Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Shaped on November 08, 2010, 10:45:13 AM
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Hi
Small problem, while ive been setting up my new machine i have had to hit STOP a few (hundred) times.
Thats fine works fine, but then when i hit GO HOME Mach moves in the x or y direction first gets to home position then moves up z
It does go home, but i want it to move up z before it moves x or y.
is this a Gcode problem or does Mach control the Go Home function.
Anthony.
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Set up a safe Z and it should move first, you will find it from Config menu.
Hood
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thanks hood
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Set up a safe Z and it should move first, you will find it from Config menu.
Hood
How do you set up a safe Z to get it to move first?
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Config Menu then Safe Z setup, you will see a box like the pic. I personally prefer using machine coords for safe Z as it is always a fixed point where as the others are not.
Hood
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Awesome, thanks. Since you have been nice enough to bail me out of previous fixes, I thought I might ask for more advice. I'm trying to set soft limits but I can't seem to get it right. The actual limits of the machine are X=47.5", Y=18", and Z=6" but when I put these numbers in motor home/soft limits screen, I get "soft limits max<min" errors in the status screen. And I'm not sure what the other settings should be, such as reversed and home neg. I have the setting currently at X=Max 47.50/Min 0, Y=Max 18.00/Min 0, and Z=Max 0, Min 6, with Reversed and Home Neg all in red. I still get errors. Can you guide me through this?
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Z Min should be a negative value so try with -6
Hood
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Try a minus value for the Z axis since it goes from positive value(top) to a negative value.
Jeff
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Sorry Hood, same answer at same time.
Jeff
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No need to be sorry Jeff, often happens that two people type at the same time :)
Hood
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That worked! Now, what is the purpose of the soft limit button once illuminated?
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It will stop you jogging outwith the soft limits. You may have to mess around with the slow zone. You want to set the distance so that when you jog towards your limit switch at full rapid the Softlimits will slow the axis down and stop in time before it triggers the limit switch.
Hood
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With the light on, it doesn't stop before tripping the limit switch. I have the slow set to 2.0.
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Now all of the sudden, the Z axis winds down in the Pos direction like the motor is bad but works well in the Neg direction. I changed the settings back and it still does it. When I take it off of Soft Limits, it goes away. But it was no where near the limit switch.
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What I am not getting is why the DRO does not read in inches, which is what I put in the soft limit option screen. When the spindle travels, for example on X axis two inches, it displays something else in the DRO. I dont get it. I have inches set up for units. What I did to begin with was travel to max axis from 0,0 and record what the DRO displayed for each axis. That didn't work but it should read the correct inches, correct? My actual DRO travel for Y axis was 2.7447 and the actual movement in inches is 18". I am so confused.
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Attach your xml please and I will take a look.
Hood
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Ok, Hood but don't laugh because I have been working on this all day and made many mistakes. At least don't laugh within the post, lol.
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No probs :)
Hood
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This is it. Can you explain why the DRO does not indicate inches?
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What are you meaning by that? If you zero the X DRO and command a move of 2 inch from the MDI line (G0X2) does the DRO not show 2?
Hood
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No, I just typed g00 x4 and the DRO displays 4.000 but it moved about 2 feet.
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Ok then your calculations for steps per unit are wrong.
Hood
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I input g00 x-1 and it moves 6 inches.
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Thats motor tuning and set up, correct?
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You dont have any home switches enabled so how are you referencing the machine? You need to reference before you can use SoftLimits as Mach needs to know where it is. You can reference without having switches, I think Rich wrote a doc on how to do it so I wont waste time retyping, you should find it in the member doc area.
Hood
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Yes Motor tuning to enter the steps per unit. If you want a quick and dirty way of getting the steps per then use the Set Step Per Unit button on the settings page and Mach will calc for you. This however will only ever be as accurate as your measuring and its normally much more accurate calculating them yourself.
Hood
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Ok, I enabled one home switch because the limit switches are wired in series so I only have one but I'm not sure how this works. I want to reference using a home switch but not sure what I'm doing. I now have X Home enabled port 1/ pin 13, same as X++ limit switch. Now what? Also I have acme drive screws, 10 TPI, 5 start. How can I calculate them myself?
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If you have limits on all axis and they are all wired in series you can use that single input as Limits and Home switches for ALL axis, just set them all to the same port and pin number. You will then possibly have to choose the home negative in Homing and limits for some of the axis, just depends on your setup.
Hood
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Thats how I had it set up originally because I have limits on all four screws, each end, 8 total. Scott (from Mach) said since I had only one pin and wired in series, it would not be a benefit.
I don't understand the Homing Neg option. As of now, they are all checked red. So now I have all set up as limits and home switches but not sure about the Home Neg.
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I used the formula 200*10*4 and came up with 8000 and the steps are still way off.
