Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: kolias on August 23, 2009, 10:09:44 AM
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Looking at the tool path screen, Lines N45, N50, N55, and N60 are tracing the outline of a square. The square looks like a square (I made it in ACAD) but the axes numbers vary.
N45 Y9.0788
N50 X3.5166
N55 Y1.9398
N60 X-3.6224
Why such a big difference in the numbers especially in the Y axis? (gcode attached)
Nicolas
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Take a look at line N30 as that is where the z plunges and is the start of the square.
When in Mach3, just scroll down by one line at a time and watch the display to see each move.
RICH
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9.0788 - 1.9398 = 7.139 tall
3.5166 - (-3.6224) = 7.139 wide
You have a perfect square.
The numbers just dictate where you drew it. Might be a good idea in AutoCAD to place you're drawing at the origin. (0,0) If the bottom left corner was at the origin, your code would look like this.
N45 Y7.139
N50 X7.139
N55 Y0
N60 X0
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9.0788 - 1.9398 = 7.139 tall
3.5166 - (-3.6224) = 7.139 wide
You have a perfect square.
The numbers just dictate where you drew it. Might be a good idea in AutoCAD to place you're drawing at the origin. (0,0) If the bottom left corner was at the origin, your code would look like this.
N45 Y7.139
N50 X7.139
N55 Y0
N60 X0
Gerry that is excellent, never thought about it
Nicolas
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Nicolas ,
Even if you don't start your drawing at the 0,0 origin in Autocad , just go to tools/ move ucs , to any point you want, usually lower left , unless your doing a circle.
Ed
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9.0788 - 1.9398 = 7.139 tall
3.5166 - (-3.6224) = 7.139 wide
You have a perfect square.
The numbers just dictate where you drew it. Might be a good idea in AutoCAD to place you're drawing at the origin. (0,0) If the bottom left corner was at the origin, your code would look like this.
N45 Y7.139
N50 X7.139
N55 Y0
N60 X0
I made another drawing in Acad and moved the UCS to the bottom left of my drawing; so the bottom left point is at 0,0
Then after I import the dxf to Lazycam and made the gcode from what I can read the X=3.0173 and Y=2.3773 (code attached)
That means that if I jog my axes to a point I have sat the paper on my table, zero the DROs and start the gcode the axes will move again away before they satrt to draw the object.
I'm sorry if I dont understand but all I want to do at this moment is to grasp how to make the machine start the work wherever I have the axes and all DROs are zero.
Nicolas
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I don't use lazycam , so can't help you there, but apparently 0,0 wasn't at the origin in lazycam.
Ed
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Can you post the .dxf?
Imo it's far easier to move the square in AutoCAD than move the UCS. I've used AutoCAD daily for over 10 years and never move the UCS.
What I'd recommend, is to set up a template with two lines, one along the X axis and one along the Y, both through 0,0 and draw your parts at 0,0. Just delete the two lines before you export.
Even if your parts origin is 0,0, it's unlikely that all your parts will start cutting right at 0,0. I don't use LazyCAM, but you'll need to tell it where you want it to start.
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Nicolas,
Lets see if i can help.
1. Use the shape file ( SHAPES LCMRO HCIR) that is available for download along with the manual in members docs.
here is the link: http://www.machsupport.com/forum/index.php?action=dlattach;topic=12078.0;attach=16641
The square was drawn such that the origin is at X & Y=0.
Just import it and then export it to MACH3 Mill.
2.In Mach3 Mill, click "Ref all home" then click each... zero the X,Y,Z axis. You have now set home as X, Y,Z equal to 0.
If you look at the display you will notice that the there is no x or y move because home has been set to X &,Y,Z =0.
3. Rewind the program, ref all the axis to zero.
Now put the value of 1.0 in the X & Y dro's. Now you will see that home is set to the other corner of the square at namely X & Y =1. If you dry run the program you will see that there is a move from where you set home to where
the program begins. Look at the program , line N60 there is a rapid move to X0.0 and Y0.0.
To get there from "home" the machine must move to the other side of the square which is at X & Y =0.
I think is what you wanted to know,
RICH
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I don't use lazycam , so can't help you there, but apparently 0,0 wasn't at the origin in lazycam.
Ed
Can you post the .dxf?
