Cut circles on the bandsaw? - Woodworking Talk - Woodworkers Forum
 
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post #1 of 9 Old 08-03-2015, 05:30 PM Thread Starter
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Cut circles on the bandsaw?

Hi,

I have the Grizzly 14" bandsaw and made this bandsaw circle cutting jig

I am testing it by trying to cut a 6" circle. By the time I get 3/4's of the way thru the bandsaw is struggling and I can't get through the cut. I am wondering if I should be able to make such a cut on the bandsaw or if the radius is too tight. I am checking through the bandsaw to reset it up in case something is out of wack. I already checked that the blade is not tensioned too tight and it is right at the line for the 1/8" blade I have in it. I am testing on 3/4" plywood.

Please let me know if my bandsaw should be able to handle such a cut or not and if yes, if you have any suggestions on what I might be doing wrong.

Thanks,

Nathan
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post #2 of 9 Old 08-03-2015, 05:43 PM
where's my table saw?
 
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I suspect the blade

I just cut some 6" circles in a stack about 1 1/2" thick using a 3/8" wide blade and my shop made circle jig..... a board with a screw hole in it..... It worked like a charm.

You blade is very narrow and may be dull, I donno?




The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #3 of 9 Old 08-03-2015, 08:02 PM
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I have a Craftsman 10" band saw, and just put a new Timber Wolf blade on it. I tried using a circle jig on mine, and had the same problem and couldn't figure it out. I was cutting a 3" circle with a 3/8 blade. It cut great if I freehanded it, but when I used the jig it would bog it down and all most stop. It's a brand new blade, so it must have been something with the jig. I followed a video online to make it, and was very simple-just a board with a nail in it. I wasn't able to use it. I thought maybe it was the saw itself, and wasn't powerful enough, but after reading your post, I'm wondering too.
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post #4 of 9 Old 08-03-2015, 08:29 PM
where's my table saw?
 
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It may be your setup

So you mount the circle to the base board using a loose screw. You saw in until your blade touches the circle you've drawn. You stop the machine and clamp the board in place. Start the saw and twist/rotate the circle until you have made the entire cut. The perimeter falls away and you have your circle.
http://www.woodworkersguide.com/2008...-radius-chart/
A 3/8" blade will cut a 1 1/2" radius OR 3" diameter circle, BUT you are on the limits.... it may not work well with a blade that's slightly dull.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #5 of 9 Old 08-03-2015, 09:16 PM
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It sounds to me like Deadherring might be pinching the gap closed. I can think of no other reason why the blade would cut fine at the beginning but not at the end. Unless the jig was shifting during the cut.

It is possible Tchara is doing the same thing. Or, since the curve is at the limits for the blade size, he may be cutting a slightly larger kerf when cutting freehand, while the jig prevents any side to side adjustments that would enlarge the kerf.

These are just my speculations based on the information given and the posts by woodnthings.
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post #6 of 9 Old 08-03-2015, 10:59 PM
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Im sorry... what was the question? I got lost in her accent and then found myself looking for flights to scandinavia...

oh right... circle jig. I would wonder that the front of the teeth should be tangential to the circle, if the pivot point is behind or in front of the teeth, the blade will try to cut a spiral instead of a circle. I would expect the blade tension to eventually bind as it walks away from neutral.

Ok, going back to the youtube video on loop. Please do not disturb me...
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post #7 of 9 Old 08-04-2015, 06:40 AM
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Quote:
Originally Posted by bauerbach View Post
Im sorry... what was the question? I got lost in her accent and then found myself looking for flights to scandinavia...

oh right... circle jig. I would wonder that the front of the teeth should be tangential to the circle, if the pivot point is behind or in front of the teeth, the blade will try to cut a spiral instead of a circle. I would expect the blade tension to eventually bind as it walks away from neutral.

Ok, going back to the youtube video on loop. Please do not disturb me...
I think he's got it!! From my own experience I've discovered that the jig MUST be lined up properly.

Do like you always do,,,, get what you always get!!
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post #8 of 9 Old 08-04-2015, 07:57 AM
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Quote:
Originally Posted by deadherring View Post
Hi,

I have the Grizzly 14" bandsaw and made this bandsaw circle cutting jig

I am testing it by trying to cut a 6" circle. By the time I get 3/4's of the way thru the bandsaw is struggling and I can't get through the cut. I am wondering if I should be able to make such a cut on the bandsaw or if the radius is too tight. I am checking through the bandsaw to reset it up in case something is out of wack. I already checked that the blade is not tensioned too tight and it is right at the line for the 1/8" blade I have in it. I am testing on 3/4" plywood.

Please let me know if my bandsaw should be able to handle such a cut or not and if yes, if you have any suggestions on what I might be doing wrong.

Thanks,

Nathan
if it were me i would have most of the circle ahead of the blade and not even with the screw or nail in line with the blade ?? may make a difference , i bet it will that way most of the cut will be out of the way of the blade and not pinch the wood at all
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post #9 of 9 Old 08-04-2015, 08:03 AM
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You have to align the center of the circle right with the tip of the blade, perpendicular from the blade. If you have it too far back the blade will want to climb out of the circle. Have it forward of the blade and the blade will try to climb into the circle. Since the circle center is affixed relative to the blade you'll get the binding you describe unless perfectly set.
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