CNC question

[Facundus Cues]

I am just about done putting together a homemade cnc taper / point / ring billet cutter. I have been racking my brain around how to zero the cutter axis with different bits. I assume that I need zero to dead center at the cutting surface of the bit. I plan on using 6 wing for taper - vertical v for points - maybe straight bit or slot cutter for ring billet grooves. I figure for height that I can make delrin collars for each bit but distance from center seems trickier. On my cnc table I have a touch plate to zero z at the top of the material. Maybe a small rod in the headstock and calculate the offset? Maybe I am overthinking this as I typically do but any pointer will be greatly appreciated.
-Thanks

 

[whammo57]

Where ever you position the cutter and then zero the DROs and press ref all............. that is zero.............

I zero Y at the head stock point............ I zero Z by bringing the tool down until I can't see light under it at the work piece surface.............

X zero is where ever you want to start...........


Not too complicated........... don't make it so


Kim

 

[Texas Carom Club]

Edge finder will put the center of the spindle over the edge of your part, then move over half the dia of the cutter, and about. 050 more for clearance

Or just take the tool and move it in till it cuts just a tiny bit so you know it's touching the edge, zero out the dro like Kim said, and move over half the dia of the tool

 

[Facundus Cues]

Thanks for the replies. So you guys are zeroing to the outer edge of the work piece and then going in whatever cut depth (1/2 of) that you we'd when tapering. I kept thinking that you would start from dead center and work out to be able to end up with an exact diameter since the starting pieces will be different sizes. I guess you rough turn everything the same and then they all get the same amount taken off each ti e

 

[MVPCues]

Thanks for the replies. So you guys are zeroing to the outer edge of the work piece and then going in whatever cut depth (1/2 of) that you we'd when tapering. I kept thinking that you would start from dead center and work out to be able to end up with an exact diameter since the starting pieces will be different sizes. I guess you rough turn everything the same and then they all get the same amount taken off each ti e

You have to decide how you want to do it.

If your programs work off of the surface of the stock and are written to take off X amount, you have to set zero for every stock but the cutter diameter isn't a factor. When you look at the GCode, you are only looking at how much is removed, you don't know what the resulting diameter is. This is sort of a relative perspective. Programs written by hand are a little easier to write using this approach.

If your programs reference off of the lather/spinner center axis, your programs work to cut to a specific diameter and doesn't matter what the starting diameter of the stock is (no need to touch up). But, the cutter diameter is a factor to consider for that approach. If you use a consistent cutter diameter all the time (or at least for each type of component you have various programs for), you can look at GCode and know (with a little simple arithmetic) what the resulting diameter of the stock will be after turning. This is more of an absolute perspective. Programs written by hand are more difficult to write using this approach.

When I started with CNC turning, I decided to reference from the center of stock/spinner axis all the time. The CueCut program I wrote references from that. If you won't have limit switches and know what the spinner axis position will be, touch up once on a dedicated touch up dowel, jog over to lathe center axis (some simple arithmetic again) after touch up, set zero. Thereafter you can turn any component to any diameter using my program without touching up or making any jogs and resetting zeros. Some guys when shutting down mach after turning for that day tell Mach to save the position for the next time. That way when they turn it back on, mach sets x/y to the last setting when mach was shut down which still matches the physical location of the machine and they just start cutting stock again...any stock...to any size...using my program. You can do the same thing with any program (again with a consistent cutter diameter) written by hand that references from the center, but again those programs will be harder to write by hand.

 

[Facundus Cues]

Thanks Kelly. I do plan to buy your software and I though t I remember reading of seeing that it calculated from center which seems to make more sense to me being that you are making repetitive parts that should end up at same diameter. I have downloaded the evaluation copy but have not even launched it yet. I have been chipping away at getting my machine right but I always running these scenarios through my head