Making a symetrical trough

[myxpykalix]

I am making a hollow design and after using a 1" corebox bit to make the hollow center I realize the hole is not circular and that will make the inside look bad for a hollow spiral so i need to make a symetrical trough and frankly I have forgotten how to. I went into PW and made my 1.5" circle cut it in half and now need to use the "extruder" tool for the length?

8427

8428

[magic]

One way is to use a large round bit and make an easy jig that tilts one end of the work piece.

[Gary Campbell]

Jack...
2 ways that I can think to do this would be: 1) use a 1.5" diameter core box bit and multiple passes. 2) toolpath a 3/4" radius semicircle below the Y zero line and send it to the extruder and then cut with a bit of your choice.

1) is simpler, but requires bit purchase if you dont have one.
2) will take more computer work (time = money) but can be toolpathed and cut with a bit on hand.

Note: Check your math, you cant get two 1" remainders and a 1 1/2" hole from 3.25" material. Takes 3.5" plus the saw kerf if cut from a solid piece.
Gary

[myxpykalix]

The way i use math in my world is 2+2=5 no wonder i have so much trouble!

You are correct, i was going on memory trying to remember the measurements so i wouldn't have to bring the material in with me.
Now lets see if i get this done right.
I have a 1" corebox bit but wanted to make the hole 1.5" and thought i could do it the easy way....not!

[Gary Campbell]

Jack...
You may be able to cut the larger hole with a 1" corebox, but it may not have the cutting depth to be used with an extruder single cut profile toolpath. A 1/2" Ballnose endmill with a CEL of 1" is a safer bet.
Gary