HAVING A PROBLEM

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    Default HAVING A PROBLEM

    Hi all.... Apologies if I imposing to the wrong board here... this place has really grown since my last visit... have been out of CNC for a while... but just jumped back in and have a problem... can anyone set me on the right path please?...
    Just got my DIY home build up and running ( Somewhat ) I am using Meshcam to generate G-Code.... My machine does not have limit switches yet... so I manually jog to a point over the stock then zero all of the axis ( my home position I assume ? ).... I can jog the machine all over, fine... then I hit goto Zero... it goes right back to where I started... so good so far.... I then load my g-code, and it comes in perfect... I can see the part in the Tool path window...... thats where the fun stops... here is the problem...when I hit Cycle start... the Z Axis just heads north,... straight up....non stop.. and I have to hit the E-Stop, to prevent a crash into the top of the mechanism... I am pulling my hair out here... every thing seems correct... but without fail.... the cutting head just climbs straight up.... I am hoping this is a simple issue?.. FYI... in meshcam my 0,0,0 origin is set to the centre of the workpiece at the very top surface...... and when it comes into mach3 I can see that 0,0,0 is indeed at the top centre of the object... so, in my mind.... when I press cycle start it should just begin cutting.... please help..... I have no experience, and is the first 3D carve job ave ever attempted...previous to this, I have used Cut 2D, to do some basic surface engraving and hole Grid drilling and had no problems with either.... one basic craving was that 'Roadrunner" file, and that worked fine, but this has me stumped. One last note... when I started up my machine...when I would jog the machine I noticed the Z axis was moving Up, when I pressed Z- and down when I pressed Z+. so I went into a setting ( not sure which one ) and switched it...could this be the problem...and if so, how do I change it back?

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    Default Re: HAVING A PROBLEM

    Are you running the correct post processor in MeshCam?

    Inverting the state that your Z axis DirLow is set to will reverse the axis travel direction. See attached image:

    Attached Thumbnails Attached Thumbnails HAVING A PROBLEM-dir-low-jpg  
    Last edited by jalessi; 05-27-2018 at 01:23 PM. Reason: Misspelled Word
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.


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    Default Re: HAVING A PROBLEM

    Thanks for the response Jalessi, I am running the same profile that I had setup, a while back when I finished building the CNC, this profile worked fine with the Roadrunner carving. I just reversed the direction in the motor output as you suggested, as expected when I jog -Z the cutter moves up... and when I jog +Z the cutter moves down. ( opposite of what I had been trying )... so I attempted to run the file.... once I confirmed that pressing cycle start will now make the cutter move down ( instead of up )...... before running the code, as a precaution I moved the cutter as far up as I could.... then zeroed all of the axis, then pressed cycle start. The cutter moved all the way down this time and I had to press the estop to avoid a crash.... I should note that my X axis has about 5 inches of range... but the file is only about 4 or 5 centimetres thick max.... and the meshcam file was set with the axis at the top surface of the piece. I will try to attach the meshcam file and g-code file maybe that will help?

    In my newbie imaginings here, it seems like although the test object was created with MM.... and processed in meshcam as MM.... Mach3 thinks its inches?...or larger than it really is.... the post processor I used in Mescam when saving it was mach3 .nc

    Hope this helps.

    Paul

    Attached Files Attached Files


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    Default Re: HAVING A PROBLEM

    Paul,

    Your first "Z" axis move appears to be 10 inches, which is huge for most machines.

    Is it possible you have mistakenly set the safe Z to 10 inches in MeshCam?

    Jeff...

    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.


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    Default Re: HAVING A PROBLEM

    Hi Jeff.... thats possible.... where would I Bookman meshcam? to check. I have been messing with this all day... I might be zeroing in.... when I tested my axis calibration..... when I put in a move for the X axis.... I was expecting it to move 10 CM...but it moved 10 inches..... I checked my native units and it was set to mm... so that has me confused now as well.... I know that the profile that I had set the machine up with was correct and accurate, as I was able to cut a couple of jobs that were extremely accurate... but unfortunately I have changed the motor thing settings.
    At the point of greatest confusion, I went in to the axis calibration.... and retested and set it up for all three axis... that is now working....meaning... when I ask the machine ( in axis calibtration ) to move 100 Milimeters..... it now moves 100 millimetres however .... now when t does move...although very accurate distances on all three axis...it is painfully slow.....I mean a snails crawl..... I took about 30 seconds to move 50 mm..... when I attempt to run a small file 150mm X 100mm X 25mm..... with the origin in meshcam set to the top surface... the cutter ( Z axis ...still moves all the way up and I have to stop it from crashing.... the file was created in Sketchup... exported in mm as an stl.... it opens perfectly I meshcam to the correct metric dimensions, appears to save the Code correctly, and comes into Mach 3 as I think it should.... I can see the part and the tool paths...... So I am missing something wrong here. My machine uses the common ACME lead screw set up with Nema 34 motors on all axis... I have tried to retune the motors...but have gotten very confused from the nine instructions and videos.... bless the guys trying to demonstrate how to tune the motors.....but I find them difficult to follow... I am in Newfoundland Canada and know of no one here with a CNC.... any suggestions?
    Paul



