60° cut?

[kruger]

I have to cut 3 pieces with an angle of 120 ° to create a future cylinder on side grain.
I know how to cut 6 triangles with an angle of 60 ° to make a cylinder ... but I stuck to do the same thing with only three triangles of 120 °
How can i cut this 60° angle on a table saw ?

Thanks

Norbert

 

[jttheclockman]

Need some more info. I am guessing you are talking about cutting staves and forming a circle. You have done in the past cut 6 pieces to form a circle and now you want to only use 3??? What size circle are we talking about.

360 degrees 3 staves = 120 degrees / 2 = 60 degrees per side. Set blade to 60 degrees. This is where a wixey angle finder comes in handy.


360 degrees 6 staves = 60 degrees / 2 = 30 degrees per side.


Again not sure if you are doing on the flat or on end. On flat tilt miter gauge, on edge tilt blade.

 

[magpens]

Just to clarify .....

..... do you want to make a "cylinder" whose cross-section is an equilateral triangle ?

If you do, then bear this in mind: the "included angle" at each corner of an equilateral triangle is 60 degrees .... I am sure you know that.

So the "excluded angle" at each corner is 120 degrees.

That would mean, if I understand your requirement correctly, that you want to tilt your saw blade to 60 degrees from the vertical position, because at each corner of the equilateral cross-section you will want a cut bevel at 30 degrees to the horizontal so that two bevelled pieces then combine to 60 degrees (included angle of the equilateral corner).

Adjusting your saw blade to that angle would be difficult or impossible, I would think.

So tilt the saw blade at 30 degrees from the vertical, and make a sloped base (to lay on the saw table) to give another 30 degrees.
(Exactly how you make and hold that sloped base I do not know.)

The edge of your work piece will then be bevelled at 60 degrees from the vertical. . (30 degrees from the horizontal)

When you put two sides of your desired "cylinder" together there will be a 60 degree included angle (which will show a cut bisecting each of the 60 degree included corners).

Anyway, I may be misunderstanding you, but that is my "conceptual" (not necessarily practical) solution to the problem.

Now, then, if you want a cylindrical ROD with the cross-section of an equilateral triangle, the process is quite a bit easier.

Are you actually making a pen ( ie. ROD ) ? . Size is what might limit you (and dictate the process) if that is the case.
But I would think that you could quite easily drill a triangular ROD on a lathe using a 3-jaw chuck in the head stock.

Of course I don't know what cross-sectional shape you require the cavity to be .... maybe it has to be of triangular cross-section also ?

 

[howsitwork]

Attach a sacrificial stabilizing piece to the back of the work. Set your blade depth at a 30* angle to just cut through your workpiece into this sacrificial bit, making sure you have plenty of safety depth above the bit being cut. Then cut the piece on both sides . removing the 2 pieces leaves you with a section attached to your sacrificial plank piece with an included angle of 120*

To,do this you must remove the top saw guard but DO NOT remove the splitter , merely make sure it is lower than the top of the blade but ONLYJUST lower.

I know what I mean but describing it in words is tricky, hope that helps?

 

[Dieseldoc]

Just make a sliding table jig.
You tube will tell you how segment bowl makers cut the pieces. Just type in ( cutting segments for bowls) Very SAFE way to do it.

 

[magpens]

It just occurred to me that maybe you would be happy with cutting beveled edges of 60 degrees (saw blade at 30 degrees from vertical).

It so, I think that is quite easily doable, but your result would have 3 exposed cut edges, and the side-to-side joints would be butt joints rather than proper "corner joints" that conceal the cut edges.

 

[jttheclockman]

Again not sure what it is you are wanting to make but here is an example of staves that were compound cut. I know not exactly what you want but the same principle if you want to make a barrel type item. This was done using a sled and tilting blade and also tilting angle of miter. If you are making rings for a bowl than no need to tilt blade.

 

[Jolly Red]

I think you will have to cut it in the manner shown on the attached drawing. It will require two cuts with the width of the board vertical. A fixture such as a tenoning jig will be required to hold it in this orientation safely. This is also limited to the depth of cut of your saw. Be sure to leave some flat edge against the top of the saw table for support.
Good luck, Tom

 

[kruger]

Need some more info. I am guessing you are talking about cutting staves and forming a circle. You have done in the past cut 6 pieces to form a circle and now you want to only use 3??? What size circle are we talking about.

360 degrees 3 staves = 120 degrees / 2 = 60 degrees per side. Set blade to 60 degrees. This is where a wixey angle finder comes in handy.


360 degrees 6 staves = 60 degrees / 2 = 30 degrees per side.


Again not sure if you are doing on the flat or on end. On flat tilt miter gauge, on edge tilt blade.

Sorry for the long time...

The 3 triangles are designed to make a cylinder 40 to 50 mm Ø and 250 mm long
My table saw can cut from 90° to 45°.

Thanks.

 

[kruger]

Attach a sacrificial stabilizing piece to the back of the work. Set your blade depth at a 30* angle to just cut through your workpiece into this sacrificial bit, making sure you have plenty of safety depth above the bit being cut. Then cut the piece on both sides . removing the 2 pieces leaves you with a section attached to your sacrificial plank piece with an included angle of 120*

To,do this you must remove the top saw guard but DO NOT remove the splitter , merely make sure it is lower than the top of the blade but ONLYJUST lower.

I know what I mean but describing it in words is tricky, hope that helps?

My goal is to achieve an assembly, resulting from the bonding of three "triangles" which will give once turned a cylinder. The Ø of this cylinder will be 40 to 50 mm for a length of 250 mm. You give me a lead. Thank you.

 

[kruger]

Again not sure what it is you are wanting to make but here is an example of staves that were compound cut. I know not exactly what you want but the same principle if you want to make a barrel type item. This was done using a sled and tilting blade and also tilting angle of miter. If you are making rings for a bowl than no need to tilt blade.

View attachment 244116View attachment 244117

That is exactly what i want to do.
There i see 8 staves (20° angle).
I want to cut only 3 (60° angle)

Have yous pics for this jig?

Thanks

 

[jttheclockman]

Sorry I have no photo of the jig I use to make these. Did them quite awhile ago when I was making bottle stoppers. It was a simple jig. It is a little hard to explain and maybe there are others who can explain it better but, the thing when you talk about 60 degrees bevel angle you have to remember the steepest angle or bevel a tablesaw can cut is 45 degrees on the flat. But if you stand the board on edge and ride against the fence then set the blade angle to 30 degrees. the corresponding angle is 60 degrees +30=90 You need to figure out a safe way to hold the board and keep fingers away. The other way is to lay the board flat on the table but now you must raise the board and hold in the angle desired. This way is much more dangerous. There are videos out there explaing how to cut bevel angles safely. You need to be able to make a jig to hold this safely. I do not want to start giving ideas on jigs in fear of you not picking up what I am trying to convey and getting hurt. But what you are attempting is to make staves with an angle bevel of 60 degrees on each side.

Here is a video of making a tenoning jig which is basically what you would need.