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How tight of a curve on a bandsaw?

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Forum topic by richgreer posted 04-20-2011 06:05 PM 4336 views 0 times favorited 10 replies Add to Favorites Watch
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richgreer

4524 posts in 1761 days


04-20-2011 06:05 PM

For curvy cuts on a BS, I usually use a small BS (Shopsmith) and I use my 18” Jet for resawing and other straight cuts. I had a situation where I needed to cut a curve on a piece of oak that was 6” thick and, for the first time, I put a 1/4” blade on my 18” BS to cut a curve with it.

Some of you saw my topic yesterday when I indicated that I was getting sparks and some of you said I was probably trying too tight of a curve (The radius was 3.5”).

This raises the question in my mind – - How tight of a curve should you be able to cut with a BS under different conditions?

Obviously, this differs by the size of blade. It probably also differs by the quality of the blade (I use Timber Wolfe) Does it also differ due to the hardness or thickness of the wood? Does the grain orientation affect this?
In my case, the grain was running vertical.

In my opinion, a 3.5” radius should be able to be cut with a 1/4” blade on a piece of oak that is 6” thick. I could do it, but I was generating sparks and it felt like I was at the limit of what I should do. It’s also my opinion that grain orientation does not matter.

On another cut, I did a curve with a 4.5” radius and that was not a problem.

I welcome any advice based on your experiences with cutting curves in thick pieces of wood with a BS.

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


10 replies so far

View spunwood's profile

spunwood

1194 posts in 1523 days


#1 posted 04-20-2011 06:28 PM

Hey Rich,

You can take a wetstone to the saw while it is running, gently place it against the back of the blade and grind the sharp edge off of it. Run it around the blade in a curve like motion. It is called stoning the bandsaw, but if you or the blade get too stoned, I do not suggest making a cut at that time:)

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View lew's profile

lew

10088 posts in 2442 days


#2 posted 04-20-2011 06:30 PM

Rich,
Found some things here:

http://www.allbandsawblades.com/bladewidth.htm

http://www.toolcenter.com/BLADESELECTION.html

http://www.woodworkersguide.com/2008/01/23/bandsaw-blade-radius-chart/

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View GregD's profile

GregD

622 posts in 1823 days


#3 posted 04-20-2011 06:50 PM

My bandsaw has a chart of minimum radius for different blade sizes, and I’ve seen this chart other places. Sadly, I don’t have a link to one. (Ah, lew has links above).

As I recall from the Carter’s presentation at the woodworking show several weeks ago their upper saw guide allows for a much smaller minimum radius.

-- Greg D.

View richgreer's profile

richgreer

4524 posts in 1761 days


#4 posted 04-20-2011 09:09 PM

I’ve located several of these charts thanks to your help. For a 1/4” blade they are saying that one should be able to cut a circle with a 5/8” radius. I think that might be true on thin and soft wood.

IMO it would be impossible to cut a curve that tight in a thick piece of hardwood.

None of these sites address the issue of thickness and/or hardness of the wood.

FYI – I have a Carter Stabilizer on my ShopSmith bandsaw. It works great, but there is no way the ShopSmith could handle wood 6” thick.

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

View Sawkerf's profile

Sawkerf

1730 posts in 1755 days


#5 posted 04-20-2011 10:14 PM

You were seeing sparks?? That sounds like some kind of metal to metal contact. Were your guides and thrust bearings set correctly? Was the blade coming into contact with the blade guard? Was there metal in your wood?

-- Adversity doesn't build character...................it reveals it.

View Domer's profile

Domer

248 posts in 2053 days


#6 posted 04-20-2011 11:42 PM

I just saw the Carter bandsaw DVD last night. As I remember it, they said that you could cut a radius of 1/4” larger than the blade especially if the blade has been rounded over in the back.

Domer

View D_Allen's profile

D_Allen

495 posts in 1471 days


#7 posted 04-21-2011 03:25 AM

I cut through 4” blocks of hard maple with my 10” bandsaw. I think ot makes a big difference what the tooth count is. I use a 3/16-10 tooth and get some tight curves and good results.

-- Website is finally up and running....www.woodandwrite.com

View gfadvm's profile

gfadvm

11233 posts in 1377 days


#8 posted 04-21-2011 04:13 AM

I can cut a 1/2” radius using a 1/4” blade in 6” thick material.I have the 17” Grizzly and use a Carter Stabilizer with my 1/4 and 1/8” blades.Stoning the back of the blade as recommended above is always a good plan.I have not found that the type of wood changes the radius that I can cut.Im currently using Timberwolf blades which Ive been happy with.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Jesse 's profile

Jesse

105 posts in 1549 days


#9 posted 04-22-2011 06:32 AM

something doesn’t seem right if you are struggling to get a 3.5” radius w/ a carter system. While I haven’t done 6” i just completed my 3rd bandsaw box using 3.5” bubinga. Using a 1/8th blade and the carter stabilizer I was able to turn on a dime and make some very tight 90^ angles for the drawers. ( pics aren’t ready yet to post this project). That said, it does clog my blade pretty bad and after each project I needed to do a formula 409 soak and scrub. Regardless, I have been able to make the same tightness of cuts with 14/4’s as I am with 3/4’s albeit much slower.

Sparks would lead me to think you are making contact on your blade guard somewhere? I’m assuming you already have the lower guides as far away from the blade as possible right? Outside of mineral deposits in the wood, the blade guard is the only place I think sparks could happen if you are set up right. The back of your blade should be nestled in the stabilizer and no other bearings should be anywhere near the blade.

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richgreer

4524 posts in 1761 days


#10 posted 04-22-2011 03:36 PM

Jesse – You misread something. I have a Carter stabilizer on my small band saw and not on my big one. The Carter stabilizer is great! My problem came about when I tried to cut curves on my big (18”) bandsaw with a 1/4” blade. Normally I cut curvy things on the small band saw and use the big one for resawing. But since this was 6” thick, it was too much for my small bandsaw.

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

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