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Blog entry by aussiman posted 07-22-2008 06:57 AM 908 reads 0 times favorited 15 comments Add to Favorites Watch

I have a question for all you much more experienced guys than me how is the best way to put a 3 inch wide half round groove down the middle of a 6 inch wide by 3 foot piece of timber when you cant get a core box bit that big to do it with I want to make 2 and join them together to make a 6X6 inch piece with a 3inch hole in it from end to end
I’m still new to woodwork so I don’t know all the tricks yet
Bill



15 comments so far

View OutPutter's profile

OutPutter

1199 posts in 3450 days


#1 posted 07-22-2008 10:20 AM

You could probably use a router. The bit choices depend on the exact shape of the hole. If you want a square hole, use a straight bit. If you want a round hole, use a cove type bit.

Your two pieces of wood would need to be 6” x 3” x 36” in order for you to join them and end up with a 6” x 6” x 36” piece. Are they? If so, you may want to consider cutting the two pieces in half along their length so you have four 3” x 3” pieces (this would require the pieces to be a little wider than 6” because the saw will take away some of the wood). Then you could use the cove bit along one edge of each piece which may be easier than routing a groove down the dead center of the two 6” x 3” x 36” pieces.

I guess it’s going to depend on the tools you have. Can you supply more information? You may get more responses with more information about what you’re doing and why you’re doing it.

-- Jim

View Doug S.'s profile

Doug S.

295 posts in 3168 days


#2 posted 07-22-2008 11:51 AM

I’d make multiple rip cuts as close as you dare to the halfround layout line the follow up with a large carving gouge then scraper (or round sanding block) to smooth out to the final shape. Woodhaven aso makes something called the AngleEase made for routing at angles. It’s intended for fixed angles but has an adjustment crank for pivoting. With appropriate safety precautions, you might be able to swing a bi in an arc, then move it down and repeat, but it would take quite a few passes.

-- Use the fence Luke

View Doug S.'s profile

Doug S.

295 posts in 3168 days


#3 posted 07-22-2008 01:16 PM

There’s something else I didn’t think of before that might work even better. I haven’t personally done this, but do a google search for something like table saw cove-cutting. You should be able to find some info on the method and formulas for setting the aux guide fence angles to get the shape you want.

-- Use the fence Luke

View NY_Rocking_Chairs's profile

NY_Rocking_Chairs

507 posts in 3057 days


#4 posted 07-22-2008 02:22 PM

I do the table-saw cove cutting quite frequently. The problem with this method for this application will be that your cove will be the radius of the saw blade. So in order to get the perfect 3” diamter, you will need to find a 3” saw blade, and then a 3” blade would not lift high enough to get the 1 1/2” depth, since half the blade would have to be exposed.

This method would be ok if you don’t care about the roundness of the hole. It would allow you to hog out a lot of wood though and then you could use a different method to finalize the cove.

The best way to do this method is to have a fence clamped to the table saw, then you can raise the saw blade 1/16” each pass, about 1/4 turn on most table saws. I would build a jig to hold the board to keep your fingers away from the ends where the blade will come out.

Good luck.

-- Rich, anybody want a peanut?

View Doug S.'s profile

Doug S.

295 posts in 3168 days


#5 posted 07-22-2008 02:59 PM

Rich
Like I said, I haven’t done this and wondered about the blade diam thing before posting. But if you had the right feed angle so that the final cut at 1-1/2” was exactly 3” wide, what do you end up with? Some sort of half-ellipse rather than a half-circle?

-- Use the fence Luke

View aussiman's profile

aussiman

31 posts in 3193 days


#6 posted 07-22-2008 03:50 PM

Thank you for all your advise so far. ok as for more information on why and what I’m doing I want the hole in the middle a round hole I am going to glue a darker wood in the middle 3inches diameter to match the hole and I am going to machine a spiral on the outside that is deep enough to expose the darker inside I have a ornamental mill to do this I am making a plant stand I hope this helps I just wondered how to get the large hole in the middle
Bill

View rtb's profile

rtb

1101 posts in 3173 days


#7 posted 07-22-2008 04:02 PM

Bill, why does the hole have to be round if you are going to machine a spiral, wouldn’t the result be the same if you used a square hole which is much easier to do ?

-- RTB. stray animals are just looking for love

View Bigbuck's profile

Bigbuck

1347 posts in 3123 days


#8 posted 07-22-2008 04:44 PM

Use the table saw to cut the cove, do a search on the net and you will get plenty of info. Here is some info
http://woodgears.ca/cove/

-- Glenn, New Mexico

View Bob #2's profile

Bob #2

3809 posts in 3482 days


#9 posted 07-22-2008 04:52 PM

If it’s flat you can dado it with the table saw.
If it’s not flat you could build a sled to run it through the dado blade.
Take little cuts to prevent kickback.
Step the cuts to rough out the hole then finish it with a router bit.
We don’t know what you are trying to make, only the form you require.
It would help knowing the end use of your project.

Bob

-- A mind, like a home, is furnished by its owner

View aussiman's profile

aussiman

31 posts in 3193 days


#10 posted 07-22-2008 05:11 PM

like i said befor its is going to be a fancy plant stand and I want a round hole so the darker wood showing will be uniform and will look like the middle of the prirel is darker.I found some info on the net about table-saw cove cutting thanks to Rich & Luke but im not sure it will do a 3inch I havent had time to read it yet its very late here im in Australia I will look at it tomorrow
Bill

View NY_Rocking_Chairs's profile

NY_Rocking_Chairs

507 posts in 3057 days


#11 posted 07-23-2008 01:59 AM

Glenn,

That is a great link, I was always cautioned and under the impression one should cove perpendicular to the blade. Bill should be able to do exactly what he wants to do with that.

-- Rich, anybody want a peanut?

View motthunter's profile

motthunter

2142 posts in 3259 days


#12 posted 07-23-2008 02:35 AM

you can get a cove cutting jig for your table saw

-- making sawdust....

View aussiman's profile

aussiman

31 posts in 3193 days


#13 posted 07-23-2008 10:01 AM

yes I think I can do it now I am going to give it a try on the week end there was a book in our local libary called jim tolpins table saw magic it has a section in it on this and other interesting stuff to thanks guys for the info Bill
ps if you can post pics on here I will show you how it turns out when i finish making it

View Jon3's profile

Jon3

495 posts in 3565 days


#14 posted 07-23-2008 09:29 PM

Wouldn’t it be easier to use a holesaw, or perhaps a circle cutter to make that hole?

View aussiman's profile

aussiman

31 posts in 3193 days


#15 posted 07-24-2008 12:15 AM

the timber is 3 feet long too long for any hole saw I know of

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