What did you do rocket wise today?

BrendanH69

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Did the "Tip to Tip-ish" fin reinforcement on the Tin Tin Rocket. Used two pieces of 200gsm F/Glass cloth across the fillets/root then meeting in the centre of the boat tail, then one large piece of finer 135gsm F/Glass cloth to go across the span to approx mid-way up each fin.

The yellow material is my rip-stop nylon I use as my "poor man's peel ply". One lesson I did learn on one side was that any slight creases in the the rip-stop just causes wrinkles/epoxy ridges to form no matter what you try. I ironed the other two so they were nice and smooth!

Tip 2 Tip ish.jpg
 

OverTheTop

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Well, this was over the span of a few days and is amazingly non-interesting, but here goes:

Went to buy threaded 8-32 nut inserts like you use in wood for my current project and was infuriated when I saw the price. 400-500% 'inflation' just aggravated me ($4.75 for 2 inserts).

Decided to buy on Amazon or similar, as its probably coming from all the same places and it was pretty pricey there too.

Guy mode kicked in (happens to both sexes, but when tools are involved, guy mode is my version) and I instead spent $70 on a RivNut tool with 150 pieces etc., and it arrived at my door on Monday.

It is typical Harbor Freight-like quality, instructions not functional and had to watch a video to figure out how to adjust it, but once I did all the right things, it does seem like a functional tool.

Installed 2 RivNuts for motor retention in the rear centering ring of my current build - literally the first thing accomplished since dry fit 2 weeks ago. DOH!

I won't say for fact that this is the best way, right method or even worth pursuing, but it seems semi-functional if you want to do it. Not at all a recommendation for buying the tool etc., but I do a few non-rocket projects that might find a use in the future, so I justified the spend in my own mind. Not sure it was worth it. We'll see.

Pics at least!!!

Sandy.

I have some Wurth fasteners that are similar. The important thing, with the Wurth anyway, is lubricating the thread before inserting the tool and crimping. Really makes a difference in not stripping the threads out, especially with the smaller diameters. It might not be a problem with yours, but it depends on the material the nuts are made of I suspect. Really important with the 3mm and 4mm inserts.
 

OverTheTop

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Sketched up some mounting brackets to clamp stuff onto the rotating shaft of my antenna tracker. Will print them later in the week.

Also found a good battery (12v, 7Ah) in a UPS that I decommissioned a couple of months back. I will use that to run the charger for my umbilical system I mentioned upthread. Sketched up a bit of a box for it to tidy things up. Something else to print eventually.

Now I need to figure the best way to drill a 1/2" hole in my big stepper motor 3/4" shaft so I can pass wires through it. My lathe and some drill bits just might do it. Time to Google.
 

jqavins

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Hit an MJG black powder starter with a hammer to see what would happen. It blew. I'll be buying some ammo boxes to store them.
That makes sense. Since e-matches in general are made to ignite with very little electrical power, it's not really a surprise that the pyrogen would be "marginally stable". That doesn't mean they'd have to be impact and/or friction sensitive, but does mean it's not really a surprise if they are.

$4.75 for 2 inserts.
$2.375 per insert.
$70 on a RivNut tool with 150 pieces...
$0.467 per insert.

Or from a different angle, at $2.375 per insert, the payback on the tool set is $70/$2.375 = 29.47 inserts. So it was a good and justifiable purchase. Well done.


My lathe and some drill bits just might do it. Time to Google.
I'm puzzled: do you plan to remove the shaft from the motor, or chuck the whole motor in the lathe? If the latter, wouldn't positioning the motor under a drill press be easier than the tedious four jaw fiddling? For that matter, maybe also easier than removing and reinstalling the shaft?
 

bad_idea

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That makes sense. Since e-matches in general are made to ignite with very little electrical power, it's not really a surprise that the pyrogen would be "marginally stable". That doesn't mean they'd have to be impact and/or friction sensitive, but does mean it's not really a surprise if they are.
Yes, it's something that should have occurred to me after I found I could set six or more of them off at once in parallel with a used AAA battery. Nonetheless, I hadn't thought about it until the recent posts here and in the "improving igniters" thread, and I decided to test after lakeroadster heard back from MJG:
The folks at MGJ responded that their BP Motor Starters are susceptible to impact and friction ignition.
 

lakeroadster

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That makes sense. Since e-matches in general are made to ignite with very little electrical power, it's not really a surprise that the pyrogen would be "marginally stable". That doesn't mean they'd have to be impact and/or friction sensitive, but does mean it's not really a surprise if they are.

I didn't have a clue. What folks have to remember is not everyone is experience with mechanical / chemical properties of rocketry related components.

There are reports of these igniters firing due to static charges, which I understand is rare. So, the prudent thing to do is store them in something like an ammo box.

