Is there any reason I shouldn't use an orbital sander to prep my fairings/gas tank for paint as opposed to hand sanding or using a block

 

i did my lower fairing with an orbital sander to start with, much quicker than hand sanding but use with caution because the grit from the paper when it clogs breaks loose and collects together and scratches the surface badlly requiring much more sanding to remove, So if you do use, use a quality paper (i didnt) change the paper often, use light pressure and stop if you feel its not gliding over the surface nicely.

 

when u say orbital do you mean a dual action? if it just spins in a circle id say no. you will have to do some hand sanding after you use the da anyway.

 

Nah, just a sander that spins in circles. Based on both of your comments I'm just going to hand sand it.

Thanks for the input!

oh and, this is what made me interested in doing it.
(yes I know that isn't an orbital sander)

 

That video is using a random orbital (spins in lots of tiny circles), but the guy is rough as guts and appears to be using a fairly low grit paper... I'm currently sanding my f3 fairings with a similar sander, but using a fairly high grit (meaning fine grade) paper - it takes a lot longer than this video, but gives silky smooth results, requiring only hand sanding for the finer detail areas, and finishing

 

Oh really. I thought those sanders just vibrated LoL.

 

no a Dual action sander spins and orbits producing a random pattern on the sanded surface. it speeds up the process of knocking down large areas . im not a body man but have played with it quite a bit if your using a body filler ud probably start with 80 and than switch to 150 da and than hand sand it. If you are going to use body filler make sure to get a large enough surface area and keep applying in larger THIN layers as you go. its highly unlikely that your first coat will be your finally coat. if any one else would care to explain this process better than i have feel free. if your just paint prepping you dont need a crazy aggressive grit either you just need it rough enough for the paint to adhere.

 

80 grit

i used 220 on mine with a sander and that was good to get the paint off, if your doing a real paint job and not a spray bomb i would recommend following up the initial sanding with a 1000 grit wet sand after primer.