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Cutting a circle on a band saw

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Forum topic by richgreer posted 12-29-2010 06:22 PM 1832 views 1 time favorited 14 replies Add to Favorites Watch
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richgreer

4525 posts in 1827 days


12-29-2010 06:22 PM

Normally, if I need a circle of wood, I use my lathe.

Yesterday, I decided to try to use my bandsaw to make wheels that would be 6” in diameter. I made one of those jigs with a pin to rotate the wood on. I was using a 1/4” blade. My blade immediately started to move away from the circle. I tried moving the pin a little forward and a little back to see if I could get a better result. Nothing worked. I freehanded on the bandsaw just outside of the line and went to the lathe to finish the job.

I know I can cut big circles (over a foot in diameter using the bandsaw. I’ve done it several times. It seems like a 6” diameter should also work because the curve is no tighter than what I can easily cut freehand with a bandsaw.

I wonder if I was doing something wrong.

Is it reasonable to expect a bandsaw (with a jig) to cut a 6” diameter circle?

FYI – I found a good trick for making the wheels on the lathe. I put all four on a threaded rod and bolted them on tight. My lathe chuck held one end of the treaded rod (needed to switch to the smaller jaws). I put a wooden “cap” on the other end and brought my tailstock up tight. I was able to turn all 4 wheels at the same time and it was very easy to get them all to the almost exact same size.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.


14 replies so far

View Loren's profile

Loren

7826 posts in 2401 days


#1 posted 12-29-2010 06:55 PM

Check you guide blocks and make sure they’re set as close as
possible to the blade.

You can also cut out disks on a table saw using a similar jig. It’s
slower, but accurate.

-- http://lawoodworking.com

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j_olsen

155 posts in 1924 days


#2 posted 12-29-2010 07:09 PM

Rich

I cut circles on a regular basis for wind chimes I make—5” head piece and a 2 3/4” striker and have no problems – I use a 3/16” blade but that shouldn’t make a difference on a 6” diameter

A suggestion is to tighten the blade tension a bit more than normal and make sure the blade guide is as close to the work as possible

-- Jeff - Bell Buckle, TN

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mpounders

750 posts in 1648 days


#3 posted 12-29-2010 09:54 PM

I cut them out also with 1/4” blade and generally have no problems. I still usually use my disk sander, which I also use if I freehand cut them, to clean up the edges. I think Jeff Olsen is probably right about the tension and the guides being the cause.

-- Mike P., Arkansas, http://mikepounders.weebly.com

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Jamie Speirs

4163 posts in 1609 days


#4 posted 12-29-2010 10:06 PM

Rich I line the centre pin with the back edge of the blade. I also set the back bearing just off the blade. Especially for small circles. I cut from 2” up to 4’ and on a 13^ angle. I know that if sawdust get between my jig and the stop that is can make it harder to get a nice circle.

jamie

-- Who is the happiest of men? He who values the merits of others, and in their pleasure takes joy, even as though 'twere his own. --Johann Wolfgang von Goethe

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patron

13182 posts in 2094 days


#5 posted 12-29-2010 10:07 PM

sounds like your blade is ‘twisting’
check the guides
it could also be the blade is dull on the side closest to the work
making it cut better on the other side
walking it that way

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View jim C's profile

jim C

1455 posts in 1851 days


#6 posted 12-29-2010 10:24 PM

Rich
One more thing to look at. Make sure the guides are behind the teeth, against the smooth band only. If they touch the teeth, they dull the sides, so the blade will only rub and move away. If that happened, you need a new blade.

-- When I was a boy, I was told "anyone can be President", now I'm beginning to believe it!

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peteg

3007 posts in 1576 days


#7 posted 12-29-2010 10:46 PM

Rich, I think David is on to it, if the blade has gone of on one side it will pull, same as a chain saw if you dont get both sides right it will drag to one side. assuming that the tension is “tight” & guides are set right.
Why not try a new blade & keep this one for rough cutting. that way you will soon figure if it is the blade.

-- Pete G: If you always do what you always did you'll always get what you always got

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poopiekat

3737 posts in 2487 days


#8 posted 12-30-2010 12:26 AM

I think Jamie is onto something. I’ve wondered myself where the center pivot should be located in reference to the blade….whether a” fore and aft” adjustment might make the blade track exactly where you want it to go. I’ve had great results, and had awful results, and I’m betting the fore and aft spotting of the center pin makes all the difference, since I didn’t make a single other adjustment to my bandsaw.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

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wiswood2

1128 posts in 2449 days


#9 posted 12-30-2010 12:38 AM

I think the blade should be a little tighter.
Chuck

-- Chuck, wiswood2 www.wisconsinwoodchuck.com

View Bernie's profile

Bernie

414 posts in 1590 days


#10 posted 12-30-2010 05:47 AM

I confess I haven’t cut circles on my band saw, but lots of free curves. At 1st, I had terrible results and played with the tension and guides. It did improve my results, but I made a big leap by learning to be patient. You need to be painfully slow with a band saw in order to get a burning, but fairly slow gets me good results.

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

View Kevin's profile

Kevin

457 posts in 1958 days


#11 posted 12-30-2010 06:52 AM

I always use my router when needing to cut circles.

-- Williamsburg, KY

View HallTree's profile

HallTree

5661 posts in 2520 days


#12 posted 12-30-2010 05:10 PM

Check this circle cutting jig out:

http://www.finewoodworking.com/Workshop/WorkshopArticle.aspx?id=30943

-- "Hold on to instruction, do not let it go; guard it well, for it is your life" Solomon

View tdv's profile

tdv

1130 posts in 1823 days


#13 posted 01-01-2011 03:59 AM

Rich I think you may have the alignment of the pivot pin too far back I personally like the pin lined up with the teeth of the blade any further back & the blade seems to cut in a straight line and be dragged round the circumference causing it to cut outside the line, think about drawing a circle with a compass the point is always in a staight line with the pivot now imagine the pencil is flat (carpenters pencil) 1/4” wide if you put the back edge of the flat on the circumference the front edge will be ahead & outside the cicumference line.The cutting point needs to be on the line,try it out
Happy New year to all
Trevor

-- God created wood that we may create. Trevor East Yorkshire UK

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dusty2

319 posts in 2182 days


#14 posted 01-01-2011 02:27 PM

I have not tried small circles on the band saw other than free hand. If I want small circles (wheels, etc) I use the belt sander with a jig as you have described. This works best when sanding wheels that have been precut but I often make wheels starting with appropriately sized square blocks of wood. This makes a lot of saw dust and consumes that sanding belt faster though.

-- Making Sawdust Safely

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