I had my e-matches, a bundle of 100 of them, stuck in my desk drawer, where I could have easily slammed them with the drawer when closing it.
 

NateB

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There are reports of these igniters firing due to static charges, which I understand is rare. So, the prudent thing to do is store them in something like an ammo box.
I was one of the reports of an E-match firing from static. To prevent any confusion, I want to clarify the story I heard second hand was not using one of the MJG Firewire initiators available without an ATF license.

I do not recall the manufacturer, but the e-matches in question were standard ones used in the firework industry which require the necessary licenses to purchase and store. The differences are small, but how the e-matches are made is different.

I do believe the report I heard, it was from the owner of the company I was shooting with and it happened to him. I just wasn't there to witness it and wasn't able to reproduce it. That said, I have seen standard e-matches ignite from friction and impact. It isn't always easy to make it happen, but simple care makes them safe to work with. The biggest thing to remember is to treat them as you would a loaded gun. Once the e-match is in place, think about your body and your surroundings. If it were to ignite, what would happen? If the BP charges aren't in place yet, the match will burn for a second. Will it destroy anything? If the charges are in place, where will the nosecone or payload section end up? These scenarios are probably easier to manage. Staging and airstarts gets more complicated.

I don't think an E-match is likely to ignite just sitting there, even when connected to an altimeter that is powered off. You're more likely to get an unintended ignition when you're inserting the coated tip into something, the shrouds protect from friction and impact, but if you must remove it, this is when you're more likely to have one go off. (still a small chance) If you do need to slide the shroud back, look for any chips on the pyrogen coating. I would discard it if it is damaged. For rocketry, I have read reports about ematches igniting when an altimeter powers up. In the fireworks world, there are reports of ematches occasionally firing when the leads are first inserted into the slat, even when the slat is disconnected from the module where the power comes from, when the modules are first powered up, or during continuity checks.

That was long winded. TL/DR

Ematches require some common sense and simple precautions, but can be used safely.
 

NateB

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One more thing I thought of. We use thousands of ematches during firework shows. 1 match per shell/cake in most cases. We double them up on things like gas mines, finale runs, and other times where we really don't want to have an effect not ignite. It safe to say I've handled more ematches in one show than I ever will launching rockets. I've only seen a small number of ematches ignite unintentionally. Only 1 was friction while it was being removed from a device. Most shows I set up had no issues with ematches at all except that they just didn't work period and the device didn't ignite.
 

Zertyme

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Fin slots...

PXL_20220810_152133316.jpg
PXL_20220810_171150257.jpg
PXL_20220810_171830247.jpg
 

gdjsky01

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Printing some rainbow nosecones... BT-80 Ogive 4:1 (about 10.5" long)

View attachment 531358

Depending on filament this stuff can change slowly / over many meters of filament. I realized the secret to getting the transition was to print multiples, look at the total grams of material being used, compare that to the number of color changes in the roll of filament, and adjust multiple count to get the fade you want.

After a quick sanding and wipe-down with acetone on a paper towel... If I wanted a really smooth finish I could sand some more and possibly clear-coat...

View attachment 531382

May I get the STL? Or the design file?
 

krislhull

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Pulled the altimeter sleds out of all of my rockets today and verified the programming on the installed altimeters, and then I modified a few of the sleds to hold slightly larger batteries than I originally built them for. the majority of my dual deploy rockets were built with Turnigy 300mah Lipos. Lately I have discovered that they have become unobtanium, and so I have started to acquire some 800mah lipos, but they are physically slightly bigger. I built my Astrobee D sled with these batteries in mind. Most of my existing sleds just required drilling new holes for zip ties, but on two of them, I also epoxied in new supports. All of my sleds are now set up for both types of batteries.
 

lakeroadster

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I was one of the reports of an E-match firing from static. To prevent any confusion, I want to clarify the story I heard second hand was not using one of the MJG Firewire initiators available without an ATF license.

I do not recall the manufacturer, but the e-matches in question were standard ones used in the firework industry which require the necessary licenses to purchase and store. The differences are small, but how the e-matches are made is different.

I do believe the report I heard, it was from the owner of the company I was shooting with and it happened to him. I just wasn't there to witness it and wasn't able to reproduce it. That said, I have seen standard e-matches ignite from friction and impact. It isn't always easy to make it happen, but simple care makes them safe to work with. The biggest thing to remember is to treat them as you would a loaded gun. Once the e-match is in place, think about your body and your surroundings. If it were to ignite, what would happen? If the BP charges aren't in place yet, the match will burn for a second. Will it destroy anything? If the charges are in place, where will the nosecone or payload section end up? These scenarios are probably easier to manage. Staging and airstarts gets more complicated.

