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Cutting Vent Channels 2

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airkidd

airkidd

Industrial
Aug 9, 2002
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I need some help creating vent channels and runners. The channel has a profile to be projected along a path. The path has a 90 degree corner. I want a cut that looks like a ball end mill came to a 90 degree corner. I tried doing a swept cut using a path that matched the cutter radius at the corner but I get the error saying the profile intersects itself. Any ideas or do i need to clarify more?
 
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Thanks for the try scott but i havent ever seen a cutter that makes square corners. The outside corner of the 90° should be the same radius as the cutter. Anyone else care to give this one a whirl?
 
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"The outside corner of the 90° should be the same radius as the cutter."

This is the cause of your problem. The outside radius should match the DIAMETER of the cutter, not the radius. It is the radius at the cutter tip that will be equal to the radius of the cutter, making the inner radius of the cut zero.
 
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If what you want is the inside radius to not make a cut in a sweep cut with the guide curve going down thru the center. Then your out of luck, as far as I know. That is why your getting the error. It is cutting into itself which is not possible in SW.

I figured out what you need to do. Instead of putting guide curve in the center of the circle, put it on the side of the circle that you don't want the circle to cut through, rather you want it to roll around the point, if you get my drift.

See my example again for better understanding of this. The image is updated to this time. Scott Baugh, CSWP [spin] [americanflag]
credence69@REMOVEhotmail.com

*When in doubt always check the help*
 
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Sweep the cutter profile as two halves, with the outside radius first. Then, before sweeping the second half of the profile, fillet the corner. After filleting sweep the inner profile. I am unable to post to our website, but if you give me your email I will send an example.
 
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Thanks Scott, using the outside guide curve gives me what i want. I had tried this technique before posting the thread and that is when i got the error message. I am on SP4.0 so maybe it was just something i did wrong. I notice you didnt use any pierce constraints so maybe that is where i went wrong. Anyway, Thanks again.
 
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WAIT! That's not right either. The outside radius should only be half the cutters diameter. Well, back to the drawing board.
 
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No, the outside RADIUS would be .250 for a .500 DIAMETER cutter. I emailed you a workaround example, hope you get it. This seems to be a more complicated problem than i envisioned. LOL
 
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OK, I have sat down with this and I talked to a professional over the phone about this. The way I made it is correct.

If I'm using a .500" Diameter Endmill, the Ball of that Endmill or Raduis would be .250". When you start cutting the material, lets say the full R.250" is removing the material. It makes the full 90 degree path. If you look down in the Z axis (TOP) the inside corner will be a hard corner. The outside Radius will be the same as the Diameter of the Endmill, Dia .500". You can't get away from that, if your using the full depth of the cutter. If you look at the X or Y axis the depth and raduis in the Material will be .250".

Try making a .500 Diameter endmill with a .250 dome (for the ball of the endmill) in SW. Try running that endmill down the slot of the part I made. You will see I'm right on this.

It seems the folks hosting my site are down and I cannot upload the files. If you would email me, I would more the than happy to send them to you directly. I will update my site for other people to download it once they are back up.

Regards, Scott Baugh, CSWP [spin] [americanflag]
credence69@REMOVEhotmail.com

*When in doubt always check the help*
 
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Ok, I'm not going to say that what you modeled is wrong, but it is not what i want, and not what is practical for the machinist. Your assembly shows 3 ball-endmills. One for the X-axis move, one for the Y-axis move, and a third in the corner. The endmill that is in the corner moves in a circular motion when you move it in the assembly. This means that the CENTERLINE of your TOOL PATH has a radius of .250. I want a tool path with NO radius at the centerline. This way, the machinist only needs to program 2 moves for his tool, an X move and a Y move. With your model, the machinist needs the X and Y moves, plus he needs to enter another line of code for the radius at the corner. I have verifyed that my model is correct with more than one of the machinists here at my work. A tool designer with 15 years of experience also confirmed it. Unfortunatly, my model wont work with any other shape than round.

I will send you back a model with a tool path drawn on it. Thanks again.
 
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No offense Scott, but Airkidd is correct about the .250 radius. I have made this cut many times (15 years as a toolmaker). If this wasn't a ballnose the corner radius would be half the cutter diameter right? All the ballnose does is add a radius to the transition line. I can't open your model to see what you are talking about, as I have 2001 sp4.
 
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The solution to this problem is to model the cut as three separate features instead of one. If you try either a sweep or loft along centerline to create the cut it won't work. At the 90 deg bend the profile must rotate and the half of the profile which is closest to the inner corner rotates back on itself. Create your cut as two separate extruded cuts (for the straight sections) and a revolved cut at the 90deg bend and you will get what you are after.
 
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There are two ways to model this correctly.

First would be to individually cut-revolve the cutter dia at the point of the 90° turn, and then cut-sweep the cutter bottom profile individually to the centerline of the cut revolve.

A better method would be to do this in two individual cut sweeps.

Since the bottom profile of the cutter is a semi-circle, you need to cut-sweeep two quarter-circle profiles.

The left side quarter (refereing to the inside on the bend half) is swept along a right angle guide line which is on the top surface and pierces the OD of the arc.

The right side quarter (outer half around the bend) is swept along a right angle guide line with an inclusive sketch fillet radius equal to the ball mill radius which is also on the top surface and pierces the OD of the arc.

Both these methods will produce the correct cutter profile after the cut.

If you want to send you a simple model of this, or need further clarification, let me know.

Good Luck....... [thumbsup2]

Remember...
"If you don't use your head,
your going to have to use your feet."
 
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meintsi,

if you could send me a sample of the second way you described of making this cut, that would be great.

airkidd@hotmail.com

thanks
 
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