SIEG X3 Z isue

[pakirk]

I have a X3 Mill that was converted by a well known engineer.
The problem I am having is that the Z axis keeps losing it's position. sometimes it is by say .1mm to several mill and some times stalls compleatly.

I have set Mach3 Motor tune to a low speed to see if this makes any direrence and it did not.
I have stripped the machigne, cleaned checked there is no friction and all appresed to be ok.

Im not sure of the best way to set the Z Gib on a CNC mill but I have tried several experiments at verious adjustments.
What ever I seem to set the gib at the isue is still there, even when relativly slack, the stepper stalls.

Now I took the gib out again and cleaned and re-loobed, it is worse. It is now making an horid grosning noise and is stalling a lot.
what ever I set gib to it is the same.

The gib looks a bit rough and you could see tool marks on it. Should I lap it?

Any sugestions would be appreciated
Thanks
Anthony

[hive8]

Could you also tell us what Stepper configuration, model number or torque you running on the Z Axis and what kind of screw...

[PriddyShiddy]

I have a counterweight on mine and run the Z @ 80ipm with no issues. 5 gallon bucket, 1/2" threaded rod, few nuts, eye bolt with 1/2" threads, two pulleys, bag of quick mix cement. I bolted a small plate into the threaded rod near the bottom, placed it in the bucket and mixed the cement holding the rod centered with a piece of scrap wood with a hole drilled in it resting on top.

Very curious what might be causing you issue though. How much nod is it indicating? Lower a DTI onto the table to "zero" then start making .0005" Z+ moves and count how many times it takes for it to get to zero after going the wrong direction on the indicator AND how far in the wrong direction did it show it went on the indicator?

There is a fine balance between tight (stalls & massive nod) and loose (no nod, tons of vibrating when cutting especially plunging/drilling)

[pakirk]

Thanks for the replys.

There is no counter weights or struts to help lift the head.
The system worked fine untill recantly.

I think the isue has been solved.
1. the lower the head got the tighter it became, If i adjusted the gib for a snug fit at the bottom end the head was very losse at the upper end.
2. the gib key and the duvets on the collom were rather gough.

i spent several days lapping the dovetails on the collom working more at the lower end and lapped the gib bar also.

Now I get a very smoove snug motion from top to bottom and I have not had any stepper stalls yet. I have tested with a dile gauge and all appears well.


I think the next project is to make a new "Lighter" head using a
3 phase ER20 High Speed Spindle - 1.1kW (1.48HP) - 24000rpm.
High Speed Spindles, Motors & Inverters - Arc Euro Trade
Any comments?

Thanks again

Anthony

[PriddyShiddy]

good dovetail/gib fit will make a big deference. scraping my gib did for sure.

what process did you use to lap the dovetail??

lighter head will help, but honestly I spent less than $100 on my counter weight + pulleys and I have hundreds of hours on it with little wear. I'm amazed at how well it works for what it is really.