Outside curves

[Bigdog72]

And inside curves. As I get friendlier with my bandsaw I have attempted some projects that require tight curves (2" and smaller radius). My question regards touch up sanding for the curves. Is there a better way than using an OSS? I end up up with small divots from the drums. I am wondering if hand sanding or filing is the way to go. How do you more accomplished members do it?

 

[Joe Scharle]

I see a jig in your Future!

Also, I have more control with a disk than a drum for this sort of thing.
Using a jig.......... Surprised?

 

[Bigdog72]

I see a jig in your Future!

Also, I have more control with a disk than a drum for this sort of thing.
Using a jig.......... Surprised?

I saw a jig for a disk sander in, I think, woodcraft Magazine. Is that the way to go, Joe?

 

[Joe Scharle]

That did look like a good one.

 

[jhreed]

OK guys, I am trying to learn a little woodworking. I am just as ignorant as when this thread started. Jig? What kind?
James

 

[ehpoole]

When you are sanding with the OSS are you:

1) Using the largest diameter drum suitable for the curves you are trying to sand? The smaller the drum's diameter, the easier and more obvious the irregularities will be.

You might also find it helps to use finer grits (e.g. 150) when you are first learning to smooth the curves. The progress is slower at 150, but that also means that brief mistakes like pausing in one place for too long don't do as much damage nearly as quickly thus making it easier to smooth out the mistake once realized.

2) Do you keep the wood constantly moving on the OSS, never stopping or pausing in one place. If you don't keep the wood continuously moving and pause (or seriously slow down) in one place to try and sand to a line (or other reference) then you will create a series of obvious ripples in those targetted areas that will take a good bit of work to smooth out -- especially if you are using a smaller diameter drum on your OSS.

3) Are you overly obsessed with sanding curves to a specific line (or other reference). Quite often in curves the naturalness and smoothness of the transition is far more important than the technical accuracy of the curve. If you have multiple (thinner) pieces that need matched curves, use some double-sided tape or hot-melt glue and stack them, then sand them as a singular piece and all will have perfectly matched curves.

Like in scrollsawing and bandsawing, the most obvious and glaring errors are the places where you tried to immediately correct a mistake (such as drifting off your line) versus gracefully working your way back to the line with no obvious irregularities due to the correction.

Where edge ripples become truly challenging is when you are trying to smooth a wood like Southern Yellow Pine where there are dramatic differences in hardness between the earlywood (Spring-Summer) and latewood (Fall-Winter).

Hope this is of some help. Otherwise, just keep practicing with some scrap curves and you will eventually get your technique perfected through trial and error. Just don't give up, you will figure it out!

 

[cskipper]

OK guys, I am trying to learn a little woodworking. I am just as ignorant as when this thread started. Jig? What kind?
James

Although I am sure others can answer this with more authority, I will give it my best shot. A jig is a "tool" you create that helps you to more easily complete parts of a project. An example would be a circle cutting jig. If you cut many circles on any saw you will discover that it is very difficult to get a nice round, smooth circle. You can easily build a jig for this which will aid you in cutting circles of any size. I do not know where the term "jig" originated but that is the gist of what it means. Did the make any sense to you?

 

[Makinsawdust]

I've found the Ridgid Oscillating edge sander to be a most valued tool for this kind of sanding. It won't work for every radius but I use it when I can. The two features that I like most about it is that you can easily transition from inside to outside curves and there's no "swirl" sanding marks to clean up like from a disk sander. It just takes a little practice to learn to transition from the drum to the platen without stopping.

 

[LeftyTom]

James, Cathy, and tohers interested in minutia....."jig" is shortened from its Latin origin: thingamajig.

:slap:

 

[Joe Scharle]

Here's another definition:

In metalworking and woodworking, a jig is a type of tool used to control the location and/or motion of another tool. A jig's primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products.[1] A jig is often confused with a fixture; a fixture holds the work in a fixed location. A device that does both functions (holding the work and guiding a tool) is called a jig.
From Wikipedia

 

[FredP]

for curves I like to make a pattern from scrap and use a pattern bit in the router to do the final cutting on my piece. I bandsaw or scroll the part leaving the line and use the pattern bit [just clamp the pattern to the work piece] to clean it up. this way there is very little sanding to do.

 

[Bigdog72]

for curves I like to make a pattern from scrap and use a pattern bit in the router to do the final cutting on my piece. I bandsaw or scroll the part leaving the line and use the pattern bit [just clamp the pattern to the work piece] to clean it up. this way there is very little sanding to do.

Tried this approach and experienced more kick back than I have ever had with my tablesaw. I might need a lesson..... I can't see m to get the hang of when to stop a regular and start a climb cut to reduce tear out. It got so bad yesterday that I feared for my hands!!

 

[BrianBDH]

Did you really mean to say tablesaw? I'm scared just thinking about that.

Brian

 

[Canuck]

Tried this approach and experienced more kick back than I have ever had with my tablesaw. I might need a lesson..... I can't see m to get the hang of when to stop a regular and start a climb cut to reduce tear out. It got so bad yesterday that I feared for my hands!!

Geoff,

Whenever I am using a pattern bit with a template, I try to do it on my RT not freehand. Also, I try not to be cutting off more than about 1/16"-1/8" of material.

