CNC Apprentice
CNC Apprentice
triac not machining properly. loosing steps??
hi everyone.

a newbie to using triac cnc mills.
I've come across an issue on my triac when machining circular toolpaths. it machines circles out of round weather its external or internal. it will randomly leave notches in the machine finish were it has dug into the material. I've checked the programs are correct. has anybody else had this problem? if so how is it sorted? its becoming more than annoying now

thanks in advance for replies
toby
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
What software are you using?
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
denford vr milling v5 software with bobcad v28 mill
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
Have you updated to the latest version of VRMilling?

VRMilling 5.63

https://website.denford.ltd.uk/index.php ... -downloads
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
no i haven't i have 5.62 will update and see if it helps. also just for future reference is there a good place to get parts for triac machines?
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
I don't think the software will make a difference if you are on 5.62.

What about backlash? Can you post a photo of the circle it machines?
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
it only seems to be on a certain point on the traverse of the x axis. if i use the far left of the table for machining it does fine, if i use the other side of the table it doesn't like machining circular paths and when facing it leaves lines as if it needs tramming. but this is only on one half of the x axis so I'm not sure what to do here, its getting me quite concerned. as theres only so much you can do with a gib strip when it seems your sideways are unevenly worn
i will upload some photos shortly today
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
and I've checked for backlash. all good there I'm only getting between 0.008 and 0.01 backlash and have coded in the backlash value in VR milling to compensate. and wrote a figure of "10" to correspond with how many microns of backlash there is. in Fanuc control systems this is the correct way, is VR milling the same? as its Fanuc based
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
VR Milling does not compensate for backlash even though you can input the figures.

It could be a broken wire which shows up when you have the bed in certain positions. I would jog the bed to where you think it is bad & wiggle the wire. Listen for the stepper motor changing pitch.
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
no change in pitch and wires seem to be connected okay with no breaks. is it possible its the electronics in the main cabinet of machine? like the drive boards?
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
i tried some engraving today and it came out double lined after i retuned for a clean up pass at the same depth. one line was clearly cut atleast 0.8 mm from were it last cut. i only get this with the x axis. i will try to post up some photos asap
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
machine is sorted now. turned out to be a worn stepper motor. the machine is cutting smoothly and accurately now. thanks for the advice :)
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
is there likely to be an updated version of vr milling software that actually compensates for backlash? i don't see any point in being able to just input the figures for the software to do nothing with that information.
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
I am not aware of any plans to use the backlash facility. I agree it should not be present if it is not active. I will have a word with our IT.
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
thankyou martin, would be a lot of help!
CNC Apprentice
CNC Apprentice
Re: triac not machining properly. loosing steps??
hi martin is there any more news regarding the backlash facility in vr milling? I'm having to draw my round parts out of round on my cam in order for the machine to machine it correctly lol
CNC Guru
CNC Guru
Re: triac not machining properly. loosing steps??
I don't think we have any plans to insert Compensation at any point.
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