How to fill grooves on body tubes?

How to fill grooves on body tubes?

Post by Jeff McClella » Wed, 14 Aug 1996 04:00:00



What is an inexpensive, but effective way to fill in the spiral groves
of body tubes(specifically Phonelic body tubes if it matters)??  Thanks!

 
 
 

How to fill grooves on body tubes?

Post by Phobos99 » Wed, 14 Aug 1996 04:00:00


Automotive spot putty

 
 
 

How to fill grooves on body tubes?

Post by Ed » Wed, 14 Aug 1996 04:00:00


Quote:

> What is an inexpensive, but effective way to fill in the spiral groves
> of body tubes(specifically Phonelic body tubes if it matters)??  Thanks!

Several people have recommended lite-weight spacking compound.  I tried
it and it works great.  No matter what you use, it takes a while to fill
all those spirals.  Didn't know there were so many!  Good luck.

           Ed

 
 
 

How to fill grooves on body tubes?

Post by Wolfram v.Kipars » Thu, 15 Aug 1996 04:00:00



Quote:

> What is an inexpensive, but effective way to fill in the spiral groves
> of body tubes(specifically Phonelic body tubes if it matters)??  Thanks!

The Public Missiles catalog has some tips.  I think they recommend using
something like Elmers Wood Filler.  Automotive spot putty works too.

Wolf

 
 
 

How to fill grooves on body tubes?

Post by Doug Gilmo » Thu, 15 Aug 1996 04:00:00


Quote:
>What is an inexpensive, but effective way to fill in the spiral groves
>of body tubes(specifically Phonelic body tubes if it matters)??
>Thanks!

This subject has been beaten to death in the past.  The consensus is that
Elmer's fill 'n Finish is a very good product to use for this purpose.

With phenolic body tubes, I prefer to fiberglass them, because they tend
to be brittle, and a sharp blow (such as the payload section snapping
back into the main tube after ejection) can crack or break it.  Even
better is Kevlar, if you can deal with it (harder to wet out, hard to cut,
 very difficult to sand).  A good compromise is S-glass.  I realize that
many people are intimidated by the thought of using composite materials
to reinforce their rockets, but it's not difficult at all if you are
willing to learn.  

DOUG GILMORE              
TRA #4666 Level 2

 
 
 

How to fill grooves on body tubes?

Post by Tracy Dung » Fri, 16 Aug 1996 04:00:00



says...

Quote:



>> What is an inexpensive, but effective way to fill in the spiral groves
>> of body tubes(specifically Phonelic body tubes if it matters)??  
Thanks!

>The Public Missiles catalog has some tips.  I think they recommend using
>something like Elmers Wood Filler.  Automotive spot putty works too.

>Wolf

Wood filler fills good but, it's a *** to hand sand. I went back to the
Bondo spot filler 'cause my fingers hurt.
 
 
 

How to fill grooves on body tubes?

Post by Tim Hick » Fri, 16 Aug 1996 04:00:00


Quote:

> This subject has been beaten to death in the past.  The consensus is that
> Elmer's fill 'n Finish is a very good product to use for this purpose.

In my brief rocketry career, tube spirals are my #1 peeve and frustration.
I've read the FAQ and tried almost every method possible on the ten-or-so
rockets I've built.  None of the methods work well, even Fill 'n Finish
(although its not too bad.)  I've tried wood filler, automotive spot putty,
sandable primer (which doesn't wet sand and fills up your sandpaper)  and
other pastes, paints and goos.  The problem is:

1 - the grooves are so shallow that the filler doesn't get a good "grip" and
often falls out upon sanding

2 - the filler and tube "sand" at different rates, leading to sanding the
finish off the tube to the rough stuff underneath (cardboard, that is)

On the last project, I tried four different methods, the last one being
Maxi-cure CA.  That tube was still spiraled when I was done!!!

Next time (hopefully soon) I'm going to start by sanding the finish off the
assembled airframe tube, coat it with finish epoxy, and sand it smooth.
Maybe do two light coats.  I have great hopes that this will kill *all* the
exterior finish glitches.  Has anyone else tried this?  If so, do you have
any tips for working with finish epoxy in this application?

- Tim
NAR#64002

--
======================================================================

 Digital Equipment Corporation, Research Triangle Park, NC
 # cat $FLAMEBAIT >/dev/null 2>&1

 
 
 

How to fill grooves on body tubes?

Post by Dave Coo » Fri, 16 Aug 1996 04:00:00


Quote:


> > This subject has been beaten to death in the past.  The consensus is that
> > Elmer's fill 'n Finish is a very good product to use for this purpose.

