cnc not cutiing right

[petlaw63]

hello all
I have problem that i not sure why it happen.
I did a sketch in fustion360 and went to cut it on my home made cnc using mach 3. The problem is that when i cut out a circle the first time is right but when it went to do the next cut
it move over a 3 mm from the first cut so the circle isn't the right size have a got something set up wrong. or what. At the moment I still have the demo version.
I have the cnc router set up right calibrate ok, move the right distance ect i would like to show the code here but not sure how too

Peter

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[jclark91]

Sounds like you have got the steps wrong for the motors, or the back lash

Best way to check is put a clock on Zero the machine move it away and back to zero and see how much it’s moved

[petlaw63]

Thanks for replying
I using a chain drive on my y and x axis and i checked the step unit and it seem right to me , eg when I put in 20mm it moves 20mm and then i put in -20 it move back to 0 the same place where i started from.
Can there be a back lash on a chain drive????
how can i shear a video to show what happen ???

[jclark91]

are you checking it with a DTI? and in program? it might be only losing its postion by 0.1 a step but once you move 50 times in different postions it really dose add up
i had a nightmare setting up my father in laws 3040 Chinese cnc router thing on mach3, it dose sound like its losing steps or its postion, unless your program is at fault can you post it here?

[petlaw63]

sorry i haven't replyed for a long time
can you please explain what you mean DTI and in program sorry really new. I really would like to get this problem fixed.
How do i post the code here

[KH0UJ]

Can you tell us how did you calibrate your machine? what are your speed and feed on each axis?

[petlaw63]

hi I used the axis calibration on the setting tab in mach3 and not really sure about speed and feeds on each axis. Where do i find that info.
I just through feeds and speed with to do with the router and i have mine on it our power supply. i hope you can help me

salamat
Peter

[petlaw63]

hi all i been waiting to hear from someone that might know why my cnc not working right but it hard to really explain what really happen but i try again.
well here goes.

My cnc is home made by me. i have calibrate it all ok and it moves i use mach3
my problem as i said before . I load my code and zero the axis to where i want it to on my table and the push start , it cut the first pass great but when it goes to the second pass it move over 4mm from my zero point then cut the same Patten as before but in a different place the third pass move over again. the code on the DRO say zero every time but the machine has moved. it only on the x axis the two work fine. Does anyone know why this might be happen
I would really love to get this fixed and start using my machine right

Peter

[KH0UJ]

Are you a filipino? can you post a video on your machine working? there are a lot of factors on offsetting problems, things like noise issue, unshielded wiring, wrong calibration on the speed and feed...if you can post a short video I think I can help you....pasalubong ha? hehehehe

[petlaw63]

No i am not a Filipino but my wife is
i will get a small video soon as i can. thanks for helping me
peter