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Mechanics and Construction => Mechanics and Construction => Topic started by: Admin on February 16, 2007, 02:09:19 PM

Title: CNC issue: removing lines with buffer?
Post by: Admin on February 16, 2007, 02:09:19 PM
Im having an issue with facing acrylic on my high precision CNC.

The issue is that no matter how many facing passes I complete, there are these lines appearing in the plastic (see picture). Anyone who has ever done part facing with a CNC or a mill has probably seen these lines at some point . . .

The lines (ridges?) are so small that you cant actually feel them (feels like a perfectly smooth surface, despite how it looks).

Originally I figured they were just optical distortions because of some kind of localized thermal heating that reorganizes molecules . . . but apparently it isnt.

Normally these lines fit very much within acceptable tolerances for people, but not today . . . This facing is used for a mold for a transparent polymer (similar to as seen in picture) that cures within the mold. Strangely, when I take out the polymer after it has solidified, the lines appear in the polymer too! This is bad because I need the transparent polymer to be an exact thickness with no optical distortions for high tolerance testing.

How do I get rid of these lines?!? I have heard of some kind of buffer tool that I can use for my CNC. Anyone know about this?
Title: Re: CNC issue: removing lines with buffer?
Post by: JonHylands on February 16, 2007, 03:07:11 PM
Picture?

- Jon
Title: Re: CNC issue: removing lines with buffer?
Post by: Admin on February 16, 2007, 03:26:44 PM
Quote
Picture?
ummm but the picture is attached . . . :P
Title: Re: CNC issue: removing lines with buffer?
Post by: JonHylands on February 16, 2007, 07:33:53 PM
Not that I can see...

- Jon
Title: Re: CNC issue: removing lines with buffer?
Post by: Admin on February 16, 2007, 07:39:07 PM
odd . . . what browser you using?

this link work?
http://www.societyofrobots.com/robotforum/index.php?action=dlattach;topic=598.0;attach=124
Title: Re: CNC issue: removing lines with buffer?
Post by: JonHylands on February 16, 2007, 09:52:32 PM
"An Error Has Occurred!
It seems that you are not allowed to download or view attachments on this board."

I guess I'm not special enough to rate attachment privledges... ;-)

- Jon
Title: Re: CNC issue: removing lines with buffer?
Post by: Admin on February 16, 2007, 11:56:44 PM
hmmm it appears the permissions werent set entirely right . . . can you see it now?
Title: Re: CNC issue: removing lines with buffer?
Post by: JonHylands on February 17, 2007, 06:34:22 AM
Yes, I can see it now :-)

You are using an endmill, right?

I typically take out the lines like that on a flat surface with a file, but I wouldn't expect that to work here.

Some jeweler's rouge might do the job, with a rag and a smooth block. You're basically trying to polish the surface. Look into stuff you use to polish a car - a buffing pad on a drill with some polish might do something as well.

- Jon