Taking your Z to New Heights

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My machine is a PRT Alpha96 and it seems that I never have the Z axis at the right height to change the bit when I want to.  Well, here is how I fixed that problem and solved a few others as well.

As you can see from the above picture, I mounted a small lever actuated micro switch above my Z axis and ran two wires to the Waco connector located on the Y car.  I am able to conveniently get ground and INPUT #1 here since the Z Zero Plate uses that cable.

My solution is quite simple.  I command the Z axis to move up until it touches the micro switch (you can use a proximity switch as well) and then move back down a predetermined amount.  This will place the Z axis at just the right place so my hands will reach the wing nut holding the dust foot on as well as making it easy to drop the current cutter and collet nut.  I have added the “raise Z” routine to a lot of my files.  Now rather than worry that the “Safe Z height” setting will clear everything, I know the tool is as high as it can be.

I think the pictures are all that is needed to show you how I mounted a switch, and I bet you will come up with a way to mount a switch or proximitity  sensor to your machine.  If you implement this modification to your machine, please post pictures to the ShopBot Forum so others can see.

Now in trying to keep everything simple, here is how I implemented the bare bones code I wrote to make all of this work.  Remember, what works for me, might not work for you without tweaking it a bit.  Always know what the code is going to do before you just run it or edit your files and insert this code into them.  Remember, YOU are the one responsible for the actions of YOUR machine.

dcwzrhmp_9gwk6pcc3_bBetween the rows of asterisks’ below is my Custom Cut #5, which places the spindle where it’s comfortable for me to change cutters.

‘*****************************************

‘Ed’s Bit Change

ON INPUT (1,1) GOSUB ZTOP
MZ,6
J2, 6,15
‘Remember to ZERO the Z axis before cutting!
PAUSE

END

‘ Subroutines below.
ZTOP:

&Z = %(3)
MZ, (&Z – 2.0)
RETURN

‘*****************************************

Here’s a commented description of the file, line by line, to show you what each command does

‘ First I tell the software to start watching the input #1 and goto the ZTOP label when the input goes on

ON INPUT (1,1) GOSUB ZTOP

The next line tells the Z to start moving up. When the switch triggers the ZTOP subroutine will run
MZ,6

‘ The tool move to the location X=6 and y=15 after it returns from the subroutine
J2, 6,15

‘ A friendly reminder that I still need to zero the Z, and a PAUSE so that it stays on screen.

Hey, I am getting old you know!
‘Remember to ZERO the Z axis before cutting!
PAUSE

‘ Finally an END statement to stop the program and prevent it from falling through to the subroutines below.

END 

‘ A comment to help me keep track of things..it marks the start of the subroutine
‘ Subroutines below.

‘ This is the label for this subroutine…you can tell by the semicolon after the name
ZTOP:

‘ Here I am reading System Variable 3 which is, the current Z height and assigning the variable %Z to that value
&Z = %(3)

‘ This line takes the current Z height from variable &Z and subtracts 2.0 from it and moves the Z to that position
MZ, (&Z – 2.0)

‘ The program will now jump back to the next line in the main program which is a Jog command.  (J2, 6,15)
RETURN

If you do not completely understand what each line of code does, I invite you to click on “HELP” at the top of your screen while in the ShopBot Control software or navigate to the folder C:\Program Files\ShopBot\ShopBot 3\Help and read the documents on the commands and their use.  You will also see that I read a “System Variable” to get the current Z height when the micro switch is touched so that document would also be a good read.  Believe me, there are a lot of things you will start to dream up when you start to understand a little more about the under-the-hood workings of your ShopBot router and its Control Software.

Next month I will show you how taking a bit of information from several different folks, then applying it to my style of work has created the best vacuum hold down I have used to date.   I didn’t directly copy them, but I allowed them to inspire my design.

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