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Hey Rick,
Go to the settings page like Hood suggested earlier.
Note where your spindle is, use the calibration utility, it's self explanatory. It'll get you in the ballpark anyway.
What drives are you using ? Any Microstepping ? Pulley/belt reduction ?
If you motor is direct coupled, no microstepping then you'd have 10 pitch/5 start screw = 2 turns per inch x 200 motor steps per turn = 400 steps per unit.
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I know it sounds crazy but i used the cal utility using a dial indicator and came up with 1600. I cal'ed all three axis' and they all repeat but when I type in code it never comes out the same. So I calibrate again with one inch. then I type in code (g00y1) and it travels more than an inch, maybe 1.5 inches.
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Well that sounds like you have 1/4 microstepping, that would be 1600.
Strange indeed, that is an extreme amount to be off but not near as bad as it was so you're getting closer.
You might try it with G1 Y1 F5 instead of G0.
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Scott was sort of right, there is really no benefit to having all the limits set to the same pin as if one trips it will fault mach no matter if you have one enabled or all enabled but there also no disadvantage. However when using the Limits as Home switches you will have to enable the Home entry for each axis and set that to the port and pin number of your limit switch. If you dont then when you do a Ref All the axis will just zero at the position you are at which is no use.
Hood
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I calculated it to 1600 and verified with a dial indicator and it repeats within .001. Now it jogs accurately but extremely slow. I was going to change the velocity and acceleration but not sure what is the proper settings. I am reading the docs on the web site to learn more about setting up. I'm sure it was the code I have been typing in as it always repeats now.
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Impossible to say as that will depend on your motors, drives and weight/friction of axis, so its just a case of trial and error when using steppers.
Hood
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Thats how I had it set up originally because I have limits on all four screws
Are you driving two of the screws with one motor or do you have a separate A axis? If you're using a slaved axis to drive both sides of a gantry, for instance, the slaved axis will have to have it's own homes switch. The other three can be on the same switch, but the A (slaved axis) must be on a separate home switch.
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Now I have all motors running properly and efficiently. And I have the soft min/max settings in the motor home/soft limits screen. I also have all input signals to the limit switches (ports and pins) set to enable with X,Y, and Z, also set to home since they are wired in series, I only have one port and pin to assign. However, I am not sure how to set the table to 0,0 so that the when "machine Coordinates" is clicked, the DRO reads 0,0. I have X, Y, and A (slave) set to Home Neg because it will move in the neg direction to get to home (machine) 0,0. Can someone offer some direction?
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Thats how I had it set up originally because I have limits on all four screws
Are you driving two of the screws with one motor or do you have a separate A axis? If you're using a slaved axis to drive both sides of a gantry, for instance, the slaved axis will have to have it's own homes switch. The other three can be on the same switch, but the A (slaved axis) must be on a separate home switch.
It has its own switch, but the same pin assignment as the rest. Are you saying I should wire it so it has its own pin assignment on the BOB? Because I can do that if it is really necessary. I just thought since it was slaved, it would run correctly.
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Yes, if you want to square up the gantry with Homing then you will need a separate switch for A.
Hood
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Regards rge machine Zero, you need Auto Zero checked on the Homing and Limits page. If your Home position is not with the tool fully negative in X and Y and fully positive in Z then Home off values would be needed.
Hood
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Done! now I have all axis' enabled and homed but "A" (slaved to "X") on pin 12 and X, Y, and Z on pin 13 on the inputs signals screen. Now how do I set up home so when "machine coord's" is lit, to display machine 0,0? In other words, how do I set up homing correctly now that my inputs are correct and motors are running correctly?
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Regards rge machine Zero, you need Auto Zero checked on the Homing and Limits page. If your Home position is not with the tool fully negative in X and Y and fully positive in Z then Home off values would be needed.
Hood
I want home position to be when X and Y are fully neg but when I travel to the switches, which are set to X,Y, and A home neg, the machine does not show 0,0. All are already set t Auto Zero by default and I have not changed them.
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Are you definitely looking at machine coords?
If so please attach your xml and I will simulate here and see if i can find the issue.
Hood
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The machine coord light is on and I it is not at 0,0. If I have the correct setting, and I trip the switch which is set to home and auto zero, shouldn't it auto zero on the DRO?
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Its working fine here in simulation so not sure whats wrong. Try disabling the A Axis home and limits and see if that helps for the time being.
What I did was simulated your Home switches, pressed ref all and Z starts moving up and I sim the switch it backs off stops and sets the machine coords DRO to zero then Y then X.
Justin case, r Machine coords is when button has red showing round it.
Hood
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No, it works, I clicked on ref all home and it did work great! I didnt know thats the button to use because it screwed up the tracking when I didnt have "A" set on its own pin. I get t now.
thanks Hood, if it weren't for you I would be hanging from a bridge..........