 

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Vacuum pack your filament:

Contributor: @John Kemker

Zwilling makes a hand-held vacuum bag system with reusable zip-lock bags to store filaments without having to buy a dry box. Toss your spool into the bag with a desiccant packet and seal. Use the wand to evacuate all the air, and you're done. The pump costs about $70 USD on Amazon, and you can get three reusable bags for under $7 USD.

 

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Staying cool at summer launches

Contributor: @prfesser

This is a phase change cooling vest. The inserts are filled with a liquid that freezes at about 60F. Toss the packets in the fridge, freezer, or a cooler of ice. Once frozen, they stay at that temperature until essentially all the solid melts, which takes 1-4 hours, depending on outside temperature and level of exertion. Increases comfort level significantly.

I just returned from a 40-minute walk at 90 degrees, and most of the solid was still there. It probably would have lasted at least another hour and a half.

If possible, get a second set of inserts so that one is in the cooler, freezing, while you're wearing the other.

They aren't cheap, around $150-200, with one set of inserts. But if you're outside a lot in the summer heat, they're well worth it IMHO. (Boo, the scaredy-cat, is not included)

 

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Heatshrinking eMatches

Here is what I do with all my e-matches, to prevent the possibility of shorting out the connections on my aluminum charge wells.

1. Cut a short piece of heat-shrink
2. Add it over the eMatch
3. Add safety glasses or faceshield to the person
4. Apply heat gun to shrink tubing

I have never had one go-off with the heat gun application, but I wear a face shield each time anyway.

Here is a tip to make sure it isn't getting too hot. If you hold the wire close to the eMatch your fingers will tell you if you are overcooking the heatshrink .

Also, note that I have used clear heatshrink. I get the Spaceport America Cup team I mentor to do the same thing. You can't hide any bad joints inside clear heatshrink, like you could if using the black stuff .

You could also use electrical tape and avoid the heat gun.

https://www.rocketryforum.com/threads/heatshrinking-ematches.180719/#post-2453278

 

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Save your brass and shotgun shells:

Contributor: @cwbullet
This tip is for the shooters in the thread. The perfect use, other than reloading or recycling, of used shells is ejection canisters.

 

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3D Printed Fin Slot Guide:

Contributor: @cwbullet

Filament printers are ideal for making slot guides for fins for rockets. You can design one in less than 10 minutes and print it in less than an hour (Depending on your printer). This will make you a cheap and relatively disposable fin slot guide.

Instruction for making on in TinkerCad:

1. Make a cylinder about 10-20 mm bigger in diameter and length than your tube and fins.
2. Next, you need to make this a tube. I usually make the hole (subtractive cylinder) in the middle about 0.2mm bigger than the body tube. I will center this hole on the prior tube and combine them.
3. Now it is time to make the fin slots. The slots will be added as subtractive rectangles every 90-120 degrees based on the number of fins you want. First, center a single one to the center of the front of the tube you have made.
4. Subtract from the rectangle and then rotate 90-120 degrees until you have a slotted tube with the desired slots.
5. Now, slide it onto your tube and use it as a guide to slot your tubes. I use a knife to slot cardboard and a Dremel for all others.

 

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This is index #6 for the tip-of-the-day thread.

List of Techniques (Index 6)
�

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
Page 5		Link to page 5 index
151	1 July 2023	More Zipperless Designs
152	2 July 2023	Fin Vacuum Bagging Technique
153	3 Jul 023	Better decal adhesion
154	4 July 2023	BlueTube and Moisture Do Not Mix
155	5 July 2023	Tweezers and Forceps
156	6 July 2023	Igniter Case
157	7 July 2023	Consider Clothespins
158	8 July 2023	Use a new blade
159	9 July 2023	Hole saws and circle cutters
160	10 July 2023	Foam that fin can
161	11 July 2023	Rocket Motor Storage Tubes
162	12 July 2023	Cheap Ground Test Equipment
163	13 July 2023	How to use Copperheads?
164	14 July 2023	Use a scale to measure your epoxy.
165	15 July 2023	Nose Weight
166	16 July 2023	Clothespins Part 2.
167	17 July 2023	Plumb fin lines on larger-size body tubes.
168	18 July 2023	Epoxy thickener
169	19 JULY 2023	Chopped Carbon Fiber or Kevlar
170	20 July 2023	Flatten Those Warped Fins!
171	21 July 2023	Making Tape Rule
172	22 July 2023	Hardening Your Fins
173	23 July 2023	Finding the center of a bulkhead
174	24 July 2023	Kaplov clip retention
175	25 July 2023	Consider Rear Ejection
176	26 July 2023	Drilling a hole in a body tube
177	27 July 2023	How to bevel fins:
178	28 July 2023	Slotting a body tube
179	29 July 2023	3D Printed Parts Shrink
180	30 July 2023	Tin, Twist, or Add a Ferule
Page 7		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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More on Zipperless Designs

Contributor: @cwbullet

This is not necessarily from me, but I found these threads while searching for content. The key to a zipperless design is protecting the tube from the shock cord. I posted a tip prior, and today I found more helpful threads.

