When the head on my TAIG is moved up (-Z direction) at 30IPM it sounds fine but when its moved down (+Z direction) at anything over 12IPM there is alot of vibration and the stepper can even stall.
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When the head on my TAIG is moved up (-Z direction) at 30IPM it sounds fine but when its moved down (+Z direction) at anything over 12IPM there is alot of vibration and the stepper can even stall.
Up is +Z and down is -ZQuote:
Originally Posted by Smertrios
Anyway usually there are problems when moving up because the gib can shift and make the slide tighter, so I haven't heard of any problems when moving the head down...
I assume you are using lube on the ways?
Could be that the gibs are just generally too tight, or too loose, so that there is a binding movement...
I'm running a new z-axis at 30 ipm rapids...
You may want to reduce acceleration or velocity, and maybe play with pulse width (what control software are you using?)
I typed the Z directions down wrong for some reason sorry about that as for the TAIG its brand new and dripping with oil running with a Xylotex 4-Axis "box" and mach2 demo. The steppers ate 269oz holding torque and can power the x,y,z no problem well at least no problem except when lowering the head.
I'm pretty much at a loss - have you taken the z-axis apart at any point?
The reason being that given the mechanics of the mill, down feed should always be easy.
If you swap the leads on the motors (so the z-axis is now powered by the x-axis drive) does the problem still occur
If you swap motors (take the motor off of z and replace with one of the other axis motors) do you still have the problem?
All I can think of is that it's related to the acceleration and velocity and pulsewidth settings in Mach2, try cutting them down and see if it helps (especially acceleration)
Did you buy the mill from me or another dealer, or Taig directly?
With the control off, does the axis feel like it feeds smoothly when fed by hand turning the screw?
Quote:
Originally Posted by Smertrios
I think the gibs need to be adjusted or rather tightened up I believe the whole head assembly is tilted so that when its going up the bottom part is being dragged up but when the direction changes the bottom part is pushed and kind of skids when the speed goes above 12.
It's pretty easy to adjust them. Adjust the clamping shoes first with the motor off the mill, then mount the motor and adjust the tapered gib on the slide.Quote:
Originally Posted by Smertrios
Here are the two pages that detail most of that:
Some Notes On Setting Up the Taig Milling Machine
and
Some Notes On Setting Up the Taig Milling Machine V2
The factory head assembly was loose I could actually make it tilt slightly just by lifting up on the motor and I did't have to lift very hard. Now after adjusting the head 5 times it feels solid but the GIB is soo loose it not applying any pressure at all in fact what I did was tighten the top screw until I felt pressure on my wrench then I backed off 3/4 turn and tightened up the bottom screw. TY Much I never would have been able to fix this without help.
Whats is a good lubricant to use with a TAIG mill? I know the machine shop I worked at used regular motor oil for everything from manual bridgeports to the $100,000 VMCs but I can't remember the oil weight.
Glad you have worked out the gib problem - working smoothly now?
For oil Taig says ATF, but any 20-30 wt oil will be fine. I use a light way oil which is "stickier" that I get from MSC.
Quote:
Originally Posted by Smertrios
I thought I did because the head was moving without the stepper stalling. Another problem is with the stepper motor mount. I can leave the screws loose and hold the motor with my hand and the z axis will move up and down with no problem at all but as soon as I tighten the screws the stepper will start stalling again when the IPM is above 12.
When mounted correctly the motor will but up against the end of the tube. If it is not in contact with the end of the tube then screwing it to the plate will cause it to cock to one side and cause stress. Readjust everything and make sure the stepper is square to the leadscrew.
The articles I posted show how...
Quote:
Originally Posted by Smertrios
I know its an alignment problem but its not caused by the stepper being "cocked". When the mouting screws for the stepper are barely tightened I can see the cable shake a little and I can feel it wobble a little in my hand (I have to hold it to keep it from moving that is how loose it is). What happens when I tighten the screws in that it can't "wobble" as easily so the screw is much harder to turn because the nylon tubing has to flex more than it should. Believe me when I say its "a little" and not from a serious tilt caused by not being seated properly. Maybe the motor mount is messed up?
My 2 cents worth says the threads in the tube might not have been cut straight or the holes in the flex collars are not straight (either the bore or 4 nylons tubing holes).
Sounds like the ends of the coupler halves (the one attached to the leadscrew and the one attached to the stepper) might not have a gap between them and are in contact, so that when tightening down they are acting as a fulcrum and throwing the stepper out of alignment. Increase the gap by unscrewing the motor mount tube a bit and see if you still have the problem.
Quote:
Originally Posted by Smertrios
Initially I used a 1/16" wrench to get the gap right but I have increased it to as much as 7/32 just to test if the stepper would still stall and it will. That gap was too large I was just experimenting its back to 1/16" now and it appears to be 1/16" all the way around although the only way I have to measure it is with a 1/16" hex wrench.
Quote:
Originally Posted by Smertrios
The gap won't tell you if the nut on the end of the leadscrew coupler is bottoming out against the stepper coupler though. Remove the nylon tubes and see if you can feel whether the couplers are actually in contact or not - if they are, increase the distance between the two then reinstall the nylon tubes...The gap is a guide, but not a good diagnostic..
The other thing is if the stepper is butted up against the tube end and the 4 screws are not evenly torqued on the mounting plate, it will cause some misalignment. I still think it is the stepper cocking...
Also the mounting plate should have the counterbore facing the stepper motor so it can be as close as possible to the face of the stepper.
I screwed in all 4 screws while holding the plate and motor together with the other hand but only tight enough to hold the plate in place then I tightened 1 screw another 1/4 turn. I noticed while holding the motor than I could apply pressure to 1 corner and the "wobble" would stop that why I did this and so far it seems to be the most stable setup yet. Kinda sux having to fiddle with the mounts this way.
I have tried swapping the motor mounts
I have tried swapping the motors
I have tried applying AMPLE 20 weight Valvoline motor oil
I have tried and retried toquing the mount evenly
I have tried torqing just 1 screw which seems to work
By tightening just the 1 screw and increasing the gap to 5/32 it has the "flex" needed to run at 30IPM without stalling. The one thing I did not try and might try tomorrow would be swapping the "flex coupler" that is attached to the leadscrew. If the center hole is not parallel and/or at the center of the 4 nylon tube holes that would definitely cause some wobble. I'm just looking for other problems since I think I have to the best of my ability ruled out the motor mount pieces that I install myself.
I have literally taken the z mounts off and put them back on a dozen times . :drowning:
Another possibility is that the nylon tubes are longer than the gap and are being compressed, which would throw the tension off, especially if one is too long. So make sure that the tubes are not being compressed at all.
The boss on the steppers is smaller than the hole on the tube it fits into and since it does not center perfectly when put together there is slight misalignment but enough to cause the Z to stall under the load of the spindle and motor when moving at high speed.
Nothing I can do about it until I get some measurment tools and a magnetic base for holding a test indicator but I'm confident that a few taps with a hammer to get the 2 round metal pieces of the flex coupler into perfect alignment before torquing down the screws will be all it takes.
Appreciate your help.