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Author Topic: Problems threading on the lathe  (Read 330048 times)

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Offline ART

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Re: Problems threading on the lathe
« Reply #410 on: June 04, 2009, 08:19:17 AM »
Chip:

  1 slot per rev? Shouldnt ever happen. If a user only has one slot per rev, then they should use the original threading scheme in Mach3, but more than 1 is OK.
Weird numbers may result with low counts. When you enter G32, the average slot time is locked, if the spindle speed changes after that weird numbers may result.

In phot #1 it looks as if G32 mode was entered, then the spindle speed ( or slot speed ) was slowed down. This means the RPM was 258 at G32 time, but then was raised to
1016 after G32 was enetered. You need to enter a g0 to get out of threading mode before changing the spindle RPM, (OR ) the spindle didnt rotate enough times to average
before G32 was enetered. It takes 64 slots to average, so if the number of slots is 1 it takes 64 rotations before you could enter G32, if 10, then 6.4 rotations is the
minimum beofre it all averages out and G32 can be entered. Looks like in testing G32 was entered, then more testing and spindle speed was changed during this testing while still
in G32 mode.

 In Photo #2, the same effect seems there, the spindle speed was greatly changed after G32 mode was enetered. You have to be carefull that G32 mode is only entered with a spindle that has been running
and has rotated enough that 64 steady time slots have been read before entering G32 mode.

 The fact that the average slot time is so far away  from the last slot time seems to indicate all this. The average slot time should, except when the spindle slows during a thread, always be close to the average time.

Does this sound true to the way your testing? ( Or are my numbers screwing up? )

Thx
Art

Offline Chip

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Re: Problems threading on the lathe
« Reply #411 on: June 04, 2009, 08:47:09 PM »
Hi Art

As I stated in earlier post, "It seems to cycle through 3 or so states, I'm trying to sort it out and get some good pic's of this to post".

I need to work on video capture some, Then I could post this issue.

OK, Are there any different  registers / addresses to get the cpu clock's for Timing value or a method to refresh or set it's mode with the Plug-In.

Also It seems that the "Plug In", Doesn't Re-Set it's self or take another look at the "Number of Slot's" Value for a re-calculation.

At the moment the Fast PCI comp. is showing the 10 slot correct and I haven't been able to get the cpu clocks to shift.

2 pic's of my other computer with "10" and "1" slot's and 2 pic's of the Fast PCI computer,

Same Index / Timing Input's data is used on both. Times are not varied or changed and stable before threading is started.

( Simulated, Signal Source is a 555 timer with a Divide by 10 Decade Counter/Divider (MC14017BCP) IC ).
With 10 Slot's, Timing Input is 555 timer speed and Index is the divide by 10 from the Divider IC.
With 1 Slot's, Timing & Index Input's both use the divide by 10 from the Divider IC. 

Thanks, Chip

Offline ART

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Re: Problems threading on the lathe
« Reply #412 on: June 04, 2009, 09:46:26 PM »
Chip:

 they all look good except the last photo. The problem is in the driver for that one. It isnt expecting only 1 slot, so the average tim ebetween slots is too high,
and that causes the trouble. As long as its got the ten slots to work with , it seems all OK, this same problem would happen if the RPM was too low in a 10 slot system though
as well.

  So Im not sure if I want to subdivide it more as yet to cure that possability, its only meant to read down to a certain level, and I recommend at least 10 slots on a disk.
Ill wait now till some actual threading runs are done. Steve has been running some for me, so more test results are expected soon. Ill redo a version then to see what I can
do for the rest of it all.

   Thats good for tests for now. I think Im about done till actual threading runs are done on various machines. That will tell us how the corrective speeds are running.

Thx
Art

Offline RICH

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Re: Problems threading on the lathe
« Reply #413 on: June 04, 2009, 10:29:24 PM »
Art,
Is Steve using a low count encoder? Make, model, etc....any info on it? I don't have any trouble ordering one and would just skip the fooling around with simulation on my end. I finaly got the loaner pulse generator. So will try
and see if i can get some screen shots to you if things work out tomorrow.
RICH

Offline Chip

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Re: Problems threading on the lathe
« Reply #414 on: June 05, 2009, 12:22:28 AM »
Hi, Art

If "Steve" or others out there could post some feedback on there findings that would be nice, I've talked to Rich and know he's close to doing actual threading again soon.

I'm moving on to encoder A/B timing Test's, While I twiddle my fingers for some opto's to show up, To fix my Comp. 5's index Issue's. Heck maybe a 3'rd computer to test with is in the future.

Scope is working fine on both Computer's as long as the "Average Slot" Time Isn't a Negative (-) Value.