> In my brief rocketry career, tube spirals are my #1 peeve and frustration.
> I've read the FAQ and tried almost every method possible on the ten-or-so
> rockets I've built.  None of the methods work well, even Fill 'n Finish
> (although its not too bad.)  I've tried wood filler, automotive spot putty,
> sandable primer (which doesn't wet sand and fills up your sandpaper)  and
> other pastes, paints and goos.  The problem is:

> 1 - the grooves are so shallow that the filler doesn't get a good "grip" and
> often falls out upon sanding

> 2 - the filler and tube "sand" at different rates, leading to sanding the
> finish off the tube to the rough stuff underneath (cardboard, that is)

....

I've used several methods for dealing with body tube spirals that I like
better than anything mentioned in this thread so far.  Some of the
choices:

   Real auto body *primer* (not spot putty) like Ditzler DZ-3 or DZ-7.
Expensive and must be applied with a spray gun, but is sandable in 1/2
hour, can be wet sanded too.  Cannot be sprayed with even the largest
tip airbrush; dries so fast the airbrush clogs instantly.  You can apply
enough in one coat to deal with any normal tube spiral.

   K&B Super Poxy primer.  This is a two-part A/B mix. Dries more slowly
than auto primer (~3 hrs) but has fantastic sanding qualities.
Wet-sandable, can even be polished.  Moderately expensive.  Can be
applied with medium to large tip airbrushes.  As with the auto primer,
you can layer up enough in one application to deal with a tube spiral.

   Hobbypoxy "Stuff".  Dilute with denatured alky to make anything from
a brushable soup to a thick paste for smoothing out fillets.  Relatively
inexpensive but dries slowly.  Two fairly thick coats usually required
to fill a tube spiral.

None of the above have any "grip" problems, and they all sand at about
the right rate.

Many people have reported adequate results with hardware store type
spray-can primers, but I find them to be a little too gummy when dry.
They have the virtue of being really cheap but still useful.  Wood putty
and auto spot putty cure out to be *much* harder than typical tubes, so
save the spot putty for plastic parts, which it's great for.  BTW at
serious auto paint stores you will not only find the DZ-3 but half-pound
tubes of spot putty at about 1/3 the price per ounce of the hobby putty
packages.

-dbc

"death to tube spirals"

 
 
 

How to fill grooves on body tubes?

Post by John H. Cato, Jr » Sat, 17 Aug 1996 04:00:00


Quote:

> What is an inexpensive, but effective way to fill in the spiral groves
> of body tubes(specifically Phonelic body tubes if it matters)??  > Thanks!

Jeff, one thing I've used on phenolic (PML) tubes is the *traditional*
Bondo.  Have heard of this 'spot filler' and think that is something
different.  The 'deal' with regular Bondo is that it sets up REAL hard
and is unworkable after about 3 minutes (from putting in the catalyst).
I used to wait until it hardened and then sanded and sanded.  Then I
discovered a little 'trick' to speed up the process (and lessen the work
*considerably*)...

This stuff will 'set up' in about 3 minutes.  At that point, it's kind
of '***y' - and will progressively harden over the next hour or so.
Let it 'set' for 4 or 5 minutes after intial set and then take a
standard No. 1 X-Acto knife and *scrape* ACROSS the spirals at about a
45 degree angle.  At this stage, the Bondo will usually shave right off
- leaving just the material down in the groove.  Sometimes, you might
'pull' a little out of the groove, but can go back and refill that.

The end result of this is practically ALL of the 'excess' Bondo is
removed before it hardens - so only a little sanding is needed to finish
off the job.  Might need to do a little 'final' filling with something
easier to work with (the Elmer's water-based stuff, etc) - but, in most
cases, a good coat of a high-solids spray primer is all you need (since
I stumbled onto Kilz, I've never used anything else).

The *KEY* in this is 'timing' - you must get that excess Bondo off
before it hardens real hard - or else it's the old sanding block and a
lot of elbow grease.  Like I said, get to this 'shaving' approach within
about 5 minutes after initial set - and the work is considerably
lessened.  Experiment to find the right 'time' to do this.

Hope this helps,

-- john.

 
 
 

How to fill grooves on body tubes?

Post by Robert K Brunn » Sat, 17 Aug 1996 04:00:00



Quote:
>In my brief rocketry career, tube spirals are my #1 peeve and frustration.
>I've read the FAQ and tried almost every method possible on the ten-or-so
>rockets I've built.  None of the methods work well, even Fill 'n Finish
>(although its not too bad.)  I've tried wood filler, automotive spot putty,
>sandable primer (which doesn't wet sand and fills up your sandpaper)  and
>other pastes, paints and goos.  The problem is:

I have used Fill 'n Finish in the past, but on my last rocket, I used
a layer of tissue applied with diluted white glue.  I did this for strength,
but it had the side-effect of covering up the groove on an Estes tube.
The tissue was fairly heavy airplane tissue that the local store sells by
the sheet.  I have experimented with yellow glue, but white glue gives
more working time to get the wrinkles out.  It leaves one straight seam
which needs sanding, but that is easier than the long spiral seam.

