X Y Zero advice needed

[hhk]

I own a PRT Alpha with PC router.

Right now, I have a rough part that I mount on fixed location on the table. I then use a 1/4" steel dowel in my chuck and establish x/y zero to a reference point on the part. This is a painful process of moving the x and y .01 inches at a time until I reach the zero which I do by eyeballing it.

There has to be a better way. For starters, is there a better way to nudge the x and y axis than typing MX .01 or MY -.01 a dozen or so times?

I thought about using the x/y to proximity sensors routine and then measuring the distance to my reference point so I can return to that point manually each time. But I noticed that the sensors are mounted with a single screw and actually rotate slightly around the screw when contacted. In other words, they are not truly "fixed". I thought about glueing them to keep them fixed but thought I'd reach out to the community first.

Any thoughts?

[kubotaman]

First off I hope I understand the questions you have posed. In the ShopBot software when you hit the "K" key you will have the keypad screen appear. In that screen is a small yellow box. Click on that and you can move in increments that you enter into the small white screen that appears. You move by way of the keypad arrows. As far as making the router go to exactely the X and Y co-ordinates that you want you can just make a file to do so. This would only be if you want it to go to the exact same spot every tme. If I were to do it I would make the file as follows:

C3
M2, 12,12
Z2
C2

The numbers are to be replaced by your co-ordinates that you need to make the spindle go to the exact place that you want. As far as your limit switches moving I don't know anything about that I have a Alpha and they are bolted on the sides along with the gantry. I can't imagine that they can move. That would defeat their purpose.

[hhk]

Moving to a location on the table each time would mean that the bit starts in the same spot. But, it seems that when I restart my ShopBot, it has a new XY location. Same thing if I hit a limit switch or the e-stop button - it loses it's XY. Is this normal?

I'll shoot a photo of my limit switches when I get to the shop in the morning. Maybe they are not mounted correctly.

[beacon14]

If you want to be able to rely on your limit switches you'll have to eliminate the rotation "feature" of the way they are mounted. Unbolt the switch, rough up the mounting area with some course sandpaper, and use a few drops of epoxy when reinstalling the switch.

They should be able to get you to very close if not right on every time.

[jimboy]

Henry, you are going to have to zero X,Y to a known point on your table and do this each time. Then move to your part location using move instructions and rezero. This can then be repeated over and over again.
Jim

[jerry_stanek]

I use a zeroing block to do this here is a link to the shopbot forum discussion.

http://www.talkshopbot.com/forum/showthread.php?t=5495&highlight=block

[zeykr]

Henry,
1st, fix your prox switches so they don't wiggle. Then use the c3 command to zero x and y to the lower left corner of your table each time you start your machine. Then use the K (Keypad) command to use the arrow keys to move the machine to new zero point. You'll need to set up the offset variables (&my_XYzeroOffsetX=-x.x
&my_XYzeroOffsetY=-y.y) in c:\sbparts\custom\my_variables.sbc to setup C3 to know where the corner of your table is. You can also run setup under the tools menu in sb3.

One way to set the offset would be to put a vbit in your router, run c3 to zero x and y by prox. then move the vbit to the lower left corner using the Keypad. (cntrl- arrow moves at jog speed, arrow at move speed, and you can click fixed to move at your small fixed increment). Look at what x and y position say now and you can add or subtract these from the current values in my_variables to correct your C3 offsets.

If the point where you need to zero varies from job to job, then once you have C3 zeroing to lower left corner of your machine, get a logitech rumble pad to make it easy to move to your new zero point and zero x,y and z remotely. If you don't always zero to a known location on the table, it's indispensable!

Rumblepad:
http://www.talkshopbot.com/forum/showthread.php?t=12682

If you always zero in the same location for a particular job, first zero to prox switches using C3 each time you start up machine, then set up a new Custom cut command (Like C23 or something) to move to this new location and set x and y to zero. You could include the C3 in this new custom command to do it all with one custom cut. Daryl detailed this above.

[jerry_stanek]

With the block that I posted about you can zero to any point on the table there are no offsets to worry about.

[blackhawk]

Henry - I use a method similar to what Jerry mentions. There is a special program that you can put into your custom cut files that will zero X and Y for you just like the Z zero plate. I made my own combination X,Y, Z zero plate. It consists of a 1/2" thick plate, that I machined flat on both sides to be as exact to 0.500 as I could get it. Then on two sides, I bolted some 1/8" thick aluminum that extends about 1/4" below the thick plate and also extends about 1/2" above. This way I can sit my plate on the corner of the material and the bottom lip of the jig aligns it. I first run the Z zero program to set the zero (you must modify the routine for the 1/2" thickness). I then run the special routine that sets the X and Y. The routine first moves in X and touches off on the side, then it moves back and then touches off in Y. Then everything is zeroed at the corner! Let me know if you need a copy of the custom cut file.

[COBOB]

Brad, would you be willing to post that file? I would love to have it. It sounds just like what I am looking for.

Thank you,

Bob

[jerry_stanek]

if you go to the link I posted and then to the link in the post there is a copy of the zeroing file with videos on how to build the unit.

[blackhawk]

Here is the custom cut file that I use. I had to attach it as a .txt file in order to upload it to the forum. Just change the file extension back to .sbc after you download it and it should work. From the lawyers: it has always worked for me, but try at your own risk!

Brad

[hhk]

One easy way I found to zero to a reference point on the part is to turn off the control box then manually move the router to the reference point, turn on the unit and then zero X/Y. Easy and simple and since everything is turned off, I can't imagine I'm doing any damage to the motors.

BTW, I secured the proximity sensors and the X/Y to proximity routine works well.

[wberminio]

check out Morris Dovey's Super Zero
I've been using for a while
Easy and works very well
Zero XYZ in on shot
http://www.iedu.com/DeSoto/SuperZero/ReadMe.html

[adrianm]

One easy way I found to zero to a reference point on the part is to turn off the control box then manually move the router to the reference point, turn on the unit and then zero X/Y. Easy and simple and since everything is turned off, I can't imagine I'm doing any damage to the motors.

BTW, I secured the proximity sensors and the X/Y to proximity routine works well.
The documentation does warn against moving the gantry without disconnecting the motors first as they can generate a current that flows back into the drivers.