I am STILL fighting with the filler...
I decided to fill the hole where my sunroof used to be...
I have got to the stage where its "close"...but there are still flat spots and dips in etc...I know they are there...but I cant easily see
them...
What is the known trick for ensuring the filler is all nice and even?....The roof curves in both directions so the filler is not "flat"....
But there must be a fairly simple way of making sure there are no flatspots/dips..
Anyone got any advice?....If I have to refill the thing and start sanding all over again I might despare!
I thought the normal thing was to spray on some black paint or something like that then give it a good overall sanding. Anything which stays black is a low point....
Daft question - is the roof the same shape, just before the hole?
if it is, why not get a bit of wood large enough to cover the roof, then get something that is big enough to go touch the roof at the outside edge and
still have a little on the wood (guide). Then use the guide to mark the shape of the roof on the large piece of wood. Cut this out and you've got
a guide for going over the food looking for low / high spots.
To help spot them, put a light behind the wood guide, where you see light, you've got a gap.
NEver done this myself, sitting in the house seems to cover what you want.
As BenB said, a light coat of paint - just enough to tint the surface - will help you spot the high and low spots. Paint, sand repeat until happy,
As above and use a long 18" X 3" sanding block and work at a 45 degree angles toward the centre. may take several tries to get it right, leave the power tools on the bench.
As above, but you will have to reapply filler several times
filler
guide coat
long board
filler
guide coat
long board
filler
guide coat
long board
etc.
In a bit more detail, once you have the guide coat on and as you sand (from multiple angles), keep squinting down the panel from various angles and
you will see the curve coming right. Then when low dips appear, the guide coat will show eactly where they are. You don't have to sand all the
guide coat off each time, just stop then and apply more filler where the guide coat shows it has to be.
What I also finds helps, if you have worked off a lot of filler, and have just a few low spots showing. Before applying filler again, put a fresh
guide coat on and do a few more passes with the long board, with a light touch. This brings up the full extent of the low spots
It gets to a stage where running your hand over the shape you can feel the dips better than looking for them.
Cheers
Fred w b
[Edited on 29/10/08 by Fred W B]
[Edited on 29/10/08 by Fred W B]
Ive seen a sanding board being used before that can be flexed into the shape of the surrounding metal. Cant remember what you call them though.
I had the same problem with the roof of my P100 it was full of dents Filling and sanding was a nightmare as the roof flexed as you sanded. I made a
long bed sander from a 50mm wide, 10mm thick flexible piece of wood about 18 inches long and screwed 2 bits of wood at either end for handles then
stuck a few sticky back sanding discs along its length and away you go.
When it felt roughly to shape I lightly sanded with 400's wet and dry and sprayed a guide coat as above.
Cheers,
Bob
Just found this that might help http://www.jefflilly.com/Fabrication/Fabrication-F/block-sanding/index.html
[Edited on 29/10/08 by splitrivet]
I've tried the long board technique (& saw it in action on Overhaulin) but it didn't work for me on my MGB Sebring. I had more luck using a 4 x 6 x 3/4" block of wood blackened with a black marker pen. The low spots stayed white which I filled & the high were obviously very easy to sand out.