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Author Topic: Spindle RPM lock error while threading  (Read 9424 times)

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Offline Hood

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Re: Spindle RPM lock error while threading
« Reply #10 on: June 10, 2011, 04:01:29 AM »
Dont know what to suggest other than as mentioned before disabling the plugin in the plugins menu, it may be that it is still affecting things.
If your RPM is steady and accurate without averaging on then I can see no reason why you are not getting threading to work.
Hood

Offline RICH

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Re: Spindle RPM lock error while threading
« Reply #11 on: June 10, 2011, 08:05:26 AM »
Quote
index debounce at 0 with no luck. Anything after 375 and my rpm reads wrong
The index debounce determines how manny times Mach will look at the index signal to confirm the signal. High values and you will see that
triggering will take longer, some will work at 0, I use a value of 10.
I also use a magnetic sensor, namely a Halls affect and it is fast sensing, some mag sensors like a reed are not fast enough at higher  rpm's
and thus won't work right. That's why I asked what type so look at the specs of your sensor and see if it is limited.
Signal quality at higher rates may be different than low rates so you may want to look at the signal with an o'scope. If the signal is not clean
it can influence triggering timing and output.  Sorry i can't be more specific.

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locked rpm in the diagnostic information plugin
Disable that plugin  / don't use it or any others from the thread testing thread, it is not functional and most of them required a specific related driver.

Spindle speed averaging, if on, will influence the threading accuracy since Mach reads the rpm  to four decimal places ( if i recall correctly).....more accurately than you can measure it. Depending on your lathe system you may not even notice the affect on the finished thread lead.
I would still recommend users use it.

One reason threading will not work is if you don't have a licensed Mach.

Since you have an index signal per the testing, rpm is read accurately ( to some rpm range ) , i think the problem is the sensor signal.
Lower the rpm for a selected thread and see if it triggers for the lower range.

RICH
 
Re: Spindle RPM lock error while threading
« Reply #12 on: June 10, 2011, 09:26:43 PM »
I went through my sensor wiring and rerouted the wires so they were clear of any other wiring. Now the threading works, not sure if it was a loose wire or the wires picking up interference.  Thanks again for all the help!

Offline RICH

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Re: Spindle RPM lock error while threading
« Reply #13 on: June 11, 2011, 08:53:18 AM »
Glad you got it working. I will assume that the sensor wiring was shielded, and if not , running it past anything that generates an electrical field can change the signal and cause problems.
The shield should be grounded or provide for a continous shield along it's entire routing ie; not grounded at sensor..though say a plug/ jack/ connection...and terminate / ground to a separate ground
which is not part of some electric circuit.

RICH
Re: Spindle RPM lock error while threading
« Reply #14 on: June 28, 2011, 09:21:43 AM »
I've just upgraded to R3.043.022 and have seen similar problems that I didn't have in the old version ( R2.something).
The spindle speed doesn't show the right value above 600RPM ( used to be ok at 1000 RPM ). This happened very occasionally with the old version but was instantly fixed by restarting Mach3, however it seemed more of a scaling factor than what is happening now. Now it seems to be a permanent fault.

Also the threads finish with a groove instead of withdrawing the tool ( creating a shear point ), using the same G Code that used to withdraw the tool during the last turn of the chuck.
I used a "run from here command" to go over the thread again ( a few lines before the threading cycle ) and it didn't pick up the thread exactly - this has never happened before.

The spindle pulse is fiber optic so there is no noise getting into the signal. It was perfect right up until Mach 3 was upgraded.

Everything was fine with the old version until I tried to edit the G Code after scrolling down a bit in the G Code window in Mach 3. I got an error message asking if I wanted Mach 3 to recover-which flashed about 100 times, and had to reboot the computer. I couldn't get Mach 3 running again so I updated to R3.043.022.

I would like to know which version of Mach 3 was the last before the threading cycle was changed. I don't need the spindle speed correction in the new threading cycle as my spindle doesn't change speed when cutting threads.

Thanks,
Glen.
I had a few parts left over - still it's always the same when you try a bit of "do it yourself"

Offline Hood

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Re: Spindle RPM lock error while threading
« Reply #15 on: June 28, 2011, 09:32:10 AM »
Have you looked in the change log?
Hood
Re: Spindle RPM lock error while threading
« Reply #16 on: June 28, 2011, 10:39:09 AM »
I had a look in the changelog but couldn't make out where the complete rebuild of the threading function started. There seemed to be many comments like "Threading Driver update for the P POrt" & "Driver update for threading".

