[RicknBeachcrest]

I've been wondering how most people align their work to their X and Y work coordinates. I've got two techniques that I use (neither of which I am really thrilled with). I will measure the distance from my home position to the 0,0 on my work piece and put an offset in. For the second method, I have a 1/4" rod with a point on the end. I jog this over to where I want 0,0 on the work piece and zero X and Y.

I've seen options using laser cross hairs and also a usb camera mounted on the spindle mount.

I know that some work just needs the X and Y zero to be close, while others need it to be spot-on. So far, the work I've done falls into the close category, but I foresee needing to be spot-on with some future projects.

Thanks for any input you can give me.

Rick

[ger21]

The easy way. I don't have to. Usually.

Here's my main method.

I have two fences on my machine at X0 and Y0, both in machine coordinates. I turn on the machine and home it, and my fences are all set. I just place the part against the fences and hold it in place with CAM clamps. I never set offsets or zero the X and Y Axis, just place the part on the table and go.

In my CAD program (AutoCAD) I have my table drawn at the actual coordinates, so I draw my parts exactly where I want them on the table.

Now, if I need to cut around the edges, I have two ways to do it. Usually, I'll use some spacers, like 1/2" MDF, to make my stock origin at 0.5,0.5
I just draw my part in the appropriate location, and it's all ready to go.

In some cases where I can bolt my part down, I use a two step process. My table has a grid of t-nuts in it. The holes are draw in my table drawing. I'll draw my part wherever I want to place it on the machine, and draw holes where the inserts are. Then I'll move the part to the 0,0 position, and program the mounting holes. Put the part against the fences, and drill the holes. Then place the part where it was originally intended, and bolt it down. Run the part. No zeroing needed. This might be a bit difficult to understand without seeing it.

For the last 15 years, I've been programming large industrial routers. These have had pop up locating pins to place the parts against at the origin. The machine didn't really have an option for setting X and Y zero. You just used the pins. With this method, you could run hundreds of unique parts every day very quickly, as you didn't have to set your X and Y zero every time. I wanted a similar method of working at home, and I'm pretty close to it.

[nlancaster]

I too am going to use the system like gerry does when I get my machine working properly. In the waterjet industry they actually bolt a piece of metal to the machine and cut it at x/y 0/0 to make sure that fences align perfectly. Also going to see about doing this to align parts as well.

http://www.cnczone.com/forums/mach_w...ification.html

Right now during testing, I just ref the machine when I first turn it on. Then I eyeball the xy 00 on the test part I am making and zero out the x/y/z and run the program. Works pretty good, and it is quick enough.

[Bubba]

On my mill, I use an electronic edge finder that I have modified by removing the battery and led and replaced with a wire that goes to the probe input on my BOB. I then probe the corner of the stock setting the X,Y, Z offsets as necessary. Before I modified the edge finder, I just used one to find the X and Y offsets as needed.


Oh and I tried the camera bit and found it to be less accurate as at times it was very difficult to determine the actual edge or corner due to lighting in my shop. Actually, the probe as modified above is a lot quicker also.

[mmoe]

Depends on how accurate you need it to be located and how the machine homes. My machine homes on the index signal of the encoder, so it will always locate to the same home position within about .02mm (due to the resolution/tolerances of the lead screw). For all practical purposes, I could not locate the machine to a tighter tolerance manually, so even using an edgefinder would not really improve anything. With home always the same down to the index pulse, I can then index fixtures to the machine table and expect them to line up without any further effort. Since the Z axis also homes on index, I can just turn the machine on and the tool length will also be within .01mm every time as long as the tool is not changed (Z axis has double the resolution of X and Y, so tighter tolerance), which means I don't have to re-measure the tool to start cutting.

If you don't home on the index pulse, home is a relative term. The slower you home the machine, the more consistently it will position to the same home, but it does have to be considered an approximation since it could vary by up to .5mm pretty easily. If you're just locating an oversized piece of material and using an auto tool measurement each time, that's not really an issue, but if you are aligning to a very high tolerance fixture, it won't be close enough. In that case, using an edgefinder will help tighten the tolerances up to match the work coordinates to the fixture.