Messages

21

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 13, 2012, 05:39:32 PM »

Just had a bit of an experiment with your C axis suggestion which seemed quite neat. Unfortunatley because Mach is sending a PWM signal to the relay, as it thinks it is driving a motor, there isn't enough continuous current to open the relay. My LED relay tell-tale light illuminates dimly but the relay doesn't engage.

...Sweep

22

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 13, 2012, 05:10:14 PM »

Hi TP,

I have had a tweak of my DC controller and can drop the speed down to 20rpm. I then measured the arc of detection of the spindle proximity switch and got about 13 degrees.
Considering 20rpm/60 = 0.33r/s or 3sec/rev, and 360/13 = 27, then 3/27 = 0.11seconds the switch is active. Is that sufficient for a reliable trigger?
I suppose we could also set a timer cycle at the same time so if it doesn't detect in, say, 5 revs bail out of the toolchange program and call an alarm.

To comment on your last post. The spindle is controlled by PWM and will run a steady 20rpm now I have tweaked the pot, but currently I don't have a seperate relay to reverse the spindle. I only have to get close, however, as don't forget the spindle will centre when the pnematic ram operates if it is +/- 20 degrees or so from perfect alignment

...Sweep

23

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 13, 2012, 02:29:37 PM »

My problem isn't the ramping down of the speed or disengaging the relay at 60rpm, it is that I can't figure out the VBscript to look for the index, or Input2, pulse and then disengage the relay. Every time I try it it either doesn't see the index or doesn't hold the next line of the program until the spindle has stopped.
An extract of what the program currently looks like is shown below in black with what I think should be used for the spindle alignment in RED. I have put a Sleep 25 as a tunable deceleration figure but it will probably be better to move the sensor to exactly the position I need it.
So, is the code any good or a recipe for disaster?

x = GetUserDRO(1200)
y = GetUserDRO(1201)
z = GetUserDRO(1202)
Code "G00 G53 Z" & z
While IsMoving ()    'pause to allow Z axis to move to change position
Sleep 100
Wend

Code "M3 S60" 'spindle run at minimum speed
Sleep 5000 'allow spindle speed to stabilise
While Not IsActive(INPUT2) 'look for spindle proximity switch
Sleep 500
Wend
If IsActive(INPUT2) Then
              Sleep 25 'alter figure to tune deceleration
              Code "M5" 'stop spindle
End If

Code "G00 G53 X" & x & "Y" & y
While IsMoving ()   'pause to allow XY axis to move to change position
Sleep 100
Wend

Slot1 = GetUserDRO(1101)
Slot2 = GetUserDRO(1102)
Slot3 = GetUserDRO(1103)
Slot4 = GetUserDRO(1104)
Slot5 = GetUserDRO(1105)
Slot6 = GetUserDRO(1106)

24

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 13, 2012, 02:56:48 AM »

Ladies and Gentlemen, for your entertainment and edification this evening I proudly present ...a video of an old milling machine

http://pictures.pollz.co.uk/#8.
There are two videos in a album called Denford Triac.
The site is my daughter's in case anybody was wondering!

Everything has been programmed except the spindle stop position. When I have donetool changes with the spindle isolated and manually positioned with the drive dog in the correct position I have never once had a toolchange failure. The last tricky bit is to align the drive dog from a spinning spindle before the carousel starts moving. I chose 60rpm as the speed as it looks pretty close to what the original on-board controller was using, is not too slow to become lumpy, and pretty much gets rid of most inertia overun with either a light tool (centre drill) or heavy tool (face mill).

...Sweep

25

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 12, 2012, 07:46:50 PM »

I found an old video of the original machine sequence which I am trying to replicate. Is there any way that I can post it on here as it will show better than words what's happening?
 
