[Mhook]

Hi friends
i have a vmc 4020 with dc motors and 88hs which is a boxway. When I run 2D machining, the surface quality is excellent, but when I run 3D machining, the quality is a disaster. All the adjustments have been done. Is the quality of Fadal really the same?

[rwskinner]

No expert by all means, but I've seen several issues with 3D machining on my Fadal 4020. You probably already checked this but here goes. If someone else has some good tips I'm all ears as well.

1) Loss of movement in Z axis will cause horrific results. (Gibs, straps, backlash)
2) Are you having to use DNC or is the program totally loaded in memory? I know 3D stuff can get large, and using DNC can cause some jerky movement. Make sure look ahead is set at max. I think 255 is I remember right. Try something small and simple that can load in memory only and see if it makes a difference.
3) Have you tried using G8 Mode to see if it helps?

There are some good tips on Google for doing 3D HSM on a Fadal. It's a big old slow box way machine and will never be like a Brother Speedio but it should do okay but will of course take much longer.

[Mhook]

No expert by all means, but I've seen several issues with 3D machining on my Fadal 4020. You probably already checked this but here goes. If someone else has some good tips I'm all ears as well.

1) Loss of movement in Z axis will cause horrific results. (Gibs, straps, backlash)
2) Are you having to use DNC or is the program totally loaded in memory? I know 3D stuff can get large, and using DNC can cause some jerky movement. Make sure look ahead is set at max. I think 255 is I remember right. Try something small and simple that can load in memory only and see if it makes a difference.
3) Have you tried using G8 Mode to see if it helps?

There are some good tips on Google for doing 3D HSM on a Fadal. It's a big old slow box way machine and will never be like a Brother Speedio but it should do okay but will of course take much longer.

Thank you for your answer, but I checked all this, in format 2, the g8 code is active by default, the machining speed of the machine when the program is sent with CIMCO is great, and I have no problem, the only problem, in my opinion, is the movement delay in the z axis compared to the other two axes, I guess The heavy weight of cnc head will cause delay and lag in the movement In machining 3 axes at the same time, my other guess is that the coupling rubber of the z axis has lost its stiffness, it will not transmit the movement correctly and the feedback is wrong.
i must replace all 3 axis coupler with zero backlash coupler and check it again

I wish it was possible to adjust the speed of its backlash compensation like the Fanuc control in the Fadal control

If it doesn't answer this time, I have no doubt that the controller is weak and the resolver is awful. Even the new resolver is useless compared to the encoder!

[motogomi]

I have found that the thrust bearings in all axes are a wear item on my 4020. It especially affects finish on 3d work.
My $0.02 (US)
DG

[Mhook]

I have found that the thrust bearings in all axes are a wear item on my 4020. It especially affects finish on 3d work.
My $0.02 (US)
DG

Yes, the thrust bearing is very important. I checked it and about 5 microns

[warrenb]

Upload your code and I will run it on mine.

What post processor and CAM packagage are you using? How are you uploading / drip feeding? It should be easy enough to measure the backlash.

[Mhook]

hi
I use Powermill for the 3 axis machining and sometimes 4 axis at the same time, as well as nx and hsmworks for 4 axis Fadal
i edit post processor for 4axis

[servtech]

Hi friends
i have a vmc 4020 with dc motors and 88hs which is a boxway. When I run 2D machining, the surface quality is excellent, but when I run 3D machining, the quality is a disaster. All the adjustments have been done. Is the quality of Fadal really the same?

Belt tensions loose
Ballscrew backlash too high
Gib strip or linear bearing wear too great
Spindle bearings drive belts or encoder belt loose
3D program cutting technology incorrect
Conventional or climb milling with incorrect tooling ?
Use of G10 to stiffen the axis response read ahead
Axis tuning gains too low.
Etc.

Start with the obvious and work through it.