A little trick for filling tube grooves

A little trick for filling tube grooves

Post by red.. » Thu, 01 Jun 1995 04:00:00



In some recent email side-conversations, I've mentioned a little
trick I use while finishing body tubes, and several folks have said
they thought it was useful, so I thought I'd post it to the full
group.

Problem: You fill small defects (esp: spiral grooves) in a body tube,
 prime it, sand it, reprime it, resand it. It looks great. Then you
 shoot your gloss finish coat and -- Yuk! -- several of those pesky
 little spots pop back into view.

Solution: The problem is that the flat surface of the primer makes
 the imperfections very hard to see. To fix this, buff the primer
 with fine (#0000) steel wool. This gives the whole surface a modest
 shine, even down inside the grooves, etc. Now sand with fine (e.g.
 400 grit) sandpaper. The sandpaper is not flexible enough to get
 down into the imperfections, so they remain shiny (and therefore
 visible) until you have really sanded them completely smooth.

I've been using this little trick for a while now, and it really
does make tube grooves disappear reliably and completely. Maybe it's
a known technique, but I haven't seen it described anywhere, so I
thought I'd pass it along.

Remember to wear a dust mask when using the fine steel wool, since
it fills the air with "steel lint".

Dave Redell

 
 
 

A little trick for filling tube grooves

Post by kaplo.. » Tue, 06 Jun 1995 04:00:00


Unfortunately, I've encountered another spiral problem. I've filled and
sanded and primed and painted, and had a "perfect" finish when done. Fly it

are back. Why? Stuff continues shrinking for a while. I've actually had more
problems not with the spiral gap that you fill, but the gap under the
glassine wrap. As things age and shrink that seam now starts showing.

Other than giving up and covering everything with a fiberglass/epoxy finish,
any ideas on how to prevent the 6-month spirals?


USPO:   HealthCare COMPARE Corp, 5ISD, 3200 Highland Av. Downers Grove, IL 60515
TPC:    (708) 241-7919 x5327            ICBM:   4149'48" North 880'51" West

"The first thing we do, let's kill all the lawyers internet postings"
                                        W. Shakespeare, 1995

Disclaimer: If this message is caught or killed, the secretary will disavow
any knowledge of my actions. These bits will self destruct in 5 seconds....

 
 
 

A little trick for filling tube grooves

Post by Mark Pred » Wed, 07 Jun 1995 04:00:00


Quote:

>Unfortunately, I've encountered another spiral problem. I've filled and
>sanded and primed and painted, and had a "perfect" finish when done. Fly it

>are back. Why? Stuff continues shrinking for a while. I've actually had more
>problems not with the spiral gap that you fill, but the gap under the
>glassine wrap. As things age and shrink that seam now starts showing.
>Other than giving up and covering everything with a fiberglass/epoxy finish,
>any ideas on how to prevent the 6-month spirals?

Lipo-suction?
;)
........................................................

Department of Physics, OSU, Corvallis, Oregon 97331  USA
........................................................
 
 
 

A little trick for filling tube grooves

Post by Rob Maste » Thu, 08 Jun 1995 04:00:00


Quote:

>Unfortunately, I've encountered another spiral problem. I've filled and
>sanded and primed and painted, and had a "perfect" finish when done. Fly it

>are back. Why? Stuff continues shrinking for a while. I've actually had more
>problems not with the spiral gap that you fill, but the gap under the
>glassine wrap. As things age and shrink that seam now starts showing.
>Other than giving up and covering everything with a fiberglass/epoxy finish,
>any ideas on how to prevent the 6-month spirals?

Howabout "curing" the tubes before use...bake them in an oven for about
six hours at 70C should do the trick. Of course this is completely untested.

-Rob

--

Then someone said to me "It's fabulous you're still around today, you've both
made such a little go a very long way". - Pet Shop Boys

 
 
 

A little trick for filling tube grooves

Post by MJewett9 » Thu, 08 Jun 1995 04:00:00


Use bondo ding filler. It comes in a toothpaste tube. I've never had the
spirals come back.

David j

 
 
 

A little trick for filling tube grooves

Post by C. D. Tavar » Thu, 08 Jun 1995 04:00:00


Quote:

> Unfortunately, I've encountered another spiral problem. I've filled and
> sanded and primed and painted, and had a "perfect" finish when done. Fly it

> are back. Why? Stuff continues shrinking for a while.

Let it dry for a year or two.  That's what I do.  All the guys in the club
laugh at me and say I don't build rockets, but see? there's a real reason.
--


                              write today for my special Investors' Packet...

 
 
 

A little trick for filling tube grooves

Post by jimmie ray jr mayfie » Sat, 10 Jun 1995 04:00:00


Amen.  Though I've never used bondo to fill grooves, I have used it in
nearly every other aspect of construction.  Keep in mind that there are
several types of auto-repair filler.  Each has it's uses outside auto
body work :)

I use "Super Red Putty" as a wood filler.  It comes in a medium-sized tube
which is enough for dozens of rockets.  It sands extremely easily and
smoothly (the results of using 400+ grit sandpaper are fantastic).  Use
with plenty of ventilation or you'll fly higher than your rocket ;)  Also,
sanding tends to be messy.  And, since this stuff is "intended" to be used
to fill small dings you notice after the primer coat on an auto, it's
not terribly strong or hard.

There exist other types of bondo/filler that require the mixing of a hardener
and the putty itself.  This is heavier-duty stuff and can even be used to patch
drywall :).  It's harder and doesn't sand as easily but can be useful where
strength is needed.  Be warned that it is heavy and is not very flexible.

Jimmie

--
Jimmie Mayfield                  University of Kentucky


 
 
 

A little trick for filling tube grooves

Post by Lee Re » Sun, 11 Jun 1995 04:00:00


: Use bondo ding filler. It comes in a toothpaste tube. I've never had the
: spirals come back.

: David j

No wonder my teeth are so orange.  :)

Seriously, though, I've used Bondo for several years, and the stuff
sands easily, and I've never had it lift out, or shrink.  You can
get it at Kmart in the automotive section.

--
     /\  /\      Lee Reep                 TRIPOLI ROCKY MOUNTAINS
    /~~\/~~\ /\   Fort Collins, Colorado                 TRA 2007

 
 
 

A little trick for filling tube grooves

Post by Lee Re » Tue, 13 Jun 1995 04:00:00


: Use bondo ding filler. It comes in a toothpaste tube. I've never had the
: spirals come back.

Just as a follow up clarifier, since so many different Bondo
products exist -- I use Bondo Spot Glazing Putty, which is
similar to Squadron Putty sold in hobby stores in its application,
but a whole lot cheaper.
--
     /\  /\      Lee Reep                 TRIPOLI ROCKY MOUNTAINS
    /~~\/~~\ /\   Fort Collins, Colorado                 TRA 2007