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Shop improvements: Circle Cutting Jig

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Project by lanwater posted 1198 days ago 4033 views 24 times favorited 28 comments Add to Favorites Watch

This circle cutting jig is from ShopNotes volume 19 issue 113
The aluminum bar used in this jig was bought from Homedepot. It is 1/4” thick and 1” wide. They sell it in 36” and 96” length.

few modifications were done to the original jig:
-The size of jig was changed to accomodate my bandsaw
-The size of the adjustable radius bar to accomodate up to 60” in diameter (by flipping the bar 180 degree)
-The use of screw insert
-The hold down to attach it to the bandsaw. I added one in the back of the jig as well to help with larger circles.

The first step in building this jig was to cut a piece of plywood that fits your bandsaw.
I decided to use some plastic laminate on the top that I glued on with contact cement.
I did not have a large enough piece so I used 2 smaller pieces. I also did not have a laminate trim bit so I have a visible line in the midle
I Used a flush trim bit to get rid off the excess laminate and a roundover bit to get rid off the sharp edges.

Bottom dado on the bottom for the sliding mitter.

Groove 1” wide centered on the line perpendicular to the blade to hold the bar that sets the radius.

Holes drilled and tapped 1.5” on center.

Small nail used as the pivot.

Slot to allow the bar to slide and set the radius of the circle you want to cut.

Stop block with screw to fine tune the pivot and blade perpendicularity. I used a length of threaded rod with an electric cap on it.

Block to secure the jig to the bandsaw so it does not move during the circle cut.

Hold down on the back to make more stable when cutting larger circles. I used some of the aluminum bar I roughly bended.

Now I can cut great circles .

Comment /remarks, critics always welcomed.

-- Abbas, Castro Valley, CA





28 comments so far

View patron's profile

patron

12955 posts in 1938 days


#1 posted 1198 days ago

Now I can cut great circles .

words to be proud of

nice rig

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

View Dennisgrosen's profile

Dennisgrosen

10850 posts in 1712 days


#2 posted 1198 days ago

great transformation :-) congrat´s with your new toy
thank´s for sharing Ianwater

take care
Dennis

View Diggerjacks's profile

Diggerjacks

1735 posts in 1735 days


#3 posted 1198 days ago

Hello Lanwater

A very good jig

I’m working on mine and with yours a lot ideas are in my mind

Thanks a lot for sharing

I will post mine when the projet will be achieved

Wait and see and thanks for the inspiration

-- Diggerjack-France ---The only limit is the limit of the mind and the mind has no limit

View degoose's profile

degoose

6970 posts in 1951 days


#4 posted 1198 days ago

A great improvement using the alli bar… and I like the hold down at the back…

-- Drink twice... and don't bother to cut... @ lazylarrywoodworks.com.au For lovers of all things timber...

View lanwater's profile

lanwater

3073 posts in 1531 days


#5 posted 1198 days ago

David: This one I am happy with. Now I can work on a round breakfast table.

Dennisgrosen: Thank you! I played with it quite a bit. I cut four circles, I am not sure what to do with.

Diggerjacks: Thanks for the kind words.

Larry: The aluminum bar was very easy to drill and tap. Thanks!

-- Abbas, Castro Valley, CA

View wildbill001's profile

wildbill001

99 posts in 1239 days


#6 posted 1198 days ago

Love the wire-nut “knob” !

-- "You can tell the pioneers by the arrows in their back" -- Unknown

View Dennisgrosen's profile

Dennisgrosen

10850 posts in 1712 days


#7 posted 1198 days ago

if they are big enoff …. you have two lazzy larry´s … LOL
or small enoff ….. bricks to put on the table to place the cold beer on :-)

View SPalm's profile

SPalm

4743 posts in 2479 days


#8 posted 1198 days ago

Hey LW, looks impressive. My jigs usually are just thrown together.

Anyway, I am not sure about this question… Where should the blade be in reference to the circle’s centerline? In one of your pics you have the teeth just up to the center line mark. This is what I had thought. But after cutting a whole bunch of really tight curves, I found that the center of the blade should be aligned with the circle’s center line. I guess it only comes into play when the radius is getting close to the minimum radius for any particular blade width. Thoughts? I could be wrong.

Steve

-- -- I'm no rocket surgeon

View tdv's profile

tdv

1114 posts in 1667 days


#9 posted 1198 days ago

That’s another fine jig I find it amazing how many permutations we come up with on the same basic jig. Martyn (Britboxmaker) made a fine version too & although in priciple the same thing it was different I like it & it looks to do a perfect job. Thanks for sharing the photo’s
Best
Trevor

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

View Jim Jakosh's profile

Jim Jakosh

11055 posts in 1702 days


#10 posted 1198 days ago

Very nice retrofit for the big circles. It seems that everyone on here is improving on designs. Keep up the good work and thanks for sharing. I once had to make some huge radius templates. I used a trammel and cardboard and a scissors. If I had seen your setup, I could have made a special bar to go out to 100”(which was my max radius) and cut them out of 1/4” plywood. I use them a lot and the cardboard is getting worn.

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View lanwater's profile

lanwater

3073 posts in 1531 days


#11 posted 1198 days ago

wildbill001: I think it’s cool too. I saw that in one of jig books about a year ago and it stuck in my mind

Dennisgrosen: Those are great ideas. Nah, we leave that to Larry.

Steve: Man you have a good eye!
My understanding is that the the circle center should be on a perpendicular line to the initial blade kerf cut line and should meet at the teeth of the balde (I hope I phrase that correctely).
You are right In the picture the blade stops right at the line. It probably need 0.5 mm more into the line.
The red knob on this jig allow to fine tune the blade along the kerf line.

Trevor: Thanks my friend.

Jim: Thank you. My next task (at least according to my wife) is to make a round breakfast table. I think I am going to go out and buy one.

-- Abbas, Castro Valley, CA

View mafe's profile

mafe

9435 posts in 1686 days


#12 posted 1198 days ago

Hi Ian,
That is a really nice jig you have made there.
I will put it in the favorites.
Thank you for sharing this with us,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View lanwater's profile

lanwater

3073 posts in 1531 days


#13 posted 1198 days ago

Mafe: Thanks! I am prety sure you will make it much better with a lot of clever changes

-- Abbas, Castro Valley, CA

View Dusty56's profile

Dusty56

11638 posts in 2285 days


#14 posted 1198 days ago

Well done and thanks for sharing it with us : )

-- I'm absolutely positive that I couldn't be more uncertain!

View kiefer's profile

kiefer

2941 posts in 1264 days


#15 posted 1198 days ago

IAN
jigs are the spice of woodworking
keep making them ! improving and incorperating others ideas is great
i am like steve and just cobble something together most of the time because it is for one time use
if it works well i may build a better version later and look for input from others
this looks like a good jig
and please make that table
i take the wire nut from this great idea !

kiefer

-- Kiefer 松

showing 1 through 15 of 28 comments

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