I don't think an E-match is likely to ignite just sitting there, even when connected to an altimeter that is powered off. You're more likely to get an unintended ignition when you're inserting the coated tip into something, the shrouds protect from friction and impact, but if you must remove it, this is when you're more likely to have one go off. (still a small chance) If you do need to slide the shroud back, look for any chips on the pyrogen coating. I would discard it if it is damaged. For rocketry, I have read reports about ematches igniting when an altimeter powers up. In the fireworks world, there are reports of ematches occasionally firing when the leads are first inserted into the slat, even when the slat is disconnected from the module where the power comes from, when the modules are first powered up, or during continuity checks.

That was long winded. TL/DR

Ematches require some common sense and simple precautions, but can be used safely.
Thanks for posting this Nate!
 

martynouze

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re-primed a $hitty paint job, prep'ed another rocket for 1st paint coat.

Also discovered this site:
 
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OverTheTop

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I'm puzzled: do you plan to remove the shaft from the motor, or chuck the whole motor in the lathe? If the latter, wouldn't positioning the motor under a drill press be easier than the tedious four jaw fiddling? For that matter, maybe also easier than removing and reinstalling the shaft?
I think I'll chuck the shaft and just hold the stator etc to stop it from spinning. I am not going to disassemble the stepper as I have seen them in the past when this is done not work again. I could use a drillpress but I think the lathe makes more sense and will end up with a more concentric result. I am hoping the temper on the shaft is not too hard and it is an easy task. Currently looking at sharpening a masonry carbide bit to have a more traditional form and drill that way.

[edit] I'll just add that this motor is a 5kg NEMA 42 stepper. Serious stepper.
 
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Sandy H.

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rocket_troy

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I think I'll chuck the shaft and just hold the stator etc to stop it from spinning. I am not going to disassemble the stepper as I have seen them in the past when this is done not work again. I could use a drillpress but I think the lathe makes more sense and will end up with a more concentric result. I am hoping the temper on the shaft is not too hard and it is an easy task. Currently looking at sharpening a masonry carbide bit to have a more traditional form and drill that way.
If it turns into a difficult job, let me know and I'll have a crack.

TP
 

teepot

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I spent several hours the last two days sanding the primer off of the upscale Big Bertha. I used a black automotive primer. Never again. When the primer dried it started to look like charred wood. I had to sand down to the paper on most of the rocket. It doesn't look like I'll be able to re-prime tonight. It is still 82 degrees at 11:42pm and a horrible 45% humidity.
 

berlinetta

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I installed rail buttons on my Parkflyer Magnum. They look good on there. Now gotta figure out how I want to attach the nosecone to the shockcord. That's a minor issue, lol. I'm excited that all that's really left is to prime ane paint it.
 

jqavins

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Finishes touches on the LOC-IV for my L1 cert this weekend.
Good luck. Break a fin.


I think I'll chuck the shaft and just hold the stator etc to stop it from spinning. I am not going to disassemble the stepper as I have seen them in the past when this is done not work again. I could use a drillpress but I think the lathe makes more sense and will end up with a more concentric result. I am hoping the temper on the shaft is not too hard and it is an easy task. Currently looking at sharpening a masonry carbide bit to have a more traditional form and drill that way.

[edit] I'll just add that this motor is a 5kg NEMA 42 stepper. Serious stepper.
Well, you've obviously thought it through, but I'm still not getting the picture. Of course, there's no necessity for me to get the picture, but if you'd care to sketch it or take a picture when it's set up, I'd appreciate it.

Oh, wait, maybe I've got it. Does the shaft go all the way through the motor so it's accessible on both ands? The long end is in the chuck, with the bulk of the motor in between the chuck and the tail stock, and the drill goes in from the back, so to speak? IF f I've got it, the rotor is spinning at drilling speed within the stator, and you've no doubt checked that the brushes and bearings are happy with that.


Now, no excuses for missing/desired parts for my build. Please, everyone, give me grief if I'm falling behind.
Here, take some grief, since you've asked. You messed up and had to adjust or correct during a build. I mean, who does that? You're supposed to have everything perfect, every build is supposed to go smoothly and flawlessly from detailed CAD drawing to launch pad, like it does for the rest of us. What's wrong with you?
 
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OverTheTop

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Oh, wait, maybe I've got it. Does the shaft go all the way through the motor so it's accessible on both ands?
Correct. That gives me access to drill from the back.

IFf I've got it, the rotor is spinning at frilling speed within the stator, and you've no doubt checked that the brushes and bearings are happy with that.
Stepper motor, so no brushes. It is a serious motor so the bearings will be no problem either. I just need to keep cutting fluid and swarf out. If I make decent sized chips that won't be a problem.
 

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