Bondo or filler for spiral grooves

Elsewhere, I started a thread by asking a question if Bondo for car repair was the appropriate "stuff" to use to fill in spiral grooves on a craft paper body tube.
It was pretty clear, pretty quickly that it is not....AND that I had asked my question in the wrong location.

So now that I've moved to a techniques for building forum, let me ask a slightly different question:

What product do you use for filling in spiral grooves in a body tube, AND why do you feel that it is necessary to do so?
Some have suggested Elmer's Carpenter Wood Filler, but I'd like to know what you use, if any, and how large an amount comes in each package vs. cost. Etc.

Thanks in advance.

I've used bindi spot putty just fine. Who said not to use it? I've also used Elmers wood filler which is nicer because it is water soluble and no toxic fumes.

Elmer's CWF. Why? 1) Fills quickly 2) Sands easily 3) Doesn't load the sanding medium. 4) Water clean up. 5) Saves repetitive applications of spray on primer and subsequent removal (prime and sand, etc.) so it's cheaper. 6) Accepts primer and paint well so the finished product looks good. Did I miss anything? I apply a little with a syringe along the seam and then spread it with an old credit card. You can use a spatula or putty knife, but I've found this goes faster this way.

fyrwrxz said:

Elmer's CWF. Why? 1) Fills quickly 2) Sands easily 3) Doesn't load the sanding medium. 4) Water clean up. 5) Saves repetitive applications of spray on primer and subsequent removal (prime and sand, etc.) so it's cheaper. 6) Accepts primer and paint well so the finished product looks good. Did I miss anything? I apply a little with a syringe along the seam and then spread it with an old credit card. You can use a spatula or putty knife, but I've found this goes faster this way.

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+1 on this !

I have tried a few different things but doing it this way or what I've heard called 'peanut buttering the tube' makes for quick sanding without rashing the tube itself.

Sands easy.. i had to push a little harder sanding the spot putty than the Elmer's ..on blue tube is not a big deal but on Estes tube it is very easy to damage. Once a paper tube is rashed it is hard to finish smooth.

I will try the syringe and card..i have diluted it slightly in a cup and spread with a little testors paint brush. I spread it on the spiral and the fantom spiral. Good fit for Estes..slow going on big 3 inch blue tube. Wait 24 hrs and sand flush ..you can really make the dust fly !

Kenny

You want to do my 5.5 blue tube that way?

The Elmer's CWF definitely works.

For my larger rockets, I have started trying to use the lacquer sanding sealer, both inside the tube and outside the tube, the seal/strengthen the tube. To get it inside the tube, I use a home-made ramrod, consisting of a broom handle, and an old sock/washcloth, covered in a large amount of wax paper, to spread it around inside (plus I stand it up in a used, clean, glass jar to catch excess runoff). If somebody has a better idea, let me know.

As mentioned in other posts, the lacquer sanding sealing STINKS of FUMES. I only do it outside, in a well-ventilated area, and then leave it in my garage for a week or two, before bringing it inside. Wearing a filter to guard against fumes would be a good idea.

That's probably another good reason to stick with Elmer's...

Why bother? I have never seen the reasoning for filling. My paint takes care of that. But I am using automotive acrylic enamels in metallics.

I sand the tube before doing anything. Then I apply Filler Primer. Then I repeat until I'm satisfied with the surface.

Then again, I don't build rockets in a linear fashion. Build several at once so there's always something else I can be doing while the paint dries.

If I really want the spiral to disappear, I'll do a FG layup.


Later!

--Coop

wefly2 said:

You want to do my 5.5 blue tube that way?

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Bring it down, buddy! Just did one last night! I've got a full length 3" I just primed if you want to see it before paint.

Anyone able to post a photo of the Elmers? Found some on eBay UK
And want to make sure it's the same stuff.

Pyropetepete said:

Anyone able to post a photo of the Elmers? Found some on eBay UK
And want to make sure it's the same stuff.

Click to expand...

The packaging seems to change often. Here is a recent thread; post number 4 has a picture of the latest U.S. labeled stuff that appears to be the "right stuff".


https://www.rocketryforum.com/showt...s-Wood-Filler&highlight=carpenter+wood+filler

I've never liked the texture of the original CWF bought back in the day and which still sits on my rocket workbench. Too gritty. IIRC, the texture is caused by a mixture of wood dust, small glass spheres, and water/liquid.

