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  1. #1
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    Continued frustration filling body tube grooves

    Hey, guys.

    I'm having a continual problem with my surface prep. Specifically, filling the spirals on body tubes. What happens is that I use Elmer's Wood Filler, thinned out a bit with water, and then when I go to sand, I end up scuffing up the tube and getting shredded fuzzies from the paper underneath the waxy coating.

    I've tried keeping the filler to a minimum, using Chris Michielssen's tip on filling, found here. I've even tried priming first, and this went OK at first. Seemed like I hadn't scuffed anything after sanding. But I went a little too far after the first dry sanding, by trying to get a really smooth surface and damp sanding with a really light touch and 400 grit wet/dry paper, and still, I got scuffs:





    As you can see, I also got a few gouges, which I only now just noticed, looking at these pictures again. Not to mention, the spirals are still not completely filled in some spots.

    This priming-first thing also feels wrong to me. First of all, I can't fill the seams before gluing anything on, so I have to sand filler off between fins. Also, it feels a bit like a cheat. I know there's no "cheating" in rocket building - whatever works, works. But I know a lot of rocketeers have really great success filling seams without shredding the tubes.

    What happens is that I'm trying to get all the filler that stands out from the tube off, because I don't want lumps. But of course, I can't just keep the paper on the filler - a little of the paper will touch the tube. I have no idea where the gouges come from, but I've had that happen before as well.

    Maybe I need to switch to an easier-to-sand filler. Anybody have any experience with HobbyLite? Is it easier to work with? I've also thought of trying plastic putty - which TRF user Krusty tells me he uses to fill fins, and that guy builds some beautiful rockets. I'm working on another rocket right now that needs some serious filling. It has a coupler, and when I put the two body tubes together, the glue seized, and there's a very slight gap that must be filled. Not to mention the spirals. That one already has a few coats of gray primer on it. I'm going to wait for your advice before I touch that one again.

    I'm also not completely satisfied with my fin filling, but I only have a few trouble spots with that. This tube shredding thing, though... It's really frustrating me.

    I know that failure is part of the learning process. The difference is, with other rocketry mistakes I've made, I've learned from them, and now do those parts better - like gluing properly, making nice fillets, etc. With this, I've failed at it five times, made the same mistake, and I don't seem to be getting any better at it. I'm a reasonably smart guy, and I just want to make a nice, smooth rocket. I'll move on to other problems and techniques when I get that down.

    So, what am I doing wrong? Help me, Rocketry Forum. You're my only hope.

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  2. #2
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    Make sure that your primer is completely dry before sanding. That way it'll come off as a fine dust. It looks like maybe it was still a little damp, or else you've simply sanded down too deeply.

    Also, I've never quite agreed with the coarse sandpaper that many people recommend for sanding primer. I'd use 600 grit at a minimum, and maybe even try 800 grit. 400 grit looks like it's really scratching the primer. If the sandpaper grit is too fine then all that happens is that it gets clogged up too easily. If that happens then you can go coarser. I usually end up way over 1,000 grit for sanding in between coats.

    At this point you can lightly prime again and make sure to let it dry completely. The primer will soak into that roughed up paper on the tube to make it easier to sand smooth. You might also need to apply some more Elmer's wood filler.

    Be sure to not thin out the Elmers too thinly or else it will lose its strength. I've tried the HobbyLite and it was way to fragile. It is indeed very lightweight and mixes well with a little water but just isn't as durable as Elmers.


  3. #3
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    I take a first pass at filling the grooves before priming, then do the prime/sand/fill cycle until I'm satisfied. It does sound like you're sanding too much, but 400 grit doesn't seem excessively coarse to me.

    Edit: I missed it the first time, but I agree that wet-sanding paper tubes is likely to cause trouble. Wet sanding is great, but only on waterproof materials.
    Last edited by JohnCoker; 5th September 2014 at 03:52 PM.
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  4. #4
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    Even with that being said at the outset, "and damp sanding with a really light touch", let's look at the sanding process itself - how is the sandpaper being held? - how is the rocket being held? - what shape and size of sanding block is being used? - how much pressure is the sandpaper being applied with - what is the sanding speed?
    There could be some dynamic in there which is having more impact than the grit of paper employed.

