My fastest spiral filling ever

[neil_w]

I always fill my spirals (using thinned CWF) but I certainly don't enjoy it. For my current build I needed to fill a 22" tube and I decided to see if I could improve my technique to speed things up. My results were... well, fantastic. Thought I'd share. I have no idea if this is what everyone else is already doing, but it doesn't match the pictures or descriptions I've seen posted before.

Start by getting a small glop of CWF on your finger. Spread it messily around (roughly) one rotation of the body tube (quick and dirty is the key). Note that this particular tube seemed to have no secondary spiral, so I only needed to deal with the primary. The black spiral is not indented, or if it is it will be taken care of by filler/primer.

Next I used a credit card and squeegeed of the excess. I kept the card perpendicular to the tube, pressed it down pretty hard, and rotated the tube slowly and carefully. After doing a bit wipe the card on a paper towel.

After this step there was *very* little excess on the tube, and it dried in barely a minute or two. Continue along the entire tube.

Finally I sanded with *800 grit* around the spirals. There was blessedly little to sand and the 800 grit made quick work of it without ruining the surrounding glassine layer. The result:

I did the whole 22" tube in about 5-10 minutes (I would have timed it if I had realized it would be so quick), and there was so little sanding it was glorious. As far as I can tell, the spirals are filled just as well as any other time I've done it more laboriously, and there are absolutely no excess CWF bumps.

The two key improvements for me were:
1) Applying the CWF roughly by hand. Very quick and easy.
2) *Vigorous* removal of excess filler with the credit card to minimize subsequent sanding.

 

[MarsLander]

Never filled spirals in 50+ years, just started the practice on my 2x Viper build. The CWF, in the manner I applied, was a bit too much and sanding it started to cut the glassine.

Too late on this build, but I'll try your technique. Thanks for the idea!

Was going to try the Chris Michielssen Dupli-color primer method next, but now I'm going to do back to back comparison of your method and Chris's.

 

[KenECoyote]

I use some watered down Elmer's CWF and a cheap hobby paint brush and it goes on pretty quickly that way.


Edit add: Imo it's easier if you add a primer base first, then the spiral fill, then sand. The primer helps provide a surface for the CWF to grip and also fills in a bit of the spirals.

 

[neil_w]

Was going to try the Chris Michielssen Dupli-color primer method next, but now I'm going to do back to back comparison of your method and Chris's.

He also does CWF followed by filler primer. The only way we are differing is the manner of applying the CWF.

I use some watered down Elmer's CWF and a cheap hobby paint brush and it goes on pretty quickly that way.

I don’t thin it enough for a paintbrush anymore. Also I don’t really like the way it gunks up the brush.

But brushing it on would be fine for me if followed by the squeegee. Eliminating most the sanding by removing >90% of the excess is what made this work for me.

 

[MarsLander]

He also does CWF followed by filler primer. The only way we are differing is the manner of applying the CWF.

I saw that "fillers results" blog post...that's what I was going to try! Your method looks promising!

 

[Spurkey]

Finally I sanded with *800 grit* around the spirals.

Eight hundred grit!!?! I don't think my razor shaves my face that nicely....

2) *Vigorous* removal of excess filler with the credit card to minimize subsequent sanding.

I can never get CWF to stick well enough to stand up to any sort of vigorous effort, it always flakes out. I'm really starting to believe there's something different about the American CWF. ...I'm sorry that my post sounds so negative, I honestly do appreciate you posting your experiences and your technique. Easily filling thin spirals has been a bugaboo of mine for going on two decades now.

 

[Hobie1dog]

800 grit

 

[Capt. Eric]

I always fill my spirals (using thinned CWF) but I certainly don't enjoy it. For my current build I needed to fill a 22" tube and I decided to see if I could improve my technique to speed things up. My results were... well, fantastic. Thought I'd share. I have no idea if this is what everyone else is already doing, but it doesn't match the pictures or descriptions I've seen posted before.

