[Mike Conboy]

We have a Bridgeport series 1 Interact machine fitted with TNC145 controller.

On rapid Z traverse away from work (never towards work) it gives a "Gross Position Error".

What does gross position error mean?
Why do we only see it on rapid Z up?

Also does anyone have circuit schematics or a service manual for the same machine? Need something showing how all the servos and tachos are wired.

All help and ideas will be gratefully received.

[pestana1957]

Hi I also have a bridgeport serie 1
you can find all you want on the bridgeport site at the adress, http://filebase.heidenhain.de/doku/o...9E/N12B9E.html

[Al_The_Man]

Probabally the following error gets too large, the difference between where the axis is supposed to be and really is.
This error margin can usually be widened by parameter.
Al.

[gridley51]

"Gross positioning error" definitely heidenhain`s most common message.It`s machine related as opposed to control and as Al says can be got around by changing a parameter.I would check the axis mechanical things first.Are they Sem motors on that machine with tacho and encoder built in?Is it possible the gib adjusting screw is letting the gib tighten the slide in one direction?I have wiring and maintenance manuals for that machine with a 150 control but the electrical drawings won`t copy.I need a magnifying glass to read them.If you have specific electrical questions,ask and I`ll look at the drawing.
Mark.

[machintek]

As mentioned when the actual position lags behind the command by exceeding a value specified in a parameter, it will give that error.
Note that the error occurs going up against gravity.
Possibly: a weak motor. It is a DC motor with brushes which are probably worn out. The drive tuning may be off, and lastly the oil around the quill/ballscrew is incorrect/lacking/gummed up. Try flushing it with kerosene and reoiling with a mobil vactra number 2 or eqivilant.

George

[caniggia_100]

My mahine gets this same error not always, but often in this same position on axis X, when fast move is done up.
with slow ones it works ok.

Any ideas?

Greetings
Pawel.

[machintek]

What model Bridgeport?
What control?

Jurek

[caniggia_100]

Hi,

It;s Bridgeport Series II Interact II with Heid TNC 151B
control.

I'm going to check motor and tacho next day, as decribed in some posts before.



Pawel.

[machintek]

Check motor brushes, armature, cable and gibs/oil, ballscrew, and bearings.
Swapping X and Y motor would tell you quickly, if it is the motor.

George

[caniggia_100]

Thanks Jurek,

I'll check my motor on Z (I did mistake -my problem is with Z).

Thanks a lot.
Pawel.

[caniggia_100]

I did some invetigation today, checked tacho, brushes, all clear. Brushes like new ones. Exact Error is with letter A -
Gros positioning error A. I called Heidenhain,
they told me that this can be mechanical fault, in the moment that it stops it has not enough power to pass trough this moment.

i'll check today.

Pawel.

[gridley51]

Al said
"
This error margin can usually be widened by parameter."

Which is what I usually do if I`m in a hurry asnd don`t want to spend time looking for the fault.Reasoning being when it gets worsre it should be easier to find.

Thing I`ve noticed with Interact 1`s is,if they are on short X cycles I can get a shortage of lube eventually on the slides at the drive end of the X.
Has anyone else noticed this?Does the lube get pumped to that end or does it rely on table travel?
Mark.

[caniggia_100]

Hi Mark,

On beginnig - my problem is with Z not X as I wrote in first post. Maybe there's problem with lube.

Now I don't know how to check. Pressure gauge when pachine is ON shows 0 as I remember, maybe thats the problem. I don't know how oiling is working, on what time it's turning on. Maybe there's neccessary air pressure to oil amchine? (currently I have disconnected air due to 5/3 valve damage).

Thanks
Pawel.

[gridley51]

Pawel,
I wasn`t referring to your problem with my previous post.
I put it up to see if Al or George had any views on the lube subject for my own info.
Sorry for any confusion.
Mark.

[machintek]

About way oil. Just because the oiler is working does not mean oil will get to every place it needs to. There are metering units that can clog. A physical check to see if a film of oil exists on a surface is a good way to see if that particular metering unit is letting oil through.

George

[caniggia_100]

as I see oil is where it should.
I solved problem temporaily. I decreased rapid move speed for Z axis in machine configuration from 5000 to 4000, also
in programs i use decreased value, seems to work OK.

Thanks a lot.
Pawel.

[bigtoad170]

I have been getting a gross positioning error when my machine is sitting perfectly still only when it is cold though after an hour or so of the machine running and getting it warm I can run it all day with no problems. I think I will run some kerosene down the z axis though I have seen it act like it gets stuck on the rapid when its cold like a very quick jerking to catch up where it needs to be.

[bigtoad170]

What are your problems gamazuf

[Hery]

I am new comer, there are some problems with one machine in our company. The type of the machine is TNC 360 made by HEIDENHAIN. Sometime, if you want the machine move ahead, but the machine move back. It also show the title" Gross positioning error x"
Do someboy help me to solve this problem? Thanks for your help.