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    Default Re: HAVING A PROBLEM

    Okay, it sounds like you've beaten your original problem (a confusion between mm, cm, and inches) and are onto a new one: everything's too slow. That's probably because you tuned your motors using inches per minute, and it's now moving in mm per minute (a lot slower, if unchanged). 50 inches in 30 seconds would be 100 ipm, which is pretty zippy on a small machine. So go back into Motor Tuning, and retune, giving it higher values for velocity and acceleration (start with velocity about 10 times the accleration, and adjust from there). Use the up/down arrow keys to see how the motors perform on each axis, and when they seem to be doing well (listen to them; the happy sounds are a lot different from the groaning and stuttering you get when they're not) Save Axis Settings and go on to the next axis.

    [FONT=Verdana]Andrew Werby[/FONT]
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    Default Re: HAVING A PROBLEM

    Jeeeze!... that was fast!...lol.. thanks..... Ok... I think I have the file running properly.... I set the home to a safe spot...and loaded the code started it running....without the router on..... it seems to be going through the motions...but painfully slow... can you give me a few more details as to how to get the speech up?...right now my setting are as follows.......... X AXIS= 1800 Steps per...... Velocity 402....Acceleration 37.5. Y AXIS= 1800 Steps per...... Velocity 402....Acceleration 38.5. Z AXIS= 1800 Steps per...... Velocity 391....Acceleration 39.5

    I should mention..... when I press Tab to pull up the jog functions.... I can move the gantry all over the place at a very nice clip...and sunning very happy..... but the actual movement running the file is at a crawl..... for example... I could hear the Y axis motor running.... but had to walk over to the machine to make sure it was actually turning the lead screw.... the screw is turning...but so slowly... that if you were not looking very closely, you can hardly tell the gantry is moving....lol... but it is.... thankfully...lol... really appreciate your help so far... I might actually get to see my creation cut something!!!..... I simple terms can you let me know how to speed the machine up bit...... once I have that fixed... I think the only think I have to do is home and zero the cutting bit at the top surface of the piece as it appeared in Meshcam correct?....lol yes.. that was a question.

    Thanks
    Paul



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    Default Re: HAVING A PROBLEM

    Assuming those are mm and minutes, it's still pretty slow for cutting wood. 402mm is about 16" a minute, which will probably give you dwell marks on your wood, if it doesn't actually catch fire. You want to be moving about ten times that fast when you're cutting, and faster for a rapid (G00) move. But what it sounds like is happening is that Meshcam is still calling out feedrates in inches, but you're running them in mm. You need to rewrite your G-code files with Mach3 and Meshcam on the same units.

    [FONT=Verdana]Andrew Werby[/FONT]
    [URL="http://www.computersculpture.com/"]Website[/URL]


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    Default Re: HAVING A PROBLEM

    Hi Jeff.... I just made the adjustments you suggested..... and it certainly jogs to where its going pretty impressively fast..... but I am not sure there is a difference, once is begins to go through the cut motion...do I have to regenerate the tool path in Mach3...or is there some other place I adjust the speed?...speeds feeds?.....

    Thanks

    Paul



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    Default Re: HAVING A PROBLEM

    Ok.... I will go back to meshcam and generate the code again and make sure it is in MM... won't take long.... really appreciate your help on this.... I built this machine almost 10 years ago...but got side tracked with life...and got into 3D printing as well as laser engraving and cutting.....soI just got back into this recently, and have to refamilarize myself with CNC 3 axis Mill....forgot a lot in that time.


    Paul



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    Default Re: HAVING A PROBLEM

    Something strange happening with the file ( Attached ).... I went to meshcam and regenerated the code in MM....which it seems to do fine ( normally )...saw the tool paths etc.... saved it as MAch3mm.nc. but who I load that file into mach3, it loads in about 2 seconds, but the tool paths do not show in the Toolpath window?... so then I reloaded the previous file...and it loads fine...just not this one....seems like I am missing something in meshcam related towering in mm?... any idea what?