Start by getting a small glop of CWF on your finger. Spread it messily around (roughly) one rotation of the body tube (quick and dirty is the key). Note that this particular tube seemed to have no secondary spiral, so I only needed to deal with the primary. The black spiral is not indented, or if it is it will be taken care of by filler/primer.
View attachment 625611
Next I used a credit card and squeegeed of the excess. I kept the card perpendicular to the tube, pressed it down pretty hard, and rotated the tube slowly and carefully. After doing a bit wipe the card on a paper towel.
View attachment 625612
After this step there was *very* little excess on the tube, and it dried in barely a minute or two. Continue along the entire tube.
View attachment 625613
Finally I sanded with *800 grit* around the spirals. There was blessedly little to sand and the 800 grit made quick work of it without ruining the surrounding glassine layer. The result:
View attachment 625614
I did the whole 22" tube in about 5-10 minutes (I would have timed it if I had realized it would be so quick), and there was so little sanding it was glorious. As far as I can tell, the spirals are filled just as well as any other time I've done it more laboriously, and there are absolutely no excess CWF bumps.

The two key improvements for me were:
1) Applying the CWF roughly by hand. Very quick and easy.
2) *Vigorous* removal of excess filler with the credit card to minimize subsequent sanding.

I have basically been doing the same thing you're suggesting, but use a putty knife. I have used a few different fillers, but find Minwax wood filler in a tube to be best. Comes out like toothpaste, which is good for the scraping. I also work fast and keep spreading what's on the knife, so get a little more mileage out of it.
Sanding - 800 seems a bit excessive. I'll use 220 to knock off the bulk of it. 320 or 400 to finish up. If you get too smooth before primer, you reduce the surface profile and it doesn't stick quite as well, although on cardboard it won't matter as much.
I also do the spirals before any other paint or body assembly. Much easier to do it before worrying about working around fins or markings.

 

[neil_w]

Sanding - 800 seems a bit excessive. I'll use 220 to knock off the bulk of it.

I squeegeed off so much there was no bulk to knock off. It was barely a few passes with the 800 grit to finish things up.

 

[David Schwantz]

Eight hundred grit!!?! I don't think my razor shaves my face that nicely....

 

[neil_w]

Regarding the sandpaper: I can't emphasize strongly enough how thorough my squeegeeing was, and as a result how little excess CWF there was for me to sand, and how quick it was to just finish off with the 800. I tend to use 800 when I don't want to scuff the surface of paper. I have *never* had a problem with paint adherence. If you want to use a coarser grit that's your call, but I had no need, as long as I have done a good enough job with the squeegee.

When sanding filler-primer, I'll start with 220 to knock off the bulk and then finish with 400. But then I'm not sanding the paper surface. Special care is given to label-papered fins, where 400 grit *will* destroy the surface.

Regarding the CWF: I use Elmer's, and I don't thin it all that much anymore, just thin enough so that I can dip my finger in and a little glob will stick to it. It's not even close to thin enough to brush on. I keep it at the desired consistency in the little plastic tub so it's ready to use, periodically adding a bit more water as it dries out (slower in the little round plastic tub than in those lousy square tubs with the poor-sealing lid). I was waiting to see if it would stay adhered to the grooves when I applied the squeegee, and it did, 100%, as you can see in the final picture I posted.

I have no doubt that different brands of CWF, different consistencies, different tube types, and different phases of the moon might require adjustments to the procedure. I'm just reporting what worked incredibly well for me this time, after having fiddled around with various methods over the years. This was by far the best results I've gotten with the least amount of effort.

 

[MarsLander]

I can never get CWF to stick well enough to stand up to any sort of vigorous effort, it always flakes out.

Do you thin it with water?

 

[Daddyisabar]

The Master Jedi told me it is all in the finer details. Mix the right type of CWF (fine) to the perfect consistency, like thick latex paint. Use tiny amounts with the proper horse hair brush. Only use the finest brushing technique, set and feather, set and feather. Light sand, touch up any gaps, but ther shouldn't be many. Then high fill primer to perfection.

 

[SolarYellow]

When sanding filler-primer, I'll start with 220 to knock off the bulk and then finish with 400. But then I'm not sanding the paper surface. Special care is given to label-papered fins, where 400 grit *will* destroy the surface.

I still haven't label-papered fins, but I block body tubes with 400 grit before filling and priming. I find that any fibers raised out of the glassine by this sand off cleanly when sanding the first layer of primer, which is Krylon Acryli-Quik.

