Z Axis touch plate
 

I would like to make a Z Axis touch plate to set the tool length offsets.

Can anybody point me in the right direction for an idiots guide for,

A: Materials and construction.
B: Pin and script settings for it to work with Mach 3.

I assume I will need a block of conductive material of known thickness and sufficient weight connected to the machine frame/ router spindle by a wire.
I again assume that is the easy part.

Should the block be mounted in a known position on the table or on top of the work ?
I think on top of he work would be better. Less human input and maths involved.

I ask the question so that future builders will find the thread and find it easy to understand.
Thanking you for your time.

https://www.youtube.com/watch?v=G4DeVa8rzA0

http://www.cncrouterparts.com/auto-z...ons-p-291.html

I personally used the following:

.5" block of aluminum
1) I drilled a hole in the end (the OD of a 1/4" TRS female metal shelled guitar jack)
2) Soldered a jumper from the Tip to the shell so electrically conducts to the plate.
3) press the female shell into the block.

4) drilled and installed another (1/4" panel mount TRS female connector) in the push button box on the gantry.
5) wired the two conductors of the tip to the J connection on the PMDX BOB via one of my bundle of wires to the gantry.
6) purchased a nice coiled cable from music store and male plug ends. ON the machine side only 1 male TRS 1/4" plug is inserted in the panel mount plug. ON the table (metal block side) I split the cable so ONE (1) CONDUCTOR is terminated in the TRS 1/4" connector. ONE (1) conductor is soldered to a large alligator clip to attach to tool bit for conductivity of the touch.

NOTE:
If you have a spindle with ceramic bearings, or water cooled, the alligator clip is mandatory as the spindle/collet is electrically isolated from the system. When I was using my Porter Cable or Milwakee router, I found the tool bit "found" a path to ground and only need a single conductor to the plate to work correctly.

Sean

Thank you Sean for a quick and informative reply.

I obtained a machined block of aluminium today. A students test piece from the Technical College.
Next, to find a 15 pin DB9 connector/ cable.
The manual interface is not used on my board.
Will it matter what pin I use ?, there are 15 to choose from.

Stick with #15 so you don't have to reconfigure so much later as you expand capabilities.

I found a 15 pin DB9 after nearly a week of searching.
Now the head scratching can start.:)

Pin 15 is normally considered to be pin 15 on a DB25 (25 pin) connector, not a DB9.

The pin on the connector used is not that important as long as YOU know and YOU understand the signals on your machine.

People use DB25 because it is from the legacy printer cables. Many of the pins are signal ground to keep down noise from cross talk, but there are typically several pins for data (8) and various ones for handshaking, power, ground, etc.etc.

I hope this helps.

I was thinking of pin 15 on the BOB not the cable, sorry.

Now I am totally confused.
Electrical stuff does that to me.

Attached is the port and pin sheet for my driver board.
25 pin parallel, X,Y,Z,&C enable and step.

4 pin DB9, Home switches.

15 pin manual interface.(DA15) This is the port I got the connector for.

What port do I use, what pin do I use.

I have a plastic framed router so I presume I will need the wire with the alligator clip on it.

Do I run 1 wire from a pin a split it into an out and return.
Would this make a short circuit rather than a complete circuit ?

Like I said I am not an electrical man.(I suspect there are others lurking)
Any help is greatly appreciated.

I will try to load a better photo later.

If you mean a 15 pin connector in the size of a DB9 subminiature, it would be a HD15. It is easy to make a cable if need be. They make solder cup connectors.

Second try at posting this..... stupid computers....

What you want to do is close a circuit between the bit and ground. You do this by connecting a wire to a pin on your breakout board, lets call that pin 15, and you connect that to a conductive plate like a piece of flat ali. You then connect another wire to one of the ground pins on you breakout board and attach an alligator clip to the other end.

You then tell Mach in the Ports and Pins tab of setup that your probe is connected to pin 15.

When you "touch off" you would clip the alligator clip to the bit and put the plate under the bit, checking first that pin 15 goes on by touching the plate to the bit.

What follows depends on what screenset you have, I recommend Gerry's 2010 screenset if your have it......

Click whatever is for probing in your screenset and the bit should start mving down until it touches the plate and then stop and retract.

Hope that helps without being too confusing

CHeers

Thank you Bruce, that is what I thought.

The only pins that are not used in Mach 3 are 9 and 15.
On the 15 pin manual interface it says that these are defined as, P9 C Dir
and P15 5V/vdd.
Can I use one of these and a ground on the DB9 4 channel input interface ?
This db9nis used for the homing switches and there are 4 ground pins on it.