Imo it's far easier to move the square in AutoCAD than move the UCS. I've used AutoCAD daily for over 10 years and never move the UCS.
What I'd recommend, is to set up a template with two lines, one along the X axis and one along the Y, both through 0,0 and draw your parts at 0,0. Just delete the two lines before you export.
Even if your parts origin is 0,0, it's unlikely that all your parts will start cutting right at 0,0. I don't use LazyCAM, but you'll need to tell it where you want it to start.
I think Ed has a point here. I did not check in LC if the origin was at 0,0 because I assumed LC will do it automatically. I will be more careful next time.
Sorry Gerry I deleted the dxf for this file, felt was not important. I will try to do what you are saying in Acad. I used to be pretty good in Acad but haven't use it for at least 10 years and therefore my knowledge is pretty rusty.
I know that not all parts will start cutting at 0,0. What I try to learn here is to make a simple drawing, get the gcode thru LC, jog my axes to a point and zero the DROs, and then I will assume when I start cutting (actually right now is drawing with a pen only), the cutting will begin at that point.
RICH I will try what you say and post the results tomorrow. Sounds good
Nicolas
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In the manual, fig 5.2.3 shows you the "origin" symbol. In Figure 6.2.3 check the "AS Drawn" which will maintain the 0, 0 as drawn. BTW, you can change the origin to anywhere you want in LC.
If you don't check the As Drawn the origin will be placed at a min value to the first entity / created chain.
You need to understand that there are machine coordinates and program coordinates.
Analogy : where am i and where am i going ........I am "HOME" i need to go to where the "Program " is.
RICH
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In the manual, fig 5.2.3 shows you the "origin" symbol. In Figure 6.2.3 check the "AS Drawn" which will maintain the 0, 0 as drawn. BTW, you can change the origin to anywhere you want in LC.
If you don't check the As Drawn the origin will be placed at a min value to the first entity / created chain.
You need to understand that there are machine coordinates and program coordinates.
Analogy : where am i and where am i going ........I am "HOME" i need to go to where the "Program " is.
RICH
RICH you are a lifesaver
I did not pay too much attention to the LC manual, thought that it was pretty much automated. I looked to what you pointed out and the As Drawn the Origin was not checked. Guess I have to read the LC manual carefully.
Thank you
Nicolas
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There is no such thing as plug and play. That's the problem with LC or any other program, folks just hack away and to often end up having difficulties, for no reason. If you are going to use LC i strongly suggest you take a look at the manual. The manual has info that you will not find anywhere.
RICH
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Right on RICH, I'm already working on it
Nicolas
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ok now I got it and all new drawings I made I was able to get mach going where I had my axes. So this problem I can put it to bed but there are still some new problems.
I get the code into mach, regenerate the tool path and zero the axes. But I still have to go to the offsets and zero them too otherwise the object is not at 0,0 on the toolpath screen. Anyway to get the offsets ON/OFF?
The above although annoying is not that important but while mach is working some times is getting “stuck” like it hit something and stopped and then I have to hit the Estop. I have checked my axes and all are working smooth when they are not coupled to the ACME screws. In addition, when the axis are coupled to the ACME screws and jog each axis, they all work nice and smooth. So I believe that it has to do with the motors tuning.
ACME screws are 1/2"-10 precision and my motors are 273oz.in and the settings are:
Vel. Acc. Step Pulse
X 36 2 10 10
Y 36 2 10 10
Z 38 2 10 10
Any suggestions for any changes to these settings? Do you see something that is not normal?
Nicolas
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What kind of drives are you using?
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What kind of drives are you using?
Sorry Gerry dont know what you mean by "drives"
Motors are Keling stepper motors with 8 wires and wired as unipolar
The 3 drives for the 3 motors are Probotix http://www.probotix.com/stepper_motor_drivers/ProboStep/
I have set the steps on the drives to half step and in mach (steps per) to 4000
Hope that is what you want
Nicolas
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Acme screws will have a lot of friction compared to ballscrews so it could just be that your motors are not big enough. Try reducing the velocity and accell and see if it helps.
Hood
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Acme screws will have a lot of friction compared to ballscrews so it could just be that your motors are not big enough. Try reducing the velocity and accell and see if it helps.