I'm planning to try a somewhat different sequence in the future, so MMMV.

 

[neil_w]

I still haven't label-papered fins, but I block body tubes with 400 grit before filling and priming. I find that any fibers raised out of the glassine by this sand off cleanly when sanding the first layer of primer, which is Krylon Acryli-Quik.

That sounds fine, I just haven’t found that pre-sanding to be necessary. What is the benefit?

 

[mh9162013]

I'm working on some LPR and MPR builds that will require a bit of spiral filling. I will use these as opportunities to try the credit card technique.

Even if this method isn't better at filling spirals with CWF, it will save time and effort on the sanding side, which is always a good thing.

 

[DAllen]

Spiral threads are almost as bad as glue threads lol.

"Hey look at how I filled my spirals!"

"I've been doing this ____ years and have never done that. I use ____ filler primer."

"You use ____ grit sandpaper?"

"I use filler primer but spend just as much time sanding as any other method."

Good times....

 

[mh9162013]

Spiral threads are almost as bad as glue threads lol.

"Hey look at how I filled my spirals!"

"I've been doing this ____ years and have never done that. I use ____ filler primer."

"You use ____ grit sandpaper?"

"I use filler primer but spend just as much time sanding as any other method."

Good times....

I'm not building a rocket at the moment, or flying one. What the hell-else have I gotta do?

 

[SolarYellow]

That sounds fine, I just haven’t found that pre-sanding to be necessary. What is the benefit?

Just knocking down the peaks on the paper before getting started adding material. Not sure there's any real benefit vs. @hcmbanjo's method of CWF seam fill, then filler-primer and sand to a mottled appearance, which is what I plan to try next. My point was just that a few fibers raised out of the tube doesn't seem to be a problem for me so far.

 

[BABAR]

Has anybody ever tried papering body tubes? Yeah, you'd have a seam on one side, and you'd need cutouts for fins and lugs (unless you use buttons.) Only other down side I can think of is you'd sliiiiigggghhhhtly increase the outside diameter, so maybe a little extra drag where the nose cone fits (unless you 3D print your cone and account for the slight difference.)

 

[hcmbanjo]

Just knocking down the peaks on the paper before getting started adding material. Not sure there's any real benefit vs. @hcmbanjo's method of CWF seam fill, then filler-primer and sand to a mottled appearance, which is what I plan to try next. My point was just that a few fibers raised out of the tube doesn't seem to be a problem for me so far.

I don't sand or roughen up the tube before using CWF in the body tube seams.
Apply CWF and sand to surface.
Spray on a fairly thick coat of filler/primer. After sanding the f/p to surface, you might see some roughness from the sanding.
A first white undercoat and light sanding will smooth things out.

 

[hcmbanjo]

He also does CWF followed by filler primer. The only way we are differing is the manner of applying the CWF.

You should use the CWF first. If you used Filler/Primer spray first it would seal the tube and fins.
The CWF wouldn't stick as well after a filler/primer spray and sand.

 

[SolarYellow]

Has anybody ever tried papering body tubes? Yeah, you'd have a seam on one side, and you'd need cutouts for fins and lugs (unless you use buttons.) Only other down side I can think of is you'd sliiiiigggghhhhtly increase the outside diameter, so maybe a little extra drag where the nose cone fits (unless you 3D print your cone and account for the slight difference.)

Yes.

https://modelrocketbuilding.blogspot.com/2013/10/10-building-card-stock-downscale.html

 

[neil_w]

You should use the CWF first. If you used Filler/Primer spray first it would seal the tube and fins.

That is what I do.

However, I don't worry so much about sealing the tube with the filler/primer anymore. It is easy enough to completely remove any trace of it (and most or all of the glassine layer) from the fin root locations with sandpaper afterwards, leaving a nice porous surface for gluing. Sometimes I'll mask the fin root locations beforehand but other times I just don't bother and clean it up with sandpaper afterwards.

 

[DaHabes]

I've never liked CWF, it either got on too thick (even with thinning) or it shrank too much while drying, requiring multiple coats.

I read about this somewhere and tried it. I threw out my almost full CWF container.

This is the absolute BOMB!

https://www.amazon.com/gp/product/B003FWCU1W/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1