hugger-4641

My Feedback: (6)

Ok, so I've searched a few threads and haven't found what I'm looking for. I'm curious about what sanding methods some of you use to get a smooth transition onto balsa from a filled surface. I'm in the middle of covering a kit I just built and had some dents in the leading edge balsa and some of the top sheeting on the wing. I filled these with micro-balloons mixed with 30min epoxy and got a really good result... Except for the edges around some of the micro-balloon filled areas. Here, the sand paper wanted to dish out the balsa instead of feathering out the epoxy. I went all the way down to 400grit, and was still getting into the balsa more than I was smoothing the edge of the epoxy.
I ended up using thick CA and a small paint brush to fix these areas and finish with the 400grit. I had to repeat this a couple times in some areas. I got the result I wanted in the end, but I'm curious what some of you fellas do in this situation. Finishing resin? Balsa filler? Just curious what you get best results with?

dbacque

My Feedback: (3)

Cover the balsa with masking tape while you sand the microballoon mix. Sand down until you are wearing away the masking tape. Replace the tape and do it again. Sand with fresh sandpaper and very light strokes. Of course use a flat sanding block to prevent gouging.

When you can't sand without eating the tape, remove it and using absolutely new sandpaper and the lightest strokes you can, sand down to the balsa. Be careful of the angle of the sanding block/bar. It will never be perfect but this will help make it close.

Once it is close and you now have a few nicks in the balsa, apply a lightweight balsa filler around there and again use sharp paper and very light sanding strokes.

Of course, always use the most microballoons you can possibly get the epoxy to take. More microballoons = easier sanding.

Dave

hugger-4641

My Feedback: (6)

Thanks for the tip Dave, I will try the tape idea.

JCOKEEFE

My Feedback: (2)

Balsa filler works for me 99.9% of the time.

grosbeak

Likewise.

carlgrover

Go to Lowes and get some lightweight spackling compound for filling in dings and dents. It dries quickly and is easy to sand. You will also need some sanding blocks. Lowes should have several different types. I've got a big rubber sanding block that fits my hand well and holds a piece of sandpaper using nails on each end. Sandpaper doesn't work too good to level everything out if it is only folded over and held in your hand. Most hobby shops also carry "T" shaped aluminum extrusions that work well too. Get several of them and you can glue the sandpaper on with 3M spray 77 adhesive.


Carl

CafeenMan

The first thing you should do to remove dents is get a Q-tip wet or a paper towel if the dent is bigger. Wring it out - you don't want it dripping wet.

Place it over the dent and press down. Look every few seconds to see if the dent is wet.

Take a hot covering iron to it and almost all dents will swell out with no further filling necessary. Just a light sanding.

If you want to use microballoons, mix it with model airplane glue instead (the stinky tube glue). Lightweight filler or spackle is a better idea though.

raptureboy

+1 this is what I do first and then filler if needed. I like the vinyl wood filler made my elmers thinned out a little it sands easily.

SushiHunter

Not sure what type of wing is in question here, but be careful if it's a foam core wing your working on trying to remove dents from the balsa skins on that type of wing. If the foam core gets too hot, and it really doesn't take all that much, the foam will melt and create much more serious issues besides some dents in the outer balsa skin.

RAGII

I "collect" all of the dust / wood particles that are created from cutting sanding other parts. I then mix it with a little wood glue to make my own filler. This sands fairly easy and has worked well for me, plus I do not need to buy anything extra for the repairs.

bigtim

My Feedback: (13)

this is one of the best fillers I have ever used for filling dents and even fairings before glassing with cloth, or using plastic film, I do add a tiny bit of water to mine so that its a little more creamy but it works well right out of the can as well.
for getting small dents out of balsa I also use a 50/50 water and denatured alcohol mix in a spray bottle, a light mist on larger areas and a small brush dipped into the fluid and spot applied to each area and the dents will swell out, the alcohol helps dry off the water quicker and won't affect the wood, after it drys a light sanding to smooth any raised grain and some wood filler or light weight spackle does the trick.