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# Difficulty patterning a cut

#### JimiH

##### New member
Hi all,

I'm having great difficulty patterning a cut I have.

It's a extruded circle with one cut on the outer edge at 90 degrees.

I want to pattern the cut around the circumference of the circle 8 times.

I've had no problem pattening a hole but cant seem to use the same method

for the cut.

Hope you guys can help

Geoff

Can't understand what your geometry looks like, but almost always the problem is references. Don't reference anything that won't be at the next location except the make datum you used for the sketch or horiz ref plane.

dimension the radius of diameter your using, use a centerline, then dimension a 45 degree angle, since you have 8 cuts, then reference that 45 as your driving dimension, use varying pattern

DO NOT dimension your cut to a centerline. Centerlines do not cary direction with them. For a perfectly semmetric pattern it won't matter but if you do a pattern of say 3 cuts at 60 deg you can not guarantee which direction the pattern will move. ALWAYS use a make datum when creating sketched features to be patterned in an angular direction.

Just to add to what Jake has said, when generating a rotational pattern, always use a make datum. This is also the receommended practice from PTC.

Never ever use a sketched centreline as a reference. Based on my experience a rotational pattern based on a dimension from a centreline is not stable (even if the pattern is symmetrical).

I have seen too many patterns that, according to the designer, Have always regenerated without any problems. that failed for no apparent reason whatsoever. And the cause has always been that the rotational pattern used a centreline dimension as the pattern driver.

Hi thanks for your input, I just cant seem to get my head round this, Is the make datum where I sketch the cut or the reference for the cut, Help confused.

JimiH

The make datum is the horizontal or vertical reference plane for sketching, not the sketch plane. Although, you could still do a make datum for the sketching plane in addition if you wanted to.

Thanks RedTide, I will give it a go tonight.

JimiH