filling spirals

[Off Grid Gecko]

How much are you guys thinning your wood filler? I'm using DAP plasti-wood in a tube and it dries pretty quickly (though not as bad as spot putty). So I do a drop then work fast, then another little bit, one squeeze at a time perhaps 1mL or less. I imagine mixing it with some water would also extend the working time before it starts to get crumbly? I've heard only a few drops are needed, is that for an entire tub? What are the consequences of using too much water, other than the cardboard getting saturated?

 

[Greg Furtman]

How much are you guys thinning your wood filler? I'm using DAP plasti-wood in a tube and it dries pretty quickly (though not as bad as spot putty). So I do a drop then work fast, then another little bit, one squeeze at a time perhaps 1mL or less. I imagine mixing it with some water would also extend the working time before it starts to get crumbly? I've heard only a few drops are needed, is that for an entire tub? What are the consequences of using too much water, other than the cardboard getting saturated?

@Off Grid Gecko Which DAP Plasti-wood are you using. I just checked DAP's website and there seems to be a number of varieties.

I use Elmer's Carpenter's Wood Filler and I add enough water to make it a little thinner than toothpaste.

 

[Wally Ferrer]

I have thinned it out different amounts, depending on how big the spirals are to be filled. For very tight spirals, like most Estes tubes, I go very thin, no thicker than paint, let's say. I want to make sure it gets into the spiral, I use the card to squeegee it because it will still be thick enough, and removes both excess water and cuts down on the sanding residue. For a larger tube with a big spiral gap I might not thin it at all.

 

[Off Grid Gecko]

@Off Grid Gecko Which DAP Plasti-wood are you using. I just checked DAP's website and there seems to be a number of varieties.

I use Elmer's Carpenter's Wood Filler and I add enough water to make it a little thinner than toothpaste.

I think it's this stuff:
https://www.dap.com/products-projects/product-categories/patch-repair/wood-repair/pw-latex/
but in a plastic 6oz tube rather than a bucket.

I tried it again on some fins that I finally managed to get a decent bevel on for an upcoming project. Even when it starts getting chalky it seems able to be worked into the wood for a while, but I still worked pretty fast. I did little glops to get all of the bevels done, then went back and did the faces. After all that, I was able to smooth it down using my fingers as sandpaper (that's pretty accurate to what you see, little bits of powder rubbing off). I did something similar with the first tube for the same project a few days ago and I've been able to sand it fairly smooth, though it's hard to tell how smooth till there's primer on it. Still, it looks like the spirals took it in alright, and rubbing it all over the rest of the tube may have filled a few low areas in the cardboard too.

 

[jrap330]

Beef
I beefed up the dowel to make it snug against inside of rocket body. Doesn’t have to be tight. Snug works. Go from there.
To connect to drill I just found center of dowel drilled into it with a drill and left it in there.

Yeah but what did you use to beef it up. Let's say the biggest dowel is 1 inch...and body tube is 1.67 inches...what did you use?

 

[Mx2]

Yeah but what did you use to beef it up. Let's say the biggest dowel is 1 inch...and body tube is 1.67 inches...what did you use?

I would take cereal box, cut cardboard into strips, wrap around dowel To increase diameter, Couple wraps of tape, etc.. insert into tube (can even wrap tape backwards so it sticks to inside body tube) and slide assembly into tube, doesn’t have to be tight, just snug and if tube needs to be tighter just add a wrap of tape. Drill in right hand, sand paper in left and gently start.

There should be a point during rotation where it spins true (no wobbling) you can accelerate rotation speed about half speed of drill and that’s were the steel wool works best as you move it along the rocket body tube. It just takes a pass or two of sanding when at higher speeds.

soft pressure when using 300 or less grit. I put sandpaper in left palm, lay tube on that and trap tube down with thumb. Sometimes it spits sandpaper out of my hand but It will stay after a couple try’s.

I’ve used paint rollers (removed handle), dowels, foam pipe insulation with dowel up middle. The more true to center the better the spin. For long tubes the dowel Extend pasts the tube and rests and spin on desk top. Think of it as making a rudimentary lath. (Favorite line from Galaxy Quest.). The dowel end I would either tapper so it fits into drill chuck or drill a drill bit center of dowel, Into center of paint roller, etc and use that as power shaft.

sounds like your getting close!

