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Mach3 Turn Set-up question
« on: October 15, 2008, 08:58:23 PM »
Need some help please!
I am setting up Mach3Turn on a 4500 MicroLathe II and a Drive Master NC 3-Axis controller and thought I was home free. However when I went to test my setup by going to the wizard screen and setting up the parameters for the OD facing template I found that when I ran the program everything was fine except the x-end diameter is off. I set my bar stock up per the posted introduction to Mach3Turn and the OD (.311 in this case) touch appears to be dead on, the rough cuts in the Z direction in distance are correct but the rough cut depth in the X direction each pass is considerably less than entered (.020). The number of passes shown on the screen also matches the number of cuts taken but the x-end diameter is considerably larger than what was entered on to the wizard template. (.263" vs entered .050).

I have tried changing the Turn Option to both radius and diameter but this seems to not make any difference whatsoever. I am sure that, as usual, this will be one of those fixes that once the solution is pointed out right in front of my nose I will say "I should have known that" but right now I am dumbfounded.

Thanks in advance for any help you can be you guys are always the best!
« Last Edit: October 15, 2008, 09:00:13 PM by jryoung29 »

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Re: Mach3 Turn Set-up question
« Reply #1 on: October 16, 2008, 02:26:03 AM »
If you use the MDI to command a move in the X axis does it travel that distance? If not then is it exactly half? If its neither then sounds like either you have the steps per unit wrong or your X is missing steps.
Hood
Re: Mach3 Turn Set-up question
« Reply #2 on: October 16, 2008, 10:43:33 AM »
Hood,

Thanks for the input.  Using the MDI to move the x and y axis .5" the y axis moves .3750" and the x axis moves .0315"  The axis position on the screen matches the command but the physical movement doesn't match. It indeed may be an incorrect steps per unit situation but I am unsure (as in haven't got a clue) as to how to correct or calibrate this issue.  When I set up the Mill 2 years ago everything just fell into place and worked from the get-go. I guess I didn't know how fortunate I was.

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Re: Mach3 Turn Set-up question
« Reply #3 on: October 16, 2008, 01:49:41 PM »
OK let me know a few details and I will post how you work it out and the figure you end up with .
1. are you setting up default units as Inch or mm
2. Steppers or Servos? If steppers are they 1.8 or 0.9 degree steppers (1.8 most common) If servos what is the line count of the encoder.
3. What is the pitch or tpi of your ballscrews
4. What kind of drives do you have and if the stepping is adjustable what do you have it set to, eg the Geckos are 10 microsteps
5. Is there any gearing between your motors and the ballscrew

Hood
Re: Mach3 Turn Set-up question
« Reply #4 on: October 16, 2008, 02:14:15 PM »
Thanks!

Here is what I have... The entire lathe set-up was given to me (as in free!) but came with NO documentation at all.

1. are you setting up default units as Inch or mm
                 Inch

2. Steppers or Servos?
                 I am assuming they are bipolar stepper motors with an open loop control because there is only a 4-wire connection to each motor.

2a If steppers are they 1.8 or 0.9 degree steppers (1.8 most common)
                 I have no idea on this one and there is no marking on the stepper motor. How would I determine this?

3. What is the pitch or tpi of your ballscrews
                  Again I have no documentation on the unit but the Taig lathe specification page shows the lathe to have a Carriage travel (z) of .60" per handwheel revolution and a Crossslide travel (x) of .050 per handle revolution.

4. What kind of drives do you have and if the stepping is adjustable what do you have it set to, eg the Geckos are 10 microsteps
                  Again I am not sure.... No documentation.  The Drive controller is a DriveMaster NC 3 Axis but that is all I know on that one. I have not had much luck finding anything that looks similar on the internet. I have not had the cover off but will if there is data in there that I can retrieve that will help.

5. Is there any gearing between your motors and the ballscrew
                    Finally an easy one.... No, the drives are connected directly to the ball screws.

Again thanks for your help and patience,
Jim

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Re: Mach3 Turn Set-up question
« Reply #5 on: October 16, 2008, 04:51:04 PM »
Just looked at the taig site and it says  the X is 20TPI which confirms your 0.05 " per rev. The Z seems to be worked off a rack in the standard Taig, is your CNC the same or does it have a screw fitted?
Right will show you how its worked out and I will do the X to give you an example.
ok so we will assume the motors are 200 steps per rev (1.8 degree) and your axis is 0.05" per rev so that means 20 turns will move 1 inch and we will assume also that your drives are half stepping.
 20 turns to move 1 inch, 200 steps  to move motor 1 rev but with half stepping that would double so its 20 x 200 x 2 = 8,000 steps per unit.

Give that a go and see what it does on a move and let us know.
Hood
Re: Mach3 Turn Set-up question
« Reply #6 on: October 16, 2008, 05:56:57 PM »
O.K. So what I have is:

in X direction I probably have 8,000 steps / unit (inch) and,


<<<The Z seems to be worked off a rack in the standard Taig, is your CNC the same or does it have a screw fitted?>>>
 
       The stepper motor is connected directly to the pinion gear. and since that movement is .6" per rev then it has 1.667 rev/inch so 1.667 x 200 x 2 = 666.8 steps/unit?  I assume this has to be rounded to 667 steps / unit?

But my question now is where do I input this data in my Mach3 configuration? Is it the incoder/mpg counts/unit table? If so how do I know which is the correct one?

Jim

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Re: Mach3 Turn Set-up question
« Reply #7 on: October 16, 2008, 06:02:24 PM »
No, best not to round as it will be more accurate if you dont, having said that it probably wont matter as if its direct from the pinion then you wont have preciscion there anyway.
 You put these values in the motor tuning for each axis, you will find it from Config menu then down to motor tuning. Click on X axis and enter your values and click save axis then same for Z. You will also have to tune your motors by adjusting the acelleration and velcity and that will just be trial and error but you can test by using the up/down arrow keys whilst in motor tuning.
Hood
Re: Mach3 Turn Set-up question
« Reply #8 on: October 16, 2008, 07:04:50 PM »
Hood,

Thank you so much! I am not exactly "on" on the numbers but now I can see where to work from. Am I correct in thinking that I now just need to measure the actual table movement in relation to the keyed-in step movement and "Tune" until they match across a distance to within a tolerance that is acceptable?

Again, thank you for the help, I am sure that I am only one of a bunch of people that are indebted.

Jim

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Re: Mach3 Turn Set-up question
« Reply #9 on: October 16, 2008, 07:17:38 PM »
Jim,
 if you put 8000 in for X step per unit and then you MDI a move of 1 inch and it only moves 1/2 inch then that means you need 16,000 in the steps per box. I was assuming one or two factors when I worked out the X value, firstly that your steppers are 200 steps per rev and secondly that your drives were half stepping. Your motors may be 400 steps per rev (not so common) or your drive may be 1/4 stepping, they could even be 1/8 stepping or for that matter even more.

Hood