Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: zxrjohn14 on October 08, 2017, 03:20:39 PM
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Hello all.
i'm trying to make a few bits for my motorbike and am experiencing some problems.
When the Z axis is set to zero/home and then i start the gcode, it's not calibrating prooperly, yet when i do the auoto caliberation it is perfect.
i have the units set to 400 per, yet it only moves decimals of a millimeter, if i set it to 800 it moves 2mm (which is correct as i'm trying to move it 1mm at a time), i then change it to 405 and its moving 0.9mm....if i switch the computer off and return to it it starts all over again despite keeping the 405 setting.
Also, my holes i'm trying to machine out of the centre are offset, even though they are drawn central.....they're South West by approximately 3mm.
Any help greatly appreciated.
Thank you
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Hi,
on your motor tuning page when you set the 'steps per' and so on are you hitting <save> as you exit?
Craig
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Hi Craig, thank you for the reply.
Yes i'm hitting save and when you turn off and go back to it, the steps per are as last saved (in this case 405) yet the z axis is not doing the same as it was.
The first hole is almost correct, but then the more it goes on through the code, the higher the z axis gets. When I click 'go to zero' the mill bit is approx 10mm higher than when it started but the DRO reads zero.
I got some verniers on it and it was moving 0.3mm per plunge, but DRO says 1mm.
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X and Y axis are spot on at 400 steps per.
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Hi,
if the 'steps per' are being correctly saved then calibration is not your problem. You have an issue with the Z axis.
Run some tests, without a workpiece:
<zero z>
MDI g0 z10
g0 z0
g0 z10
g0 z0
g0 z10
g0 z0
The Z axis should move up and down 10mm. Do it do so? Does it end up in exactly the same place it started? Note
I would expect the DRO to go back to zero but if the axis is faulty then it may not physically return to where it started.
Craig
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On the auto calibration it is spot on.
'How far do you want axis to move?'
I've typed 10mm 30mm 50mm -50mm -25mm
'How far did it move?'
It is spot on every time.
'Axis set to 400 steps per. Do you accept this?'
I click yes.
I start the job and the z axis moves 0.3mm
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Hi,
yes its calibrated, thats not your problem. You need to shift it up and down a small amount repeatedly to see if
the Z axis is gaining or losing steps. Leave the calibration as is and do the test I suggested.
Craig
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Thank you Craig.
I'll get on it tomorrow after work and let you know.
Thank you for your help.
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Good evening Craig,
I did your test and all was moving as it should.
What I have noticed that if i mess with the motor tuning, it starts to work something like it should???
I did a few air tests and all seems well....ish
So i thought I'd do a cut piece in MDF. The holes are still off centre, and after finishing the job, i clicked got to z, the DRO is reading zero, but the mill piece was 5mm north east of where it started from
I did the tests on the x and y axis and all is perfect with vernier gauges
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I have to say though, apart from the minor niggles i'm having, i am really liking the cnc, sheetcam and mach3.
if as complete novice like me can get somewhere with it all, anyone can....obviously with a little guidance ;D
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Hi,
I still think you are gaining or losing steps and not just restricted to the Z axis.
The acceleration setting in motor tuning is very important, if its set too high it will loose steps. One recommendation is to set it
at no more than 10% of the velocity setting. The general principle is start slow, very slow and then increase the settings until it
starts misbehaving and then back off a bit.
Craig
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i feel i'm getting somewhere with it :D
i have velocity set to 1999.8 and acceleratrion at 300. do you have a suggestion what to change each one too?
looking at the work piece, the off centring is caused by the x and y moving slightly between each plunge.
the south of the piece is flat and the north side stepped like the pyramids, which would make sense as the south steps would be cleaned off with each plunge.
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Hi,
try velocity a lot lower then work up.
Craig
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Hi,
what controller/BoB are you using?. Just wondering if its configured for pull-up resistors where your drivers
might be active low. A conflict of that nature doesn't break it as a rule but can leave it very susceptible
to noise, ergo gaining steps.
Craig
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Sorry Craig. I don't know the answer to that.