From a prior tip thread:

https://www.rocketryforum.com/threa...-of-the-day-thread.177679/page-3#post-2425676
More links found:

https://www.rocketryforum.com/threads/zipper-proof-designs.132688/#post-1559203
https://www.rocketryforum.com/threads/zipperless-design.106892/
https://www.rocketryforum.com/threads/zipperless-coupler-question.51388/

 

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Fin Vacuum Bagging Process​

Contributor: @rharshberger

https://www.rocketryforum.com/threads/fin-vacuum-bagging-process-by-rharshberger.159193/

 

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Improved decal adhesion:

Contributor: @cwbullet

I am not sure where I got this tip, but I learned this years ago with water slide decals. It goes quite contrary to popular belief that thing stick better if they are roughed up.

This fact is not true with water slide decals. Water slide decals adhere better to a smooth and gloss finish. If a decal is placed on a flat finish or one that is roughed uo, the edges will peal up. Once it is try, a touch of clear coat can make them last longer also.

I apply all decals over a gloss finish, let dry, then apply the flat clear coat.

 

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Blue Tube and Moisture Do Not Mix:

Contributor: @cwbullet

Blue Tube can be an excellent airframe, but it does have its drawbacks. Humidity and moisture in my book are the top reasons to avoid it or change the way you use it.

My learning lession has to do with my level 3 rocket. I wanted a tough motor tube the the paper one in a Polecat kit did not meet my standards. I swaped it out for Bluetube and my journey began. If you know anything abotu Georgia, Humidity here is a bear. A few weeks after finished my fin can, I came back to test fit the motor again to add the retainer. The motor would not fit.

The experience taught me two lessions:

1. BlueTube should only be used as a motor tube if you can store in low humid environment.
2. Buy a flap sander for your drill if you do.

You can coat or seal blue tube to prevent humidity from expanding it but it is not an option for the motor tube.

 

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Forceps and Tweezers:

A nice set of forceps or tweezers can help in a build or repair. The longer, the more it will be useful. I keep a set of 7" to 14" long tools that I acquired from the pile to be thrown away at work a few years ago. They are great for reaching down in a body tube to grab cords or to put a cord through an eye bold. The uses are endless.

Tools I suggest:

1. A long set of Tweezers
2. A long set of Alligator Forceps
3. A long set of Sponge Forceps
4. 24-inch Hemostat (tough to find).

A word to the wise: Buy the ones without teeth.

 

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Igniter Case:

Contributor: @cwbullet (Chris Michielssen originated it)

I read about this one the Model Rocket Building Blog atleast 10 years ago. Until that time, I have used a lot of little containers from the dollar store. The thing I like about Chris Michielssen's idea is that you can put this container in your pocket and carry them to the launch pads.

Chris posted on his blog about using a used dental floss container.
Now, a misfire or broken igniter will not mean you have to walk back to the trailer to get another. Now, you will have them with you all the time.

The igniters fit easily in the container without bending and the plastic container will protect the wires from bending and breaking in your pocket.

See his blog post for more information.

 

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Consider Clothes Pins:

Contributor: @cwbullet

Clothes pins have many uses in rocketry. They are a great gentle clamp. This use has been highlighted by Chris Mechielessen in his rocketry blog.



I have also used them as a standoff on low to mid power rods.

I have also used them to make drying racks for igniters.



The possibilities are endless.

 

[cwbullet]

Use a new blade:

Contributor: @cwbullet

When slotting cardboard tubes, I use a hobby knife for low power and a box cutter for mid-power to high-power. It works better if you use a new blade and don't try to go through on the first pass.

I don't use a straight edge on through-the-wall slots, but on occasion, I do use a jig that is 3d Printed. I often draw the line and then trace the line with the hobby knife. A little straying from the line is not a problem, as it will be filled with glue and fillets.

Cheap Blades? Consider buying a 100 pack.

 

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Hole Saws and Circle Cutters:

Contributor: @cwbullet

If used correctly, these babies make good bulkhead and centering ring cutters. They are best used on drill press.

https://www.rocketryforum.com/threads/hole-saw-for-centering-rings.175408/
https://www.rocketryforum.com/threads/best-way-to-cut-out-centering-rings.59669/
One tip to using a circle cutter: make sure the cutting bits are securely clamped of they can become the flying cutter of death.

 

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Foam that fin can:

Contributor: @cwbullet

Instead of doing internal fillets, considering 2 part foam instead. The end result is a near bullet proof fin can.

http://jcrocket.com/foam-fincan.sht...ake a,additional bond between all components.

 

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Rocket Motor Storage Tubes:

Contibutor: @cwbullet

Some people bring all of their motors to the field in big ammo cans or marine boxes. Some use a small tool box. Some only carry the motors they need.

This soltuion is on that could be for the minimalist. I saw this years ago on our launch field. M&M mini or coin tubes can be used to store motors. The M&M tubes are colored plastic, and have a resealable cap that is attached to the tube. They are the perfect size to hold 1-2 D engines or 24mm RMS casing.

 

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Cheap Ground Testing Equipment:

Contributor: @cwbullet

If you need easy ground testing equipment, you can always use an Estes launch controller or another low-power launch controller to test your powder charges. Heck, I have used a 9-volt with long leads.