Robert Brunner

 
 
 

How to fill grooves on body tubes?

Post by Wolfram v.Kipars » Mon, 19 Aug 1996 04:00:00


Quote:

> I recently got some Bondo spot filler and It's all liquidy and runny.
> Is this how its supposed to be? or did I get the wrong thing?  how do
> you get it to stay put?

The solvent separates from the "goo."  Squeeze the tube all around to mix
the solvent back into the paste.  Don't squeeze too hard, or the tube will
rupture, and you'll have a mess.

Wolf

 
 
 

How to fill grooves on body tubes?

Post by Konrad Hambri » Mon, 19 Aug 1996 04:00:00


Quote:


>> Wood filler fills good but, it's a *** to hand sand. I went back to the
>> Bondo spot filler 'cause my fingers hurt.

>I recently got some Bondo spot filler and It's all liquidy and runny.
>Is this how its supposed to be? or did I get the wrong thing?  how do
>you get it to stay put?

Seth --

Keep sqeezing the tube, nozzle end up, and the solid
goop will eventually come out.  I've seen the same
thing, apparently it's the solvent separating from
the solids.

Still works though, once you get past the runny part ;-)

-- kjh
--
------------------------------------------------------------

310 Third Ave - Suite C21    |  work:   (619) 585 8611     |
Chula Vista, CA  91910       |  home:   (619) 423-4451     |

 
 
 

How to fill grooves on body tubes?

Post by Tim Hick » Tue, 20 Aug 1996 04:00:00


Since the thread has yet to die...

I'm now experimenting with a "fiberglassing" finish resin that I bought
at Home Depot for about $10/quart.  Its not called epoxy, but has
similar properties, gels in 1/2 hour, cures in 24 hours, etc.  One
fluid ounce of resin is mixed with 12 drops hardener, and the
pancake-syrup-like fluid is brushed on with a china bristle brush.  I
did this with an old section of body tube and a spare motor mount tube,
with sections marked for sanded vs. unsanded, and 1 coat vs. 2 coats.  

After curing overnight the stuff looked soft and wet, but I found that
it sanded very easily with 150 grit sandpaper, and didn't load the
paper.  Of the sanded vs. unsanded tube, it seemed to grab very well to
the unsanded side, and the sanded side was a little bumpy (I think the
100 grit sandpaper was too coarse and left small paper "nibs" which
created the bumps.)  Both sides sanded to a very nice smooth surface,
and the tubes are noticably stiffer, though still flexible.  I think
next time I'll sand the tube with 320 grit sandpaper before starting,
as a compromise.

Next step is to see what a second coat looks like.  Although it may be
changing too many variables for a good experiment, I'm going to thin
the resin with a little acetone to make it level a little better, as it
did have high and low spots from brushing.

Anyways, I'll continue this experiment with painting the two tubes to
see what the final results look like, and report here...

"DEATH TO BODY TUBE SPIRALS!"

- Tim

===========================================================
 Tim Hicks: UNIX Systems Consultant & MCSE; NAR # 64002
 Digital Equipment Corporation, Research Triangle Park, NC
 # cat $FLAMEBAIT >/dev/null 2>&1

 
 
 

How to fill grooves on body tubes?

Post by Ted H. Apk » Tue, 20 Aug 1996 04:00:00


Quote:


> > Wood filler fills good but, it's a *** to hand sand. I went back to the
> > Bondo spot filler 'cause my fingers hurt.

> I recently got some Bondo spot filler and It's all liquidy and runny.
> Is this how its supposed to be? or did I get the wrong thing?  how do
> you get it to stay put?

> Seth


Tracy,
        I've had this happen with the last two tubes I purchased.
I used a little trick learned watching "This Old House".  I cap the
tube.  Clamp it in one of the paper gripers of my orbital sander,
turn the sander on and gently squeeze the tube.  About 1 minute of
this mixes the contents very nicely.  They seemed to stay mixed for
well over the month or two it takes me to use up the tube.  Note
that I sand a lot of this stuff off. :-(

Ted

--
Ted H. Apke

Global Wireless Systems

 
 
 

How to fill grooves on body tubes?

Post by Phobos99 » Wed, 21 Aug 1996 04:00:00


Ted,
I always kneaded the tube, never thought of the sander! Thanks for passing
it along!
Thanks, Marty