# How do I smooth out curved cuts?



## LateNightOwl (Aug 13, 2009)

I am working on a special gift for a friend (Wood Mag Dancing Clock) that calls for some smooth curved cuts and I end up with ripples instead.

I am getting pretty good, but my bandsaw and I are not a perfect team yet and I end up with kerf lines and a few little jogs where I missed following the line exactly… nothing too drastic. After the bandsaw, I take it to my Rigid Oscillating Spindle Sander to smooth things out, but the edges end up feeling wavy.

Should I be able to get the smooth curves I want with the bandsaw and OSS? Maybe I am not using the OSS properly? Or is there something else I need to do? I hope someone can steer me to a way to get the curves smooth and consistent.

Thanks!! It is so great to have the many experienced woodworkers here to turn to when I run into a problem.


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## grizzman (May 10, 2009)

yea when it comes to curves…there a little tricky…i know when im doing something like that i can have problems too…are you making sure your wood is totally flat when you use the oss…, that might be one thing…the other is making sure your blade is good and sharp on the bandsaw, so that you get good flow when your cutting the curves….i dont know if any of that will help…but maybe someone who knows more on it will help too…good luck mary ann…....hows that room of yours doing…did you get the hot tub in there yet…grizz


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## Abbott (May 10, 2009)

Diet and exercise


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## Abbott (May 10, 2009)

I have found that an oscillating spindle sander is a great aid…I have also used dowels of various sizes wrapped with sand paper. That interior you are doing looks real nice


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## tdv (Dec 29, 2009)

Mary Anne Two ways I use to get smooth curves are make a 1/4" ply or MDF template (it's easier to refine smooth curves on thinner material) & then stick the template to the work piece with doulble sided tape & rout with a bearing guided profile bit. Or 2) use a belt sander to refine the largest area of the curve & finish the tightest areas with the spindle sander. One other little tip I find works well for me is when you are trying to level out bumps with a spindle sander passing your work from right to left ( assuming your sander rotates anti-clockwise)only accentuates the flaws. If you get a good grip of the work piece & lightly yet quickly traverse from left to right It seems to hit the bumps & smooth them more evenly. This is like climb routing so be careful your work is travelling in the same direction as the sanding drum. Have a little practice first I've never had a mishap with this method but just take care & be gentle. hope this is useful to you
Best
Trevor


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## randi (Sep 5, 2010)

Yep, oss here, keep the drums nice and clean and feed the work to it with a smooth action, and you can smooth out pretty much anything very cleanly.

Theres always good old fashioned hand sanding as well…always fun.


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## JJohnston (May 22, 2009)

Try using the belt, or some other flat sander, for the outside curves as much as practical. Trying to sand outside curves with an outside curve (sanding drum) just makes it harder.


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## Abbott (May 10, 2009)

Both good points you guys! I and others were only thinking of inside curves and only gave up half of our techniques.

I keep one of those small combination rasps with four sets of teeth in various roughness's handy. Sometimes it sees a lot of use.


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## BarbS (Mar 20, 2007)

Mary Anne, you don't say how large the curves are you are trying to cut, but one method on the band saw is to overlay your table with 1/2" or 3/4" ply in a larger sheet, cutting into it with the blade, then mark the corners underneath and attach blocks to hold it in place. To this, now zero-clearance tabletop, you can attach jigs. In your current problem, a pin to swivel the workpiece through the blade (how tight a curve? use the appropriate blade.) If it is a large arc, as for a rocking chair, your center pin may have to sit off the table out in the nether lands of your shop somewhere, and a router template may be the answer. Either of these would make your sanding job easier Several ways to do it!


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## LateNightOwl (Aug 13, 2009)

Thanks, guys! Sounds like I am on the right track with the OSS, but maybe need to refine my technique and practice to improve my skill.

*tdv*
Thanks for the different suggestion, Trevor. Now I have a reason to try something else I've never done before… template routing and climb sanding.

*grizzman*
It took 10 big guys to tote the hot tub (it's a huge 7-person tub) from my garage to the new room, but it's in there! Next nightmare is dealing with the mess the electrician who thought "close was good enough" left behind. Still got a couple more ceiling sections to go with the T&G, but the end of the job, on the interior at least, is in sight. Thanks for asking.


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## a1Jim (Aug 9, 2008)

Hey Mary Anne
I agree that a OSS is a great tool and it works great . I've also used a pattern makers file and a Japanese saw file.
If you want to make more than one of some of thing or your not having success with your OSS a pattern and a flush trim router bit works well too, As Trevor suggested.
After some more practice or changing drum size I'm sure you can make the OSS work too.


