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Contour/ramp leavinin facets


mcpgmr
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Maybe a bug?

 

Any one ever come accross this? Cutting a groove (rectangular racetrack with rads at corners) with a ball endmill using contour ramp. Using .5 degree ramp angle and have linearization tol set to .0002 which is as low as it goes. Geometry is lines and arcs only no splines. Two of the four corners are smooth and the other two are faceted.

 

headscratch.gif

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quote:

Two of the four corners are smooth and the other two are faceted.

I'd be looking at the machine. Is it happening in the 2 corners where the same axis would be reversing? Backlash issue?

 

I'd "expect" at least all 4 to be this way if it were a "code" issue.

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I've seen this several times. Usually a circular or oval cone or dish surface. Two opposite quadrants have a nice smooth finish and the backplot and code show arcs here. Two remaining quadrants have facets, back plot and code show short straight line cuts. Sorry but I never got this problem solved but I think I saw a solution for it but it wasnt needed at the time I saw it so I moved on. I will watch this thread, it's one problem that will bite me again some day, I'm sure of that.

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Thanks guys. I have linearize helixes unchecked. I turned on the filter and set it to .0002 as well. I haven't cut the part yet. This shows up in verify with quality cranked all the way up and tol set to .002. What worries me is I made a bad part a few months ago and the part looked exactly like what verify was showing. Fortuantely we were able to polish the facets out but it was close to being scrap. I have to ramp due to the nature of the material and can't have any tool marks from plunging down in z. My last pass is a simple contour without ramping taking just a few thousanths but that doesn't help much since the ball mill already cut the walls on the "z" roughing passes. No room for comp. Driving the tool down the center of the groove.

 

 

What I would like to do is use the ramp height setting in the lead in and lead out parameters but that only works with a perpendicular approach not tangent. The tolerance of the spherical shape of the groove is +/-.0005 so not much room to play.

 

I looked at the code and since I turned of the linearize on helix and turned on the filter I get this which looks good. It shouldn't leave facets now. At least not that I can see. Thanks again!

 

( .204 CARBIDE BALL ENDMILL T-41947 TOOL - 13 DIA. OFF. - 13 LEN. - 13 DIA. - .204 )

N8 (RF GROOVE 1ST PASS +.005)

N10 T13

N12 M6

N14 G0 G90 X0. Y1.5925 S3745 M3

N16 G43 H13 Z2.

N18 Z.1

N20 G1 Z0. F1.87

N22 X-6.1496 Z-.0537 F7.49

N24 X-12.209

N26 G3 X-12.619 Y1.1825 J-.41

N28 G1 Y-1.1825

N30 G3 X-12.209 Y-1.5925 I.41

N32 G1 X12.209

N34 G3 X12.619 Y-1.1825 J.41

N36 G1 Y1.1825

N38 G3 X12.209 Y1.5925 I-.41

N40 G1 X-6.1496

N42 Z.0463 F50.

N44 G0 Z2.

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[ What I would like to do is use the ramp height setting in the lead in and lead out parameters but that only works with a perpendicular approach not tangent. The tolerance of the spherical shape of the groove is +/-.0005 so not much room to play.]

 

You can use ramp height setting in the lead in and lead out with tangent but just make sure that the "gouge check" is un-checked on the lead in and out page. I just figured this out yesterday. I too thought the same as you but when I un-checked gouge check it works.

 

As far as your other problem I'm not sure.

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  • 2 years later...

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