Backyard Aquaponics
A place to discuss aquaponics

Rob post a video a while back on one way to do this, I have another way so I thought I would explain this as well. First off here's Rob's method which is pretty simple - http://www.youtube.com/watch?v=8PIEsgCJ0fc

But if you don't have a block of wood handy here's what I did to enlarge some messed up bottom drain holes in a barrel -

First I cut out a piece of cardboard and I already had a can of spray adhesive for temporary adhesion, not intended for permanently attaching things (Super 77)



All you need to do is spray the adhesive on the cardboard and stick the cardboard on over the hole until is is firmly attached. It's a little like contact cement in that you may need to hole the cardboard for a while and you may need put some adhesive on the barrel as well.



Once all the pieces are firmly in place drill the hole out with a hole saw but go slowly, if the hole saw grabs it could mess up the center in the cardboard (thicker cardboard is a bit better for this method but it will work with thin stuff if you're careful).



This adhesive cleans up with a damp cloth really easily and the cardboard will pull up easily when your done and can just be pitched.

Here's a couple more pics to finish up -



and the finished hole before cleaning up the cut



One nice thing about this method is the cardboard will bend to follow a curve. I would try to orient your work so you're drilling downward. It's better not to have the weight of the drill pull at the cardboard center hole (hope that makes sense)

Cheers

Ronmaggi told me a novel idea
If you can fit 2 hole saws onto the same drill bit, then put the original one inside the larger one - this will hold the shape of the hole 'plugging' up so it supports the new hole saw on the outside.

Good stuff Scotty

That's a neat idea, might want to put a thin spacer between them to keep from messing the paint job on the holes saws up too much.



Thanks Slowboat