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## LateNightOwl (Aug 13, 2009)

More great answers. Thanks! Maybe I can hit some areas of the outside curves with the belt sander. Nothing looks drastically off enough to go at it with a rasp, but heck, I have one so I'll see what it does. 

I hope Otto doesn't mind me using his as an example, but this is what I am working on:


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## Spoontaneous (Apr 13, 2009)

I've never used an OSS before but I have done a LOT of sanding on curves using a spindle/drum type sander (Usually on a drill) and what I found to be true is that the bigger the drum/spindle the easier it was to avoid bumps and ridges. I'm talking inside curves. On the outer, if it is a manageable piece, a belt sander (a free-floating one esp.) can be used with great results… just keeping in mind long and light and consistent strokes.


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## lew (Feb 13, 2008)

Mary Anne,

When using your Oscillating Spindle Sander, try to use the largest spindle possible for the area you are sanding. That will tend to minimize the waviness. Also, after you get the sanding just about where you want it, move the piece quickly back and forth across the spindle. This will help to even out the little wavies.

Hope this helps,

Lew


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## Dennisgrosen (Nov 14, 2009)

Mary Anne 
try the old school metode …LOL
both rasps and spokeshaves can do the trick with inside and outside curves
but with this one I will surgest a compass plane

take care
Dennis


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## LateNightOwl (Aug 13, 2009)

*lew*
You hit on my problem-- *SPEED*! It looks like I was going way too slow. I was easing the piece along the spindle trying too carefully to follow the line, and that is what was causing the waves. Once I sped up and whipped it past the spindle a few times, everything smoothed out nicely.

Thank you all so much!!


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## helluvawreck (Jul 21, 2010)

Mary Anne, you'd be amazed at what a good three piece set of half round bastard files will do. You can also add some good half round smooth files. I've been making dovetailed boxes with curved middle uprights with handle holes in them. The uprights are 8 to 12in. in width and 16in. in length in size with smooth curves cut on a band saw. For the hand hole I simply take a 1-1/4in. forstner bit and drill through a series of over lapping thru holes in a line across four inches. I then take a good sharp chisel and chop out the sharp ears just below the tops of the holes. Then I take a half round bastard and smooth out the handle hole all the way around to give a good smooth bearing surface and go around both sides with a half round router bit with a flush bearing. This method makes quick work of a handle hole because one stroke on each pair of holes with a good sharp chisel will go clean thru leaving just a little clean up with the file. For the concave and convex outer curves I just put the part in a wood vise and clean the outside band sawn curves with the round or flat side of the bastard files depending on which side works best for each part of the curve. I know this sounds slow but it's not bad at all. If you want a rounded over edge just run around both faces with the round over router bit. I know that this could be done with a router and jig but I build these one box at a time and all I have to have is a straight fence on my drill press and a band saw and some hand tools and it can be done surprisingly fast. You can see the upright in the picture below:


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## patron (Apr 2, 2009)

MA
the best way i have found to bandsaw curves
register off the back of the blade
as in this drawing








it is the only smooth part of the blade
slightly push work to it and it will stop blade chatter
letting you 'work' the teeth as they are not wobbling 
and leaving score marks








as you change curve directions
you will also go to the other side of the blade 
for that registry

it means that your curve is visually slightly askew by a few degrees
but does help immensely

try it on some scrap
and you will get a feel for it
and how much side pressure to use

in practice it lets you come at the cutting edge 
and control it better


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## degoose (Mar 20, 2009)

Practice, practice and more practice… as you become more experienced and more familiar with your equipment you will find the work will be smooth and crisp…


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## sras (Oct 31, 2009)

I see you posted my suggestion Mary Anne - light passes made quickly. I was also going to suggest diet and exercise, but Abbott beat me to it. Besides that trick never works for me anyway


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## LateNightOwl (Aug 13, 2009)

*Dennis*,
I have no idea what a compass plane is but it sure sounds like a cool tool. One of these days, you're going to persuade me to try going old school! 

*helluvawreck*,
That's a really fine looking tote! I thank you for the excellent tips; I'll surely be using them when I get around to tote making myself.

*David*,
You are just full of helpful information! I always look forward to your posts; I always learn something. Your clear explanation of the mechanics of cutting curves on a bandsaw helps me understand blade drift and why it sometimes twists and turns on me and makes it hard to stay in the lines. It's hard enough as it is… I never liked to color in the lines when I was a kid. 

