Mirroring a part

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Dave_C
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Mirroring a part

Post by Dave_C » Tue Jun 26, 2018 3:32 pm

I need some advice on how to use G50/51 (Centroid Mill)

I am getting ready to make some knight chess pieces to complete the chess set I started years ago. I have the knight profile all done and I have the CAM complete except for being able to chamfer the back side of the knight.

I have my stock for the knight set up in a 5C collet and the collet is in a square collet block so that I can turn the part over to the backside once I mill the profile and chamfer the front of the knight.

So here is my question: Since I have the G code to chamfer the front of the knight, if I turn the part over and keep my collet block at the same location in the vise using a stop, can I just use the G51 "Mirror" command to run the same code [cut and pasted in] except have it run as a mirror image?

Then add the G50 to end mirroring.

Thoughts,

Dave C.
I learn something new every day! Problem is I forget two.

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Bill Shields
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Re: Mirroring a part

Post by Bill Shields » Tue Jun 26, 2018 4:12 pm

Theoretically yes, but you have to be careful regarding tool changes and approaches that you may not want to have mirrored...so just sticking in G50 / G51 is not that straightforward.

THEN there is the question regarding cutter offset.

I am not sure if Centroid 'MIRROR' also reverses cutter comp...

Generally when you mirror a part, you also end of going around it in the opposite direction...which may affect things since you will be G41 instead of G42 (or visa versa) or just plain cutting the opposite direction and getting a different finish. If all you are doing it cutting a small chamfer, it probably matters not...just BEWARE of G41/G42.

One way to handle it is to put the contour in a sub routine that gets mirrored and all the other stuff elsewhere...

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Dave_C
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Re: Mirroring a part

Post by Dave_C » Tue Jun 26, 2018 7:44 pm

Ok, I don't think cutter comp will be an issue as the path is done in Fusion 360 with the comp set to "computer" instead of doing it in the machine.

There would be no tool changes so this just might work!

Dave C.
I learn something new every day! Problem is I forget two.

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NP317
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Re: Mirroring a part

Post by NP317 » Wed Jun 27, 2018 12:06 am

Run a test piece in dense foam, or plastic.
Better if a problem occurs.
~RN

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Dave_C
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Re: Mirroring a part

Post by Dave_C » Wed Jun 27, 2018 9:08 am

Run a test piece in dense foam, or plastic.
Better if a problem occurs.
~RN
I agree! No need in wasting the part or the tool...

Dave C.
I learn something new every day! Problem is I forget two.

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GlennW
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Re: Mirroring a part

Post by GlennW » Wed Jun 27, 2018 10:06 am

I've never tried the "Mirror" function on my controller, but I'm curious if the location of the "part zero" comes into play as it does in CAD.

I forgot to root through the manual last night to see what is involved.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Dave_C
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Re: Mirroring a part

Post by Dave_C » Wed Jun 27, 2018 10:33 am

I've never tried the "Mirror" function on my controller, but I'm curious if the location of the "part zero" comes into play as it does in CAD.
Glenn, good point and this was my concern when I started trying to set this all up.

In my case, I made the centerline of the stock my "Y" zero and the outer end of the stock my "X" zero. So when I turn my part over, the centerline of the part will still be the centerline.

In reading my manual, it looks like you can specify offsets in all three axis and mirror the part (flip it over) and have it cut in a different location. But that is not what I need to do, I need to just turn the part over and run the chamfer around the outer profile but in a mirrored path.

I'll have to set this up, make some air cuts above the actual part and see if it looks anything close to what I'm trying to do.

I love this site because there is usually someone here who has a pretty good idea of how to do just about any task when it comes to machining! I'm never afraid to ask as I find it easier to ask then to just plow ahead and make costly mistakes.

Thanks for the input so far! Keep it coming if you find out more...

Dave C.
I learn something new every day! Problem is I forget two.

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GlennW
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Re: Mirroring a part

Post by GlennW » Wed Jun 27, 2018 10:56 am

I usually just plow ahead and make the mistakes so I know the answers for later...

I have mirrored parts before, but as you have already done, I draw it accordingly, and just flip the CAD drawing and generate new code. I always drip feed the machine anyway.

I'm kind of curious to try the "mirror" function now to see how it works.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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