Bondo or Spackling

[Adam Schaible]

Hi guys,

Finishing up my XF410 - everything is glued so I plan on pulling the screws out and running a 1/4" round cut across most of the edges. When I fill the screw holes, should I use Bondo, Spackling, PL Premium, other?

Thanks

[SoundInMotionDJ]

Bondo. Good adherence, easy to sand, takes paint well, stable and lasts a long time.

[Adam Schaible]

Ok thanks man, you've been very helpful.

[pgolde]

I used bondo on some boxes for fill and now the paint peels in those spots. I am not sure if I mixed it wrong or what but the Duratex water based paint doesnt stick so well to the oil based bondo. After some road time with the boxes, this became worse, I have to repaint and use water based fill from now on.

[Harley]

I used bondo on some boxes for fill and now the paint peels in those spots. I am not sure if I mixed it wrong or what but the Duratex water based paint doesnt stick so well to the oil based bondo. After some road time with the boxes, this became worse, I have to repaint and use water based fill from now on.

One of the tricks with bondo ( that is a two part filler ), is to massage the plastic hardener tube well every time before you squeeze out the hardener. The liquid in the hardener tends to separate and so when you squeeze it out, you get a blob of liquid before the solids. I found I had trouble with surface treatment where I had used a mix made with mainly that liquid.

I also use automotive bondo-fill. That gives me the best results. I tried one called Bostik Bog recently, espcially for wood so they say. It was a disaster.

[Rickisan]

Bostik Bog? No wonder it didn't work, horn players don't know anything about spackling or Bondo!!!
http://en.wikipedia.org/wiki/Earl_Bostic

[LelandCrooks]

One of the tricks with bondo ( that is a two part filler ), is to massage the plastic hardener tube well every time before you squeeze out the hardener. The liquid in the hardener tends to separate and so when you squeeze it out, you get a blob of liquid before the solids. I found I had trouble with surface treatment where I had used a mix made with mainly that liquid.

+1

Sand with 60-80 grit, no finer. Prime before applying duratex. I use krylon all purpose flat spray primer

[bgavin]

I remember a comment from Tim, who prefers wood filler to bondo.
I've used both, similar results for quality of fill and sanding.
No experience with paint sticking or not stickng.

+1 on the kneading required for the catalyst tube.

I buy an extra catalyst tube, because the big can of bondo seems to have more bondo than catalyst.
The real advantage to bondo is the fast cure time. Ready to sand in 30 minutes or less, depending upon temperature.
We have no end of temperature here, so cure time is ghastly fast.

[Adam Schaible]

Great! Thanks for the advice.

One quick follow up question...

Should I apply the bondo before rounding the corners or after?

[Harley]

Great! Thanks for the advice.

One quick follow up question...

Should I apply the bondo before rounding the corners or after?

I have found that after is better because sometimes, if you don't manage to get the bondo down into the holes far enough, the router bit can prise the bondo out.

Putting bondo into the screw holes after the rounding is a bit of an art because you can get "slump" and you'll have to go over the hole with bondo again after you sand it. Too much bondo to prevent the slump, and you have too much sanding to do. Like Leland says, nothing finer than 80 grit to sand off bondo.

You can't do any harm by trying before though, the only thing you will loose is a bit of bondo and some time. If you're 100% successful with before, then won't have to learn the black art of filling holes in 1/2 rounded edges.

I've got some Jacks to build this weekend - I'll just might try "before" again myself

[Radian]

Just curious,

Seeing that I can remove all the screws once the PL has cured, why countersink at all and just use pocket-head screws all around?? They clamp really nice without splitting the wood and their heads aren't an issue because I'll be pulling them after the adhesive cures anyhow. Then all I will have left is a bunch of tiny screw holes (and the shallow dips from where the head clamped down) to fill as opposed to the full-on countersinks. Any takers? I was thinking of doing this on a TT I'm building this summer.

-Radian

[Harley]

Seeing that I can remove all the screws once the PL has cured, why countersink at all and just use pocket-head screws all around?? ...Any takers? I was thinking of doing this on a TT I'm building this summer. ...

Well, let's have a think about this.

Rounded heads would be OK provided you don't need to either clamp, sand, line up with a square or have need of a flat surface on which to carry out the next operation.

Rounded heads could get in the way when turning over, easily mark another piece of wood, or your bench or take the skin off your knuckles if you;re not careful.

Countersunks have a larger surface area by means of their cone with with to apply pressure than the round heads have. They apply pressure at a slight angle as well compared to a roundhead, but on flexible ply, I doubt this would be important.

With any screws, you are going to need a pilot hole anyhow to maintain accuracy plus have the top sheet you are screwing through have a better chance of seating against the one you are screwing to.

There are countersunk screws ( SureFix is the brand here ) where the countersink cone has a sharp lump on it so when you screw it in it creates its own countersink. These are never to be used on Gib Board ( drywall ) as they'd screw right through it, but for wood they're ideal. The problem is though that you have to be careful not to screw through at a high torque as the screw just keeps on going. Generally you have a large pilot hole in the top sheet so that the screw threads do not bind and hold that sheet off what you are screwing to.

Having said all that, if you get good at bondo filling, then having countersunk holes shouldn't be too much of a hassle.

[Tom Smit]

Ulp! I dint counter-sink.....just kept driving the screw in till it was moezly in (flush). I did one or two panels per occasion, the next day I'd pull the screws.

TomS