282545167242 eBay number for my exact machine.
I desperately want to upgrade the crap dremel type head for a spindle motor. But it does for learning at the moment.
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Hi,
unfortunately that number doesn't translate into a usable link.
Craig
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https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F282545167242
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Try that one.
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Hi,
yep got that. Definitely parallel port input. Do you feel inclined to take the top off to get some close ups of the BoB and drivers?
Craig
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Hi zxrjohn14,
Which version of Mach3 are you using ??
Tweakie.
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Hi zxrjohn14,
From the link you have supplied here is a quote from the machine suppliers instructions…
Friendly reminder:
The engraver will come with MACH3 software（Free Version
If you followed the intsalation tips offered by us, it works like full version.）
intsalation tips：
The software perferm better on the 32bites system computer.
Please close the firewall and antivirus software on the computer before DOWNLOAD AND install the software.(This is very important)
Otherwise, the antivirus will regards the cnc software is virus and stop the installation.
PS:Please don't update the software when installed, then it will not need the license Numbers.
If you are using your suppliers ‘hacked’ version of Mach3 then you are on your own and there is little we can do to help you on this forum.
Tweakie.
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I bought the set second hand from a chap who couldn't get it set up.
If it is a hacked copy, I have bought the set in good faith never hearing of mach3 until i turned the computer on.
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No problems.
My suggestion is that you download and install Mach3 version .062 ftp://anonymous:guest@ftp.machsupport.com/Mach3/Mach3Version3.043.062.exe
then we can proceed from there.
Tweakie.
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zxrjohn14,
I noticed in your post you said: "The holes are still off center,". You seem to be saying the Z axis is not moving up and down properly. But if I understand your statement 'off center' that would mean a problem with the x and y movement would it not? Do you mean to say the holes are not drilled to the correct depth? I know just enough about Mach3 to be dangerous so just asking. The Z axis gives me fits so I have a faulty understanding at best of the Z and safe limits.
I use Vcarve Pro 9 and Mach3 running on an old XP machine.
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Yes. There seems to be an issue, albeit minor, on all axis.
If you do a circle within a circle, and wanted a 6mm ring left, one side is 6mm and the other side 3mm.
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Hi,
There seems to be an issue, albeit minor, on all axis.
Minor? This just about buggers the machine
to do anything.
Craig
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Hi,
There seems to be an issue, albeit minor, on all axis.
Minor? This just about buggers the machine
to do anything.
Craig
I was playing it down
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Hi zxrjohn14,
Can you please attach your <profile> .xml file (the one from your Mach3 folder) then we can check all your Mach3 settings. Copy and rename the file to zxrjohn.xml before attaching using the Additional Options tab. Your profile is shown bottom right of the main Mach3 screen.
Assuming you are now using Mach3 version .062 (as suggested) then I suspect the problem is not Mach3 related but all down to your machine mechanicals, however, checking your set-up is prudent as the first step.
Tweakie.
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Hi,
I would like to suggest another simple test...try running the same code but without the material so the spindle can be switched off.
It might be electrical noise from the spindle....
Craig
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ZXR,
One thing, draw a straight line of a length you can measure with a dial caliper do so in each direction x and y. This will tell you if you stepper motors are set to the correct steps/rev. If you are experiencing errors on all axes then I strongly suggest you look at the square of your CNC. If for any reason it's not square you'll never fix the symptom. One good test is to cut or draw a square of equal sides say 10" by 10" if your cnc can handle that size. Then measure all sides they should be within specs. Another way is to cut 4 squares whose sides can be measured by a dial caliper. Let's say 4" by 4". These sides should be almost exactly the same for a small 4" square. Cut or draw if you have an accurate pen mount, these 4 squares at each extreme corner of the cnc. This will test for squareness. Additionally, if you're driving the steppers to fast or too slow you'll get errors. I know this is a lot, but eliminating each possible cause help you narrow down the cause. Sadly my cnc was poorly designed and would not stay square. I also had flex in the spindle mount, there is no substitute for metal in an cnc frame trust me on this.