Messages

7231

General Mach Discussion / HOW TO PICK-UP A THREAD - CNC THREADING

« on: July 21, 2008, 10:03:10 PM »

Hi All,
How do you pick-up a thread and re-run a threading program to take a few more passes over the threads?
The piece is already done, removed from the chuck and of course the motor was stopped.
The CNC lathe has a single slotted disc and steppers. Just need some general guidance if it's even possible.

I have no problem doing this on my manual lathe. Just never had to do it on a CNC lathe.

RICH

7232

G-Code, CAD, and CAM discussions / Re: Simple G code example needed

« on: July 21, 2008, 09:34:33 PM »

Kristin,
Try using one of the wizards to generate the code and the add the dwell in after each pass.
See attached files.

RICH
 

7233

General Mach Discussion / Re: milling text

« on: July 19, 2008, 01:24:35 PM »

GPDC
There is a wizard in Mach called "WRITE" (free but haven't used it) , didn't see any in Newfanged.
Go to sherlines website and download "DESK ENGRAVE" ( free and have used it). To get mutiple lines
of test just append 2nd line of text to original gcode file ( you will have to position it).

You can also convert text from a CAD program to GCODE. I am sure there are a lot of other free programs.
RICH

7234

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: July 19, 2008, 11:01:54 AM »

Hi all,
Attached is a modified file of the gear used for some testing. It keeps the four machined quadrants but eliminates the depth repetitions. So you still have the sharp x y moves, lead in's, etc. I ran this on my mill about 50 times total with F at 10,20,30,40. Since I use a SmoothStepper there was no backlash implemented. My mill has a four axis digital readout so comparison to the MACK DRO is easy at different points and at the end. No progressive error was seen. 

I'll waite to see what Hood comes up with, and if you want, can run the program with a different PC not using the SS, and will provide for be a better comparison.
RICH

7235

General Mach Discussion / Re: I could use a GCode file for Lathe

« on: July 17, 2008, 06:40:56 PM »

Dave,
Glad to hear you didn't throw in the towel. Not having any specific projects is the ideal time to just play around
with the wizards, one by one, and then when the time comes, you can work with some confidence.
As far as slow movement goes, as a hobbiest,  if it takes 10 or 15 minutes instead of five, so what!
Enjoy the moment,
RICH

7236

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: July 15, 2008, 05:31:29 PM »

Hi all,
If you swapped cables so that you used the x drive for the y drive and vise versa, wouldn't you see a change in returned position if it was a drive or signal path problem?


Put a small dot on your vise. put a toothpick in the chuck, manualy move table to allign toothpick point to dot, lock the quill. Just an easy visual check.
You should be right over the dot after running either of the following.

In absolute and exact stop and using the MDI line for moving:

G01 X1 Y1 F20
G01 X0
G01 X1 Y0
G01 X0

Now swap the x & y cables to the steppers  ( make sure you shutdown the drives before disconnecting the cables)

G01 X-1 Y-1 F20
G01 Y0
G01 X0 Y-1
G01 Y0

This provides for same crossed pattern. (Note this is 4x to 2 y movements, thus you favor an axis.
Make a file and test using constant velocity or exact stop.

RICH

7237

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: July 14, 2008, 10:56:44 PM »

Carl,
Thanks for the pictures as it really helps just knowing it's not some 40 year old mill ( mine is !).
One thing mechanicaly woud be the attachment of the screws ball to the underside of the tables and if the bolting moves you will never get consistantcy. So thats something worth eliminating. This would also be more pronounced at higher travel speeds. I assume you can't rack your tables, when my friend installed his ball screws into same kind of mill
as yours is was a PITA as the anchoring of the nuts had to be just right with the gibs adjusted.

Just a comment on testing, namely keep your moves the same, ie. same pattern.

Reduce your velocity to 10, and keep the acceleration low and maybe make your moves always over say 3" square and accross the corners so you have the same pattern to judge against. It's just an inerita thing.
Just for kicks,lower your tuning, do a test,  then do a test with the  heavy vise removed. This can give you a glue if the nuts are moving.

Not an EE either, so excude if the lingo is off , in terms of noise traveling / being inductively coupled to other wires, the solution can be difficult and sometimes like black magic. If you find something like spreading wires makes a difference just play around with those wires and gage results. ....One thing at a time...... The electrical field around the wires will increase as as current, voltage, and of course frequency is increased. The field can build up over time and at some point could cause interference with a device.  Sort of sounds like what would that one extra line of code do! Shielding will help this as it contains that field, neatly wrapping aluminum foil 100% around each cable is a quick shield without trying a different cable. Additioinaly just have the shield touching against the grounded box and not the stepper.

Just some thoughts,
RICH

7238

General Mach Discussion / Re: I could use a GCode file for Lathe

« on: July 14, 2008, 08:06:48 PM »

Thanks for the post Jimpinder and what to do with the files.  Will try them out in the near future.

How are things going Dave?

RICH

7239

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: July 14, 2008, 07:55:02 PM »

Carl,
Remember one change at a time.
Have you tried any of the other suggestions to eliminate components?
What current set resistor do you have on the G201's?
Can you post a picture of you mill?
RICH

7240

General Mach Discussion / BACKPLOTTING - CONVERT G CODE TO DXF

« on: July 13, 2008, 09:11:29 PM »

Have you ever wanted to convert G code back to a dxf file easily?

There is a slick free program you can download from CNC ZONE archives . I fooled around with a few files and it worked well.
One thing I did with the text file of the code was to remove some of the starting g codes for the lathe or mill and remove sub-routines
where your only cutting deeper.

Here is the link:
http://www.cnczone.com/modules/Downloads/userfile.php?id=22

If you use Autocadd you may want to check out this site for backplotting G code directly into Autocadd.
I have not tried any of them.   

http://www.wjbzone.com

If you know of something for "free" which works, please post.

RICH