Diamond Cutter build thread

6 more days Neil, will it be ready? LOL

JJSR said:

6 more days Neil, will it be ready? LOL

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Let me figure that out, hmm... 6 days... minus 2... square root... carry the 7... multiply by PI and take the cosine... and the answer is.... dragonfruit. Actually, I probably won't be at another launch until at least March, so it doesn't matter when it actually gets done. But my hope is 2 weeks from now.

Removed the masking tape and it actually looks not bad, other than the one fin with excess silver paint (which the careful reader will note I have not shown):

I also decanted some key lime into a cup and touched up (somewhat) the paint bleed on the canard assembly. Also rates as "not bad", if your standards are low.

After putting the last layer of silver on the main fins, I realized that I probably did need one more coat on the canards, but that ship has sailed, and they look OK. Silver is indeed tricky.

The final finishing step is the stripes and lettering, which must be masked and then painted. That'll be next weekend, weather permitting.

Well, it looks like a combination of weather and other unforeseen and highly frustrating circumstances will be delaying my completion of the paint job for... well, a while at least. So it's time to start my winter builds until my last painting opportunity arises.

In the meantime, this turned up today:


For the 2.5 people still following this thread, first person to identify it gets one in the mail (if you want one, which you may very well not). In any case, I have at least one extra so I'm happy to offer it up. It is for this build.

Shock cord mount? Great looking build, still liking the paint job.
Nate

Close but not quite.

Nose cone (or possibly av bay) bulkhead, with integrated shock cord mount.

s6

Wow, didn't expect such quick responses.

stealth6 is getting warmer, but still missing a key detail which is probably pretty hard to tell from the pictures. But this is fun so let's keep it going.

[edit: and that key detail is the reason why you would *not* attach a shock cord to this]

hmmmmm, looks to be removable, or easy to pull apart. Something designed to release something else maybe? It definitely looks 3d printed...

Nate

it holds your jolly logic 2 alt.

nute said:

hmmmmm, looks to be removable, or easy to pull apart. Something designed to release something else maybe? It definitely looks 3d printed...

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Yes, yes, and yes.

JJSR said:

it holds your jolly logic 2 alt.

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And yes.

It's a twist-lock nose cone retention system. The loop is indeed for tying an altimeter, which in my case probably will be a JL Altimeter Two (which I haven't bought yet).


The blue part attaches to the bottom of the NC; the red part is glued into the BT.

I wanted something that would securely hold my NC without needing any holes, or too tight a friction fit. This should be pretty easy: insert NC, twist clockwise until it stops, and it's.

This is ridiculous overkill for the intended purpose, but I was looking for an excuse to do some more 3D printing.

I'm thinking of a better design (lighter and simpler), but this one should work.

I'll document the installation process when I get to it, eventually.

For accurately calling out the altimeter two I've gotta give Joe the win, but I'll be happy to send any of you (Joe, Nate, stealth6) one if you want. These are sized for BT60.

Thanks for playing!

:eyepop: Wow out of nowhere a neat innovation...

Can't wait for the field tests. No more screws and tape... cool idea.

leave it to those RADICAL ROCKETEERS to to come through!!

so now what Nate gets half and I get half???? LMAO

that's a really neat idea Neil

Haven't forgotten about this, just waiting for painting opportunity. Maybe this weekend as we have a very warm week coming up and enough snow might melt that I can access my shed again. Fingers crossed!

In the meantime I've glued the 1st piece of the nose cone retainer to the nose cone, but will install the other piece into the BT after painting (since I don't want to mess with the masking tape right now.) I'll document the installation later when I have it all done. It's looking good I think, although I've identified a weakness in the design that I'll have to try to fix, but haven't figure out how yet. More to come...

Preparing for final paint.

I masked off everything for the green lines on either side of the transitions. I used Tamiya tape for the fine stuff and 3M blue tape to fill the large areas. I think I did a decent job here; gotta remember to make sure all the tape is really burnished down before I paint.

At last it was time for the Diamond Cutter paint mask.

I prepared the area of BT where the mask was going, leaving a rectangular window open for it while covering everything else with the blue tape. I sized the window so the edges of the mask would just overlap the blue tape (which should make it easy to grab to remove later on).

(picture has fins on left, top end of BT on right)

Next I laid down the mask as slowly and carefully as I could. I needed to reposition it slightly once, but overall I think I got it pretty straight and in the position I wanted.

This, too, I will burnish again before painting. I'm not removing the backing until the last moment, so the paint surface stays clean.

And here is the main body, ready for final paint. The payload section is similarly ready, but not pictured.