*degoose*,
One of the best (and one of the most frustrating) things about being a newbie at this is that there is always something to learn and practice. I have a feeling the same is true even after years of experience.


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## helluvawreck (Jul 21, 2010)

David, the next time I put a part to a band saw blade you can be sure that I will have your advice in mind. It makes good common sense and I will definitely see what I can do with your idea in my work. Thanks.


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## Dennisgrosen (Nov 14, 2009)

every chance we get we will take trying to convince you that its not always 
the best and fastes way to make a project by killing electrons…..LOL
but it ain´t only handtools or powertools they work very well together in a companionship 

if you have a chance to look in Garret Hack´s handplanebook
then you will on page 207 see a little chapter with compassplanes both in wood and steal

and here is a modern one made by Kunz










have a great day
Dennis


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## helluvawreck (Jul 21, 2010)

Thanks, Mary Anne. Actually I've done more machinist work than woodworking. I guess maybe that's why I love files of all types. They are the lowliest of metalworking tools and with a few strokes can coax a few ten thousands off of a piece of steel but by the same token can coax a few thousands off of a piece of wood. They should be in the tool arsenal of woodworker and metalworker alike. I'm not a machinist or wood craftsman, BTW. If the truth be told I'm more of a shade tree mechanic or maybe jack of all trades and *MASTER of NONE*. Files should not be neglected by woodworkers because they are cheap and can be used to do very delicate and accurate things.


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## Howie (May 25, 2010)

My sound like a small thing but make sure your table is perpendicular to the spindle.


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## Magnum (Feb 5, 2010)

First…. The Band Saw.

I made a Jig using a Combination of the 2 Jigs Pictured below. Sorry, but I don't have a Picture of My Finished Jig. They are both "Flush Cutting Jigs" using Templates.

The large one is a "Top Template" in this case for "Production Runs" but could also be used for "One Offs" with a Less Complex "Template".

The smaller one is an "On The Table Template" which is closer to mine and is Simply Clamped to the Table when needed. My Design has an (Extra) "Slider Piece" on Top Of what you see in the Picture and 2-45 Degree Flat Support Pieces Under the "Slider" to the Outside Edge of the "Fence" Piece. My Fence is Flush with the Top of the BS Table.

As you can better see in the Large One, the BS Blade fits/sits Flush "Within" the Tip of the Jig and can be Adjusted with the Wing Nuts.

I use 1/4" MDF for the "Template Pattern" and Double Sided Tape (Carpet Tape). Actually….if you have an "Existing" Leg or whatever shape you want to Duplicate you could also use it as the "Template".


















Next…The DP Sander.

I purchased from Lee Valley a "Flush Template Sander" for $18.90 with one 50 Grit Sleeve. 5 Sleeves are available for $3.80. The Hard Rubber Drum is 1" in Dia. X 2" Tall. Recommened DP Speed is 2500 RPM.

Cut the Basic Shape to Rough Size on your Band Saw about 1/8" Oversize (Or No More than, if it is a "Wavy" cut). If you're reasonably good at it, and can "Wavy Cut" on the Outside of the Line you don't even need to use the Above BS Guides. I usually don't, since I bought the "Flush Template Sander" OR …Vice Versa.

Template again is 1/4" MDF (But doesn't have to be) attached with Carpet Tape. Sand Slowly. Put as Little Lateral Pressure on the Drum so as to avoid excess Pressure on the DP Quill, and the 50 Grit rips it off pretty fast.


















Hope this is not to Confusing and is of Help to you Mary Anne.

Rick

PS: If I am in Error on any of the above please forgive me as it is now 6:22 AM Monday Morning and I'm in Desperate need of some ZZZZZZZZZZZ's …LOL…


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## patron (Apr 2, 2009)

ma 
the band saw arm has a notch in it
where the saw blade goes ( like a 'U' )
the blade is inset slightly ( maybe 1/8" )
so the arm touches the template
and the blade cuts slightly over

good one *rick*


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## LateNightOwl (Aug 13, 2009)

I asked what I thought was a simple question and got a ton of information and options.
I learned things I didn't even know I needed to learn.

A *BIG* thanks to all of you!!


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## Magnum (Feb 5, 2010)

Now that I'm awake again…I had a look at my Posting. DAMN it's Pretty Good!! ....LOL….

Thanks for the Nice Comments Guys. I Appreciate it.

Rick


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