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### Author Topic: Homming against work piece  (Read 2051 times)

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#### Quentinb

• 2
##### Homming against work piece
« on: August 15, 2011, 03:24:00 PM »
Hi All,

I have been playing with Mach3 for a while now and have the homming and limit switches etc working correctly. Something that does bother me a bit is, how do I zero my CNC router against the work piece?

E.G. I have a square piece that has been cutt using a table saw and is of the correct dimentions, say 400mm x 450mm. I want to cut a circle in exactly the middle of the piece and is located "about" 50mm on the X and say about 50mm on the Y, in other words, the article is not at the homming potitions. My G Code is set according to the dimentions (400 x 450) I have and my tool table in Mach3 is preset with the tool diameter (6mm) etc.

How do I get the tool at exactly 0 on the work piece (about 50mm away from physical home) and with this I am assuming that Mach3, knowing the diameter (6mm end mill) will auto calculate a -3 offset to cater for the tool diameter?

Thanks for your help and great product!!

Kind Regards
Quentin

#### ger21

• 6,291
##### Re: Homming against work piece
« Reply #1 on: August 15, 2011, 06:30:56 PM »
Typically, you jog the X and Y axis to where you want the 0,0 position to be, and zero them at that point. You can also use a probe to find the edges, and then set your zero that way.

My machine has fences along X and Y zero, so I just slide the part against the fence, and start cutting.

Quote
and with this I am assuming that Mach3, knowing the diameter (6mm end mill) will auto calculate a -3 offset to cater for the tool diameter

No, Mach3 can not auto-calculate the offset. You can program it to use G41 or G42 cutter compensation, but you must prgoram proper lead in and lead out moves for it to work correctly. Most people do the offsets in their CAD or CAM software.
Gerry

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