I've installed Version R2.63 and most of the problems I mentioned in R3.043.022 disappeared. The spindle speed now displays correctly and the thread can be re-cut. I just have to try to get the threading tool to withdraw during the last turn now.

I'm sure the "L" value in the G76 cycle used to be the number of degrees of rotation it takes to withdraw the tool. In R3.043.022  if the "L" value is 45 it cuts a sharp groove for a full rotation after the Z axis has stopped and then does a 45 degree chamfer. An "L" value of 45 should withdraw the tool during 45 degrees of rotation. An "L" value of zero should remove the tool at maximum speed at the end of the last rotation of the helix BEFORE the z axis stops moving.

All the parts I have made before had the tool withdraw without leaving a groove and had an "L" value of zero.

A sharp groove is the best way to make the weakest possible component.

Thanks,
Glen.


I may try an even earlier version of Mach 3 to see if it fixes it later.
I had a few parts left over - still it's always the same when you try a bit of "do it yourself"

Offline RICH

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Re: Spindle RPM lock error while threading
« Reply #17 on: June 29, 2011, 09:17:48 PM »
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which version of Mach 3 was the last before the threading cycle was changed
I would need to go back a number of years since it was actualy broke at one time and if memory serves me it was even before R3.041.22.... forget the past versions  for threading.
Use at least  3.042.032 and even better 3.042.034 and beyond.....I use 034.

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I don't need the spindle speed correction in the new threading cycle as my spindle doesn't change speed when cutting threads.
Well maybe .....but...... it is changing some and you just can't see it via a DRO. For the most accurate threading the spindle speed averaging can help some, it all depends on
just how good your lathe system is and you will need to really accurately measure the thread lead over the length to even find accuracy differences. The basis of Mach holding a lead accuracy is shown in the write-up in figure 4.4.5. Class 1 threads, when not chasing, will be not be possible for most lathe users.  If you are happy with the results then don't check it's use in config. 

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try to get the threading tool to withdraw during the last turn now.
The axis needs to be fast enough to withdraw during the degree of rotation and the Z  must slow down to achieve the pullout. A 90 degree pullout at fast feedrates for example would be impossible. See the note at the top of page 34 in the write-up on the L value. The fastest I  could test threading at was around 120 IPM and that was scary fast threading for me.

BTW, I like to use G32 code output from the wizard as i can see the code for each pass and makes for easy modification in one so desires. To each their owne. ;)

RICH 
Re: Spindle RPM lock error while threading
« Reply #18 on: June 30, 2011, 12:35:57 PM »
Thanks Rich,
It looks like a high value in the CV setting makes it withdraw the tool early to try and keep a constant velocity - inadvertently creating the correct tool withdrawal function. I had set this to a low value when I reinstalled Mach 3 because I've had major accuracy issues using CV on a router. The threads I was cutting were 2mm pitch @ 300 RPM.

The original point I made about the displayed actual RPM in version  R3.043.022 being wrong above 600 RPM seems valid as it was fixed as soon as I installed Version R2.63.

Also, there has been a bug with the G Code window for a long time. I don't know if it has been fixed in later versions but the way to test it is to feed hold while running a G Code and then press Edit G Code. I realize it's not something you would normally do, but you can forget it's only in feed hold and not stop if you're looking for an error in the G Code. The last time the bug occurred I had only scrolled down in the G Code window and then wanted to change something in the code. The bug produces a never ending cycle of error messages until it locks up the computer. This is in Mach 3 Turn ( several versions ).

Regards, Glen.
I had a few parts left over - still it's always the same when you try a bit of "do it yourself"

Offline Hood

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Re: Spindle RPM lock error while threading
« Reply #19 on: June 30, 2011, 01:39:24 PM »
Also, there has been a bug with the G Code window for a long time. I don't know if it has been fixed in later versions but the way to test it is to feed hold while running a G Code and then press Edit G Code. I realize it's not something you would normally do, but you can forget it's only in feed hold and not stop if you're looking for an error in the G Code. The last time the bug occurred I had only scrolled down in the G Code window and then wanted to change something in the code. The bug produces a never ending cycle of error messages until it locks up the computer. This is in Mach 3 Turn ( several versions ).

Regards, Glen.

Cant recall seeing this but suppose its something I only do occasionally as like you say sometimes you forget. Anyway just tried here with the lockdown and you get an error message telling you to stop before editing, so looks like its fine now, not sure when/if  it was fixed as I have never seen the problem you get.
Hood