How to smooth curves....

[Gary Cunningham]

Currently making a shelf for niece. I cut the pattern into the supports, but being new to the "finer side" of wwk'ing I need a way to smooth the edges. My old way was a belt sander.

I'm thinking a spokeshave, as the curve is rather gentle, and convex. (Plus I have been wanting a reason to get one, or three).

Thoughts, tips or ????????

[Prashun Patel]

If the curve is convex, I prefer a block plane. Skew it, and it will fair a curve very well.

[Joel Thomas Runyan]

Spokeshave, usually. But if the curve is mostly in end grain, maybe rasp and file. You can clamp a small square block to the end of a file to make sure the finish is square.

[steven c newman]

Maybe a compass plane?

[Brian Holcombe]

Fine set smoother or block plane will do well.

[Pat Barry]

The spokeshave will do the job of course. The block plane is more limited situationally. Obviously there could be clearance issues using the block plane depending on the curve position in relation to other features, ie: inside / vs outside radiused profile, overhangs, etc, not to mention the direction the wood wants to be planed. The spokeshave is simply the more flexible tool for something like this since you can easily attack the curve and tighter situations from the proper direction. Another option is, OK I'll say it, sandpaper on a flexible backer such as adhered to a flexible wood strip. Something like this allows you to make a much more uniform curve, relatively easily.

[Prashun Patel]

Pat, I agree that for other situations a spokeshave has versatility over a block plane.

However, he is specifically fairing a convex, gentle curve. For that, even if I have a spokeshave, I reach for a plane. Skewing a block plane creates a broader surface that finds high and low spots very efficiently - especially if you skew it. I am certain this can also be done with a spokeshave, but for some reason I find a plane more ergonomic on gentle+convex curves.

With any tool, the grain on a curved piece will likely switch, so you have to be careful to come from different directions; that usually means planing away from the apex on both sides.

[george wilson]

Making and DRAWING smooth curves is also something that YOU SHOULD BE LEARNING.

[Phil Mueller]

George, one of my many short falls. I try to find something with a similar curve as a template, but that often doesn't work out. Haven't tried trammels or string and nails, and the like, and french curve templates can be short for longer sweeping curves. Never quite sure how to go about it, other than a bunch of free hand curves on paper.

Not to divert this thread, but any insight would be helpful.

[george wilson]

You might try a long,fairly thin,but bendable strip of wood. Made like a bow and arrow. Notch both ends and attach a double "bow string". Add a twisting stick in the middle. You can wind the twisting stick as much as needed to produce a long,gentle,or more bent curve to trace your pencil on. I have a thickness sander,and sawed some large as possible bamboo into 5/8" wide strips. Then,I ran them through the sander and made them nice and parallel. I was planning to make a laminated archery bow from them,but they lost their strength when the hard outer skin was sanded off. But,they certainly are flexible! I used a strip of wood bent to trace and make a plywood template for an arched passage way in our house,when the plasterer could not manage to get it SYMMETRICAL!!!!

Better yet,find a long,thin strip of steel about 1/32" thick and make your bow from that. Preferably spring steel. Or,find a strip of plastic that can bend without breaking. A piece of poly carbonate will do. BUT,this is funny material. ALWAYS loosen the string and let it go back to flat,or you may WELL find it full of little stress fractures if left bent. I know this from experience using the stuff in other applications.

Here is a GOOD TIP: Some craftsmen who can't draw real well have used a large,old CLOCK SPRING as a drawing aid. But,not for long curves,as it will not make long curves,having been coiled for a long time. The spring from an old time wind up floor model Victrola record player(WWI ERA) has a great spring. Good for drawing spirals,too.

[steven c newman]

Case in point on curves..
342086
Smooth both curves....

[george wilson]

Could use more smoothing,Steven. Look carefully along the curves. There are flat areas and dips. Now,don't get upset,just look carefully and improve on them before you attach them to a chair. Remember,any time you post pictures of your work,you are subject to criticism,myself included.

[Bill Houghton]

I want to second Prashun's comment on planing direction. Look closely at the wood, and make sure you don't plane against the grain. This can make it harder to get a smooth curve at the point where you need to change directions; practice is the only cure for that. Well, or sandpaper.

[Mike Holbrook]

Both the plane and spokeshave can start lifting the grain if you are going the wrong way, as others have mentioned. Thinking of going the wrong way against the bristles of an angled paint brush helps me. You also may need to make multiple passes as a single pass, or multiple passes along the same plane, may just leave two sharp edges.

I frequently run a plane or spokeshave over the corners to take them down a little and then round them over a little with an Iwasaki rasp. Iwasakis are more like a float than a rasp, leaving small shavings instead of dust. These files have curved cutting edges vs teeth, which are sort of like running a single blade over the surface many times.

[george wilson]

Agreed. As long as those Iwasakis are sharp,they are great. But,even more my favorite,but no longer available to my knowledge,is my limited supply of Nicholsons,with serrated curved float teeth. They are "Super Shear"files. They came in much larger sizes than the Japanese ones,like 12" and 14"(I'd have to hobble out to the shop to measure them,but don't want to,broken foot). They have very sharp teeth like the Japanese files in question,and cut like crazy. Curiously enough,the smallest Super shears that Nicholson made,a bit larger than the Isawakies,were never quite sharp for some reason. At one time,over 10 years ago,I was able to buy a Simmonds file identical to the Nicholson From Travers Tool Co.,but that was then,and Simmonds is made in India now,I think.

Unlike a lead float,which starts chattering right away(and might be better with technique in the way it is slid over the work),the round teeth of the Super Shears were off centered,and had neatly ground serrations in them to break up the chips.

I tried cutting serrations in a lead float a long time ago,to no avail. I just used a Dremel tool with a thin cutoff abrasive disc. Lead floats were a LOT less expensive than the Super Shears(at about $40.00 each decades ago,and when my income was less!)

[steven c newman]

Maybe a little better?
342107
The first photo was right after they had been sawn out, as a reference for the curves the OP was trying to smooth. Nothing more...

[Gary Cunningham]

Making and DRAWING smooth curves is also something that YOU SHOULD BE LEARNING.

I can't draw a straight line, and me drawing a smooth curve free hand would be like pulling teeth from a chicken.

I should have stated that most of the edge is convex. Part of it is concave. I used a french curve template. Mostly edge grain with about one inch of end grain.

[Phil Mueller]

Thanks George. Great tips. In fact, I think I have a few thin cutoffs somewhere I was saving for who knows why...should work well.

[george wilson]

boat draftsmen use long,flexible strips held in place by little lead weights along their length. So,nothing wrong with a "bow" type of drawing aid. When I have to draw LOOONG curves,I resort to aids,too.

[Keith Mathewson]

I used to use 1/4" x 1/4" for curved stair work to fair laminated elipitical stringers and 1/8" x 3/4" for single point radius.

lf you taper one end you'll get an elliptical type of curve