[rideredcr]

I have a taig mill and it is run by Mach 3. My issue is when the mill rapids (G00) it locks up (no movement of the table). When it does that the machine loses its place. I was thinking if I could reduce the rate at which it rapids, the machine would function properly. I just don't know how to do that. Can anyone offer me some help?

[rideredcr]

Oh and a little bit more info. When I jog continuously, even 2 axis at a time, I have no issues. Its only when a G00 is programmed.

[ger21]

Reduce the velocity setting in the motor tuning screen. The Velocity is your rapid (G00) speed.
There's also a rapid override slider that you can use to slow down the rapids, but you really should reduce the velocity.

[rowbare]

You might also want to tweak your acceleration settings downwards. That can also cause what you are seeing.

bob

[rideredcr]

Ok thanks guys. Ill try tonight.
Ray

[littleCNCjohn]

If someone has a Taig and doesn't have this problem, please look at your velocity/acceleration/rapid-override settings and let us know what they are! It looks like it is very a common issue.

I would really appreciate it,
John

[rideredcr]

Ok so I slowed down the velocity and acceleration and it ran fine until the last line of code. I tried slowing everything down even more but no luck. The best setting I can find is where the machine locks up randomly on G00 instad of every G00. I'm starting to think it's the controller or the computer or the comunication between both.

[BAMCNC.COM]

You using sherline 1/2 mode?

My settings are as follows
40-60 velocity
18-20 acceleration
Step / dir around 5
Sherline mode ON

Is it only in certain spots on your mill? As in, is your center worn and you tighten your gibs, then when the axis gets to extremes its to tight.

As for homing limits page, 20% is when your close to the limit it slows down...

[rideredcr]

I recieved an email from Taig Tools that contained a file that had all my machines perameters. I loaded it into Mach 3, so those are the factory settings I have in there.
Factory settings are as follows:
30 velocity
5 acceleration
and I'm not sure about the others. I'll check tonight.
The stepper motors lock up randomly. It is always at G00, but it never happens at any specific line and it's never the same axis. Sometimes it happens once and sometimes it happens 3 time through out the program.....just completly random. When the machine locks up, it is only one axis that does so. Meaning if x,y and z are moving only one of those axises will lock up.........with that said it will still lock up if only one axis is moving also.

[br1]

You using sherline 1/2 mode?

As for homing limits page, 20% is when your close to the limit it slows down...

Thanks for that, you are correct. My error, I have edited my statement.

[BAMCNC.COM]

Thanks for that, you are correct. My error, I have edited my statement.

Np, I also believe you can change the distance away it will go to 20%, so theoretically you could make it 20" and it will always run 20%, not that you would want to, lol

[rideredcr]

So as luck would have it I was introduced to a guy here at work that owns a mobile machine shop and has years of experiance building his own CNC equipment. After talking to him, I believe he knows what he's talking about. It just so happens he has the exact same Mach 3/Taig mill set up as I do. According to him....because the lead screw on taig mills are so fine.....10 in/min is about as fast as it can rapid before loosing steps. That is significantly slower than what the factory perameters are. I will try 10 in/min tonight and post what I find.

[littleCNCjohn]

I attached a dial to mine and jogged the full length of the table at 30 ipm 5 times. It lost 0.0003" (two steps). You might want to try that to see how yours compares.

When it jams, does the motor turn slowly and squeal, or does the table completely lock up?

Can you remove the motors and then run the program to see if they still lock up?

-John

[BAMCNC.COM]

10ipm without losing steps.... really? What does he have acceleration set to? I have a feeling he doesnt know as much as he thinks he does, OR he runs his table super TIGHT, which.. there is nothing wrong with that.

BUT, there are to many variables to say... I'll run mine at 30ipm all day long, but I don't have a "factory setup" so saying that 10ipm is the limit is.... Just wrong...

I run .0002" backlash or so on my X axis with tight gibs... What about him?