    And, it could be merely the "damp" bit which is the culprit.
    Wood fibre products and water have a volatile relationship, it could be that any use of water until multiple solid coats of primer and paint are between you and the cardboard will end up causing this.
    later, Forrest "Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality." -- Nikola Tesla, Modern Mechanics and Inventions, July, 1934

  5. #5
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    Quote Originally Posted by modeltrains View Post
    ...
    And, it could be merely the "damp" bit which is the culprit.
    Wood fibre products and water have a volatile relationship, it could be that any use of water until multiple solid coats of primer and paint are between you and the cardboard will end up causing this.
    I agree with modeltrains, damp sanding primer is your culprit. The moisture wicked right through to the surface and found all the nicks in the glassine. Based on your photo, I'd say you're still either sanding too much or bearing down too much. FWIW, I use either 400 grit or a fine sanding sponge and I try to stop just short of the tube surface. But no water gets near the thing at this point in the process.
    Last edited by samb; 5th September 2014 at 11:52 AM.

  6. #6
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    Quote Originally Posted by samb View Post
    I agree with modeltrains, damp sanding primer is your culprit. The moisture wicked right through to the surface and found all the nicks in the glassine. Based on your photo, I'd say you're still either sanding too much or bearing down too much. FWIW, I use either 400 grit or a fine sanding sponge and I try to stop just short of the tube surface. But no water gets near the thing at this point in the process.
    2+ with Modeltrians and Samb.
    It is a very bad idea to damp sand primers which are porous by nature allowing the moisture to penetrate all the way to the bodytube surface.
    Yes some Primer can Labels say "wet sand" but remember these Primers were formulated for use on Metal substrates.
    You'll be much better off DRY sanding your 3 coat primer covered body tube with 320 or 360 grit sandpaper(Personally I use progressive 120,240 360grit on My builds). Further sanding with finer grit papers will not ensure a smoother finish but will remove some of the needed "Tooth" left behind with 360grit sandpaper to help our primers Grab onto the surface.

    Keep in mind (Primer) is a MECHANICAL Conversion coating ment to Help Paint adhere to the substrate. Giving this coating a little bit more surface area in the microscopic hills and valleys of the Sandpapered surface gives a much stronger HOLD between Primer and Substrate as well as Paint to Primer.
    Last edited by Micromeister; 5th September 2014 at 03:16 PM.
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  7. #7
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    Here is an "out of the box" method, if you REALLY want to end spirals once and for all. This is "A" method, not "THE" method for getting rid of the dreaded spiral.

    It involves fiberglassing. You need fiberglass laminating epoxy and ~0.5 oz fiberglass cloth. Place one or two wraps of the cloth and the problem goes away. You can sand into the substrate, or add epoxy laminate layers and polish it. It will add a bit of weight, but more strength to the airframe (more "kink" and "ding" resistant).

    This way is not for everyone, but it it works everytime.

    Greg

  8. #8
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    It's fairly wasteful, but I prime about 5-6 times, then sand it all down to one coat lightly with a fine sponge. Then repeat as needed until they're gone.

    I'd put down a base of white primer, then all gray or black, or vise versa. When you start to see the base layer, stop. if the spirals aren't smooth, recoat.

    I've never wet sanded primer. just get it smooth enough with a fine or extra fine sponge and deal with the rest in the final coat.

    bluetube filled entirely with primer.
    Last edited by DizWolf; 5th September 2014 at 03:06 PM.
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  9. #9
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    When I did my Vertical Assault, I used epoxy clay from Apogee. I know a lot of people don't like it, but I didn't have any problems. I followed Apogee's video instructions, using a razorblade and a thinly rolled line of clay. After it hardened, I lightly sanded it with 400 grit. I was very pleased with the results, but then I am not as critical as some.
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  10. #10
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    Simple fix , yes glass is the best way . Take it to the next set of pads out .
    Recertification coming soon
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  11. #11
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    Quote Originally Posted by Micromeister View Post
    2+ with Modeltrians and Samb.
    It is a very bad idea to damp sand primers which are porous by nature allowing the moisture to penetrate all the way to the bodytube surface.
    Yes some Primer can Labels say "wet sand" but remember these Primers were formulated for use on Metal substrates.
    You'll be much better off DRY sanding your 3 coat primer covered body tube with 320 or 360 grit sandpaper(Personally I use progressive 120,240 360grit on My builds). Further sanding with finer grit papers will not ensure a smoother finish but will remove some of the needed "Tooth" left behind with 360grit sandpaper to help our primers Grab onto the surface.

