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help needed for the compound miter challanged

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Forum topic by j_olsen posted 06-06-2011 08:34 PM 1186 views 0 times favorited 7 replies Add to Favorites Watch
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j_olsen

155 posts in 1917 days


06-06-2011 08:34 PM

Topic tags/keywords: question tablesaw joining

HELP!!!!!!

I am trying to build an octagonal shaped bowl (????) that flares at 30 degrees and I am at a total loss as to how to cut the sides on the table saw

I put together a small dresser valet a while back that was 4 sided—it was pretty straight forward—saw blade at 45 and miter guage at 30 and bevel the top and bottom at 30—simple enough

I went about the octagon in the same manner—saw blade at 30 and this time miter guage at 22 1/2—what I ended up with was a pentagon that was off by 2 1/2 degrees

I know this can’t be as tough as I’m making it out to be—could someone please help get this mathmatically challenged woodworker a crash course with this???

-- Jeff - Bell Buckle, TN


7 replies so far

View darinS's profile

darinS

406 posts in 1613 days


#1 posted 06-06-2011 08:52 PM

Try this, maybe it will help you out:

http://www.csgnetwork.com/sawmitercalc.html

-- If at first you don't succeed, skydiving is not for you!

View mrg's profile

mrg

533 posts in 1745 days


#2 posted 06-06-2011 10:26 PM

What type of miter gauge are you using? If it’s the stock gauge it probably is not accurate.
8 sides is 22.5 degrees.

Do the cuts in two steps. Rip your board to its 30 degree bevel, then set your blade at 22.5 degrees and cross cut your pieces with a stop block and flip back and forth to get your angles.

-- mrg

View Jim Finn's profile

Jim Finn

1743 posts in 1668 days


#3 posted 06-07-2011 12:33 AM

In making these kind of cuts I have found that if I keep the flare angle to 5 degrees the 30 degree angle will work just fine with no adjustments.

-- In God We Trust

View j_olsen's profile

j_olsen

155 posts in 1917 days


#4 posted 06-07-2011 02:46 AM

darinS—thank you for the info but that is for a miter saw and I am trying to do this on the table saw and if it will work I’m just being thick and not seeing it—if this is the case if you could grop me a line with a little more info I would greatly appreciate it

mrg—I am using an Incra Miter 1000SE

Jim Finn—thank you but as with darinS I’m not seeing your method and a little more info would be great

still in a fix at this end

-- Jeff - Bell Buckle, TN

View dwlckn's profile

dwlckn

47 posts in 1310 days


#5 posted 06-08-2011 05:03 AM

On your octagon bowl you have reversed your saw blade and miter gauge rolls from your dresser valet, was this intentional? Try setting you saw blade to 22.5 degrees off of vertical and your miter gauge for the flare. To cut the pieces on a table saw you will need to cut them in two step all right side or left then the other. After changing your miter gauge to the mirrored angel and rotating you pieces 180 degrees.

FYI using your miter gauge for the 8 sides of an octagon is used for segmented turning, where you get the flare by making larger and larger rings stacked on top of each other.

-- “Enjoy what you do, or do something else!”

View Jim Finn's profile

Jim Finn

1743 posts in 1668 days


#6 posted 06-09-2011 01:53 AM

Here are two images of items I made using just 5 degrees flare and cut in 6 or more sections.

-- In God We Trust

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j_olsen

155 posts in 1917 days


#7 posted 06-09-2011 06:29 AM

Thanks all

I was able to find a pdf chart that did the trick

-- Jeff - Bell Buckle, TN

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