i recently patched my front fenders on my 66. now i have filler applied to areas needed. how do you know when filler is smooth? i have a couple of light coats of filler and have sanded. it feels pretty smooth, but is there a method to use when doing this to make sure it is smooth? thanks

When I work on any long panel, spread your filler, then use a longboard sanding block sand in an "x" pattern until it all blends good. Run your hands along the panel and feel for dings. after you are satisfied with the feel of it put on a coat of primer. after primer dries mist some black spray paint (or lighter color if using a darker primer) let dry. then block panel again. This gives you a visual guide, if you cut through the primer to quick you have a high spot, if any remnants of the spray paint stays you have low spots, rework, repeat, until panel is arrow straight.
Another note some guys don't like using spray paint, and use a powder you can get at most auto body suppliers, same concept, just you apply the powder instead of misting spray-bomb paint.
I have little body experience, but a friend does it full time and he showed me this trick and it helped me alot. I am doing my own body work on my project.

I hope this helps some and good luck,
Jason

Well, another method to use is to spray some wax and grease remover over the filler. This will give it some shine and you can very easily see if you have any low/high spots.
Be sure to wipe the filler dry and allow it to sit before you sand, topcoat basically do anything to that filler. I would use a water borne cleaner like PPG's DX103, or use what I use the water borne from SPI.
www.southernpolyurethanes.com (http://www.southernpolyurethanes.com) ..Eric

Also something to note, in the link below in my sig I have a album with pictures doing a repair with body filler. Might give you some food for thought

thanks for tips guys. so if i have high spot just sand down? low spot, fill and re-sand? thanks

Be careful with the spraying of wax and grease or any other solvent onto your filler, sevt uses a WATERBORNE wax and grease remover. A solvent based material can and will break down your filler, which can cause failure along with improper adhesion of primers etc. My preferred method is to feel it very well, and 95% of the time I can get it straight just off of feel. Feel is really the only way to tell if it's straight or not. I do like to do the wax and grease remover trick over sanded primer, it will appear as if the panel has clearcoat on it and then you can see what it will look like after paint. When you spray your primer coats on, you can also look at them when they are still wet and it will give you a good indication of how it will look.

thanks for tips guys. so if i have high spot just sand down? low spot, fill and re-sand? thanks

well thats tricky... if you have a low spot close to a high spot, if the low spot is accessable from the back try pushing out on it while bumping the hi spot and it sorta 'rolls' back in place, if its a tiny high spot more like a bump in the metal, just try tapping it down lightly with the pick end of your body hammer.

Jason

A high spot in the filler and a high spot on the body are two different things. If you find a high spot in the filler, yes, just keep sanding until it is flush. Determining whether something is high or low can be tricky. A true, stand alone high spot would be something like a qtr panel where something rattled around in the trunk and put a dent on the inside. When you run a sanding block over that it will quickly cut through and show bare metal. You can most likely dolly that out and if you're good or lucky or both you may not have to use filler.
Most high spots, however, are in conjunction with a low spot. The metal has been stretched. You'll usually find these when you think you're just working on a low spot. Usually you just tap the area with a pick hammer, refill and get after it again.

There are also conditions known as High Crowns which result in a high spot in the metal surrounding a dent. These areas need to be taken care of before doing any filler work by lightly tapping them down so the metal returns to the previous state. If the metal is too stretched, an oil can condition may or may not be the result. Also make sure that you featheredge the filler so that it runs smoothly into the metal. You should not feel a high spot when you run your hand across the repair area crossing from the metal on to the filler. I was using a black laquer based spray bomb fr a guidecoat when I was blocking the Charger, worked just fine.

thanks again guys. the low and highs were just the filler itself. the patch was pretty straight b4 filler. i tried a couple of the sugestions, and it seems to be nice and flat now. i will sand one more time with some finer grit and spray. then see what it looks like. thanks for all the tips.