Doosan Lynx C-axis Milling Concentricity Problem

Good Morning All,

We have an issue on our late model Doosan Lynx with the c-axis milling. The part being machined has an internal 1.6875-18 thread .350" deep. Small thread bar we had was flexing too much but we had a thread mill on hand so I programmed a thread milling cycle to mill it live horizontally. Now the problem is that the threads are not concentric with the bore, they are off .008 TIR from the bore (minor diameter). Is this just a matter of comp in x and or y in the tool wear page or is there a parameter that needs to be adjusted? We indicated all tools in the turret with round holders parallel with the spindle bore and they are all off the same amount (.016" Y and .004 X I believe). We've not had to use c-axis to create something that needed to be concentric yet so this is a first for me. If all else fails we will order a beefier threading insert holder and turn the threads again but the c-axis needs to be solved for future work.

Thanks everybody and anybody!

You are saying your live tools are off .016" in y? If so it sounds to me like you are using xy to threadmill and misalignment is your issue.

Just to check - Are you actually rotating the C or are you cutting with XY and C is locked?

If you are XY then cut it rotating C, that should take care of any location issue.

Yes, x and y are milling with c locked, and it does seem like an alignment issue. For the time being I switched my axis rotation and have it thread milling using c rotation, but this is only a bandaid solution. I figure there will be times where c axis rotation milling wont work like on an eccentric slot profile or something. Thanks for your input gang

I work for Doosan and would like to help but I need more information. Have you contacted your dealer service rep? I agree that what you did to fix temporarily is a bandaid solution and need this fixed for good. So, start by contacting your dealer and have them look at your machine and find out what happened. The permanent fix is most likely a simple alignment. If X is off that much and Y is also off, having Y off that much has greater impact on things like drilling, turning and boring than your issues with thread milling.

Paul Anderson
Applications Engineer
Doosan Machine Tools America
[email protected]
973-618-2457