Old Mits Not Correct Feedrate

I have a 1990 Mits.
Don't know the model - but it would Shirley be the flagship of the day as it is a 3 path control on a Swiss.

Somewhere along the line - the feedrates have doubled.
On path 2 for sure, and pretty sure path 3.
Not 100% sure about path 1, but I think maybe....

It seemed like it was feeding pretty hard, but when I recently had to dial the F down to 1/2 for an M4 tap on path 2 .... then I'm sure.

Any clue where to look?


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Think Snow Eh!
Ox

Since most lathes use FPR and that is based on the spindle encoder, that's the first place I would look.

The encoder in my lathe has an inner disc and an outer disc. Each with its
own output. When one of the pickups died, my lathe thought that I was only turning
1/2 the spindle RPMs, so my feeds were cut in half. I had to program a .100 lead to
cut a 1/4-20.

Exactly double or half tells me its something that shouldn't be hard to find..

Double feed, maybe encoder on the screw is dropping out half.. If its on all
axis.. Then I don't know..

But I would start figuring out everything that counts pulses in the machine, and
find the common denominator.. Is the spindle geared? or is it a single speed?

Feeding in IPM

When I get between jobs, maybe I should try to chase some threads and see what I git.




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Think Snow Eh!
Ox

Found it!

Turns out that the FEEDRATE OVER-RIDE pot had gotten run up to 200%.

But the thing is that this machine does NOT have a switch/dial, it is a digital value that is buried a cpl pages away from where-ever it is that you are.
You have to WANT to go there to see it.

I wouldn't have even guessed that it would have gone up to 200%.
I'm not sure if that was the max or not, but I'm guessin' so....

This machine doesn't have hardly any switches on the HMI at all.
It's clean and cheap to reproduce, but boy it sucks to run!

But what gits me is that I would never have guessed that it would hold an edited value even after re-boot!
I understand "how" that would werk, but not clear on the "why" you would program it that way?
I actually guessing that it would have taken more werk to make it reset at reboot...

Yes, the chased threads were all on spec.

Now I will be editing progs for a while to git back to square one....


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Think Snow Eh!
Ox

So on my newer Mits controls, there is a setting that, when checked, will not allow the feedrate to exceed 100%, regardless of the position of the feedrate override dial. No idea if such a thing would exist or be useful on a control that doesn't have a physical dial, but could be worth looking for.

TeachMePlease said:

So on my newer Mits controls, there is a setting that, when checked, will not allow the feedrate to exceed 100%, regardless of the position of the feedrate override dial. ......

Click to expand...

Locking out feed or spindle override control is determined by the machine builders ladder, not Mitsu. Most builders implement that as an M-code, but having it be a setting switch or softkey is just a ladder function. It is pretty commonly used in high production environments. Having the feedrate override as a knob or setting data is machine builder determined too.

As Vancbiker said I understand this a up to the MTB but on my Meldas 320 it will throw an alarm that it can't cycle start cause federate override is over 100%

Hardplates said:

...... on my Meldas 320 it will throw an alarm that it can't cycle start cause federate override is over 100%

Click to expand...

That's a machine builder choice that I have never seen before. I'm scratching my head at the thought behind putting that in the ladder.

Vancbiker said:

That's a machine builder choice that I have never seen before. I'm scratching my head at the thought behind putting that in the ladder.

Click to expand...

My guess is to make sure the operator is aware the machine is in "warp overdrive". While it can be annoying to me if I wrote a program conservative and don't want to rewrite it, I would like the feature if I had Joe Blow "operating" the machine.