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Messages - davidimurray

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General Mach Discussion / Re: calibration problems need help please!
« on: April 04, 2006, 12:06:03 PM »

You need to move in the same direction, an amount greater than the backlash before you start your actual measurment move. Lets try an example as it is probably easier to see. Lets look at the X axis which has say 0.5mm of backlash.

Initial postion is X27 - random number I came up with !
Now move in the -Ve direction i.e. G0 x-10
We now need a +ve move to remove the backlash i.e. G0 x0
The backlash is now removed
Now start the measurment move e.g. G0 x50 (+ve move)

Make a note of the measurment - you now need to go back to G0 x-10
then G0 X0 (remove backlash again)
Now change the step settings (you don't need to remove the backlash as you already have!)
repeat over and over until your happy.

The important thing is that where you change direction you need to do two moves, first to remove backlash, second the actual measurment.

Any more probs just shout



General Mach Discussion / Re: calibration problems need help please!
« on: April 04, 2006, 11:40:35 AM »

If you go to the settings page there is a button bottom left is marked "Axis Callibration" - You tell the machine how far to move, it moves, then it asks you to tell it how far you measured that it moved. It then calculates the steps per unit required.

Are you aware of backlash? You need to make sure that this is taken out before you perform you're measurement. I.e. before you do you're measurment move, you should move in the same direction as you plan to measure. If you need any help just give me a shout.



General Mach Discussion / Re: calibration problems need help please!
« on: April 04, 2006, 06:48:46 AM »
Hi Brian

Sorry I think I confused things a bit. The basic problem I have found is this :-
I eliminate backlash (g0 x-10)
Move to start position (G0 x0) set DRO to zero
Run calibrate axis, enter 50mm, enter value, e.g. 48.97mm
Remove backlash (G0 x-10)
move to start (G0 X0) ser DRO to zero
then move to x50 (g0 x50)
Read Dro Value - this value (even after about 6 calibrations) does not equal 50mm
If I manually tune the motor values I can get the table to move exactly 50mm as read on the DRO.

Has anyone else experienced this. Brian, I don't mean to have a go but the calibration doesn't work on my system when compared to the DRO. The values are always fractionally out. However, it is possible to achieve the exact values through tweaking. I wondered whether some where there was a rounding being performed too early in the routine.



General Mach Discussion / Re: calibration problems need help please!
« on: April 04, 2006, 05:37:13 AM »

Just noticed this thread - I am very wary of the calibration tool. I have a DRO on my machine so used this to do various tests. I used the calibration tool to try and set the correct values over various distances - from 10mm upto my full table travle (only 200mm). After calibrating I repeated the same tests (all this was done with backlash turned off so I compensated manually). Every time I used the calibration wizard I found the values were slightly out - e.g. a move of 50mm gave a physical move of 49.97mm. Every time I used the calibration tool it was slightly out. I then went to motor tuning and decided to 'hand tune' the values. These had been calculated to about 6 or 7 decimal places. I found that if you reduce the value down to about 3 decimal places, and play with the last two decimals then you can get really good results. (I use about 500 steps per mm)

This may be a rounding problem in the software - perhaps Art can shed some more light.



General Mach Discussion / Re: Serial Toolchanger Macro
« on: March 27, 2006, 04:20:48 PM »

Now I'm confused. Just ran a test using serial monitor to look at the input and output using both Hyperterminal and Mach. Here are the results in the attached screen dump. As you can see, the electronics actually return a CR and LF. The problem seems to be that Mach doesn't seem to be opening the port. Anybody got any ideas?



General Mach Discussion / Re: Help with Mach3Mill Motor Tuning
« on: March 26, 2006, 05:59:32 PM »

Haven't had a look at your XML file but looking at what you've described, you state that pin 2 is connected to both the step and dir line. The step and dir line should each have their own pin e.g
Step - Pin 2
Dir - Pin 3

If both step and dir are connected to the same pin then as each step pulse is sent,the dir line will change leading to the motor vibrating on the spot. Due to the step size being so small you probably won't see the motor trying to move.



General Mach Discussion / Re: Serial Toolchanger Macro
« on: March 26, 2006, 12:01:28 PM »
Hi Graham

This section always seem to shows 'None'. Is there a wait to put a timed delay in ? I was wondering if I could put a 5 second loop in the program, in case the loop is updating faster than message can keep up.

I'm using V1.9*********xx. I used some software a while ago that gave me the serial input in the form of hex so I will try and dig this out to check that a CR is being sent. I ha a look through the yahoo list and I think Art had now changed it to support CR+LF and CR. Just got back from the workshop so I will have another look in the next few days - new Acme screw ready to go on my mill!!! And i'm in the middle of fitting up the spindle control for the mill, and this toolchanger for a friend, and must get round to doing some more on my two steam engines. Hmmmmm - you can never have enough jobs on the go at once!!!



General Mach Discussion / Re: Serial Toolchanger Macro
« on: March 25, 2006, 02:33:47 PM »
Hi Graham

The electronics have worked both with the terminal emulator in the AVR software and in Hyperterminal so I know that the electronics side seems to be working ok. Transmitting codes to the electronics seem to work fine as well. There is no handshaking invovled, it is a simple two-wire RS232 connection with CR at the end of each line.

I've included part of the coden note that i've used the message to help with debugging - Currently only setup for tool 1 as I want to try and fix one set of code before I copy it along for each tool :-

Code: [Select]
tool = GetSelectedTool()
' Max number of tools

num_positions = 8 

' do not allow tool number greater than number of turret positions

While tool > num_positions Or tool < 1
Tool = Question ("Invalid Tool Requested, New Tool Number?")

Select Case tool

Case 1
message "Changing To Tool 1"
Call sendserial ("t1d" & Chr(13))

While getfifoentry() = "None"
message getfifoentry

if getfifoentry() = "t1s" & Chr(13) then
message "Tool 1 Selected"
SetCurrentTool( tool )
End select
Message "Tool Change Error"
end if

Case 2
message "Changing To Tool 2"
Call sendserial ("t2d" & Chr(13))

Case 3
message "Changing To Tool 3"
Call sendserial ("t2d" & Chr(13))

End Select

I will warn you that this is the first macro I have written for Mach so its probably some simple mistake!

Thanks for your help.



General Mach Discussion / Serial Toolchanger Macro
« on: March 25, 2006, 12:43:54 PM »

I was wondering if someone could help me. I'm working on the electronics for a friends lathe toolchanger. Using an Atmel AVR micro-controller, I've produced a board that accepts the tool number in the form of t1d, t2d etc with a CR on the end over a serial link. The tool is changed and once complete, the toolchanger sends back a t1s, t2s etc to show that the change is complete and the correct tool is selected.

I've written a macro that sends the code to the electronics and performs the toolchange. However I can't seem to get the serial input back in to work. I tried using getfifo entry in a while loop such that when getfifoentry does not = "none" it should leave the loop and enter the next section of code. However the code seems to get stuck in the while loop. Anyone have any ideas?



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