For safety purposes, test a match with a continuity test on the controller before adding a charge. Some systems will set off an e-match.

For legal purposes, make sure it is legal in your local community to set off a charge. It can make the HOA or local office upset.

 

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How to use copperheads?

Contributor: @numerous but a strong post by @qquake2k

Copperheads, AKA Crapperheads, are an old phased-out ignite from Aerotech. They are difficult for some to use but with the right technique, they are a very slim igniters that are very capable way to lighting a motor. If you have some and feel you need to use them, this thread might help:

https://www.rocketryforum.com/threads/how-to-use-copperhead-igniters.138665/
I would burn them up in a fire and toss them in the trash, but if not, the thread above can help you find an easy way to use them. I prefer the one by @qquake2k :

https://www.rocketryforum.com/threads/how-to-use-copperhead-igniters.138665/#post-1663810

 

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Measure your epoxy with a scale:

Contributor: @augendoc

Bob Smith epoxy is a 50:50 mix based on volume, not weight. Many other epoxy use volume and not weight. You can weigh brand new bottles or look at the Bob Smith FAQs, but the weight ratio is something like 1.19:1. I’ll have go check my notes as to whether it is hardener : resin or resin : hardener.

As for the scale, most of the time, you are mixing up small volumes, so consider a scale reading in 100ths of a gram.

 

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Nose Weight:

Contributor: @cwbullet

I have built many rockets that require nose weight. Recently, I needed some nose weight for a scratch-built V-2. I did not have any lead or BBs. I had no clay handy

I remember a guy putting pennies in a sock as a weapon. Rolls od pennies weigh nearly half a pound. I grabbed a few pennies from my stash and added them to the nose for weight. I held them in place with a little epoxy and I had instant nose weight!

So, if you're ever in a bind for nose weight, grab some pennies and drop them in there!

Personally, I will probably just use nuts and bolts or fishing sinkers in the past but this is another option. And if the nose cone cracks open...you have pennies from heaven.

 

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Clothespins Part 2:

Contributor: @BABAR

Clothes pins are excellent for lots of things but are easily modified to be even better.

https://www.rocketryforum.com/threads/cow-tools-a-thread.167308/page-2#post-2159037

 

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Plumb fin lines on larger size body tubes.

Contributor: @John Kemker

When drawing lines to cut fin slots or fin attachment points, take a tip from Amos 7:8 “And the LORD said unto me, Amos, what seest thou? And I said, A plumbline.”

Set the body tube on the end away from the fin lines where it hangs off the edge of a table just a bit. Make sure the top of the tube is level. Then, tape a plumbline over your mark where the line is supposed to go. Wait for the plumb bob to stop its oscillations. If you've chalked the line, lightly snap it to transfer the line to the tube. If not, as in my picture below, make a mark along the line so you can line a ruler up between the two marks and get a straight line.

 

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Thickener for Fillets:

Contributor: @cwbullet

Epoxy is great for making a tight bond, but sanding is not easy. For external fillets, you want something easy to sand. It does not matter for internal fillets as long as you get them in the right place. In a prior thread, I reviewed how to use a piece of PVC to shape fillets.

I like to use micro balloons because they make sanding a cinch. There are many brands, but I have found Systems Three cheap and high quality. Another easily sandable and cheap option is wood flour. You will sacrifice a little strength but gain the benefit of sandibility.

Micro balloons are suggested for weight as well as standability. A small container will last you a long time. I usually add about a cup to 6 ounces of epoxy. It is easy to mix into the epoxy but be careful, or this stuff will go airborne, and I am sure it is not healthy to breathe. I often use it in cheap epoxies and premium products like West or System Three. I have used it in Bob Smith's 5-minute epoxy with great success.

If I want quick and do nto care about sanding, I go with a prefilled product like Rocketpoxy. You can buy it from your favorite rocket vendor.

Next, I am going to discuss making epoxy bonds stronger.

 

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Chopped Carbon Fiber and Kevlar:

Contributor: @cwbullet

I am 100% certain someone will disagree with me on this, but in my opinion, these are only useful for internal construction and fillers. Externally, they can increase strength, but you better be darn sure you get it right and will not need to sand. If you think sanding epoxy is tough, wait will you add these.

I add a pinch of chopper carbon fiber or kevlar to my internal fillets. I have done them as an injections and just applied them. I have never tested the strength, but it does make the bond stronger. I have never had one fail.

Is it needed? That is another story. It is fairly expensive but only a dab is needed per batch.

 

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Flatten Those Warped Fins!

Contibutor: @John Kemker

My LOC Warlock has a warped fin. Also, I managed to warp the 1/16" plywood fins for the Dyna Soar Titan booster. A quick search on Google turned up this video:

 

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Masking Tape Rule:

Contributor: @jqavins

Necessity is truly the mother of invention, and I invented this today.

I was using the edge of my cutting mat to make layout marks. The problem is, with the piece of cereal box up just enough to see the ruler divisions, you can't see the numbers.



So, I added a strip of masking tape, numbered every inch, and tick-marked the half inches.