    Keep in mind (Primer) is a MECHANICAL Conversion coating ment to Help Paint adhere to the substrate. Giving this coating a little bit more surface area in the microscopic hills and valleys of the Sandpapered surface gives a much stronger HOLD between Primer and Substrate as well as Paint to Primer.
    Yep.

    I missed the point in the OP about wet sanding the primer or filler. You want the process to be DRY. Make sure the primer and filler are fully dried before sanding. And then sand them dry. Like in the post above, when I am sanding, I go through a progression of grits, depending on how much material I am removing. I don't usually go any higher than 360 on primer. The color coat will self level into any texture left by 360 grit. If you want things smoother, you can wet sand you color coats, which I never do.

    Then, once you get it absolutely perfect, launch it. There's a good chance you'll never sand out the damage from that first launch!

  12. #12
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    I missed the wet sanding part of it too. The only time I use water is when I'm doing a final sanding on the finish coat which should be waterproof.

  13. #13
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    I'm thinking the wet sanding was the problem, and in the future that won't be an issue if he sands it dry.

    Does anyone have any ideas about what to do with the fuzzies he has now? Can you spray a few coats of filler primer over those and dry sand them out? Would something other than primer work better?

  14. #14
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    Ok... First, I personally have never had ANY luck using the Carpenter's Wood Filler (CWF) for filling spirals... I usually thin mine to the consistency of hot dog mustard and brush it on, and it works GREAT for balsa parts like fins, nosecones, and transitions. But when I try using it to fill spirals, it will looks good, but then once I sand it the stuff seems to disappear... almost like I never applied it! There will be SOME left in places, but most seems to be gone. Then you get to do the same thing all over again, sometimes three times, before the spirals are finally filled. I don't like doing the same thing over and over again for no purpose just to do the SAME JOB that can be done in ONE STEP using a different material...

    What I use is Bondo Glazing and Spot Putty, available from pretty much any auto supply store. You can get a small tube for about 3 bucks or a steel toothpaste tube about a foot long and 2.5 inches in diameter that will last for YEARS for about $4.50... The stuff works terrific. It's basically a thickened primer, essentially think the powdered "solids" in primer, with just enough LACQUER THINNER to act as a carrier and make it a paste. If you added more lacquer thinner to it, you'd end up with basically a brush-on or spray-on type red oxide primer, so think of the stuff as primer that's thickened up to the consistency of toothpaste.

    How you use it is, on the UNPAINTED ROCKET TUBE, daub a little dab onto the end of your finger, and then daub it onto the spiral, making sure that it's filled and covered well. Of course the less you put on the tube, the less you have to sand off later. You can even "float" the stuff with an old expended gift card or something (I pick up waste gift cards off the tops of the pumps at Walmart and stuff when I get gas to use for such jobs... they're handy because they can be cut, shaped, etc. for a variety of uses, and they're FREE!) I just daub the stuff into the spiral, let it dry (since it uses lacquer thinner, it will harden rapidly-- even the warmth on your finger will cause what's on your finger to thicken up quickly, so use a fairly small amount (pearl size at most) and work fairly quickly, and wipe any excess onto a piece of paper towel-- don't get it on your clothes; it will ruin them. Basically, by the time you've applied it to the entire spiral, the other end will about be dry enough to sand. I give it an extra 10-20 minutes just to be sure. Then I sand the stuff down with 220 grit (which I use for all my first sandings) and then follow up with 400 grit wet/dry.

    Looking at your sanding problems, you said you used a "light touch". Looks to me that either you're still sanding too hard, or sanding the wrong way. I HIGHLY recommend the sanding methods use in autobody work... NEVER sand in a straight line if you can help it... ALWAYS sand in small circles (small circular motion of your fingers) and KEEP THE ROCKET MOVING... DO NOT sand in one spot... I take the rocket or part in one hand and SLOWLY TURN IT in my fingers as I sand in small circles with the other fingers... try to use either a sanding block (especially if you're a newb) or the flats of your fingers, not the fingertips. That will spread the pressure out. Sanding in small circles avoids or minimizes sanding scratches, and helps keep the paper from loading up. Constantly moving whatever your sanding will prevent sanding in "flat spots" and "going too deep" when sanding.

