. So here i am ,I've sanded down to the polyester resin and coated entire body with west epoxy. I have used West 405 wood flour mixed with epoxy to fair out all the sunken screw holes(another note to self, do not use lumber yard wood fillers to hide screw holes) and finally, I have built up the area where the sides meet the top with 405 wood filler and epoxy. this has been sanded to a knife edge (square corner) . my question is there a good method to sanding a contour ? I was hoping to keep the radius consistent , any help would be much appreciated. JIM
Teardrops n Tiny Travel Trailersor t n ttt for short (tnttt.com) |
radius edge trick question
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radius edge trick question
by zukamini » Mon May 26, 2008 11:21 pm
Hey guys and gals , I built my tear back in 2003 using tie & tape process and polyester resin. several coats of a high build primer were used to fair out the sides and top and instead of a metal trim strip, I sanded a contour (radius) to the area where the sides meet the top to give it a smooth appearance. however, I was never really happy with the sanding job I did,and I learned that you must seal hi build primer before the top coat goes on or you will be sanding it all off and redoing it again . So here i am ,I've sanded down to the polyester resin and coated entire body with west epoxy. I have used West 405 wood flour mixed with epoxy to fair out all the sunken screw holes(another note to self, do not use lumber yard wood fillers to hide screw holes) and finally, I have built up the area where the sides meet the top with 405 wood filler and epoxy. this has been sanded to a knife edge (square corner) . my question is there a good method to sanding a contour ? I was hoping to keep the radius consistent , any help would be much appreciated. JIM
. So here i am ,I've sanded down to the polyester resin and coated entire body with west epoxy. I have used West 405 wood flour mixed with epoxy to fair out all the sunken screw holes(another note to self, do not use lumber yard wood fillers to hide screw holes) and finally, I have built up the area where the sides meet the top with 405 wood filler and epoxy. this has been sanded to a knife edge (square corner) . my question is there a good method to sanding a contour ? I was hoping to keep the radius consistent , any help would be much appreciated. JIM-
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by angib » Tue May 27, 2008 8:29 am
There must be a router bit that will give the round-over radius you want, but I imagine it would have to be a big router and a big bit.
To do something like the deck edge radius on a yacht (say, 2"-4" radius), we would first trim by hand using a power planer to get something like the right shape and then sand it by hand using a sanding block, checking regularly with a radius template.
One of the two tricks with sanding a rounded edge is in using a long, narrow sanding block that has the sandpaper stuck to it. Doing this job with a power sander won't work - it's just too hard not to take off too much material and create flat spots. Clearly, doing it by hand isn't a 10-minute job, but if you want it right.....
The second and most important trick is to move the sanding block correctly - the block is aligned along the edge and moved diagonally - so not only does it move along the joint, it also rotates around the radius, and that rotation is 100% essential. You cannot get a smooth radius if you try to sand at a constant angle. If you have bad wrists, you need to find someone else to do this job!
If the joint gets to a tight curve, switch to a shorter sanding block but keep the same diagonal, rotating motion.
This job sounds like it requires an impossible level of skill, or hand-eye coordination, to make an exact radius, but it's surprisingly easy to do once you take the plunge. I can do it, so it's neither skilled or hard.....
Andrew
To do something like the deck edge radius on a yacht (say, 2"-4" radius), we would first trim by hand using a power planer to get something like the right shape and then sand it by hand using a sanding block, checking regularly with a radius template.
One of the two tricks with sanding a rounded edge is in using a long, narrow sanding block that has the sandpaper stuck to it. Doing this job with a power sander won't work - it's just too hard not to take off too much material and create flat spots. Clearly, doing it by hand isn't a 10-minute job, but if you want it right.....
The second and most important trick is to move the sanding block correctly - the block is aligned along the edge and moved diagonally - so not only does it move along the joint, it also rotates around the radius, and that rotation is 100% essential. You cannot get a smooth radius if you try to sand at a constant angle. If you have bad wrists, you need to find someone else to do this job!
If the joint gets to a tight curve, switch to a shorter sanding block but keep the same diagonal, rotating motion.
This job sounds like it requires an impossible level of skill, or hand-eye coordination, to make an exact radius, but it's surprisingly easy to do once you take the plunge. I can do it, so it's neither skilled or hard.....
Andrew
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JIM
I get eager to see the finished product and I think thats how I got here (sanding off and redoing) so , please enlighten me on the do's and don'ts. I thought you only had to seal the primer before the top coat was applied. I have been careful not to break thru the epoxy that was applied after the first sand down.