So i posted in another area on this forum regarding some software issues i'm having where i'm loosing my zero points in the middle of a program run.
This got me to thinking how i could pick a zero point and go back to it after i loose it for whatever reason such as a power loss, shutting it off at night, etc.
I'm not as concerned with the Z, but rather the X and Y.
Any ideas/suggestions?
How do you setup and maintain your zero points?
Moderators: al wolford, sbk, Bob, Kayvon
Re: How do you setup and maintain your zero points?
With me being a brand new user, I don't know what the other use but I use a fine point bic marker. When I Zero, I let the tool press just a little in the wood. Then I back it off enough to place a dot on the center that it made. Then I re-zero Z. I can always find zero on the board no matter what I or the machine does.
Of course, this doesn't work after I cur the pieces from the tabs.
Of course, this doesn't work after I cur the pieces from the tabs.
Re: How do you setup and maintain your zero points?
If you know the size of the project board, and use center as the origin point, then finding center is as easy as find an edge. Use the SET option and you can input 0 or any other number for each axis. So I'll line my bit up centered on the left edge of my board, use SET and set X to -1/2 my board width. Then I'll line the bit up centered on the front edge, and use SET to set Y to -1/2 the board height. Use the touch plate to set Z anywhere on the top of the board. Now a move to 0,0,0 should move the bit to exactly the center of the board. No marks needed.
4D
4D
Re: How do you setup and maintain your zero points?
"Work indexing" is a huge topic, very much part of "work holding", and has it's own set of cool tools and techniques. I'll spare myself the endless link gathering and let you use the googly machine yourselves. 
For z-height, nothing beats a well-calibrated touch-off plate. Some in some CNC machines even have a 3D zero-ing tool. Looked cool when I saw it.
For finding the X0Y0, it's common to accurately locate to a corner on the material. Or the center, or a machined feature. It all depends on what kind of accuracy you're trying to get, how fast you want the setup to happen, how repeatable, and so on.
There are "click-type edge indicators" people use if they can get their spindle down to ~800-900 RPM, that you gently and slowly jog the spindle up against and watch for the head to shift. There's a click, but often it's very faint. Those can get you to about 0.001-0.002" accuracy in the X and Y.
If you're doing conductive material like aluminum, they also make ball-indicators with LEDs that come on when it touches metal. I've gotten <0.001" repeatibility over three insertions on occasion, with 0.002-3 pretty common.
For those, do a google search for "edge finder"
For very-rough alignment, I added one of those drill-press crossed-laser attachments. Works good, gives ~10-20mill accuracy, but intentionally trying to closely focus my eyes at the spot isn't my idea of fun. So, I use it to just make sure the 00 and tool path are inside the material, and for fun watching the cutting.
For parts that I need to flip back and forth more than once, I machine an L-shaped registration slot. I make it 0.204" wide across each arm, and use one of those LED edge finders. The ball is 0.200" diameter, and I jog it in 0.001" increments across the slot as I lower the ball into it...gently and carefully...to find the place in the very center of the slot that's true zero. If you go this way, don't try to just go with a circular hole, no matter how round. You won't be able to figure out which way to move as you lower the ball down. Use the L-shape, and zero the x-axis in the slot arm that runs along the Y axis, and vice-versa. That way you only have to jog in one horizontal direction; makes it much easier to home in on. Once you try it, you'll see how it works. If your Z-axis is well-trammed so the cut is in the same place at the bottom, you can flip back and forth all day long, load and unload pieces. Part-to-part aligning, once your zero is pretty much on takes just a minute or so....
Which then brings up alignment pins. That's another way to get things closely aligned and registered. It's not always as accurate as re-zeroing each time, but usually very repeatable. The accuracy in large part depends on what the alignment pins are secured into, and how accurately the alignment holes (in the stock) are located, sized and shaped. Hardened steel alignment pins are awesome when you have to separate a design in multiple panels. as long as each panel has those exact same holes in exactly the same place, things will magically line up for each panel, which then cuts the next set of alignment holes.
If you're doing repetitive work, like multiple lots of 10 pieces on the top-side, then those 10 pieces on the bottom side, then you're eventually going to look into making a jig for easy alignment and holding. They're often either custom-designed (by you!), or standard configurations of standard work holding devices. Things like a custom cutout in the spoil-board to hold a specific size of stock. Same thing for "soft jaws" on a machining vise, where the point is to mill out an inset to place the in-process part. I use a Kurt machining vise (model 688) on top of the Shark HD bed, and hold the aluminum stock using machined parallels. I love it, but it makes it rather useless for making a wooden sign, and the vise eats about 2" from the vertical reach. All solutions, including magical ones, have side effects
Another cool tool I stumbled upon (only to discover it's too tall for use with the vise
) is a (Fowler) Coaxial Centering Indicator. You put it in the spindle, let it run at < 800 RPM, with a feeler in it. Carefully jog it into the hole you're using as center, and as the feeler spins in a hole...one you machined at zero-zero, say....it indicates to 0.0005" if the spindle is in the middle of that hole. Once of the attachments goes into a countersink hole, so it doesn't always need to be a through-hole. Seems to work great, but wants more vertical height than we typically have on these CNC routers.