Having never worked with this vinyl stuff before, I have to say I'm pretty impressed. I'll get the final view after I remove the backing, but from what I can see so far the quality is really good. I have no idea how much time Mark spent picking all the little bits of mask out of those letters. :eyepop: I hope I can do it justice with my painting; I think my general strategy will be to keep the coats light, with no real heavy final coat. That is how I hope to be able to peel off the mask successfully at the end. We'll see how it goes.

Looks nice, good luck on the paint! The only thing I'd be nervous about is pulling off the vinyl. I've never tried to remove it after it "sets" but hopefully it doesn't do anything to the underlying paint. Here's hoping all goes well!

Nate

Yes, me too. My hope is that, given that this stuff is specifically "paint mask", it has an adhesive is designed not to set hard.

Otherwise I will have a nice mess on my hands.

...and a nice mess is exactly what I have. I think it's time for me to face the fact that I suck at finishing.

I had an unexpected window of nice weather to try and finish up the rocket, so I re-burnished all the masking tape, and went at it with the Key Lime. Worst fears were realized when I removed the paint mask:


Lots and lots of black was lifted off. Note that various little bits of paint mask are still there in and among the letters; I'll remove that stuff later. It's too bad, because it looks like the mask produced some beautiful sharp edges and nice lettering. But I'm going to have no choice but to sand it down and repaint. Although Mark was nice enough to provide two paint masks (in case I screwed one up), I'm not going to try it again. This rocket will have to live without the name, cool as it would have looked.

It is certainly possible I left the mask on too long, but it wasn't intentional: I had a paint window a couple of weeks ago and then lost my opportunity when life intervened and it got delayed.

The green stripes by the transitions were a mixed bag. Some came out OK, some suffered a good bit of bleeding. It is likely that I won't be able to fix those areas, so it'll have to stay the way it is.

Also, the blue 3M tape (I'm not sure which of the many varieties I'm using) I've been using totally sucks for this job. After it gets wet with the first coat of paint, it starts lifting up and then the second coat goes right underneath. It just seems to have much too weak an adhesive.

Anyway, I think am going to be pursuing less ambitious paint jobs until I gain some confidence here; these screwups are disheartening.

*sigh*

Here's the whole thing in its current state, with all the paint mask removed:


It actually looks pretty nice until you zoom into the area around the lettering. I am actually thinking I might try to attack the areas around the lettering with a brush. Maybe it'll be better than having no lettering at all.

neil_w said:

Here's the whole thing in its current state, with all the paint mask removed:
View attachment 282999

It actually looks pretty nice until you zoom into the area around the lettering. I am actually thinking I might try to attack the areas around the lettering with a brush. Maybe it'll be better than having no lettering at all.

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Dude... That looks great! Good enough from 10 feet is good enough. No one will know when it's traveling at 80+mph

Neil it looks good, like its had a few flights in already. try the brush thing, I'm sure you'll get it to look great.
don't despair buddy

Sorry to hear about the decal troubles....
I'd say give the brush a try, and see what you get. Overall, though, that thing looks awesome! It turned out darn near what the OR mockup looks like. Definitely don't pull all that paint off!! Will we see it tomorrow?

Nate

Get a set of brushes like these: https://www.eastwood.com/touch-up-a...e=&network=g&gclid=CIXQ5rHQh8sCFQkwaQodwpIC4Q. Spray paint into a Dixie cup and simply dab it on.

neil_w said:

...The green stripes by the transitions...

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The paint job looks great.
looks like the Diamond Cutter is very neatly circumscribed

Well, after sleeping on it I decided that the lettering looks too good to remove, so I'll try to fix it. The plan:

1) mask off the lettering area, and re-spray the body. This will fix all the areas outside the lettering, some of which are pretty large (and it'll also fix the areas on the opposite side of the BT that got green overspray between my crappy blue masking tape)
2) hand-touch up the black in and amongst the lettering.

It won't be great but it'll be good enough.

Actual weight without parachute: 4.35 oz
Weight predicted by OR: 3.5 oz

Not too bad, in-line with what I've come to expect. I know I build a little heavy.

Here's a slightly better beauty shot:


It really does look quite like the OR rendering, which is cool.

Sorry Nate, I won't be at a launch until at least April, this thing will definitely be done by then.

Still looks great!, I'm sure after a little brushing by hand no one would notice unless you told them.

Well, I did my touchups today (mostly), as described in my last post. I masked off the lettering and sprayed the body with 2 fresh coats of black metallic. Then I removed the masking and touched up the areas among the lettering with a brush. Given how tight the areas were, and how shaky my hand was (and not even on caffeine), I think I did OK. And so this is now upgraded from a 10 foot paint job to a 5 foot paint job. I'll take it. Pictures to come in the future.