 

[gna]

Kind of new to all of this and I hope these pictures work. Taking others ideas this is how I do my spirals:



B. Using ??-putty from Hobby Lobby. Dip finger in alcohol if needed, cover spirals “thinly“. If it makes little clumps don’t worry, don’t overwork putty. Set aside to dry in sun about 5 minutes, while shaking primer and get cordless drill.

View attachment 423018

That looks like Tamiya Putty
https://www.tamiyausa.com/shop/finishing/putty/

 

[Mx2]

That looks like Tamiya Putty
https://www.tamiyausa.com/shop/finishing/putty/

That’s it!
I had never used it before but a member on this site made recommendation and I liked it. I try to wear a glove because of the chemical-ness of it. Anything that dries that quick and hard probably shouldn’t be handled with bare skin. Just my thought.

 

[Zbench]

I have not seen anyone mention this product which I have been using for years:

https://www.seymourpaint.com/product/pbe-flexible-light-gray-primer/
This stuff is really excellent. Dries hard in like 20 minutes and can be immediately sanded and recoated. I find most tubes require two coats to finish, deep spirals 3. I recently had a project where this stuff really shined. Was building a Rocketarium Hydra Sandhawk and there was some unevenness where two tubes joined. One side perfect, the other side .030" low. I decided to see if I could even that up using this stuff. I used some masking tape to mask off the high area and hit it twice, not even sanding in between. Peeled off the tape when dry and then sanded. You can see the result. Since it is used for the automotive industry, it dries fast and hard. I don't notice the paper getting clogged as some report.

You can buy single cans on Amazon, but I get a case from the manufacturer which is the cheapest way to get it. Works great on balsa, any surface really.

 

[Joshua F Thomas]

I have not seen anyone mention this product which I have been using for years:

https://www.seymourpaint.com/product/pbe-flexible-light-gray-primer/

Oh, thank goodness. I came here specifically looking for a good hi-build primer. I used nearly half a can of the Rustoleum 2-in-1 on my most current rocket and I can still see the spirals. I'll pick some of this up.

I keep my small rockets next to me on my desk. I want them to look because I'm the guy who sees them every day, and I like having birds that look as high-quality as I can make them. It's some perfectionism in me, I guess.

 

[neil_w]

Oh, thank goodness. I came here specifically looking for a good hi-build primer. I used nearly half a can of the Rustoleum 2-in-1 on my most current rocket and I can still see the spirals. I'll pick some of this up.

Pre-fill your spirals with cheap-and-easy CWF or Bondo or whatever and then you won't need so much spray primer.

 

[Joshua F Thomas]

Pre-fill your spirals with cheap-and-easy CWF or Bondo or whatever and then you won't need so much spray primer.

Yeah, I did that [CWF], and I still can see them after the primer. Am I incorrect in wanting to see perfectly smooth tubes with no spirals visible at all?

 

[neil_w]

Yeah, I did that [CWF], and I still can see them after the primer. Am I incorrect in wanting to see perfectly smooth tubes with no spirals visible at all?

No, you are not incorrect. That just means you didn't get enough CWF into the spirals when you did it. There are several possible reasons for that.

I get a stray little bit of spiral peek through once in a while but that's only because I try to power through the spiral-filling process as quickly as possible (Do Not Enjoy). I do thin CWF on the entire tube, sand, then one heavy coat of Rusto filler/primer, sand, then at least 99% of spirals are gone.

 

[Joshua F Thomas]

I applied CWF thinned with a little water to the spiral areas, pressed in with fingers. I then waited for it to dry and sanded down the excess. Hit it up with primer. Spirals visible.

The white tubes are the kind with the "filled" spirals and the non-filled spirals, where the filled spirals are visible but don't have any apparent depth to them; I assume these are part of the manufacturing process. Maybe I'm seeing these?

Edit: Think I'll try the 3M Bondo next

 

[neil_w]

The white tubes are the kind with the "filled" spirals and the non-filled spirals, where the filled spirals are visible but don't have any apparent depth to them; I assume these are part of the manufacturing process. Maybe I'm seeing these?

The "filled" spirals do often have a visible indent; it depends on the tubing. That is why I just cover the whole tube in CWF, it's easier than trying to isolate it to just selected areas.