At least for me, the drive for registration ability is the realization that seating a new piece of stock can take 20s, while a tool change and re-zero takes 60s at least. So if a product takes 5 bit changes (6 bits total), it's a lot faster to do ten parts in the first tool, then change the tool and re-run those ten parts. But, that calls for accurate and repeatable registration achieved quickly.
Well, that touches upon some of the options available in our world. Best of luck, and keep us up on your progress!
Regards,
Thom
For z-height, nothing beats a well-calibrated touch-off plate. Some in some CNC machines even have a 3D zero-ing tool. Looked cool when I saw it.
For finding the X0Y0, it's common to accurately locate to a corner on the material. Or the center, or a machined feature. It all depends on what kind of accuracy you're trying to get, how fast you want the setup to happen, how repeatable, and so on.
There are "click-type edge indicators" people use if they can get their spindle down to ~800-900 RPM, that you gently and slowly jog the spindle up against and watch for the head to shift. There's a click, but often it's very faint. Those can get you to about 0.001-0.002" accuracy in the X and Y.
If you're doing conductive material like aluminum, they also make ball-indicators with LEDs that come on when it touches metal. I've gotten <0.001" repeatibility over three insertions on occasion, with 0.002-3 pretty common.
For those, do a google search for "edge finder"
For very-rough alignment, I added one of those drill-press crossed-laser attachments. Works good, gives ~10-20mill accuracy, but intentionally trying to closely focus my eyes at the spot isn't my idea of fun. So, I use it to just make sure the 00 and tool path are inside the material, and for fun watching the cutting.
For parts that I need to flip back and forth more than once, I machine an L-shaped registration slot. I make it 0.204" wide across each arm, and use one of those LED edge finders. The ball is 0.200" diameter, and I jog it in 0.001" increments across the slot as I lower the ball into it...gently and carefully...to find the place in the very center of the slot that's true zero. If you go this way, don't try to just go with a circular hole, no matter how round. You won't be able to figure out which way to move as you lower the ball down. Use the L-shape, and zero the x-axis in the slot arm that runs along the Y axis, and vice-versa. That way you only have to jog in one horizontal direction; makes it much easier to home in on. Once you try it, you'll see how it works. If your Z-axis is well-trammed so the cut is in the same place at the bottom, you can flip back and forth all day long, load and unload pieces. Part-to-part aligning, once your zero is pretty much on takes just a minute or so....
Which then brings up alignment pins. That's another way to get things closely aligned and registered. It's not always as accurate as re-zeroing each time, but usually very repeatable. The accuracy in large part depends on what the alignment pins are secured into, and how accurately the alignment holes (in the stock) are located, sized and shaped. Hardened steel alignment pins are awesome when you have to separate a design in multiple panels. as long as each panel has those exact same holes in exactly the same place, things will magically line up for each panel, which then cuts the next set of alignment holes.
If you're doing repetitive work, like multiple lots of 10 pieces on the top-side, then those 10 pieces on the bottom side, then you're eventually going to look into making a jig for easy alignment and holding. They're often either custom-designed (by you!), or standard configurations of standard work holding devices. Things like a custom cutout in the spoil-board to hold a specific size of stock. Same thing for "soft jaws" on a machining vise, where the point is to mill out an inset to place the in-process part. I use a Kurt machining vise (model 688) on top of the Shark HD bed, and hold the aluminum stock using machined parallels. I love it, but it makes it rather useless for making a wooden sign, and the vise eats about 2" from the vertical reach. All solutions, including magical ones, have side effects
Another cool tool I stumbled upon (only to discover it's too tall for use with the vise
) is a (Fowler) Coaxial Centering Indicator. You put it in the spindle, let it run at < 800 RPM, with a feeler in it. Carefully jog it into the hole you're using as center, and as the feeler spins in a hole...one you machined at zero-zero, say....it indicates to 0.0005" if the spindle is in the middle of that hole. Once of the attachments goes into a countersink hole, so it doesn't always need to be a through-hole. Seems to work great, but wants more vertical height than we typically have on these CNC routers.At least for me, the drive for registration ability is the realization that seating a new piece of stock can take 20s, while a tool change and re-zero takes 60s at least. So if a product takes 5 bit changes (6 bits total), it's a lot faster to do ten parts in the first tool, then change the tool and re-run those ten parts. But, that calls for accurate and repeatable registration achieved quickly.
Well, that touches upon some of the options available in our world. Best of luck, and keep us up on your progress!
Regards,
Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)
Re: How do you setup and maintain your zero points?
And another method of relocating your project:
https://www.youtube.com/watch?v=8Jjd4Yy ... e=youtu.be
Ralph posted this a couple years ago.
Bob
https://www.youtube.com/watch?v=8Jjd4Yy ... e=youtu.be
Ralph posted this a couple years ago.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)
Antonie Van Leeuwenhoek (Developer of the microscope.)