Hood
But why the axes work fine when I jog the motors and they get stuck "SOMETIMES" when I make a drawing?
I will try reducing the vel & accl as you said
Nicolas
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Looking at the axis settings your on inch's, 36" <m/min so I would have thought that's ok and Acc 2! Does it ever get upto speed?
You may be hitting soft limits, do you zero the axis and is the table size setup (can't remember which tab that is).
Normal use is to have the table size setup and have the soft limits on. Zero axis (ref all) before doing anything when the machine is first turned on.
You then clamp down you stock and drive the axis to a point you determined in your cam, usually bottom left, and press each button to the left of the DRO.
You should then be able to look at the table view to the right and it will show a white line around with you gcode lines in blue, if these blue lines are inside the white line you will be fine, other wise you'll get a warning that your code goes out of the table limits.
I'm quite tipsy at the moment on our second bottle so hopefully I've said it all right ;)
Steve
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Ah ok so its only when you are running code? If so then what happens if you jog two at once or MDI a two or three axis move?
Check your power supply is not dropping in voltage when moving axis together.
Hood
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Ah ok so its only when you are running code? If so then what happens if you jog two at once or MDI a two or three axis move?
Check your power supply is not dropping in voltage when moving axis together.
Hood
Yes it only happens when I run code. I did a simple square code and it was fine. I did the dwg RICH told me yesterday (Square, Triangle & Circle) and it was good but when I do a dwg I made which has a lot of half circles inside a square it gets stuck half way thru (file attached).
When I jog 2 axes at once, all works well. MDI also works well
Never payed attention to the DCV meter I have to see the voltage. I will have a look and post back results.
Nicolas
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Looking at the axis settings your on inch's, 36" <m/min so I would have thought that's ok and Acc 2! Does it ever get upto speed?
You may be hitting soft limits, do you zero the axis and is the table size setup (can't remember which tab that is).
Normal use is to have the table size setup and have the soft limits on. Zero axis (ref all) before doing anything when the machine is first turned on.
You then clamp down you stock and drive the axis to a point you determined in your cam, usually bottom left, and press each button to the left of the DRO.
You should then be able to look at the table view to the right and it will show a white line around with you gcode lines in blue, if these blue lines are inside the white line you will be fine, other wise you'll get a warning that your code goes out of the table limits.
I'm quite tipsy at the moment on our second bottle so hopefully I've said it all right ;)
Steve
Guess the second bottle must be Gin, cheers to you mate....
To my opinion it does get up to speed especially when she makes circles she is pretty fast on the X & Y axes. As for the rest you described all is done correctly.
Nicolas
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Decreased the velocity on X & Y to 35 and did what is in the pic. Better than before but stopped in the last couple inches of the code (see attached)
No drop in the voltage
Can someone tell me if my motor settings looks reasonable or there is not such a think as reasonable?
There is no other method except by trying to set the motors to an optimum setting?
Nicolas
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Unless someone has a machine that is identical to yours then no one can say what your settings will be, just too many variables.
Your velocity and Accell seem reasonable, not fast but again not that bad.
When it stops do the motors just squeal?
Do your motors get hot?
Do the drives get hot?
Hood
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Unless someone has a machine that is identical to yours then no one can say what your settings will be, just too many variables.
Your velocity and Accell seem reasonable, not fast but again not that bad.
When it stops do the motors just squeal?
Do your motors get hot?
Do the drives get hot?
Hood
Now I understand and its fine, I will manage one way or another the motors settings. Thank you for commenting on the Vel / Accl, at least I know that I'm in the ball part
Yes the motor squeal, I'm not sure but I think is only one motor that stalls, either the X or Y
Never touched the motors or drives so I dont know if they are hot. I will verify tomorrow.
Nicolas
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ger21,
Question for you. I've also used Autocad for 10 years since acad 14. If you have a drawing with 3 or more views ,
how do you do ordinate dimensioning without moving the UCS to each view? I've learned cad on my own, and I know theres lots I don't know, so please clue me in.
Thanks
Ed
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Ed, I do all my dimensioning in Paper Space. But most of my work is Architectural and woodworking, if that makes a difference. I don't usually dimension any 3D drawings.