If there is just a wee bit to take off to match my template, I also use a Bosch Colt with about a 1/2" pattern bit - top bearing.

Maybe you were trying to take too much material off in one bite!:elvis:

 

[Gofor]

Not a "more accomplished member" but, for what its worth:

I do the same as Fred posted: pattern and router. Trick is to not leave a lot of waste, go with a quick run to remove most of the waste and then a final slower run to finesse the edge. For tear-out prone woods, I work from the center of the curve to the ends on the outside curve, and ends to center on the inside. With QSWO, though, sometimes it is best to flip the piece so you are always cutting away from the grain. I always put a center line on my template and also on the work, so that I can flip it or realign it if I need to flip the piece over.

Always use a bit smaller than the radius of the curve. If the bit and radius of the curve match (say 1/2" for instance) tear-out, kick-back and burning are almost guaranteed in my experience. A smaller diameter bit also will reduce the amount of any tear-out, but is a bit more prone to burning.

That said, making the pattern or template (probably better terms than jig for this use) still requires getting a smooth edge. For that I usually use a flat hand sanding block for outside curves, and a rasp and then paper on a rounded block or dowel for the inside curves. Because the pattern is usually only 1/4 to 3/8 thick, it is easily sanded. I also have used this on the final item if its a one time cut and the piece is not too thick (less than 1"). If making a template with a radius that matches one of my forstner bits, I drill the inside radius curves and then align any abutting edges to it.

Please note that I do not have an oscillating sander, which would probably make my life easier.

JMTCW

Go

 

[Joe Scharle]

Geoff, I just re-read your post....either I'm getting senile or need better glasses! I thought you were making 2" circles. After seeing Fred's response on my email, I re-read your post and yes, pattern cutting is the easiest way if the grain allows. Once, I stepped down bearing sizes on a bottom bearing bit twice in order to sneak up to the finale cut. The key is shallow cuts.
Also, I expect the trouble you're having with your OSS is perhaps you're exerting too much pressure against the drum. Light touch and constant motion will eliminate the gouging, with practice.

Sorry if I confused you earlier..but since I was confused, what can you expect!:rotflm:

 

[ehpoole]

Tried this approach and experienced more kick back than I have ever had with my tablesaw. I might need a lesson..... I can't see m to get the hang of when to stop a regular and start a climb cut to reduce tear out. It got so bad yesterday that I feared for my hands!!

Just an FYI: If you are using a table mounted router for your final templated (aka 'jig') forming/tracing, you should install a Starter Pin in your router table to provide you with a fulcrum to improve control as you lever your project into the router bit. Once you make contact with the router and the guide bearing is resting on your template (jig) you can slowly back off the starter pin and carefully trace the outline of your template AGAINST the rotation of your router (assuming you are using the front of your router table, that means from right to left -- just like any other job on the router table -- if you switch at some point to using the rear face of the bit, then the relative direction switches, but it should all be a single continuous and (ideally) uninterrupted motion throughout the tracing of your template's contours.

Also keep in mind that in templated pattern routing you are typically just nibbling away a fairly thin section of wood outlining your project (e.g. you've already cut away most of the excess with a scroll saw, band saw, jig saw, fret saw, coping saw, etc.). Whatever is left to be cut away should be no more than 1/3 the router bit's diameter (for 1/2" pattern or flush-trim bit, that would mean less than 3/16" in a pass). If you cross the 1/2 diameter point you will notice that your project becomes more difficult (though not impossible) to control.

For small projects USE GREAT CARE. Always ensure that, even if you get kickback, your hands and fingers are not located in such a way that they might get drawn into the bit!!! Use push pads, sacrificial boards, or whatever other such implimentation that you feel is necessary to ensure your safety. If using a homemade jig to hold and control your template (e.g. handles mounted to the template or otherwise) DO NOT USE STEEL SCREWS OR BOLTS -- use aluminum or brass (solid brass, not brass-plated) screws, bolts, washers, or nuts. If your router bit (especially carbide router bit) strikes a steel screw or bolt it will likely shatter and self destruct, if it hits brass or aluminum it should simply cut the screw or bolt without damage. The same advice applies to your other cutting tools as well, steel hardware equals damage to blade, brass and aluminum equals safe for blade.

 

[sushinutnc]

Just throwing this out there... it won't be appropriate for all jobs, but for light jobs on thin stock (like less than 1/2"... but less than 1/4" is better), I really like freehanding with my Dremel with the flex-shaft attachment. For some jobs, I can use it in a carving motion... as long as you keep it moving, it can make nice, flowing curves.

 

[FredP]

:icon_thum:icon_thum yeh what go said. flip the board and template so you don't have any climb cutting to do. If I have several pieces to do I will set up two routers. One with a pattern bit and the other with a bottom bearing strait bit. That way I never have to move the template. I simply flip the work piece and change routers.:wwink:

 

[Jeff]

+1 on pattern routing as others have mentioned.

In a pinch you can take a wider cut-off curve, spray some LocTite adhesive on the curve, and affix a piece of sandpaper slightly wider than the thickness of the cut-off. Clamp the work piece vertically or horizontally and use the cut-off like a sanding block to follow the curve incrementally. It's not instant gratification, but maybe slow as she goes is what you want. :dontknow:

End grain should be sanded to higher grits so that stain/finish doesn't appear darker than the surface finish.