• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
  • Several Regions have held meetups already, but others are being planned or are evaluating the interest. The Ontario GTA West area meetup is planned for Saturday April 26th at Greasemonkeys shop in Aylmer Ontario. If you are interested and haven’t signed up yet, click here! Arbutus has also explored interest in a Fraser Valley meetup but it seems members either missed his thread or had other plans. Let him know if you are interested in a meetup later in the year by posting here! Slowpoke is trying to pull together an Ottawa area meetup later this summer. No date has been selected yet, so let him know if you are interested here! We are not aware of any other meetups being planned this year. If you are interested in doing something in your area, let everyone know and make it happen! Meetups are a great way to make new machining friends and get hands on help in your area. Don’t be shy, sign up and come, or plan your own meetup!

JCDammeyer's 42 projects

jcdammeyer said:
@David I'm afraid 42 furlongs per fortnight is a rate measurement not a distance measurement.
Click to expand...

Apparently you didn't pass calculus. Distance is easily derived from rates. In fact, for constant rates, calculus isn't required - it's a linear equation. Distance = rate x time.

You could even just program your fancy thing-a-ma-dingy with all the wires and electron manipulators to do numerical calculus for you. Heck, it might even be more accurate than a direct measurement ......
 
Let's take a quick look at what is happening under the covers or if you didn't have a button on the screen to measure a tool length and place it into a tool table.

G-Code for CNC expects to have a co-ordinate system defined. When we refer to machine co-ordinates we're really referring to the G53 co-ordinate system.

Normally by default we use the G54 co-ordinate system which has a series of X,Y,Z values that move that 0,0,0 from the top left corner to somewhere inside the work envelope. That's why if you have 3 fixtures set up with work clamped in each you can set the 0,0,0 for each fixture in say G54, G55, and G56. Now run the same G-Code to machine stuff.

But let's rewind here for a moment. We're still trying to find out how long a tool is and what happens under the covers. To make sure one of these other co-ordinate systems isn't changing our 0,0,0 position we need to execute a:
G49
which cancels any tool length offset from the last tool change. Our reference point is now the bottom of the quill again.

Time to move the table or (or the Quill) to the tool setter location. As there may be offsets in play we'll expressly tell the system to use machine co-ordinates rather than just a simple new position command by preceding each line with the non-sticky G53

; Ensure we're in G90 / absolute mode
G90
; First go up & then move to change position to clear tool setter for long tools just off from home switch.
G53 G0 Z-0.2
G53 X0.500 Y1.000
; and to make sure also cancel the existing tool offset
G49
; And change tool command
M6

Now we've put a new TTS tool into the holder, tightened down the draw bar and we need to measure this tool so let's move over to a point above the tool setter.
G53 X1.00 Y1.000
G53 Z-1.00

Next installment. The actual probing of the tool setter.
 
In order to keep up with @David I've finally after many years bolted down my Tool Setter. It's now permanently at X0.5 and Y6.5. Of course the Y value assumes I haven't cranked the head way out.

1741902838786.png


And since I bent the tip of my touch probe (also now a while ago) I thought I'd go through and remeasure a few things and update the dimensions.
1741902941523.png
 
See I still need to measure the 3D touch probe but since I don't have a TTS holder for it yet I haven't bothered.
But I am printing T-slot covers for the table :P
 
David said:
See I still need to measure the 3D touch probe but since I don't have a TTS holder for it yet I haven't bothered.
But I am printing T-slot covers for the table :P
Click to expand...

What does a printed T-slot cover look like?
 
David said:
See I still need to measure the 3D touch probe but since I don't have a TTS holder for it yet I haven't bothered.
But I am printing T-slot covers for the table :P
Click to expand...
I'm about to quit metal working forever... For the life of me I cannot get this tool measurement stuff working. I've measured my tool setter. I've measured tools. And my probe appears to measure correctly. And yet when I measure a tool and move it 1" above the probed work piece it's off by as much as 0.2"

Signed
Very Frustrated in Victoria.
 
jcdammeyer said:
I'm about to quit metal working forever... For the life of me I cannot get this tool measurement stuff working. I've measured my tool setter. I've measured tools. And my probe appears to measure correctly. And yet when I measure a tool and move it 1" above the probed work piece it's off by as much as 0.2"

Signed
Very Frustrated in Victoria.
Click to expand...
Do repeat measurements of the same tool provide the same measurement?
 
TBH this is one of those things that drove me crazy with LinuxCNC. There are 2 "touch off" commands (work and tool), and as far as I was concerned, they seemed broken but I always assumed I was the fault. Could never get it to work how I thought it should. The fact that it just works in Pathpilot (LinuxCNC derived / skin) means it can work.
Sorry I can't contribute more than a remote shoulder to cry on, been there done that, moved on.
 
FWIW - the tool table in PathPilot is the tool length referenced from the spindle nose (positive #). So a small endmill and holder is say 50mm tool length and a large drill chuck and 12mm drill is 180mm tool length. And Pathpilot recommends you to reference the spindle nose before doing any tool length measurements. If there's any files or other stuff that you want I can have a look at them in Pathpilot and make a copy for you to have a look.
 
David said:
Do repeat measurements of the same tool provide the same measurement?
Click to expand...
Yes. I think I must have a hard coded parameter somewhere. The tool lengths entered manually into the tool table appear to work although I'm still finding even there about 0.005" gap to the 1-2-3 block. That could also be a backlash issue with the acme screw and bevel gears so I'm not worrying too much about that one.

Although my rule for software has always been fix the obvious ones first and often the not so obvious fix themselves.
 
Mike R said:
FWIW - the tool table in PathPilot is the tool length referenced from the spindle nose (positive #). So a small endmill and holder is say 50mm tool length and a large drill chuck and 12mm drill is 180mm tool length. And Pathpilot recommends you to reference the spindle nose before doing any tool length measurements. If there's any files or other stuff that you want I can have a look at them in Pathpilot and make a copy for you to have a look.
Click to expand...
It's that way in LinuxCNC too. And those work. But the psng screen for the touch probe and other code done by users looks at the length of the tool. If it's zero it uses the tool setter since it may be a drill bit in a Jacobs Chuck or some sort of R8 tool instead of a TTS holder.
 
You must log in or register to reply here.
Back
Top