Z Axis motor removed and replaced... a problem??

[scadvice]

I have a 1997 Fadal VMC15xt with cnc 88 hs I'm refurbishing. I removed the Z axis motor during the move into the shop and just replaced it. As I’m still waiting for the 3 ph power to be wired in, I cannot power up yet to see if there is an issue with Z axis orientation, which I do not expect there to be, as the encoder should just pickup the next mark. I’ve done this once before with a 1989 Fadal, and had no problems.
Is there something wrong with this assumption? I recently read a thread about someone having problems after removing a z axis motor and replacing it in the same manner I described, but I cannot find that tread now.
If someone can explain to me how I’m wrong in the assuming as I stated...it would be helpful.
Thanks -Steve

[donnelson]

when you power up the machine and do a cold start look at your z alignment mark if it is right on the money your ok if not you are 180 deg. out take off the motor and turn it 1/2 turn to get the a height properly you take the cover off the top of the encoder and loosen the screws and rotate the encoder the z axis will follow you up or down hope this helps

[Al_The_Man]

If your Z axis requires to be at the correct position such as when a tool changer is used, most controls have a Grid shift parameter that you can artificially move the marker position without physically moving the motor itself.
Al.

[donnelson]

the lines have to be lined up to make a tool change the marks have to be right to do a cold start i dont know how you could do it in the control and then ever be able to use the home marks if you have to move the motor it takes maybe five minutes just do it and get over it

[JR1050]

I believe th XT used dc motors,which will have resolvers,not encoders(ever notice Fadals dont have limit switchs,and jerk when you fire them up).Put the motor back on,line the headstock casting with the marker line and finish the cold start.It 'ill be fine.Since you are "refurbishing it"-you can buy a good portion of the parts you will need from Mcmaster carr-Much cheaper then Fadal.Fadals are
set up for 7 data-2 stop and even parity,baud rate is set by parameter,save you some hassle down the road.......

[scadvice]

That sounds right, and thanks for the input. I guess I was lucky the last time I removed the other Z axis motor. Its good to be able to bounce thought off of others. Steve

[little bubba]

Originally Posted by JR1050 I believe th XT used dc motors,which will have resolvers,not encoders(ever notice Fadals dont have limit switchs,and jerk when you fire them up).Put the motor back on,line the headstock casting with the marker line and finish the cold start.It 'ill be fine.Since you are "refurbishing it"-you can buy a good portion of the parts you will need from Mcmaster carr-Much cheaper then Fadal.Fadals are set up for 7 data-2 stop and even parity,baud rate is set by parameter,save you some hassle down the road.......

JR, I've found that they don't "jerk" as much when you send her home before shutting her down, it doesn't even seem to move or make a noise(I get scared when Fadal isn't making a noise), jogging back to the cold start marks after an error or power out, then she jumps.

On the McMaster Carr thing, they do have parts cheaper(if you put in the time to figure out what you need), but anything Mcmaster has, there is somebody that has it even cheaper. They are just convenient when you need it NOW!! CNCpros has some prices on things even better than McMaster Carr, the ballscrew thrust bearings were cheaper, Fadal wants to sell you the whole carrier for almost $500. I'll take the $80 set of bearings.