It is possible you're seeing those, or else you just didn't get the CWF to really stay inside spirals, or you sanded it out, or who knows what. But it works if you do it right.

Edit: Think I'll try the 3M Bondo next

Process is more important that product here. Bondo should give similar results to CWF, just smellier. I would *not* spread Bondo over the entire tube like I do with CWF.

 

[Joshua F Thomas]

What's the mass addition like for covering a whole tube in CWF? Has anyone done that calculation?

Yes, I'm a little crazy about getting CG/CP and sim numbers as accurate as I can.

 

[neil_w]

What's the mass addition like for covering a whole tube in CWF? Has anyone done that calculation?

I haven't measured, but the very vast majority of it gets sanded off, so it's really minimal.

If you have a piece of scrap tubing, I suggest trying it that way and see if you like it. Then you can also weigh it before and after and see.

If you do try it, spread it *thin* with your fingers. Don't leave yourself too much sanding to do. Just make sure the spiral areas have good coverage. I keep running my fingers back and forth over it to spread it and even it until it's almost dry. For me it is much faster to do this than to apply carefully to the spirals.

Note that covering the whole body will also help fill in general unevenness in the BT surface.

 

[o1d_dude]

I do not worship at the House of Filled Spiral but have no problem with those who do.

I sand the cardboard tubes to remove the gloss, go through a few iterations of prime/sand, and then move onto to the paint.

The launch fields where we fly are rugged and in short order my rockets will look like they have flown a few times.

A display model is a different matter but I have built only two of such things and early in my BARhood. Once I found myself not wanting to fly them because of potential damage to their pristine finish, I resolved only to build flying rockets from that point forward.

Edit: Typo

 

[Joshua F Thomas]

If you do try it, spread it *thin* with your fingers. Don't leave yourself too much sanding to do. Just make sure the spiral areas have good coverage. I keep running my fingers back and forth over it to spread it and even it until it's almost dry. For me it is much faster to do this than to apply carefully to the spirals.

Do you just do it once? I've also been a bit wary of thinning CWF too much - I did that once when using it for fins and it warped the fins...

 

[neil_w]

Do you just do it once? I've also been a bit wary of thinning CWF too much - I did that once when using it for fins and it warped the fins...

Just once. I get it to mustard consistency, easy to spread with fingers. Too thick and it won't stick in the slots. Again, suggest just trying it on a scrap tube. For pictures: https://www.rocketryforum.com/threads/build-thread-blackfish.157851/post-1980600

Avoiding fin warp is a different issue.

 

[Joshua F Thomas]

Nice. I think I'll give that a try on the next thing I'm working on, which is my first scratch build. Gonna need a decent amount for the 22.25" of BT-70 tube, tho

 

[neil_w]

Nice. I think I'll give that a try on the next thing I'm working on, which is my first scratch build. Gonna need a decent amount for the 22.25" of BT-70 tube, tho

That's pushing the limit for this technique I think, but still doable. Doesn't use a lot of CWF cuz you spread it on really thin.

 

[Bill S]

The "filled" spirals do often have a visible indent; it depends on the tubing. That is why I just cover the whole tube in CWF, it's easier than trying to isolate it to just selected areas.

It is possible you're seeing those, or else you just didn't get the CWF to really stay inside spirals, or you sanded it out, or who knows what. But it works if you do it right.


Process is more important that product here. Bondo should give similar results to CWF, just smellier. I would *not* spread Bondo over the entire tube like I do with CWF.

I do cover the entire tube with Bondo and sand with a sanding sponge. A lot of work, but I find it gives me better results than CWF, which I detest. The last build, I cheated and just did the spirals and not the entire tube. Have to see how the rocket turns out to decide if I want to just do spirals in future, or the entire tube.

 

[John Brohm]

I'm a Bondo advocate, and have been for many years. But I learned some years ago that just filling the surface spiral, the one in the glassine wrap, sometimes isn't enough to ensure a smooth final finish. Some tubes can have an even deeper spiral underneath the glassine (the one in the underlying Kraft paper wrap), and left unaddressed, over time it can expose itself in the final finish , perhaps due to changes in humidity, or perhaps due to the stress the tube takes from ejection pressure events. So with that last coat of paint one can have one's self thinking what a terrific finish on the model, only to have a spiral eventually appear over time, much to one's dismay.