...Sweep

26

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 12, 2012, 07:22:28 PM »

Hi TP,
The spindle drive is a DC motor and Lynx 08 DC controller which is a pretty basic. Both motor and controller are the original equipment of the machine and are probably 20+ years old.
I appreciate that the inertia will carry the the spindle beyond the switch off point, hence the point about the delay for tuning the stop position, but there is also quite a lot of friction in the system as there is also a 1:1 timing belt between the motor and the spindle. This is also the reason why I have dropped the speed down to 60rpm to reduce the affect of the inertia to a minimum. At this speed I am witnessing maybe a 1/4 turn of the spindle when the relay disengages.
There is also a mechanical self-aligning mechanism in the spindle which will take up around +/- 15degrees misalignment when the air operated tool holder release is operated.
The system that i am suggesting is really the same that was installed with the machine from new. The only thing that I am doing is operating it from Mach as opposed to the obsolete motherboard.

...Sweep

27

VB and the development of wizards / Re: SystemWaitFor(INDEX) ...will it work?

« on: November 12, 2012, 05:13:52 PM »

isn't it annoying when you type out a long post and the system times out before you submit it. grr

Anyway, I have been away from playing with my machine for a few weeks due to work commitments and have now started to complete the missing link of my toolchanger macro, namely the spindle dog alignment.
I have tried various combinations of If and While commands but have failed at every step and I am coming perilously close to causing some serious damage after crashing the carousel into the still spinning spindle on more than one occasion. ouch!
What I am trying to do, as mentioned in the original post, is to run the spindle at a very low speed, say 60rpm, and then switch off the spindle relay as the INDEX proximity passes the detector. As the detector is about 90degrees off from the correct dog position i am also trying to put in a Sleep delay so I can 'tune' the position. If this is impractical I could physically move the proximity to perfectly align with the dog position which might be better.
As I wasn't getting much success with IsActive(INDEX) I have duplicated the Index port and pins for a seperate input so I can use IsActive(INPUT2). Whilst I can get the spindle running, Code "M3 S60", I don't seem to be able to figure how to get the thing to stop before the program steps further into the macro and sends the carousel into the spindle.
I don't suppose it really matters at what early point in the macro the spindle alignment commmands are executed, be it before or after the table moves safe (Code "G00 G53 Z" & z etc), so please feel free to make any suggestions.
I am just worried that if I carry on 'trying' to get it right i'm going to detroy my machine in the process.

As always, your assistance would be greatly appreciated ...Sweep

28

General Mach Discussion / Re: Mach3 or CAM tool offsets?

« on: October 15, 2012, 12:22:12 PM »

I would let the CAM run the Tool Radius offsets(toolDiam) and Mach3 run the toollength offsets(length)

It is the best of both worlds.  (;-) TP

That would be the ideal scenario. I completely agree.

...Sweep

29

General Mach Discussion / Re: Mach3 or CAM tool offsets?

« on: October 15, 2012, 02:37:49 AM »

Thanks TP & Ray,

I will try and find out what file format the CAM uses or is looking for but I guess it will be whatever type is used within a Fanuc equipped machine.
I think I need to run a few sample programs and compare the axis movements between both. I noticed that within the first couple of dozen of G code that G43 is programmed so I'm not even sure yet if the CAM has taken length offsets into account or its just used in the simulation.
If it has and is also calling a G43 then Mach will also act on this during the M6 command and add its own offset.
I am working away for three days so it may be the weekend before I can run any trials.

Thanks ...Sweep

30

General Mach Discussion / Mach3 or CAM tool offsets?

« on: October 14, 2012, 11:50:29 AM »

I like the method that Mach3 provides for setting various tool offsets into a tool table as it's very easy. I just change datum all axis, choose a tool, lower it onto my DTI gauge block, and click Set Tool Offset. Simple.
I have now just started using a CAM program which has its own tool library but which also suggests that the 'Machine' tool library, Mach3 in my case, can be imported into the CAM.
I have tried to find the Mach3 tool folder but can't. I could hand type all the offset lengths but this could lead to errors. I am also worried about compounding offsets if they are applied by both the CAM and Mach3 at the same time e.g. an offset of 214.402mm becomes 428.804mm etc.
Any guidance would be appreciated.

...Sweep