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how to create pattern for fan ventilation?


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I am trying to pattern an obround punch about an axis to create a ventilation cutout for a fan. has anybody done this before, know how to do this or possibly have a saved UDF they could send me? There has got to be an easier way to do this than what I have been trying...



An obround punch UDF should be easy to do. Please be more specific as to what the problem is.

You should have a coordinate system on the punch and have only 1 cut, multiple cuts don't work. You can make the one cut and then pattern it in the finished part.

If you are referencing the location to a bend line or edge then use the same reference in the UDF.

Thank you for your response jperkins. I am trying to pattern a .125x1 obround punch to create a ventilation cutout for the inlet of a standard 80 mm fan. From my limited understanding of patterns, I am having trouble getting a 2D pattern to follow the circular profile of the fan. If I was to make a simple rectangular pattern it would work easily. I have tried patterning 1/4 the fan cutout, then mirroring twice about the centerline but have not gotten it to work. My next effort will be to contruct the entire pattern in sketcher mode :(

Can you create a larger pattern than necessary and go back and select individual features to delete?


Are you doing a circular pattern? I'm kinda lost when you say your having trouble getting it to follow the circular profile of the fan

I am not doing a circular pattern. Ill try to explain it better. Say 10 rows wide the punch would hit 3 or 4 times (lengthwise) across the middle of the fan. Then as the pattern gets further from the center of the fan, I would like to have a row of 2 or 3 hits. Then when it gets towards the outside just have a single hit. I am trying keep the pattern only in the area where the air is circulating, thus roughly following the circumference of the fan. I dont want it to overlap to much over the edge of the fan for aesthetic purposes. I hope this helps explain my problem better.

Do you have a specific patterned punch that you plan to use?

If not then think about this, most punches on CNC machines set to 0 or 90 degrees. Only special punches go at other angles but they are usually prespecified and only 1 or 2 places. A pattern punch with multiple cutouts are sometimes used but these are also specials refered to in the first line.

You can pattern features both circular and rectangular. If you plan to use a single obround punch with multiple hits then a rectangular pattern would be much easier to fabricate by the shop.
Ok I've got it now, thanks.

You can't delete individual instances of a pattern (unless you are using wildfire) and you're probably losing some references when you try to mirror the features.

Your best bet is to use a pattern table, I may try it to see how it works, but sheetmetal is not my strong suit :)
Sorry, I hit the wrong key.

You might just think about making a cut and patterning it rather than a UDF. They are great for complex shapes like a D-sub connector but a waste of time for simple shape like an obround.


I have never tried using a pattern table. Ill play around with it a bit and see if I can get it to work. Thanks for your help...

is this approximately what you wanted?

View attachment 199

I used a pattern table referencing a cut. I am sure you could do it with a punch. The datum curve represents the fan diameter.

Let me know if you want the model file.

Regards.... :)

that is exactly what I am trying to do. I would greatly appreciate the model file to see how you created the pattern. What cut did you reference to create the pattern? My email is [email protected]. Thanks again for your help.