I did notice, afterwards, that there was one area of overspray (next to the launch lug) that I failed to cover completely, so next weekend I'll give that one more quick shot and then it's done. Now I have to get rid of the new paint dams. What do folks suggest? I was thinking of some 0000 steel wool. I have some 1500 grit sandpaper but even that seems a bit harsh for just knocking down the dams.

In the meantime, the payload section is basically complete (other than a coat of Future, to be done... in the future), so it was time to finish installing the nose cone retainer. To refresh, here's what the pieces look like when locked together:


The yellow piece in the center attaches to the nose cone, while the mustard-colored piece mounts into the BT.

Step one is to glue the piece to the nose cone. With the two pieces latched together (as above), I applied a dollop of epoxy to the center of the base of the nose cone, and pushed the retainer into a spare body tube. This ensured that the piece was aligned correctly. It looked like this from the other end of the tube:


After the epoxy was fully cured, I pulled the whole thing out and disconnected the tube insert, to yield this:


So far so good. Next, the insert needs to be glued inside the BT. There are two most important rules in this step:
1) The insert must be positioned perfectly
2) The nose cone must not be inadvertently glued into the BT!!!!!!!!!!! (this one is *super* important )

Rule #2 is why the two "fingers" are present on the insert, and also really the whole design of the thing. There are a lot of other (simpler, better) ways to design two pieces to lock together but every other one of them presented a grave threat to rule 2. The way I ended up, there is a straightforward way to satisfy rule 1 and 2.

First, I put the pieces back together, then measured the distance from the bottom of the nose cone (top of the shoulder) to the two "fingers". Then I applied to blobs of epoxy to the inside of the BT, at a distance so that only the fingers would reach it.

Then fully insert the nose cone + retainer assembly into the BT, and rotate clockwise until the fingers land in the epoxy. Need to keep track of where things are to do this correctly.

After the epoxy is set, turn the NC counterclockwise and remove it. Here's the result:


This picture shows one of the fingers in the epoxy blob (well, kind of; hard to photograph inside there):


You can maybe also see how the epoxy never comes near the NC, so there's no danger of gluing it in by accident (which really would be a bummer, no doubt about it).

And that's that. Insert NC, twist clockwise until it stops. To remove, twist counterclockwise a quarter turn and remove.

Why go to all this trouble?

Mainly because it was fun to design and 3D print the parts. But also, to be sure, I like not having to create a tight friction fit for my NC. In past builds I've accidentally put a bit too much tape on and then had a heck of a time getting the cone out without damaging either the NC or the BT. With this system, I can keep the NC fit fairly loose but still have 100% confidence that it's not going to come out except when I want it to.

I'll call it a success so far, with the caveat that it hasn't actually flown yet.:wink: At some point in the future I'm going to make it lighter, right now it's a bit over-built. I'll probably also fiddle with the design a bit, definitely some things that could work a bit better. But it's a good start.

Look'n Good!

neil_w said:

I decided to CA the nose cone next, following K'Tesh's tutorial (I had never done this before, and approached I t with some trepidation.) It did not go particularly well.

First I got a good coat of CA onto the cone. This actually seemed incredibly easy. So far so good:
View attachment 275884

Then I black Sharpied the whole thing:
View attachment 275885

Then I attempted to sand off the sharpie, and here's where things started to go south. No matter how much I sanded, lots of black spots remained. In my final push to sand through the black, I pretty much removed all the CA from the cone, and there was *still* lots of black. Apparently there were some deep pits in the balsa. (Sorry, no pic of this stage, I was frustrated and forgot to take one.)

Also, I did not at all enjoy sanding the black sharpie, for what it's worth.

Anyway, nothing to do but apply another coat of CA. I figured I had at least filled in some holes the first time. So on went the CA, until it looked like this:
View attachment 275886

This time I dispensed with the sharpie and just went at it with sandpaper. It sanded very strangely; I could not seem to achieve a consistently smooth finish. Eventually, afraid of taking off all the CA again, I just gave up and cried uncle. The final result looks like this:
View attachment 275887

It is definitely darker and glossier than the raw balsa, so I know there's CA on there, and it is smoothish. I'll find out how good a surface it is when I prime. I feel like there's not much more I can do at this point other than hope for the best.

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Check this out.

https://rocketrycenter.com/showthread.php?tid=399

Touched up the paint, wet-sanded with 1500 grit to knock down the paint dams, applied the vinyl diamonds to the fins, finished with a coat of Future. Assorted defects here and there, but the overall result is good.


I'll get a better picture at some point, but that's a start.

Here's a close-up of the lettering:


Still need to attach the shock cord and parachute and it is ready to fly.