[Jeff-Birt]

According to him....because the lead screw on taig mills are so fine.....10 in/min is about as fast as it can rapid before loosing steps.

That is just non-sense. On my set up I do 85IPM rapids and cut at 15~30IPM on a regular basis and never miss steps unless I ask more from the machine that it is capable of. For example I had a bit that was getting dull and after finishing a part it was obvious that the Z had lost 0.010" or so as it was no longer cutting all the way through the material. This was the fault of a dull bit though, not the machine.

A lot of thing effect the performance of a machine. The biggest is the physical condition. Is it lubricated and adjusted properly? Are the lead-screws in good shape? What about the stepper connector straws and the preload on the bearings? Also keep in mind that a machine has its inherent limits. About 100IPM is tops for a Taig as after that the lead-screws really start whipping around and your stepper motors will be spinning so fast there will be little torque produced.

The combination of stepper motors, driver and power supply also play a big part. There is a myth in the hobbyist community that huge stepper motors will always give you better performance and that is almost never the case. With the 20TPI screws on the Taig acceleration and maximum velocity are more important as you have a LOT of mechanical reduction (i.e. torque) already. You really do not need a motor larger than 200oz-in or so. I use 166oz-in motors and out-perform about anything out there.

The stability of the pulse train your PC is putting out also has a large impact. The parallel port drivers used in Mach and LinuxCNC are at the mercy of the underlying hardware. There are thousands of differnet motherboards out there and some of them just do not play nice. That is to say they will never produce a good. stable pulse train no matter what you do. Myself I have been using an external motion control board (SmoothStepper) for years now. I still have machines driven by the parallel port but build all my new machines with a SmoothStepper. (I also have a large mill with a Galil board doing the motion control and Mach in the drivers seat.)

[BAMCNC.COM]

Do you see a BIG difference with the smooth stepper then? As I assume you tested both on one mill/pc combo to Actually know.. apples to apples

[rideredcr]

All good info guys, thanks. I didn't have a chance to try 10 in/min last night. To answer some questions raised.....I bought this mill about 10 years ago and it has a total run time on it of maybe 10 hrs. I cant imagine anything is loose on it, but I will check. I was talking to another machinist here at work....he seemed to think it was the computer's processor or operating software that might be the issue, stating that sometimes those peices of the puzzle don't play nice. Is that what you where eluding to Jeff?
One other thing that popped into my mind was I have run some simple programs with very little G00's in the program and had no issues. The current program Im having problems with is an engraving with lots of rapid Z up and X movements. Would the large volume of G00 create an issue some how? All programs where generated using BobCad v23.

[rideredcr]

Question for you Jeff and please forgive my ignorance. I looked at the SmoothStepper board and it peaked my intrest. Does that board completly replace the factory Taig controller box? How is it physically hooked up from computer to motors?

[BAMCNC.COM]

It replaces parallel port and BOB.

Originally designed to be used on newer PC's with no parallel port, now they are going Ethernet aswell as USB.

[Jeff-Birt]

To answer your questions:

@BAMCNC.COM: yes I have tried the same machine with both a parallel port and SmoothStepper. The PC I was using did a good job through the parallel port and would run the Taig up around 90IPM but pulse train was a bit sketchy at that point. With the SmoothStepper I was able to do 250IPM on the same machine. Now, 250IPM on a Taig is not reasonable, it was done just to test the limits. If your PC works fine with the parallel port you may not see much of a difference. The feedback I have from customers though shows that about 90% of them do see a significant difference.

@rideredcr: The SmoothStepper takes all the timing critical things that are normally done in software through the parallel port driver and moves them into external hardware. Since all the timing signals are done in hardware the step pulses are very accurate and can be generated at a much higher frequency than is possible with a parallel port. The SmoothStepper does not replace a break-out-board, while it's outputs are able to drive more than a parallel port (able to source/sink more current) it does not provide any isolation, etc that are common with a BOB.