X, Y, and Z zeroing routine

[dana_swift]

Gerald, there should be a "center in hole" routine located in the SBParts folder. It works great at centering in a cup, I use it for my highest precision centering on a fixture. On my bot, I get a 0.001 repeatability on that center point. Usually 0.000.

Additionally after a long cut, if your cup is still on your fixture you can check the center in hole again and find out how accurate you were able to relocate the same point after a lot of jostling. Its a good way to test shopbots claimed position repeatability of 0.002".

I have found the cheapest way of making this test is to embed a copper sweat fitting end cap into a fixture. They are cheap and I can leave them in the fixture if desired. I use both 1/2" and 3/4" sweat fittings depending on the bit size I am using. Also there is a 3/4" sweat fitting pocket in four locations on my spoilboard so I can check for changes in X/Y squaring actual move distances, etc after months of operation.

To hook the sweat fittings up to the ZZero plate I just hooked up two car-battery-size alligator clips from the local auto-parts store with a wire. If you like I can post some photos.

D

[backyard_cnc]

Dana,

Thanks for taking the time to reply and offer your comments. I will check and see if I do in fact have a file by that name in the shopbot parts folder.

I have actually milled a corner jig out of 1/2" aluminium (a benefit of owning a large CNC mill) but the ZEROing hole goes all the way thru as I intend on making a lexan insert with cross hairs to allow centering over any point not just corners. Because of this I want a routine that first finds the center of the hole and then offsets to a new point to zero the Z. Even better yet might be a routine that does all this by default but prompts along the way so that it could be used to zero any or all axis. Does this make sense? I am guessing at some point I will have to spend the time to learn more about righting these sorts of files for the SHOPBOT but just no time right now so I was hoping a simple mod to existing code would at least allow me to just offset the Z by the needed amount!

Cheerio
Gerald

[dana_swift]

Gerald, dont be afraid of the code in an SBP file. Its not complicated. Look at regular cut files, then look at something like the ZZero routine.

With a little thinking about it, you should see what is happening and get ideas how to make modifications to do exactly what you want for the X, Y, zero using your plate.

Good luck with your project!

D

[srwtlc]

Here's the fixture I've been using and the file used with it. I don't use it for zeroing the Z axis as it's just easier to use the supplied Z zero plate when needed, but it could be used to do so if desired. It can be flipped for inside/outside corner usage. No crosshair setup as I don't need that function and it would only be as accurate as my eyes anyway.

The file relies on the user positioning the probe/tool over the hole and then at the start of the file, it moves to a position above the plate and sets the plate height/thickness then moves over the hole and down to within 0.125" of the bottom of the hole to start the routine. This file is also somewhat based off the one supplied in the SBParts folder. Mathematically it could possibly be a little better, but it works.

[JDGJr]

Can you describe the plug that you're using in the 5/32" holes, possibly where to buy one?

thanks

[srwtlc]

I got some overstock ones from here...

http://desco.descoindustries.com/Des...tockCoilCords/

One with a 4mm banana plug should work.

[JDGJr]

Thank you Scott. I got a pair of measurement leads today, and they work fine, and include an alligator clip on one end.

Modified your script to set zero and I'm ready to start working on both sides of my parts!