    If it looks like you're "sanding too far" or "too deep", then STOP! Make another application and then sand that down. Sanding deeper will just compound problems, NOT solve them! If your sandpaper is getting warm or sanding is difficult, you're using too much pressure. If the paper gums up, either you're using too much pressure and "grinding the gunk into the paper" or your material isn't cured hard enough for sanding yet. Give it more time, and LET THE PAPER DO THE WORK... sanding should be done with literally NO pressure on the surface-- just enough to keep the paper touching the work surface, NO MORE... exerting pressure, even "light pressure" only serves to create heat, which can make surfaces gummy and hard to sand, and wastes energy, and leads to sanding scratches and sanding too deep and stuff which WILL have to be fixed later.

    You said you used 400 grit. It looks from the photos, since you said you're using a light pressure, that you're just flat sanding WAY too much. You mentioned damp sanding... I'm wondering if you're getting things too wet, or using too much water... that could certainly be a problem.

    For one thing, *I* don't use damp sanding except as a FINAL sanding just before painting the final color coats. I WOULD NOT RECOMMEND using damp sanding on earlier steps like sanding down early primer layers or tube filling or balsa filling or anything like that. It doesn't really matter much if you have a few sanding scratches or other SLIGHT imperfections in a filled spiral or filled fin or balsa nosecone or transition... the idea is to get the surface as smooth as possible... and sanding the point of tube fuzzies tells me your just plain sanding WAY too much, or using too much pressure (which you say you're not), or too coarse a grit (which from what you said shouldn't be a problem with 400 grit-- I use 220 for the first sanding on EVERYTHING and don't have this problem). The only time I'd recommend damp sanding is AFTER you've filled your spirals and wood grain, primered and sanded the rocket with 220 grit followed by 400 grit, and basically have it ALMOST ready for the final coats of paint... THEN you can dip some 400 grit into water, and shake it off or daub MOST of the water off onto an old bath towel-- the paper should be MOIST but NOT SOPPING WET, and most certainly NOT dripping wet! While true "wet sanding" used on automotive finishes DOES use copious amounts of water, as both a lubricant and coolant as well as to flush away paint particles, the purpose of using moisture in "damp sanding" is solely to prevent the paper from "loading up" with sanded off primer solids to the point it will no longer "cut" (sand off material). The other purpose is to provide a slight lubricating effect, as the moisture combines with the sanded off primer solids to form "sanding mud" which then acts as a lubricant and also somewhat as a polishing compound, giving a very smooth final sanding finish to the part... I can make primer shine like gray or red spray paint if I work it long enough and fine enough... but you don't REALLY want to take it that far-- ONLY damp sand JUST ENOUGH to remove all the sanding scratches and leave a very smooth, fine surface with NO visible defects, as paint does not cover up defects in the surface, but it MAGNIFIES them... Hold the part up the the light of a lamp or chandelier or bright window across the room and observe the "glint" of reflected light off the surface, and turn the rocket or part slowly, or for flat fins, tilt them this way and that and observe the reflected glint of light off the surface-- You should see a smooth, straight line, with no irregularities or dark spots or anything like that which would indicate a pit, void, or imperfection in the surface. Even when you're doing your best work, you'll still probably have to live with a FEW minor problems-- it's up to you to decide what you can live with and what you want to spend the time and effort to fix or "make better", since sometimes you can't TOTALLY fix a problem completely, due to limitations of the materials.

    The key thing to remember when damp sanding is to KEEP MOISTURE TO A BARE MINIMUM... remember we're working on balsa and cardboard for the most part-- things which DO NOT respond well to excessive amounts of moisture. That's another reason I'd say save the damp sanding for the LAST STEP BEFORE PAINTING-- by that point you should have a smooth, unbroken, even application of dry primer on the rocket and balsa, covering those parts and keeping the moisture away from them... the moisture is being applied to the PRIMER, NOT the balsa or paper itself...

    One other thing-- are you wrapping a sheet or partial sheet of sandpaper around the tube and then sanding it that way?? If so, that is the QUICKEST way to oversand the tube and cut through the glassine layers and into the paper fuzzies beneath... I always cut a roughly 2x3-4 inch piece of sandpaper off the corner of the sheet and use that with the first three fingers, on the FLATS of the fingers (NOT the fingertips, except for very tight areas, and then being EXTRA careful not to oversand!) to lightly keep the paper touching the tube or part... the pinky and thumb I use to keep the paper pinched against the palm of my hand and keep it taut...