Didn't you Discover an Issue with ( Integer/ Non-Integer ) and "Mach3.sys" Code for Handling CPU Timing Issue"s, " Homing  Zeroing Error's ".
It had "Brian" scratching his head as to how I had helped on that one.

Back to the Trenches Hear, How about Someone sending some additional Supply's, Were getting a Little Low Hear.  ??? ;D

"Rich", Help's on the way' !!!!!!!!!!!!  ;D

Edit: Hi, All, I went back through the Post's, On page 24, "Art" posted this on the Encoder Setup.

"( Oh.. just a note.  You input the index pulse to INDEX  and use TIMING for the input of slotted wheel, OR turn off TIMING and use INDEX and Encoder#4 inputs as the encoder count input. Thx Art )"

Man,  ??? There's been Allot of hard work on this Topic, All the Way Around By ALL, and Again, Thank You, "ART"  MR. COOL  8)

Thanks, Chip
« Last Edit: June 05, 2009, 04:33:31 AM by Chip »

Offline ART

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Re: Problems threading on the lathe
« Reply #415 on: June 05, 2009, 08:05:14 AM »
Hi Chip:

>>Didn't you Discover an Issue with ( Integer/ Non-Integer ) and "Mach3.sys" Code for Handling CPU Timing Issue"s, " Homing  Zeroing Error's ".
It had "Brian" scratching his head as to how I had helped on that one.


   Cant recall that one, but its likely, Ive gone through a lot of chnages over the past year in the code. Your scope readings showed the total for the averaging was
overloading. Your timer is so high a value, that adding up the 64 numbers required for an average, made the total more than 32 bits can hold. So now that we're
64 bits, it seems OK. Bu tin the driver, even the 64 bit total overloads unless I subdivide it. Thats how large the numbers are that we're dealing with. The counter on your
fast machine is counting from 0 on one slot, into the billions till the next slot hits it. Thats pretty high resoultion, pity I have to nerf it down some. :)

  Steves tests, ( Steve hates web forums..:) ), seem to show a well formed pitch, BUT his X was goign too far in , I suspect a separate issue there, and he's going to retest
now that we found a rad/dia issue. It seems the G0 move that preps before the thread is losing steps, so we're checking to see if thats systemic, or just on his machine.
Ill post some pics of the resultant threads when I get them. Heres a post of two threads, one EMC (correct), and one Mach3 (incorrect) , but the mach3 thread is too deep, ( rad/dia issue or something)
but you can see the pitch looks pretty good other than being too deep.. I suspect we're getting close.

Thx
Art

Offline RICH

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Re: Problems threading on the lathe
« Reply #416 on: June 05, 2009, 05:18:48 PM »
ART,
Here are some tests.
Single spindle index was used and a function generator was used to emulate timing impulse signals.
This test: SPINDLE RPM @ 100RPM
               100 SLOT TIMING INDEX ( actual timing pulse was 166.44 HZ )
                                                  ( 100 RPM=1.666HZ    SO  166.44 / 1.666= 99.9 SLOTS )

RICH
« Last Edit: June 05, 2009, 05:35:04 PM by RICH »

Offline RICH

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Re: Problems threading on the lathe
« Reply #417 on: June 05, 2009, 05:23:38 PM »
ART,
Here are some more tests same as before with more timing pulses.
Single spindle index was used and a function generator was used to emulate timing impulse signals.
This test: SPINDLE RPM @ 100RPM
               400 SLOT TIMING INDEX ( actual timing pulse was 667.9 HZ )
Both test were done on a Dell Optiplex GX520 3gig hz computer using the motherboard PP.
Note that the interupt time changed some when taking the screen shots and they were actualy lower like about
35 us or so range before the screen captures.

When i get a chance will try the Nec laptop that i also use.

Do what anything in particular run / slots combinations?
RICH
« Last Edit: June 05, 2009, 05:30:54 PM by RICH »

Offline ART

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Re: Problems threading on the lathe
« Reply #418 on: June 05, 2009, 07:05:32 PM »
Hi Rich:

 Looks pretty good and stable. Thx for the tests, I think only the actual threading tests over time will tell us how it all works..
Thx
Art

Offline Chip

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Re: Problems threading on the lathe
« Reply #419 on: June 24, 2009, 09:06:32 PM »
Hi, Art

Hears a 2 inch long 1/2 X 20 thread picture, It's done on my Comp 5 lathe, Using Printer Port, 100 slot Timing and 1 slot Index.

The nut I tested with is a MIL Spec. MS aircraft quality castle style nut .570 long and it will run the full length without binding.

Chuck end is on left, Looking from right to left, First .500 thou of thread is real nice then it start's to lose thread profile width. The root of the thread seems to widen/wonder which reduces the thread profile, Peak's diminish and the nut will wobble.

I think the Z feed is slowing a little to much or over correcting some.

Chip