3" Radius Edge

[erniek]

I've been asked to build a circular sign with a 3" radius quarter round edge.

How is the best way to program cutting that edge since there's no such thing as a 3" radius router bit.

I'm thinking I could use a ball nose bit and do multiple passes. I don't have
much 3D type design experience so could use some help.

[steve_g]

Ernest...
What design software do you have... that will make the biggest difference in how you approach this!

SG

[erniek]

I have artcam, ecabinets and autocad. I'm thinking the thickness may be an issue as well. I may have to move my spindle up higher if that's possible and get a 4" long bit. The only thing I've seen that long is a 3/4" ball nose bit.

[steve_g]

I have artcam, ecabinets and autocad.

If some of those experts (not me!) can't help you... the "extrude" tool in SB3 my be the answer. Let's wait and see if those users can help first!

SG

[gc3]

create a 1.5" radius form tool use lead in toolpath half the depth of the blank flip and repeat toolpath for 2nd side you should be able to find a 1.5" radius bit without a bearing

[coryatjohn]

Oberg Brothers (obergbrothers@verizon.net) has two 6" length 1/2" bullnose bits. Here are the details:

1/2"dia 1-1/2"loc 6"oal $87.91ea XXL200B12
1/2"dia 3"loc 6"oal $88.04ea SL200B12

[Joe Porter]

You should be able to do this with ArtCam Pro. A two rail sweep with the proper radius. Maybe check on the ArtCam forum for some help...joe

[Steve M]

If you are cutting a constant radius quarter round, you will likely get the smoothest results and shortest cut time if you use the largest diameter FLAT bottom cutter that will fit your router. You can only do this if your program the tool path to raster at 90 degrees to the edge.

A long ball nose, .5" diameter, cutter will also work well if programmed to cut along the edge at 4% stepover. This will take much longer than a flat cutter and will require some sanding.

[erniek]

Thanks for all the advice, guess I'm gonna have to learn ArtCam a bit better.

Steve M. I don't think I can raster 90 degrees to the edge as I only have a 3 axis machine.

[bob_dodd]

Ernest If you use the "spin tool" in ArtCam , with a vector 1/2 the dia of the sign , with the radius that you need on one end , and the thickness of your blank on the other (middle) , you could limit the machining to just the area of the radius with vectors . If you remove dust shoe , you should be able to reach the radius with a shorter bit If you need help with the file let me know Bob

[Steve M]

I don't think I can raster 90 degrees to the edge as I only have a 3 axis machine.

It's done on a 3 axis machine. Instead of cutting along the edge like you would do with a ball mill, you cut across the edge.

I'll try to post a screen shot from RhinoCAM later today.

[Steve M]

Machining a large radius. You should be able to do this with a .5" diameter cutter that is 2.5" long.

Desired radius, 3".

http://www.tacpro.com/images/radius machining.jpg


Along the edge with a ball mill:

http://www.tacpro.com/images/ball mill.jpg


Across the edge with a flat mill:

http://www.tacpro.com/images/flat mill.jpg

[tomwillis]

Steve - do you have RhinoCAM Pro? I only have standard....and as a practice session - I also was playing around with this both in Rhino & RhinoCAM.
Tom

[Steve M]

Steve - do you have RhinoCAM Pro?
Tom

Yes.

I neglected to mention that the cutter can be 2.5" oal, or less if measurements are made carefully.

[erniek]

Steve, interesting way to do that with and with an endmill bit as well.
I will keep it in mind if the job comes my way.