Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: furkan on February 20, 2010, 04:34:09 PM
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Hi there,
I have made a 3 axis cnc machine (60x60x30) with 3 stepper motors. Firt everythnig was ok. At the first tryings the speed was very good. But after making motor tuning the machie starts to perform really really slow and noisy. When using manuel not bad (but again too slow), but when working with g codes the motors sound like screaming and they move too slow like nearly shacking. I couldn't solve the problem.
my motor tuning setup is "step:113.3786847, velocity:703.8, acceleration:254.6775" and the feed rate is normal.i tried different values but didn't worth much.
Could you please hepl me to solve the problem?
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What kind of drives and what micro stepping do you have the drives set to?
Is there any reduction between motors and leadscrews?
What is the pitch of the leadscrews?
Hood
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I use this driver circuit.
http://cgi.ebay.com/NEW-4-Axis-CNC-Stepper-Motor-Driver-12-36V-3-5A-TB6560_W0QQitemZ170446592459QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item27af6899cb
The screws are directly mounted to the motors with couplings, there are no other gear between. The pitch of the screaws is 5/3 mm and the motors are 200 steps, I use full step. For calculating the values I used "set steps per unit" function under settings alt6.
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I would think using 8 microsteps would likely be much better than using full step.
Not sure what you are meaning by "The pitch of the screaws is 5/3 mm" could you explain that further?
Hood
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I meant the screaw moves 5/3 millimetres per circle or I can say the dimension between two teeth of screaw is that.
Actually I tried different step options but didn't worth.
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So you are saying the pitch of the screws are 1.6666666666666666...... mm ? That just doesnt sound right.
Are they metric screws?
Do you have a link to the screws?
Are you set up in Metric or Imperial units?
Hood
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ah yes I mean pitch. I use metric units. I set Mach3 metric. I measured it with a metric ruler. I'am not know much about these mechanical stuff. They are basic screaws, thinner of the one in the photo.
http://images.gittigidiyor.com/1935/aliminyum-govdeli-profesyonel-cnc__19356818_0.jpg
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Still sounds a very strange number for the pitch if they are metric screws, do you have a link to them from the place you purchased them?
Ok assuming they are 1.666666666666....mm pitch I would suggest you use 1/8 stepping so that would mean to turn your motor 1 revolution you would need 1,600 steps, one rev of the motor would move 1.6666666mm so for 1mm you would need 1600/ 1.66666666 = 960 steps per mm
Your Velocity looks slow but keep it that for now but your acceleration is likely way to high so set it down to about 50 for now and see how you get on.
Hood
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Unfortunatelly I don't have a link or document about the screaws, I bought them from a little shop. But maybe I measured them wrong if it's not possible to have that pitch.
Here the time is to late for that noise I will try it in the morning for the first
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I set the circuit for 1/8 microstepping as you said. And re-set the steps per unit again by using "set steps per unit" wizard. Now the sound problem is like solved and also the speed problem. But now the machine draws too little than the original dimensions when using g codes.
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What have you got the steps per unit set to?
Hood
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Now it is 907.0294776 . But I didn't give that value manuelly. I used the wizard for example I give the value 40 and it moved 15 millimetres instead of 40, then I entered 15 and software calculated it.
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Can you please attach your xml and the code you were running.
Hood
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This is the g-code that I created to try cnc. But I don't now how to have that xml file
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If you are using the standard Mach3Mill profile then look in C:\Mach3 folder and copy the file called Mach3Mill.xml to your desktop then rename it to furkan.xml and attach to the forum.
Hood
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a yes. here it is.
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XML looks fine from what I can see.
If you do the set steps wizard again what happens?
Hood
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Now I did step wizard for the 3 axis. I enterd 80 and 3 of them moved 80 millimetres. But then I open the g code file that I send here, the machine drew it in 5 millimetres area.
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The GCode file is about 3mm in X and about 4.5mm in Y.
Is it meant to be bigger?
Maybe your CAM is set in inches but not putting a G20 in so Mach thinks its in mm.
Hood
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Oh I drow it in Ares (an electric circuit software) and used lazycam to convert dxf file to the gcode, it must be bigger.
Mach3 is set to metric.
(by the way, I appreciate you, even I'm not enough to understand you try to help me with patience.)
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The code you attached is small, what size are you meaning it to be?
Hood
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It must be bigger than 6 centimetres but I'm not sure because I didn't save the dxf file.
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It sounds to me like you have forgotten to tell LazyCAM the units and it has assumed you were in inches.
Try doing some code with a wizard and make sure you choose its in mm if you get the option.
Hood
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Ok. So I think no problem with hardware but the codes. I'll try to create a correct code and try again.
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thanks a lot.