Type of sandpaper for fiberglass?

Type of sandpaper for fiberglass?

Post by George Bal » Mon, 05 Oct 1998 04:00:00



What is the best type of sandpaper to use when sanding glassed body
tubes?    Besides the obvious differences in grits, what about the types
of sandpaper?  i.e. aluminum oxide, emery cloth, etc..   Which ones
won't "load up" as quickly?

Also, do you use a sanding block, or just your hands?

Thanks!
George
NAR 72878 level 2  LEUP

 
 
 

Type of sandpaper for fiberglass?

Post by David Theden » Tue, 06 Oct 1998 04:00:00


Quote:

> What is the best type of sandpaper to use when sanding glassed body
> tubes?    Besides the obvious differences in grits, what about the types
> of sandpaper?  i.e. aluminum oxide, emery cloth, etc..   Which ones
> won't "load up" as quickly?

> Also, do you use a sanding block, or just your hands?

Whoa, Jim.

Use your hands?.  Yeah, I do, on top of a Makita palm sander.  And even
then I have spent hours sanding some projects.  My nominal work involved
on a 5.5 or 7.5 diam tube involves a layer of 6oz glass.  Light sanding
just to get the bumps off.  Then a layer of 3oz cloth, again light
sanding.  Then fill and finish and sand that stuff to eliminate any
imperfections.  Then a layer of 1.5 oz cloth and I figure I sand half of
that layer away to get a "glass" smooth finish.  The way I sand is to
drop the tailgate on the truck and place the tube on the tailgate.  Use
a good dust mask and sand away with the Makita.  Just a back and forth
movement along the length of the tube.  You will not get any flat spots
if you keep moving.  I just sweep up the dust into the trash.  Keeps my
work room a little cleaner, and besides, the truck is just a truck, it's
not a rocket  :)

As for material, I don't know.  I just use the contractor packs of
80,100,220 grit paper at Home Depot.  The key is to make sure that the
epoxy has cured.  That may take a week.  no kidding.  I usually glass
one weekend and sand the next.  This will help reduce the load up.  But
when sanding the final layer it is not uncommon to use up a page and a
half of sandpaper.  The Makita is nice because you just split the page
up into 4 quarters.  I have tried a 1/2 page sander but it is just
harder to use.

In the winter (Idaho's winter is mild) I will have to glass the airframe
and after a few days I'll have to bring it into the house to get a good
cure and sometimes I'll wait two weeks before sanding.

dave
--
TRA #5145      NAR  #69923      LEUP
Level 2        Level 0

 
 
 

Type of sandpaper for fiberglass?

Post by Jimbo Fran » Tue, 06 Oct 1998 04:00:00


Quote:

>My nominal work involved
> on a 5.5 or 7.5 diam tube involves a layer of 6oz glass.  Light sanding
> just to get the bumps off.  Then a layer of 3oz cloth, again light
> sanding.  Then fill and finish and sand that stuff to eliminate any
> imperfections.  Then a layer of 1.5 oz cloth and I figure I sand half of
> that layer away to get a "glass" smooth finish.  

-- Life will be easier and bonds better if you use a peel-ply between
layers instead of sanding. A light sanding will give a poor bond, all of
the thin wax that allows the epoxy to achieve a full cure (even down in
the dips) must be removed (or use a laminating epoxy without the wax).
Never fill between laminations. Also, never sand into the glass, only
the epoxy. Butter the last lamination, after removing the peel-ply, with
micro-ballooned epoxy, and only sand through that.

Lighter, stronger, faster, less sanding.

--Jimbo Franz--

www.USRockets.com

Perspective is everything

 
 
 

Type of sandpaper for fiberglass?

Post by Andy Schecte » Tue, 06 Oct 1998 04:00:00




Quote:
> -- Life will be easier and bonds better if you use a peel-ply between
> layers instead of sanding.

What's a peel-ply?
--

-Andy Schecter

 
 
 

Type of sandpaper for fiberglass?

Post by Gang » Wed, 14 Oct 1998 04:00:00


use wet/dry paper "wet"
and keep it that way for the best results,
on body tubes just sand it like polishing a shoe!