Obtaining a smooth rocker curve

charlese · Post by **charlese** » Wed Dec 12, 2007 8:24 pm

Although I have never made rockers- Why can't you use the "Drum Sander/Shaper Fence Kit" 555144. Just set the split fence far enough apart and the drum sander to just take off the high spots and then move the rockers by the drum while bearing on the two fences. This way you will have a bearing (rubbing) surface that will not allow you to sand into the curvature of the arc.

reible · Post by **reible** » Wed Dec 12, 2007 9:55 pm

If these parts are done on a router table or OPR and they are done right (the grain direction is going to be wrong for parts of the cut and you will have to use some special tricks to solve that). You will need only do a light hand sanding. That's the story that's the glory of routing.

The other method I mentioned of pattern sanding is really the only way to make the edges flow if cut on a bandsaw or scroll saw... of course the better the pattern the better the finished product.

If these things are not in your bag of tricks as a wood worker they sure should be. Dig out the bible of shopsmith and do a little looking around, a lot of good stuff in the book. And by all means make jigs to do things.

Ed

a1gutterman · Post by **a1gutterman** » Thu Dec 13, 2007 12:38 am

I have a rocker that is built for a child, and in fact, it was given to me by my grandfather when I was a child, about 45 yrs ago. I just went and looked at that chair. The grain on the rockers on that chair follow the shape of the rocker which leads me to believe they were bent. Maybe that art has gone by the wayside, but bending a board that is wide enough for two rockers but otherwise already cut to the shape wanted (except the curve of course) and then, after being bent, is split into two equal pieces seems a good way to create rockers that need no machining to shape them and have an equal curve to both pieces.

I bought my wife a rocker close to thirty years ago. Looking at it today, the grain is such that the rockers must have been cut, not bent. About 10 years ago, I had to repair one of the rockers on my wife's chair. I had rocked a little too far back and the rocker broke right at the rear leg. It broke off with the grain which went diagonally across the point the leg entered it, allowing me to glue, clamp and screw it back together. It has not failed since, but I have never had to repair the rockers on the childs chair which has gone through me and my four children and is currently waiting for grandchildren.

charlese · Post by **charlese** » Thu Dec 13, 2007 1:55 am

Hi robg! - If you get concerned about grain and breakage, or none of the above suggestions work for you - you could always cut out some thin strips and laminate them on the desired curve. That way you shouldn't have a sanding problem.

Greenvilleguy · Post by **Greenvilleguy** » Thu Dec 13, 2007 2:02 pm

OK, I couldn't resist. Here are some pictures a rocking horse I made several years ago (I actually made two). They are from plans from Wood magazine.

To the issues:

Sanding smooth - I just finished a doll cradle with rockers. As has already been mentioned, I just sanded then to a line using the disk sander and then smoothed it all out on the bottom of the belt sander.

Grain direction - The rockers on the rocking horse in the picture are actually glued up from two 5/8" thick blanks. One of the blanks was two pieces glued together in sort of a "V" with the grain at an angle and the other blank was actually three pieces glued together with the grain parallel to floor. Three pieces were used to reduce the width needed to accommodate the arc.

I know this sounds complicated, but what it did was have each rocker constructed from blanks with dissimilar grain direction thus making the rockers much stronger. Some far, six grandchildren and ridden them hard and they've held up well.

I can't resist pointing out my mistake as well. You may notice the lighter dot on the rear leg. I carefully matched grain on the plugs covering screw heads, but somehow got a maple one in this spot instead of cherry.

charlese · Post by **charlese** » Thu Dec 13, 2007 2:08 pm

Beautiful Horse and RIDER! Very nice photos too!

john · Post by **john** » Thu Dec 13, 2007 5:46 pm

The SS plans require that three 2" long dowels, spaced about 1 1/2" apart, be put in near each end of the rockers. I think this is to solve the problem of the rockers splitting along the grain.

John

foxtrapper · Post by **foxtrapper** » Tue Dec 18, 2007 9:50 am

Wouldn't a pivot point out several feet from the bandsaw work well at creating a uniform and smooth arc for the rockers? It certainly works on many other projects involving a large uniform arc.

robg · Post by **robg** » Tue Dec 18, 2007 2:09 pm

Foxtrapper, I am sure I used the wrong blade or didn't adjust something properly (or made some other beginner error), but the band saw was not dependable to make a 90 degree cut, much less a smooth curve in 8/4 oak. I will try a bigger blade next time, but I couldn't depend on the band saw for the curve.

I made a pattern based on the outline of the rails I have, but reduced slightly and smoothed out. Tonight, I will attempt to use this pattern with the router and hopefully end up with near identical and decently curved rockers. The pattern rocks great (but has a flaw I am not happy with on the top, so I will probably remake the jig instead of using it tonight, but we will see).

I hope the pins in the plan will prevent the rockers from splitting, but I am going to attach them only with screws in case they do break. Then I will get another opportunity to improve my design and technique. hah.

Ed in Tampa · Post by **Ed in Tampa** » Wed Dec 19, 2007 12:15 am

robg wrote:Foxtrapper, I am sure I used the wrong blade or didn't adjust something properly (or made some other beginner error), but the band saw was not dependable to make a 90 degree cut, much less a smooth curve in 8/4 oak. I will try a bigger blade next time, but I couldn't depend on the band saw for the curve.

I made a pattern based on the outline of the rails I have, but reduced slightly and smoothed out. Tonight, I will attempt to use this pattern with the router and hopefully end up with near identical and decently curved rockers. The pattern rocks great (but has a flaw I am not happy with on the top, so I will probably remake the jig instead of using it tonight, but we will see).

I hope the pins in the plan will prevent the rockers from splitting, but I am going to attach them only with screws in case they do break. Then I will get another opportunity to improve my design and technique. hah.

Robg
I would check out my bandsaw. I know when I cut circles on my bandsaw they are nearly perfect. In fact I think cutting circles or arcs on my bandsaw produces the bandsaw's best cuts.

I built an aux table than I clamp onto my band saw table that allows me to cut any circle out to a 3 foot radiius. It was simple to make a sheet ply about a foot wide and a little over 3 ft long. I cut about half way into it and drew a line from the blade front out as a center line. I drill a hold and stick my piviot anywhere on that line to match the radiius of the circle/arc I want to cut. I then either cut my circle out of ply or I cut a template out of ply to mount my dimensioned lumber to and make the cut.
Ed