Purchased a small 6090 cnc from Jinan Senke CNC Co. in China which was a size downgrade from my old Jiachen 1212D due to me moving premises. Didn't buy another jiachen as the response was very laboured and vague upon my enquiry which made me nervous.
Senke were very quick and answered all my questions straight away so was confident this was a good machine to purchase..
I've had minor issues over the years with my old machine so am quite familiar with little problems and fixing them.. But the issue I have with this Senke CNC has baffled me and I'm starting to think the manufacturers too...
Now I have not used this machine yet other than to fit acrylic to the bed and skim it ready for production.. Went to start a job and noticed the Z 0 position changes when I simply move the Z up and down!
On Instructions from Senke I've re-wired/swapped the Z & X servo to make sure this is not faulty and Senke have sent me a new Z stepper motor and ball screw which I changed all ok.. Only issue with the ball screw was they supplied one too long for the machine but resolved this by moving the bottom holder underneath the head so got over this..
Anyway, this has not solved the issue. Senke's quote said the repositioning accuracy was 0.01mm.. Now I'm not rocket scientist but .6mm is not 0.01mm and when I'm engraving .7mm material this variation is no good.
Senke's support then tried to suggest that I set callipers up and check by eye in a way telling me that the machine is good and I'm just being given the wrong information and I'm being fussy because .6mm is acceptable!!
My last communication was me saying this is not a correct way to measure the Z position.. It's either the machine or the DSP controller that is not working properly.
Hence to say now they're not getting back to me so I'm getting the feeling I'm going to be on my own with this soon!!
Can anyone help?? Or suggest any possible changes/upgrades to the machine or the DSP controller that can help me here...
The movement does seem very jerky and not smooth, so is there a way I can change this within the controller to illuminate this from being the problem (can't see it but still)
I have work lined up for this machine but I'm scared to try anything because of this and for what's left of my hair I'm currently pulling it out!!
Happy to talk to any UK based company that could possibly help me here also.. PM me
Disconnect the motor/belt from the Z axis and see how it moves when rotating the screw shaft by hand. It should be easy and smooth. If not, there's a mechanical issue. Sounds like a binding problem. If you moved the bottom "holder" to accomodate the longer screw shaft it's likely the top bearing was not snugged "up" tight and the shaft is moving when direction changes.