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Sorry Gerry dont know what you mean by "drives"
Motors are Keling stepper motors with 8 wires and wired as unipolar
The 3 drives for the 3 motors are Probotix http://www.probotix.com/stepper_motor_drivers/ProboStep/
I have set the steps on the drives to half step and in mach (steps per) to 4000
Hope that is what you want
Nicolas
Couple things. Is the current pot set correctly on the drives to match the motors?
And What voltage are you running at?
Do the motors sound "smooth", or do they sometimes sound rough at certain rpms?
I'm in the process of setting up my router using a Xylotex drive, and on my Z axis, with 1/2-10 acme, I'm currently getting 50ipm with an accel of 7. You should be able to set your accel much higher than 2.
If the motors sometimes sound rough, you could be seeing resonance. I made a damper for my Y axis, and increased velocity from 80 to 180 with a huge increase in smoothness, and accel set at 12. Although this is with 1/2-8 2 start acme.
I'm guessing you don't have the current adjusted right, possible. Also, try running in 1/8 step mode and see if it'll let you go faster, as microsteps allow the motor to run smoother.
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ger21,
Question for you. I've also used Autocad for 10 years since acad 14. If you have a drawing with 3 or more views ,
how do you do ordinate dimensioning without moving the UCS to each view? I've learned cad on my own, and I know theres lots I don't know, so please clue me in.
Thanks
Ed
Sorry Ed but I can’t help you right now
During my working years I definitely knew much more than now but I was never an ace in Acad. I just knew enough to assist my clients. It has been almost 10 years since I touched Acad and I only started last April when I got interested in the CNC.
I have all the manuals for V12 and looking up the subject I found an exercise with 14 pages describing how to do ordinate dimensioning in a machined bracket. I don’t have a flat bed printer to scan the pages but if you want I can take a picture of each page like the sample attached and send them to your email.
If you agree, I can’t do it before the weekend.
Nicolas
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Couple things. Is the current pot set correctly on the drives to match the motors?
And What voltage are you running at?
Do the motors sound "smooth", or do they sometimes sound rough at certain rpms?
I'm in the process of setting up my router using a Xylotex drive, and on my Z axis, with 1/2-10 acme, I'm currently getting 50ipm with an accel of 7. You should be able to set your accel much higher than 2.
If the motors sometimes sound rough, you could be seeing resonance. I made a damper for my Y axis, and increased velocity from 80 to 180 with a huge increase in smoothness, and accel set at 12. Although this is with 1/2-8 2 start acme.
I'm guessing you don't have the current adjusted right, possible. Also, try running in 1/8 step mode and see if it'll let you go faster, as microsteps allow the motor to run smoother.
Don’t know what “pot” means but a few days back I posted my motor settings in another thread and Hood had said that all was ok
The drives are rated for up to 42VDC. My power supply is adjustable 12-32VDC and it is set at 28VDC. My motors take 3.0A each wired as unipolar
Motors sound very smooth to my opinion.
I have played extensively with the motor tuning and as far I can see the 32ipm, 2 accel seems to be the best setting. Motors never stall and sound good. What slides do you have? Mine were V-Grooved bearings running on aluminum 3/4"x 3/4" x 1/8” angle but due to noise I made my own slides with UHMW material. Now I have less friction and it is silent. I will experiment tomorrow with your 50ipm / 7 accel.
No I don’t have any resonance. Some times when the gandry is in the middle of my 36” long Y axis I do get a bit but if I reduce the travel speed it is not there. I’m ready to make dampers too if the need arises but so far I see no need for them
I also did try all the microsteps on my drives but the one I have now (1/2) seems to be the best. But I have no issues to give it another try with 1/8 step.
Gerry my friend you are my man, it just clicked on me……… I have had problems with my drives and had to send them back for new ones and although I did check the current setting on the original ones, I completely forgot to set the current on the new ones. I will do that first thing tomorrow
Excellent comments Gerry, much appreciated
Nicolas
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Mine are roller blade bearings on pipe.
If you find that you haven't set the current, after you set it, try the other microstep settings. Also, turn the supply up to 32V if you can. The higher the voltage, the faster it'll go.
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Mine are roller blade bearings on pipe.
If you find that you haven't set the current, after you set it, try the other microstep settings. Also, turn the supply up to 32V if you can. The higher the voltage, the faster it'll go.