    My best recommendation-- do everything DRY until you're ready to paint... THEN do a final damp sanding to the primer, VERY LIGHTLY-- JUST ENOUGH to remove any residual sanding scratches and get the surface smooth and blemish-free. ALL the tube, fin, nosecone, and transition sanding steps before assembly should be done DRY, NOT using damp sanding. Once the rocket is assembled and primered with 2-3 good coats of primer, and sanded with 220 grit and 400 grit until it's smooth, THEN do a final "damp sanding" until you get a good surface with no visible defects, THEN wipe it down with a damp paper towel (thoroughly wrung out) and finally dry it with a dry paper towel, and let it dry at least several hours or overnight before applying your color coats. Sand in small circles using only enough pressure to keep the paper touching the tube, DO NOT wrap sandpaper around the tube to sand it, and ALWAYS keep the surface moving, by turning the tube or part constantly as you sand, or moving across the surface in a methodical fashion when you're sanding fins or other flat surfaces... SO NOT sand continuously in one spot.

    Some people swear by the CWF or lightweight spackle or Hobbylite fillers or stuff for spirals-- I've tried the CWF and lightweight spackle and never could make them work as well as the Bondo Glazing and Spot Putty (BGSP). I'd HIGHLY recommend you try some of that stuff and see how you like it. I even use it for filling any pits or voids in balsa parts that are apparent after filling with CWF. One warning though-- DO NOT apply BGSP over a previously-primered surface (with ENAMEL primers anyway) The hotter lacquer thinner solvents in the BGSP WILL attack and "eat up" the enamel primer, essentially softening it to the point it will simply wipe off the tube... It should be okay with lacquer primers, but I don't use lacquer primers so I don't know.

    One other tip-- if the tube has VERY SMALL spirals, I wouldn't bother with any of it... just hit it with several good solid coats of primer and then sand it down smooth-- most of the time that will fill small spirals to the point you can't see them anyway... if you still can, give it another couple coats of primer and sand it again... it should wipe small spirals out completely. If the spirals are larger and deeper, though, that's when BGSP works REALLY well to fill them before primering...

    Later and good luck! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  15. #15
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    For filling fins, the simplest and best way I've found is just to paper them... Strengthens the fin considerably with only minimum weight, and eliminates the filling and sanding steps entirely-- paper the fins and glue them on the rocket, and it's ready to primer... The papering is covered in some other recent threads...

    One other thing-- personally I don't fill the spirals until the fins are glued on... I don't want ANYTHING between the tube and the fin root edge-- Not filler, and CERTAINLY not primer... In fact, I DO sand the glassine enough to cut through it where the fins will physically glue to the paper fibers, and then the fillet will be bonding to the scuffed-up glassine on either side... and I use a good yellow wood glue double glue joint to join the two together...Either the fin will break or the tube outer layer of paper will rip off before the glue joint lets go...

    Once the outer construction is complete, THEN I daub BGSP onto the spirals, if they're big enough, and sand it down with 220 grit followed by 400 grit, prime with several good coats, and then sand again with 220 followed by 400, decide if I need to RE-prime anything to fix any "problem spots", sand again with 220 followed by 400 if I reprimed, and then damp sand with 400-- works like a champ!

    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  16. #16
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    Quote Originally Posted by modeltrains View Post
    Even with that being said at the outset, "and damp sanding with a really light touch", let's look at the sanding process itself - how is the sandpaper being held? - how is the rocket being held? - what shape and size of sanding block is being used? - how much pressure is the sandpaper being applied with - what is the sanding speed?
    There could be some dynamic in there which is having more impact than the grit of paper employed.

    And, it could be merely the "damp" bit which is the culprit.
    Wood fibre products and water have a volatile relationship, it could be that any use of water until multiple solid coats of primer and paint are between you and the cardboard will end up causing this.
    ABSOLUTELY... This is spot-on advice...

    A lot of folks around here will tell you using ANY water around cardboard and balsa is anathema... Maybe for them it's true, but there's plenty of folks around here (me among them) that KNOWS that it can work, IF you use good techniques!