    Paul

    Attached Files Attached Files


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    Default Re: HAVING A PROBLEM

    ok... just went in poking around mshcam.... and discovered that in the select stock section... I still had inches selected...so I changed it to mm...but after I did...I went back and checked it and it had reverted to inches?...even tried Locking the geometry...is there somewhere else in Meshcam that I Globally change the units I am working in?

    Paul



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    Default Re: HAVING A PROBLEM

    What version of MeshCAM?

    Gerry

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    Default Re: HAVING A PROBLEM

    Meshcam 6...... but I might have found the issue.... I just went back to sketch, and the part was exported in Inches...so I am thinking that might override meshcam??..not sure... saving the file now to upload to mach 3...to test... I will get right back to you...sorry for being such a PIA...but I am sure you remember the first time you fired up your first CNC...lol... its in the blood...lol

    Thanks

    Paul

    UPDATE EDIT.... Ok I tried again.... Meshcam is sneaky.... I discovered that there are a few places I had to change the MM. one of which is the actual tool...I had to edit it to be in MM not inches... so I went through all of the settings and made sure it was all mm... and generated the code.... I just uploaded it to Mach3, and it loaded perfectly... I am got to do a test run on it now...

    Paul



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    Default Re: HAVING A PROBLEM

    Ok just tried the file that I reserved in Sketchup..... Meshcam accepts it just fine.... but when the code comes not MACH3... it loads way to fast...and nothing appears in the tool paths window...I am definitely missing sorting here///...stumped now for sure.

    Paul



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    Default Re: HAVING A PROBLEM

    Ok... the speed is up, for jog and cut, machine seems to be working normally...yeahhhh..... I tried a test cut, and although it does seem to be working, I think there are a few tweaks needed I meshcam... I think I have the depth of the cut set way too shallow
    it is barley skimming anything off the test piece... I am using apiece of rigid styrofoam....... I need to design a piece, maybe smaller that I can see the effect of carving faster...

    Thanks Guys!...big help.....but I think I have just scratched the surface.

    Paul



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    Default Re: HAVING A PROBLEM

    Thanks for the help and input ( Everyone )..... Have made a few attempts at cutting... still not quite there...meaning the code is coming in fine at the right size etc....machine speed is good... but I am having an issue orienting the piece properly I am pretty sure it is something I am dong in meshcam.... when the part comes in it is standing on its end straight up tall....so I have to rotate the y axis 90 degrees and then its flat.... the origin is at the top surface front left corner.... all seems normal but when I hit cycle, the router moves over to where it should be and starts.... but then moves way outside the area of where the part is ( is actually cutting air )...So I need to know how to orient the part, the easiest way.... to basically have it start cutting ptryymuch close to home..... choosing a corner doesn't seem to work for me....does int makes sense for me to set the part up to have the price at the top surface centre and make home on the CNC the centre of my cutting board?...will this solve my orientation issue until I can figure it out? I think something is happening the orientation translation from Sketchupstl file...to Meshcam...to Mach 3

    Any suggestions?

    Thanks

    Paul



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    Default Re: HAVING A PROBLEM

    Try reorienting the part in the original program you made it in (Sketchup?) so that Z is up. Things can get confusing when different programs have to change the orientation. Yes, try changing the X/Y origin to part center, but put the Z zero at the top of the part, so that you can touch off to the top of the stock, in the middle, and zero the tool tip there. Make sure it's not adding any offsets to the g-code, those are normally used to make up the difference between "machine zero" and "part (or floating) zero"), but at this point you don't want to deal with machine zero yet. If your machine has home switches, you can work on that next, after things start making more sense.

    [FONT=Verdana]Andrew Werby[/FONT]
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    Default Re: HAVING A PROBLEM

    Ok... finally had a chance to try cutting, with the origin at centre of the part....cutter at centre of the piece...both at top surface...in addition I told Meshcam to just cut the geometry, worked fine except... the circles are ovals not circles.... I am assuming this means that I need to calibrate the axis, which I didn't do after adjusting the motor tuning....I just picked some arbitrary numbers and did some jogs until the jog speed was fast...and the cutting sped came up bit... I need to find a good straightforward tutorial on tuning the motors...as I know it should be cutting faster... ay recommendations?....for an ACME lead screw set up?.... So my quest now is am I correct in thinking I just need to calibrate the axis...or do I have to properly tune as well?

    Thanks In Advance

    Paul



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    Default Re: HAVING A PROBLEM

    Yes, that sounds like either the X or Y axis has the steps per unit set wrong. Measure the ovals, and if one dimension is correct, use the steps/unit setting from that axis on the other one (assuming the screws are the same pitch). That's all set in the Motor Tuning dialogue. If both are incorrect, then you need to start from scratch in calibrating both axes.

    [FONT=Verdana]Andrew Werby[/FONT]
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