Rippled Finish??

[Tinny]

Hi Guys,

I have a problem where I am doing a surface finish parallel over multiple surfaces on a part model supplied by the customer. Sometimes the surface finish is "rippled" with some very small gouges into the faces it is meant to blend into. Anyone else have this problem?? I have created one surface with the same result. I have tried a Flowine but this produces wierd results with the tool forever retracting off the job! Help!!

 

Tinny

[mross]

If you use flowline. Play around with the gap settings to keep the tool from retracting

 

It is set to broken by default.

I use direct and change the gap size to distance and enter a large value.

 

HTH

[BernieT]

Is your cut tolerance or filter tolerance set to less than .001 ?

 

Try total tolerance of say .0006 or less with a filter ratio of 2:1

 

HTH

[Lumpnut]

I use finish parallel alot with great results. What are your cutting parameters? Material? Is the cutter diameter to big to blend the two surfaces?

 

Chris

[Chris Rizzo]

Ripple looking affect could be total tolerance settings. What are your filter settings/total tolerance? Tighten those up a bit possibly, (2:1 .0005) even turn filter off maybe.

[Mike Whitten CAD/CAM Contractors]

Tinny,

 

Is it just in the steep areas?

[Tinny]

Hi,

my total tol for the parallel finish was 0.05mm, filter ratio of 2:1. Material is aluminium. I will try tightening it up tomorrow.

The flowline was wierd because I am generating a stepped diameter with a 2 mm chamf with a ballnose and the toolpath would start at the 12 o'clock postion, run down to 3 o'clock position, then retract, move to 9 o'clock and feed to 12 o'clock.

 

Tinny

[Tinny]

on further reflection could this be because the "normals" start in the 12 o'clock position?

 

Tinny

[Mike Whitten CAD/CAM Contractors]

Tinny,

 

Is the problem just in the steep areas?

 

The key with flowline is the gap settings. You may need to drastically increase them.

 

Is sounds like you may want to try Project blend with a center point.

 

http://www.mastercam.com/Support/TechTips/#projectblend

 

HTH,

Mike

[Jim at Gentex]

If it were done w/ a 5 axis multisurf prog you can use lead/lag angle to keep the tip from dwelling and leaving surface drag marks. Otherwise, as previously stated, you will need to manipulate the flowline gap settings and try the Project blend as Michael suggests.

 

[Chris Rizzo]

Project blend works how you think flowline SHOULD work. I've gotten flowline to work by being very careful when selecting multiple surfaces to select them all in the same relative "position" to each other....ie. "upper right corner" of each surface, or such. esp. noticable when doing round features where you want the tool to just travel around the thing, and not jump all over the place..

 

then again, try project blend

[Mike Whitten CAD/CAM Contractors]

Ooh, so cmr, it matters how you select them? I have never got real good with surfacing because we never get to do it very often.

 

Thanks cmr,

 

Mike

[cadcam]

The problem and the ripples are coming from Parrell surface tool path.

 

This particuler path does not do well with step or close to virtical walls.

So as the stepper the wall the more the path starts to break apart in ways.

 

Not like Flowline were it trys to stay constant step over know matter the surface angle.

 

Try the Project blend 3d option.

 

Can you share the file?

[Tinny]

Jay/Everyone

I have tried the project-blend but that produced a toolpath with a very good finish, but had a large file size. It may be the geometry I used for the blend. I will tinker futher. I had a lot more success with the flowline. Like I said earlier the toolpath was starting at the "normals". If I rotated the surface 60deg to a place where the tool could not get to, it behaved well. Better still was an open surface rather than the full diameter crated before. My only complain now is that the tool stutters around the chamfer slightly.

 

My file is not one I can share, I can strip out everything but the few surfaces concerned, and post later when I return home.

 

Many thanks to all of you for the assistance

 

Tinny

[Teh Bear without Brains kinda idiot]

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I can strip out everything but the few surfaces concerned,

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That`s not perfect ,if you will not delete blanked entities too .

Just a thought .

Better to make File->save as and select your appropriate entities .

[Mike Whitten CAD/CAM Contractors]

Tinny,

quote:

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My only complain now is that the tool stutters around the chamfer slightly.

---

You may need to change the cutting method to "one way" instead of spiral so that it filters better. Look into high speed or look ahead codes for the machine. You also might have to loosen up the tolerance a bit.

 

Mike

[Tinny]

Thanks Mike,

I have loosened the total tolerance ( I had tightened it right up ) and it is a lot better.

 

Tinny

[Mike Whitten CAD/CAM Contractors]

Cool!