Messages

6481

General Mach Discussion / Re: Problems threading on the lathe

« on: February 26, 2009, 08:45:27 PM »

Well you get the written version and a picture also!
 -----------------------
I am scracthing my head on this one also. Back a week or so  i fooled around  and couldn't get the
x axis to do what is being described.  I harp on the mechanical stuff,  just want to be sure that
that is eliminated.
 
I have Art's postings on how threading works, but, hate to post something since if they changed threadng
or something in Mach versions it would only add to confusion.

If you loose a step with a stepper, and you usually know it, the x would take on a mind of it's owne calliing for a
hit of the estop. I have had them run away and also have had them skip but continue with the code,but if they skiip
a step usually it's for a time more than what these folks are experiencing.

If it's intermitant, finding the kremlin is tough.  Rf / noise can be a culprit here and that can be tough to converse
on.
RICH

6482

General Mach Discussion / Re: Problems threading on the lathe

« on: February 26, 2009, 08:09:20 PM »

Here is what you change to get G32 code.

MODIFIED: SORRY ABOUT THE PIC AND ALSO NOTE THAT THE FILE NAME IN THE PIC IS INCORRECT.
IT SHOULD SAY "M1076".

6483

General Mach Discussion / Re: Windows Processes Cleanuup checklist?

« on: February 26, 2009, 07:56:32 PM »

So what did you do that made a difference?
Rich

6484

General Mach Discussion / Re: Pausing while cutting

« on: February 26, 2009, 06:22:44 PM »

If i played with my mouse while running a program and using a slow computer.
Or zoomed in or out of the path window, again only with a slow computer.
But will admit that it never can to a stop and only slowed down some.
RICH

6485

General Mach Discussion / Re: Problems threading on the lathe

« on: February 26, 2009, 06:11:18 PM »

Rieks,
My question is this.......how are you missing a cut? Are you really missing a pass?
 
Backlash in the system and the resulting pass cuts can take on a strange appearence / illusion.
It is very difficult to definitively say / see  what happened. Even with a measuring microscope attached to
the lathe carriage. And you need to be very disciplined in the observence.  

Are you taking out the X & Z backlash on setup?
This will help.....to some degree....i won't debate the point as logic says one thing but in my experience it just dosen't cut it over numerous pressured passes. It just takes one or two thou and then a move in the other direction and now your cutting what seems like almost a double depth of cut. I can mimic that somewhat  just with or without cutting fluid.

Try this, put ten 0.0001" spring cuts in. Try it in the begining, mid-way, and at the end of the threading.
What happened during the spring cutting?  
  
I would like you to do something. Do two threading operatons. One using G32 and one using G76.
Both of them should be done with "exactly" the same paramters, metal etc. ie; spindle speed, depth of cut, etc.
In fact use a threading operation that caused fault.
One is a canned cycle and the other numerous X/Z moves.
What are your results?

Try the same using G32 with and with out backlash compensation.
What are your results?

Try another run, the only variable change is exact stop and constant velocity.
What are your results?

Try another run, the only variable change is not to provide cutting fluid on some cuts.
What are your results?

Please take the above in this light. Only trying to help not judge. I quess i believe there is nothing wrong
wth the threading cycle, that the built in compensations work to within some resonable degree, and that if things get
out of whack too much the thread is history. Every part of the system has an effect on the outcome.

RICH

6486

General Mach Discussion / Re: Problems threading on the lathe

« on: February 26, 2009, 01:24:33 PM »

TrevorH,
Only expect software to compensate so much for the mechanics of the lathe. What the program does to compensate for the mechanical ill's is very complex. It may take you additional passes but if in the end you get a good thread
that's what's important. My understanding of what happens is that the threading program does adjust to rectify a bad pass in the next pass. It can only do so much. Since threading is very machine dependent, i would suggest to anyone, that they do some experimentation.  

1. As you have done, try air cutting and see if timing is working as it should  and that the axis's have the
    accelleration / velocity to do the required moves. If you are using the wizard to generate the code , it will calculate
    and see  if you are within your motor tuning,
    and if not, you should change passes and spindle speed accordingly. I also must remark that if your max velocity
    and acceleration settings don't leave any headroom for cutting, then your not being very conservative and will
    surely run into a problem sooner or later.

2. Next confirm the quality of cutting by doing doing manny very small passes onto a marked shaft. You should get a
    single nice clean spiral. You will see if all is not well. I have posted pictures of this in other threads on threading.

3. Next comes the actual cutting. All the things associated with threading come into play. How well the "system"
    actuall does  may require you to adjust accordinly for your "system". Small lathes need to have as much going
    for them as possible. Sharp cutting tool nicely ground for the thread, properly placed for cutting, and adjusted
    accurately ( taking into account tip radius , etc.). So find out where things will go sour by doing some
    experimentation at different speeds, feeds , and .....material.  That experience will go a long way to being
    successfull.

I wish someone could say that at "x%" variation of speed threading will fault but just don't find that to be practical.
You shouldn't be there to begin with!

We just tried my Punny Lathe out the other day cutting a 1/4-20 @ 900 RPM / .001" first pass, .006" other passes with 2 spring passes in Al. Thread was perfect. BTW, I only have a fourth of your HP.

RICH


 
 

6487

General Mach Discussion / Re: Windows Processes Cleanuup checklist?

« on: February 26, 2009, 07:05:39 AM »

Here is a link to what you are lookiing for.

www.jasonn.com/turning_off_unnecessary_services_on_windows_xp

Another one is:

www.blackviper.com/WinXP

They give an explanation of each service and one by one you can go thru and modify. It dosn't take a few minutes
to go through them all.
Hope this helps.

RICH

6488

Show"N"Tell ( What you have made with your CNC machine.) / Re: Miser engine

« on: February 25, 2009, 08:57:19 PM »

Vince,
Nice going on the Miser. Surely gets the mind off of other things.
RICH

6489

Newfangled Solutions Mach3 Wizards / Re: New version of CopyCat, V1.1

« on: February 25, 2009, 08:08:27 PM »

Hi All,
I have posted an appendix to the CopyCat Manual which covers probing.
Here is the link.

http://www.machsupport.com/forum/index.php/topic,10498.msg66486.html#msg66486

I would appreciate any comments you may have. If you want to add to the appendix please
post in this thread. Hopefull there will be no "bent" probes.

The next appendix will be on using a video camera. Once that is done then there will
be a tutorial which covers combined use of video and probing.

RICH 

6490

LazyTurn / Re: LazyTurn

« on: February 25, 2009, 06:38:26 AM »

Looking good Art!
Although quitely on the side, I'm still following the postings. Hopefully will get
around to doing some testing. Keep up the good work.
RICH