How long should you let Bondo set before you start sanding it?

[Jdurg]

Just curious as I've never worked with Bondo before.  I've begun cutting the angled side pieces for my Control Panel and saw that there was a gap of about 1/6" on the outside of the right front angled piece.  I thought it was too much of a gap for the wood-putty I have to fill, so I decided to pick up some Bondo.

The Home Depot near me didn't have the regular "pink-stuff" Bondo, but they did have a version called "Bondo-Glass".  It was $14.00 for a quart, but the package said it could be used for wood repair if one wanted to.  I took a little bit of the purple/black "goop" from in the can and put it on a wax-paper covered piece of cardboard.  I then mixed in a very tiny bit of the red hardener to it and started mixing.  When it started getting a bit thicker, I went and smeared it into the gap and then around the gap area.  It appears to have settled quite nicely, but I want to make sure I let it cure long enough before sanding it. 

While at HD, I also picked up a 12-amp Circular Saw for only $30.00 (Nice sale) and a random orbital sander to sand the CP exterior prior to priming it and painting it.  I also learned that Bondo gives off a TON of NASTY fumes when it's mixed and curing.  I've got some good ventilation, but there's still that chemical odor in the air throughout my house.  Ah well.  This is a fiberglass based Bondo so it will cure quite strongly and will do a great job in filling this small gap.  I just need to know how long I should wait before I break the sander out and start smoothing the exterior.   

(Chances are I won't get a chance to work on it again tomorrow, so I'll probably get to the sanding next weekend.)

[Jdurg]

Well, in case anybody wants to know, you only need to wait a few hours before the Bondo is rock hard and can be worked with.  (Though I'm sure that it was workable even before then).  I sanded the Bondo smooth and (in addition to now loving my Random Orbital Sander with Vacuum attachment) this stuff is AWESOME!  The Bondo-Glass variety is a fiberglass impregnated version of Bondo and this stuff is like glass when it's sanded.  If it wasn't so expensive, I'd coat my entire cabinet with this stuff.  That's how great this stuff is.

I now have 6 of the 8 sides of my CP attached to the bottom panel.  Tomorrow I'll cut the final two pieces, miter them so they fit, Bondo any gaps that will surely result, then admire my work.

Thus far, I'm already starting to wonder if the CP is too "thick".  It's about 6.5" high in the front and about 7.5" high in the back.  I'm wondering if I'd be able to cut an inch off the front and back (using my new circular saw) and still leave enough room for the innards to sit.  Or, I could just leave it be and be able to store a keyboard in there in case I need to use a keyboard.............

[pcb]

I've used bondo quite a bit.  Generally, in a matter if a few minutes it will start to harden and get rubbery.  At that point, you can carve it up with a utility knife, a hand planer or a bondo rasp.  Just make sure you leave enough to do a final sanding, usually within 10 to 15 minutes you can start sanding it.

Best,

 - Mike -

[Jdurg]

Yeah, I'm really loving this Bondo stuff.  My ability to make perfect miter cuts is still very primitive at this point, so the Bondo does a great job of filling in the gaps.  In addition, since this is my first experience with woodworking, I probably should not have made a complex design such as a sloped panel with angled outcroppings on each side.  (It's kind of football shaped, but with flat ends, not pointed).  So it was difficult for me to cut the side and angled side pieces and have them all be the proper height.  They looked the right height to me, but when I put the top on the P1 side had a pretty big (~1-2mm gap) between the top of the side pieces and the CP Top.  I went and took some wax paper and put it on top of some spare plywood I had.  I then clamped/tacked the plywood to the CP sides to create a mold for the Bondo.  I put a good bit of Bondo in there so that I'd have more than I needed, and let it harden.

Once it hardened, I took out my sander and sanded it down to the level I needed it at.  (I went and took some masking tape as a guide to where I needed to sand down to).  Once sanded, I removed the tape and test fit the CP top again.  PERFECT fit.  Plus, this Bondo-Glass is reinforced with fiberglass so the repair is incredibly strong. 

I will say that the fumes from this Bondo is pretty damned potent.  I have worked with some stuff that emits noxious fumes plenty of times in my life, but this time it really got to me.  I was light-headed for a good while and learned NEVER to work with Bondo unless it's outside.  When I got done, I made myself a mixed drink, and suffice it to say, my cabinet build for the day is done.