    That said, skip the damp sanding until you've got SEVERAL layers of primer and stuff between the paper/wood parts and the moisture... that's the key, like modeltrains said!

    Good luck! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  17. #17
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    Quote Originally Posted by chris m View Post
    Simple fix , yes glass is the best way . Take it to the next set of pads out .

    More anti-tank rounds...

    Geez...

    Glad nobody does this in our club... I wouldn't want stuff like that flying on my farm...

    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  18. #18
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    [QUOTE=luke strawwalker;755362]More anti-tank rounds...

    Geez...

    Glad nobody does this in our club... I wouldn't want stuff like that flying on my farm...

    Later! OL JR :
    If I'm in TX flying I will have no spirals . I'm going to start glassing everything
    Last edited by chris m; 5th September 2014 at 06:57 PM.
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  19. #19
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    Quote Originally Posted by ThirstyBarbarian View Post
    I'm thinking the wet sanding was the problem, and in the future that won't be an issue if he sands it dry.

    Does anyone have any ideas about what to do with the fuzzies he has now? Can you spray a few coats of filler primer over those and dry sand them out? Would something other than primer work better?
    Fuzzies are tough... I used to get some 3 inch + Christmas wrapping paper tubes (well, various sizes actually) from a friend of my Grandmother (20 or 30 years ago when Christmas paper was actually rolled up around really nice tubes, not a sheet of paper like now). These tubes were great for building rockets, BUT, they had NO glassine whatsoever on them. That makes things pretty difficult then you get to finishing, because the first few coats of primers basically stick to the paper hairs and you end up with something as fuzzy as a raccoon...

    I dealt with the problem a few different ways...

    1) you can just primer and lightly sand again and again until the fuzzies go away... this works because more and more of the primer will stick to the surface of the tube with each pass and eventually you'll be less with less and less "fuzzy" sticking up above the primer, and the sandpaper will cut the fuzzy fibers off when you sand between each coat or two of primer... may take 3-4 cycles to get rid of it, sometimes 6 if it's REALLY fuzzy.

    2) Apply white or wood glue smeared over the damaged spots... allow to dry COMPLETELY, then sand down smooth- Sand GENTLY because white and wood glue tend to get GUMMY if sanded too hard and fast, especially if you generate any HEAT while sanding... When you do this to an entire tube, it's a BIG job... (but it works pretty well for fixing minor sand-thru spots, like these).

    3) Coat of epoxy... works great, but it takes a lot, need the gloves and disposable brush and all that jazz that makes epoxy such a pain to work with, plus all the waste and mess...

    4) glue a wrap of paper to the tube... for full-fuzzy non-glassine tubes, this is probably the easiest... sorta like the Dr. Zooch wraps, but fully encasing the tube in a layer of printer (or other) paper. For this kind of repair of a glassine tube, I wouldn't bother... unless you want to decorate the rocket with some "wraps" of some kind like a Zooch kit... maybe some "roll patterns" or "interstages" or something, with a wrap of corrugated paper or corrugated mylar or something glued over the damaged spots... quick and easy and would look neat...

    Best solutions I've found to the problem... Well, the BEST solution is DEFINITELY "prevention"...
    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  20. #20
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    [QUOTE=chris m;755365]
    Quote Originally Posted by luke strawwalker View Post
    More anti-tank rounds...

    Geez...

    Glad nobody does this in our club... I wouldn't want stuff like that flying on my farm...

    Later! OL JR :
    If I'm in TX flying I will have no spirals . I'm going to start glassing everything
    Meh... whatever...

    But I *STILL* think it's about as STUPID as that totally glassed bulletproof anti-tank round little Estes rocket that was in "Sport Rocketry" a few years ago...

    You can pay in full for all the damages it causes if it goes awry, too...

    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  21. #21
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    Lots of good tips, especially around sanding. My 2 cents, I've been using (on small paper and wood rockets) thinned joint compound (as in, the stuff you buy from Home Depot for working with sheetrock). I thin it with water to the consistency of honey or mustard, and paint it into the spirals. Once dry, it sands (in my opinion) much easier than wood filler, and after one or two coats at most I have fully filled spirals.
    --
    Matt Laudato
    NAR# 91867, L2
    Member CMASS, MMMSC, RIMRA, CATO

  22. #22
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    Quote Originally Posted by luke strawwalker View Post
    Fuzzies are tough... I used to get some 3 inch + Christmas wrapping paper tubes (well, various sizes actually) from a friend of my Grandmother (20 or 30 years ago when Christmas paper was actually rolled up around really nice tubes, not a sheet of paper like now). These tubes were great for building rockets, BUT, they had NO glassine whatsoever on them. That makes things pretty difficult then you get to finishing, because the first few coats of primers basically stick to the paper hairs and you end up with something as fuzzy as a raccoon...

