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Author Topic: I Wish There Was A Wizard For This!  (Read 6818 times)

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Offline Bjorn Toulouse

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I Wish There Was A Wizard For This!
« on: April 14, 2011, 05:03:01 PM »
What I'm trying to do is machine a convex segment of a hemisphere.
Yes, I know it would be a slam dunk with a lathe, but I'd like to do it on the mill (no manually cranking handles, thank you).

The dimensions of the hemisphere:   R1- base radius - .3935"
                                                    R2- top radius -  .1625"  If you look closely at the setup pics you can see there is a .325" hole in the center of the stock.

Tool: 3/8" ball end mill (tip radius .1875") 

If my math is correct the finished height (H) of the segment will be .231" ( R1 - R2 = H )
The formula seems too simple, am I missing something??

I figure that the program will be a series of circular cuts beginning at the edge of the center hole with each successive cut being .001" larger in diameter as the tool
progresses downward .001" from Z-0.
What I'm having trouble wrapping my head around is the relationship between the radius of the segment and the radius of the tool.

At Z-0.001 the tip of the tool will be engaged on the top of the stock. As the cut progresses the the engagement point will steadily move away from the tool center (zero radius)  towards the side of the tool and full radius at a cut depth of .1875".
Can Mach do this, or do I have to program the X-Y circular moves to compensate for the increasing cutter radius? 

Here's a couple of pics of the setup, any constructive comments will be greatly appreciated.

Thanx,


Rex



Offline BR549

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Re: I Wish There Was A Wizard For This!
« Reply #1 on: April 14, 2011, 09:45:34 PM »
There are two ways to do it in mach3.

1 the circle approach where you make expanding circles that form the shape

2 a X/Z arc method starting from one side and going to the other to make the shape.

I have a macro here somwhere that will do it. Ill see if I can find it for you.

(;-)

Offline Bjorn Toulouse

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Re: I Wish There Was A Wizard For This!
« Reply #2 on: April 15, 2011, 02:06:50 PM »
I will GREATLY appreciate any assistance!!


Rex
Re: I Wish There Was A Wizard For This!
« Reply #3 on: April 15, 2011, 03:14:34 PM »
I have trouble understanding what you want.

Do you have some kind of drawing to better see what's in your mind.


Then I could draw it in a cam software and get the program


Jeff

Offline Bjorn Toulouse

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Re: I Wish There Was A Wizard For This!
« Reply #4 on: April 15, 2011, 09:46:01 PM »
Jeff, look at setup pic #2..........in my mind the end mill cuts in a widening circular X-Y motion (G17),
starting at the OD of the .325" center hole, arcing down to the finish diameter of .787".
The end result will be a truncated (flat topped) hemisphere. Simply a ball end on the stock.

In his reply BR549 mentions an alternate method using X-Z motion (G18) that I had not considered, thinking it
would require a rotary move of the part.

Thanx for your interest!


Rex

Re: I Wish There Was A Wizard For This!
« Reply #5 on: April 16, 2011, 02:08:19 AM »
Is the part look like this, sorry.



Jeff
« Last Edit: April 16, 2011, 02:10:44 AM by ostie01 »

Offline Bjorn Toulouse

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Re: I Wish There Was A Wizard For This!
« Reply #6 on: April 16, 2011, 08:28:00 AM »
Jeff, that is exactly what is in my mind! Although I was thinking a shade of red.  ;)

What program did you use to develop the image?
I've got to get into CAD/CAM.


Rex
Re: I Wish There Was A Wizard For This!
« Reply #7 on: April 16, 2011, 12:05:04 PM »
Use Mastercam.

Can save it to some format and post it.


Jeff

Offline Bjorn Toulouse

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Re: I Wish There Was A Wizard For This!
« Reply #8 on: April 16, 2011, 09:51:39 PM »
A MS Word .txt should work, eh?


Rex

Offline Graham Waterworth

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Re: I Wish There Was A Wizard For This!
« Reply #9 on: April 17, 2011, 06:08:14 AM »
Why not mount the part on a mandrel in the mill spindle and mount a tool in the vice and use the mill like a lathe.

Graham
Without engineers the world stops