New to CNC

Ok, I am having a couple of issues, I am a complete noob. I have a G0704 that I just converted to CNC and am running Dustin 360 and Mach4.

The first issue is zeroing. I don't have limit switches set up yet. When I mount my workpiece, I bring my tool to my X0, Y0, Z0 spot. Let's say top left corner, I touch off the Z and zero all my axis. I then ref all the points and zero them again, ref them one more time. Now everything is zeroed out. I set tool offset to zero, and the mill starts milling 1 inch higher than the workpiece. I have to set the workpiece offset to -1.00. Why is that?

Second issue, when I get everything milling correctly the mill drags on my workpiece. The z drops down, drags a slight trench across the piece, then comes up before coming back down and milling the piece. When it finishes, it comes off the piece, then drops back down and slightly drags across the piece returning to home.

Why is it dragging on my workpiece? I even raised up the clearance and retract heights in Fusion, but that didn't help.

Thanks,
Doug

Don't be offended if/when this thread gets locked. Discussion of homebuilt CNC Grizzly machines is a no no here. This is a forum for professionals, using professional grade equipment. You will get a better response at the Home Shop Machinist or CNC Zone forums. Those guys grok homebuilt CNC stuff. The guys here run machines that have workpieces heavier than your whole machine. Some guys here make chips that weigh almost as much as your machine.

That said, if you can rephrase your questions to not include reference to a banned machine, there's no reason you can't get good help with all of your machining related questions here, there are centuries of accumulated knowledge available on this forum, you just have to know how to ask.

Oh, and have a thick skin, the old timers here can be kind of grumpy sometimes, don't take it personally.

TeachMePlease said:

Oh, and have a thick skin, the old timers here can be kind of grumpy sometimes, don't take it personally.

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I only get grumpy when I have to stop and look up slang, never heard of "grok" before. I do believe the internet age has exacerbated the turn over of slang words. Before the internet certain slang terms went on for decades, now some fizzle out and get replaced in a couple years, some of us old dudes have trouble keeping up.

No problem, I was not aware. I will ask elsewhere. After 22 years in the Infantry and 14 years as a cop in South Phoenix, my skin is plenty thick. No one typing words on a forum is going to get me all worked up.

QT: [Why is it dragging on my workpiece?] Some times a light duty machine will spring or deflect from cutting forces to then make a cut or drag going back..
Surprised the free play in feed screws is not a problem..don't think that rig came with ball screws? Or tight enough to make direction turns with not setting a table lock?

Dualkit said:

I only get grumpy when I have to stop and look up slang, never heard of "grok" before. I do believe the internet age has exacerbated the turn over of slang words. Before the internet certain slang terms went on for decades, now some fizzle out and get replaced in a couple years, some of us old dudes have trouble keeping up.

Click to expand...

GROK.... I don't think the internet is to blame for me using a word from a 1961 novel by Robert Heinlein...

My recommendation is that you take this discussion to CNC Zone. They have Mach and benchtop mills forums there.

Good luck,


Chris