By the way, when sanding body tubes it's probably best to sand diagonally across the tube to prevent flat spots. Random orbit palm sanders will most likely work if the body tube is large in diameter and strong enough to stand up to the weight of the tool. Can't say as I've ever used a palm sander for anything other than smoothing plywood fins, tho, so take that with a grain of salt.

samb said:

The packaging seems to change often. Here is a recent thread; post number 4 has a picture of the latest U.S. labeled stuff that appears to be the "right stuff".


https://www.rocketryforum.com/showt...s-Wood-Filler&highlight=carpenter+wood+filler

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https://pages.ebay.com/link/?nav=item.view&alt=web&id=131029035330

Pyropetepete said:

https://pages.ebay.com/link/?nav=item.view&alt=web&id=131029035330

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That looks like a winner Pyro.

^ That's it!

https://pages.ebay.com/link/?nav=item.view&alt=web&id=121539202430

Bigger one nearly 1kg for a tenner. Think I'll get this one ordered.

So what's the process for using it.

I've 3x 4" blue tubes needing some filling

https://www.amazon.com/dp/B00GQ1X1MQ/?tag=skimlinks_replacement-20

this stuff works great and hardens in about 5 minutes.

So it's just arrived at last. Only taken 2 weeks. Most of come direct from the USA.

What's the method for using this to fill spirals then?

Pyropetepete said:

View attachment 263822

So it's just arrived at last. Only taken 2 weeks. Most of come direct from the USA.

What's the method for using this to fill spirals then?

Click to expand...

Pete-down and dirty method for applying the filler. Thin your batch with a touch of water, to reduce the consistency to a little like catsup or mustard. Use a sandwich bag or any other cellophane type bag and put about three teaspoons' worth (more for bigger tubes), remove as much air as possible, seal and then twist to force the filler into a corner. Act like you are making an icing bag for a cake. Snip a (very) small corner off and apply it for about a 1/2 a meter along the spiral gap, then squeegee it with an old credit card or similar. It takes a little practice, but fills the spirals quickly with minimum waste. Note this will thicken up a bit as its moved about and the moisture is absorbed by the tube. Don't try to do this all in one go. You don't cover the entire tube with it this way and saves sanding time. 220 grit seems to work for the most part-you can go back for a final sand with something finer (I use 400) before hitting it with spray primer. I hit it with 400 (you can go nuts and polish it out if you want) and then colour coat(s). Hope this helps. Straight smoke and good chutes, brother!

Haven't bothered with any type of body tube or Balsa filler in more then 20years. Just use filler primer or better cheapest auto sandable primer you can find.

Spray 3 wet coats allowing about 1-5 minutes between coats. Let dry overnight. sand with 240grit, if you reach body tube and still have seam lines or balsa grain, repeat with another 3 wet coats. Let dry overnight. Sand with 240grit. when all grain or seamlines are gone switch to 320, or 400grit sandpaper to smooth before applying first base color coat. Makes for Babies butt smooth finishes with very little expense other then a can or two of Cheapy Primer and some small pieces of sandpaper.

I use Red Devil lightweight spackle. Works fantastic.

It does work but be careful of brand - some sand easier than others.

I have used both , and both tick me off .

Filler, mwah...
Sand the tube down so the glasline is spotty at best.
Give it 3 coats of titebond, letting each coat dry.
Sand until smooth.
No spirals, stronger tube, less primer required.
Helps in sticking surface mounted fins too.

Woody's Workshop said:

Filler, mwah...
Sand the tube down so the glasline is spotty at best.
Give it 3 coats of titebond, letting each coat dry.
Sand until smooth.
No spirals, stronger tube, less primer required.
Helps in sticking surface mounted fins too.

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You mean sanding the glassine, yes, not sticking fins to the primer... (wouldn't want someone to misinterpret your post).


Later!

--Coop

Coop said:

You mean sanding the glassine, yes, not sticking fins to the primer... (wouldn't want someone to misinterpret your post).


Later!

--Coop

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Yea, stick the fins to the coated BT, NOT after priming it.
Can't imagine anyone trying that though.
But who can tell.

Titebond wood glue? With a brush?

ascastil said:

Titebond wood glue? With a brush?

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Yes, a brush.