Just trying to be careful so that the special smoke does not escape.:o

Al, what breakout board are you using, I'll look it up and answer your question :)

Cheers Bruce,
It is a 4 axis TB6560
Looks just like this one.

http://reprap.org/wiki/4_Axis_TB6560...ard_Controller

While looking for some information I came across this.

It explains how to connect a router to a TB6560 board.
Most of the steps would apply to other makes of board.
Very well presented and explained.
I might do this when I get my touch plated sorted.

http://www.hobbycncaustralia.com/Ins...1wirerelay.htm

I am no wiser or nearer getting the touch plate working.

I have however got the router to start and turn off under control of the computer.
I followed the instructions on the link I posted.
The only difference was that my spindle plug was a 4 pin not a 3 pin.
Looked up the driver board relay on the net.
Used pins 1 and 4.
Works well.
Right, now back to this plate.:(

I cannot use the 15 pin manual interface port.

As soon as I plug in the ribbon connector/ cable(just the cable, nothing attached) a red led lights on the driver board.
The Y and Z axis then do not work, but the X does.

The 4 input interface is full X,Y &Z home \, E Stop.

Do I tap into the 25 pin parallel for a spare pin and earth ?

Any thoughts or ideas anyone ?

If a red light activates on your BOB that means, your zero plate setup in mach3 is set wrong.
Try to go to your pins and ports, and go to input signals... Check if active low is set for pin 15.

It works.
My solution was this.

Find pin 15 on the back of the driver board.
Solder a wire to it.

Same for pin 25(Ground).
My skill with a soldering iron has greatly improved since constructing this machine.

Run 1 wire to the plate, run the other to the spindle nose.

I used the VB Script mentioned in the video at the start of this thread.
A very good video.
I hope some of you will find this thread of use.

Very relieved and very happy.
Celebrating with a cold beer.:D

Thanks for sharing

...I'm glad the information was useful! Have fun with this great tool.

Just happy to contribute a few drops to the pool of knowledge and experience that make up this 'Band of Brothers'.

Sean , do you mean that the touch plate is a great tool or that the Mechmate is a great tool.
I have had a lot of fun with the latter.

:) Both

I used the touch plate for real yesterday and today.
A big improvement on using a piece of paper.

Also having the router turn on and off under control of the computer means I can go and do other things.

However I need to make some improvements.

What I want to do is,
1. Get the computer to store the Z height offset under T1(H) in the Tool table.
At the moment it is putting the height offset in the G54 Z in the Work offset page.

2. Fit a laser cross hair pointer on the machine and store the adjusted X and Y coordinates under G54 in the Work offsets.

Have anyone done this ?
Can anyone point me in the right direction.
Thanks in advance.

You could write a script for a button in Mach and automate the whole process. I used a touch off probe with a plate mounted to the table. I however use z zero as the surface of the spoilboard. I used the code from Big Tex screenset and modified it to do what I wanted. It will touch off, set zero or whatever value I have in a box and proceed to cut the material. You could use the same principle. If you wish to use the plate on top of the material, have it touch off, retract but remove the start from the script. Then you can remove the plate and press start manually. Either way you will not have to store the tool offset as it is set to the Z zero position at tool change.

Thanks Paul.
I got a solution to the G54 offset storage.

http://www.cooperman.talktalk.net/files/17.htm

I cleared the script in the 'G codes' button and pasted the script for the X,Y offset in.
It works.

The script for the tool height keeps throwing up an alarm.
'Scripter compile error. In:'

Nothing obvious but probably something simple.
Just have to pick my way through it.

I got the other script to work.
The culprit was the '.
There was a warning about the unicode symbols used.
I deleted all the ' and retyped them.

I still have the same problem. The offset is stored in the G54 Z box not the H1 box.
Must be to do with the Oem button number.
I will have to find the box or button number for H1 in the tool offset page.
Enough for today, the sun is setting, Time for a beverage.

Get machscreen and find out the number you need

Use SetToolParam().

Look it up in the manual:
http://www.machsupport.com/wp-conten...o_Prog_Ref.pdf

For the laser, try this. You need to change the numbers to the actual offset distances from your laser to the spindle.



XOffset = 3.43 'X offset from laser crosshair to spindle
YOffset = 4.322 'Y offset from laser crosshair to spindle

SetOEMDRO(800,XOffset)
SetOEMDRO(801,YOffset)

Sleep(125)

I would recommend storing the XOffset and the YOffset in an USERDRO and not hard code it in. If you are not good at detailing the code with an outline or commenting, in 2 years when you change something it will seem foreign.