    I dealt with the problem a few different ways...

    1) you can just primer and lightly sand again and again until the fuzzies go away... this works because more and more of the primer will stick to the surface of the tube with each pass and eventually you'll be less with less and less "fuzzy" sticking up above the primer, and the sandpaper will cut the fuzzy fibers off when you sand between each coat or two of primer... may take 3-4 cycles to get rid of it, sometimes 6 if it's REALLY fuzzy.

    2) Apply white or wood glue smeared over the damaged spots... allow to dry COMPLETELY, then sand down smooth- Sand GENTLY because white and wood glue tend to get GUMMY if sanded too hard and fast, especially if you generate any HEAT while sanding... When you do this to an entire tube, it's a BIG job... (but it works pretty well for fixing minor sand-thru spots, like these).

    3) Coat of epoxy... works great, but it takes a lot, need the gloves and disposable brush and all that jazz that makes epoxy such a pain to work with, plus all the waste and mess...

    4) glue a wrap of paper to the tube... for full-fuzzy non-glassine tubes, this is probably the easiest... sorta like the Dr. Zooch wraps, but fully encasing the tube in a layer of printer (or other) paper. For this kind of repair of a glassine tube, I wouldn't bother... unless you want to decorate the rocket with some "wraps" of some kind like a Zooch kit... maybe some "roll patterns" or "interstages" or something, with a wrap of corrugated paper or corrugated mylar or something glued over the damaged spots... quick and easy and would look neat...

    Best solutions I've found to the problem... Well, the BEST solution is DEFINITELY "prevention"...
    Later! OL JR
    Looking at the pictures in the first post, and considering these suggestions, I would probably go with the primer method --- there still is a trace of spiral left anyway, and this would be a chance to practice the suggested dry sanding anyway.

    Here's what I would try for fixing the left over fuzzies:


    1. Spray 3 coats of Rustoleum Filler Primer over the whole rocket about 5 - 10 minutes apart (not more than an hour apart).
    2. Allow to dry THOROUGHLY.
    3. Dry sand with 220 grit to remove fuzzies, small gouges, and spirals.
    4. Repeat as necessary.
    5. Once the blemishes are gone, sand with higher grit if a finer finish is desired.
    6. Color coat.
    7. Clear coat.
    8. Post pics to TRF for praise and adulation!

  23. #23
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    I don't bother to fill spirals. Whatever gets filled by the primer is good enough for me.

    Besides, nobody can see them when your rocket is hanging from a tree branch, 80 ft. up in the air.
    Last edited by BobH48; 5th September 2014 at 07:57 PM.
    Bob Harrington
    NAR #62740 L1
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    CMASS & RIMRA Member

  24. #24
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    Quote Originally Posted by BobH48 View Post
    I don't bother to fill spirals. Whatever gets filled by the primer is good enough for me.

    Besides, nobody can see them when your rocket is hanging from a tree branch, 80 ft. up in the air.
    Or core sampling with only the fins visible!
    John S. ---- NAR #96911 ---- TRA #15253 ---- MDRA #067 ---- BARC #028
    L1, 3/15/14: Aerotech Sumo, CTI H133BS
    L2, 6/21/14: Giant Leap Vertical Assault, CTI J240RL
    L3, 3/12/16: MAC Performance Radial Flyer, CTI M1101WH
    Altitude: 13,028', L3 flight; Speed: Mach ???, L3 flight

  25. #25
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    30th July 2014
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    101
    Looks to me like you're just sanding too hard and too much, so that your body tube is coming apart. Good finish is in the technique more than the tools. Take strawwalker's advice and you'll get better with practice.