The only reason I did not set the power supply to 32VDC is that I could not find a DCV meter locally with a higher rating. The one I have not is max reading at 30VDC and so I went a bit lower. Perhaps later, if I need more speed, I will scrap the meter.
Nicolas
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ger21 , kolias,
Thanks for the replies. I do lots of drawings with ordinate dimensioning, and move ucs to my views. This has always worked for me.
Solid works and other 3d programs are a different story.
Kolias, Thanks for the offer , but I don't need the info.
Ed
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Thanks to Gerry for the tip, I checked the current on my drives this morning and it was set to about 25% of what I needed. Then I adjusted the current to specs and now I notice the big difference; did 4 drawings and she never stopped. I did play with the microstepping but I like best the sound and feel with 1/2 step.
Now that I have more current I also adjusted the velocity / accel. To 50 and 7 and it seems good. Probably I will fine tune it in the future as I gain more experience.
The only annoying problem is the wabble I get on my 36” long Y axis. As I said when the gantry is in the middle of the Y axis I get this annoying sound like “running gears with no oil”. The lines the machine draws at this point are straight, so it does not affect the performance – just sounds like a coffee grinder.
Does anyone have an easy fix for this?
The Y axis has a single Delrin nut (see attached pic)
Nicolas
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No both bottles were only wine, but it was the last drop of the 3rd that gave me the head ache this morning ;)
I have the same problem with my router, I have used 16mm tricoidal thread and brass nuts, the thread has room to move up and down in the nut while having little movement along the thread, when it gets in the middle and spinning fairly fast you get a squawking sound as the thread flaps around (technical term) and it can even lock up my axis.
I found the best method was to split the nut and compress it somehow, I know it's not an elegant solution but it works.
A better and much nicer solution is to have a brass nut and Delrin nut, turn out half the brass one and thread, turn down the outside of the Delrin one and thread to suit the inside thread of the brass one and then you have an adjustable backlash nut that should also help with the "flapping"
A temporary solution is to oil the tread as it stops the grabbing that causes the problem.
Or
As some one else has mentioned you could also add a damper, apparently these work very well
Steve
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I thought that Gin was the name of the game in UK; wine is for the blocks across the channel LOL
Thanks for the tips, I will keep them in mind. I have a few of my own and working on them.
When I’m done I will post the results
Nicolas
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The only annoying problem is the wabble I get on my 36” long Y axis. As I said when the gantry is in the middle of the Y axis I get this annoying sound like “running gears with no oil”. The lines the machine draws at this point are straight, so it does not affect the performance – just sounds like a coffee grinder.
Does anyone have an easy fix for this?
The Y axis has a single Delrin nut (see attached pic)
Nicolas
I get the same sound. resonance. I added a damper and it got perfectly smooth, and allowed me a 2.5x speed increase. I'm finishing up 2 more tonight, and I'll take some more pics. Here's the first one.
http://www.machsupport.com/forum/index.php/topic,12411.0.html
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Nice machine Gerry,
Will be interesting to see how do you mount the damper to the motor shaft
Nicolas
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I have double shaft steppers. They mount on the back.
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I have double shaft steppers. They mount on the back.
Me too but how you attach the damper to the shaft, with a coupling?
Nicolas
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It's got a hub that get's glued into it, and has a setscrew.
Read through this.
http://www.cnczone.com/forums/showthread.php?p=256639#post256639
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Here's some pics of the dampers and a YouTube video showing with and without.
http://www.youtube.com/watch?v=UJjivsVwSsQ
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Nice work Gerry, thanks for sharing
Nicolas
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Well Gerry my dampers are a shame in comparison to yours but I did notice a reasonable decrease of resonance on the Y axis. The damper is press fitted to the motor shaft and as the time goes I may get some better ideas but for now it will do.
The diameter of the disks is 2-3/8" and that is the max I can fit there considering the available space. The Y axis motor is under the table and I have very limited space to work on the shaft without major modifications.
Nicolas
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This design I got it from the web sometime ago (solsylva?) and after the installation resonance=0. Very happy about it
Did not notice any speed increase in the Y axis but at least she now works smooth and silent, coffee grinder sound is gone
The caster wobbles a bit, very difficult to do a good align job, but makes no difference.
Later I might get a proper coupling and then there will be no wobbling.
Nicolas