So if I'm working on a scale model, for example, something that's expected to have no sign of spirals, I'll open up that underlying seam and fill it too. Yes, twice the spiral filling and sanding fun!

The photos below show a before and after. As was stated earlier in the thread, not all models necessarily warrant all that filling work. But for the ones that do, it's tough to ignore that second spiral.

 

[o1d_dude]

I'm a Bondo advocate, and have been for many years. But I learned some years ago that just filling the surface spiral, the one in the glassine wrap, sometimes isn't enough to ensure a smooth final finish. Some tubes can have an even deeper spiral underneath the glassine (the one in the underlying Kraft paper wrap), and left unaddressed, over time it can expose itself in the final finish , perhaps due to changes in humidity, or perhaps due to the stress the tube takes from ejection pressure events. So with that last coat of paint one can have one's self thinking what a terrific finish on the model, only to have a spiral eventually appear over time, much to one's dismay.

So if I'm working on a scale model, for example, something that's expected to have no sign of spirals, I'll open up that underlying seam and fill it too. Yes, twice the spiral filling and sanding fun!

The photos below show a before and after. As was stated earlier in the thread, not all models necessarily warrant all that filling work. But for the ones that do, it's tough to ignore that second spiral.


View attachment 424771View attachment 424772

Clearly a Broncos fan.

My Denver nephew would be jealous.

Beautiful finish...the kind of rocket I would definitely NOT fly.

 

[John Brohm]

Actually, no...

 

[Blast it Tom!]

John, are you with Pittsburgh Space Command? I'll bet when you buy local we shop at the same store - Hobby Express in Cranberry! That's a beautiful rocket, and the teardrop-shaped rail buttons on the other one... and man, what a finish. You'd think is was turned & polished from a piece of solid plastic! (How come we don't have a "green with envy" smiley in the collection?)

I've been hoping I run across folks from the Pittsburgh area on here.

 

[jrap330]

No, you are not incorrect. That just means you didn't get enough CWF into the spirals when you did it. There are several possible reasons for that.

I get a stray little bit of spiral peek through once in a while but that's only because I try to power through the spiral-filling process as quickly as possible (Do Not Enjoy). I do thin CWF on the entire tube, sand, then one heavy coat of Rusto filler/primer, sand, then at least 99% of spirals are gone.

As a person who does not fill spirals sometimes you have to remember they are build to launch. You want perfect rockets , buy a plastic model kit. And yeah those tube s with low depth spirals ,I assumed it would be hard to fill so find a good primer maybe one suggestd.

 

[afadeev]

As a person who does not fill spirals sometimes you have to remember they are build to launch. You want perfect rockets , buy a plastic model kit.

Filling the spirals, like laying decent fin fillets, are both optional skills.
Both efforts do produce superior visual and aerodynamic outcomes, but the differences are 95% cosmetic and subjective, and at most 5% performance oriented.

The reason I now invest effort into both activities is a nod to perfectionism.
After you put together the first dozen or so rockets, the appeal of repeating the same process with the same expected outcomes is starting to fade. So you raise the bar on improving your building and finishing skills to keep yourself challenged, to produce better looking and slightly better flying rockets.
Or, maybe, that's just me.

And yeah those tube s with low depth spirals ,I assumed it would be hard to fill so find a good primer maybe one suggestd.

Fiberglass tubes have no spirals, and fiberglass fins have no wood grain!
But they do produce much heavier and less exotic looking rockets.

a

 

[John Brohm]

Well the great thing about this hobby is that it's easily personalized to one's preferences; other than the basic requirements of the Safety Code, nothing and no one requires models to be built or finished a certain way, and unless one is flying competition, there's no judging either, another choice one can make. Build them the way you like, and for the reasons that matter to you. Whether they have a "perfect" finish or not, they still go up and come down the same way.

Like afadeev says, finishing is just another challenge in this hobby; pursue the challenge(s) that provide you the greatest enjoyment. Otherwise, why are we doing it?

Blast it Tom! - Yes, Hobby Express is about 10 minutes from my home, and the owner Harry and his family are about the nicest folks one could hope to find in a hobby store.