    I think I posted something back in your mini honest John thread about sanding primer - lightly scratch up the tube first to give it something to stick to, and avoid damp sanding primer at all. It's porous and you'll essentially end up giving your body tube a shower, which is not good. 220 or 400 grit is enough to get the tube perfectly smooth in all honesty. Higher grits are for sanding color and clear coats and polishing the final topcoat.

  26. #26
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    I just re read your post and I think part of the problem is that you're watering down the filler that you're applying to the body tube spirals. I don't think that's a good idea due to the poor interactions between cardboard and water. Try applying the CWF in full strength putty form and pressing it into the spirals with your fingers. Easy to get it off, clean up with water! Hopefully that helps you out.

  27. #27
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    Quote Originally Posted by matthewdlaudato View Post
    Lots of good tips, especially around sanding. My 2 cents, I've been using (on small paper and wood rockets) thinned joint compound (as in, the stuff you buy from Home Depot for working with sheetrock). I thin it with water to the consistency of honey or mustard, and paint it into the spirals. Once dry, it sands (in my opinion) much easier than wood filler, and after one or two coats at most I have fully filled spirals.
    Is this like regular spackle?? I've tried the "super lightweight" stuff (feels like the tub is empty when you pick it up off the shelf) and it works OKAY, but it not as well as CWF and takes usually at least 2 applications to fill the spirals...

    Best of luck! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  28. #28
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    Quote Originally Posted by ThirstyBarbarian View Post
    Looking at the pictures in the first post, and considering these suggestions, I would probably go with the primer method --- there still is a trace of spiral left anyway, and this would be a chance to practice the suggested dry sanding anyway.

    Here's what I would try for fixing the left over fuzzies:


    1. Spray 3 coats of Rustoleum Filler Primer over the whole rocket about 5 - 10 minutes apart (not more than an hour apart).
    2. Allow to dry THOROUGHLY.
    3. Dry sand with 220 grit to remove fuzzies, small gouges, and spirals.
    4. Repeat as necessary.
    5. Once the blemishes are gone, sand with higher grit if a finer finish is desired.
    6. Color coat.
    7. Clear coat.
    8. Post pics to TRF for praise and adulation!
    Good advice...

    If in doubt, avoid the damp sanding.

    Always time to incorporate that procedure later on as an "experiment"... gotta crawl before you can walk (or run).

    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  29. #29
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    Quote Originally Posted by BobH48 View Post
    I don't bother to fill spirals. Whatever gets filled by the primer is good enough for me.

    Besides, nobody can see them when your rocket is hanging from a tree branch, 80 ft. up in the air.
    Or "rotting on a power line" as Dr. Zooch says... LOL

    Kinda hard to see 25 feet away on the pad, too... or moving through the air at 200 mph...

    Still, I take a lot of PRIDE in achieving the best finish I can... remember that 99% of a rocket's life is spent on DISPLAY, not on the pad or in flight... (and neglecting time spent rotting on a power line or in the top of a tree of course... )

    BUT, Murphy's Law of Rocketry states that the likelihood of a rocket being stuck on a powerline, in a tree, or in some other permanently inaccessible place (neighbors or school roof, behind razor-wire fencing around an industrial complex, etc.) is DIRECTLY PROPORTIONAL to the time, effort, and expense put into perfectly finishing that rocket... the likelihood of it core sampling, catoing, or landing on asphalt and being dragged across the parking lot in the wind and getting road rash, or landing in a part of the park infested with soccer hooligans who will stomp it to bits just for kicks, or running over it in said parking lot and flattening it out before the chute drags it to safety in the gravel surrounding the parking lot, also increases in direct proportion to the perfection of the surface finish when completed...

    Just something to bear in mind! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  30. #30
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    Quote Originally Posted by luke strawwalker View Post
    Is this like regular spackle?? I've tried the "super lightweight" stuff (feels like the tub is empty when you pick it up off the shelf) and it works OKAY, but it not as well as CWF and takes usually at least 2 applications to fill the spirals...

    Best of luck! OL JR
    Joint compound is a bit different from spackle, thicker and more plastic - it's main job is to smooth and strengthen (often along with joint tape) the joints between pieces of wallboard (Sheetrock, blue board). I use it home all the time to fix dings in walls, and it seems to work well on the rockets. I've tried spackle too and prefer the joint compound (both on rockets and on my walls).

    --
    Matt Laudato
    NAR# 91867, L2
    Member CMASS, MMMSC, RIMRA, CATO

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