Fagor 8055T: Unexpected diameter change on second part

alphonso · Mar 20, 2019

Fagor 8055T on a cheesy Taiwanese flatbed lathe with Sauter turret. I run Gcode, not conversational.

Ran first part without issue.

Ran second part without issue except I noticed the initial cut on the OD and ID roughing tools seemed deeper than on the first part. Measured ODs and they were all .2" small. Measured IDs and they were .238" large. FWIW, finish OD 23.8, finish ID 19.0

Cog belt driven X axis screw. Belt jumped or servo motor mounted encoder malfunction??????

Manually brought tools to programed diameters as displayed on screen and the tools were out in the air, like they were where they were supposed to be.

I don't really know where to start looking.

Ox · Mar 20, 2019

Well, if the belt jumped, it would have had to jump 2wice to have OD's large and ID's small (or vs/vs)

And then for it to jump back in the right pocket after the fact?

You bought a "cheesy" lathe with ??? control (and I understand that those controls seem to be WAY more than my old skewl mind conjours up at first thought) but you did this on a >24" lathe? :dopeslap:

Are you new to this machine/control?

What if you actually try to run the third cycle?
Will that run the same as your manual positioning indicates that it should?
The part is junk now anyhow eh?
Keep adjusting the offset and keep hitting - to try to find a pattern?

--------------------

Think Snow Eh!
Ox

alphonso · Mar 21, 2019

The fact that the ODs are small and the IDs are big really baffles me. I could understand if both were large or small, but one big, the other small dosn't compute.

Lathe is L&W 30 X 80 "CYCLONE 30808" flatbed. Products - L&W MACHINE TOOLS,INC. They do not seem to have a US presence and have not responded to email inquiries in the past. Hand written names and phone numbers in the (incorrect) parts and operation manuals have been dead ends. I have had it for 4 or 5 years.

By "cheesy", I mean that the tailstock is such a poor design that when trying to run part between centers, it would lift off the bed .04". After a lot of modification and adding more clamps it will lift about .001. Which led to the next discovery that the bed will bow up and tilt the headstock back about .017 at the spindle centerline. Spent a month or more trying to overcome that design flaw with some success. Headstock will tilt back about .003 now.

The Fagor control certainly deserves a better machine to sit on.

Did rerun the ID portion of program with fucked part still chucked up and it seemed to close to right as it only cut air.

Currently working on modifying the covers over the servo and belt to try to limit the amount of chips that have been getting in there.

alphonso · Mar 21, 2019

Possible answer: chip stuck on home dog. While cleaning out trough that screw runs in, I homed X several times. Last time home wound up about .1 out from where it homed before.

Ox · Mar 21, 2019

But that doesn't make one tool big and the other tool small, only to go back to zero after the fact.
Unless maybe you re-homed the machine after part 2?

On my Big Bertha, she has a gearbox between the servo motor and the Z screw (2 to 1 ratio)
A taper pin fell out of that joint and laid in the bottom of the gearbox.
I was getting erratic Z results, so it still grabbed most of the time.

So - maybe you have something "slipping"?

----------------------

Think Snow Eh!
Ox

alan speyrer · Mar 21, 2019

You have mentioned lathe ridgity problems, and said the control belongs on a better suited machine, so if you just playing around, hobby stuff, just learning, ok. But if your trying to do production work, get a better lathe.

yardbird · Mar 21, 2019

Ox said:
What if you actually try to run the third cycle?

--------------------

Think Snow Eh!
Ox

I wondered the same thing? Or at least take and measure a few test cuts by calling X the diameters in MDI in rapid mode. Then maybe jog the machine around in X call a another X diameter and measure again to see if it does what you're telling it?

Brent

alphonso · Mar 22, 2019

Ox said:
But that doesn't make one tool big and the other tool small, only to go back to zero after the fact.
Unless maybe you re-homed the machine after part 2?

On my Big Bertha, she has a gearbox between the servo motor and the Z screw (2 to 1 ratio)
A taper pin fell out of that joint and laid in the bottom of the gearbox.
I was getting erratic Z results, so it still grabbed most of the time.

So - maybe you have something "slipping"?

----------------------

Think Snow Eh!
Ox

Yeah, not a real good answer. And I don't know why the home position changed as I thought the chips had been blown off the dog and switch. Totally exposed dog and switch, another cheesy aspect of this machine.

Tightened up belt a little. Not sure what permissible deflection is on a 1 inch wide cog belt on eight inch centers.

Ox · Mar 22, 2019

Banjo string.
D flat generally, or close.

----------------------

Think Snow Eh!
Ox

alphonso · Mar 22, 2019

alan speyrer said:
You have mentioned lathe ridgity problems, and said the control belongs on a better suited machine, so if you just playing around, hobby stuff, just learning, ok. But if your trying to do production work, get a better lathe.

It must be hobby stuff, playing around, just learning because I've only been doing this for 60+ years.

That would be nice but I don't have the money to get a 30"actual cutting diameter, 6" inch spindle bore machine at the moment.

alphonso · Mar 22, 2019

Ox said:
Banjo string.
D flat generally, or close.

----------------------

Think Snow Eh!
Ox

Hhhmmmm, guess I need to call in a piano tuner.

alphonso · Mar 22, 2019

I think this may solve the problem. As you can see, there isn't much protection for the dog or switch. The flat plate the dog is mounted to is only 1/16 thick out in the air. I could see it flex a smidge when the switch got to activate point on the ramp. This machine goes past the activation point and comes back to establish home point. Welded a piece of key stock to plate and seems to have stopped the flex. Time will tell.

Ox · Mar 22, 2019

I kan't see that having any effect on the issues that you mention.

Shirley your machine didn't come back and reference zero between part 1 and 2?

And did it ref between ID tool and OD tool?
And it would have been off from actual zero point both times - and in opposite directions?

???

---------------------

Think Snow Eh!
Ox

alphonso · Mar 23, 2019

You got me, I am completely baffled as to why it did what it did.

Ox · Mar 23, 2019

Have you ran the machine since?

-----------------

Think Snow Eh!
Ox

lionelt · Mar 25, 2019

Deleted.

Misread post

guest · Mar 25, 2019

alphonso said:
Ran first part without issue.

Ran second part without issue except I noticed the initial cut on the OD and ID roughing tools seemed deeper than on the first part. Measured ODs and they were all .2" small. Measured IDs and they were .238" large. FWIW, finish OD 23.8, finish ID 19.0
.

Sounds weird alright. Were you taking the same DOC each part?

Its as if the tool is pulling in, but it should have done it on the first part too?

alphonso · Mar 25, 2019

guest said:
Sounds weird alright. Were you taking the same DOC each part?

Its as if the tool is pulling in, but it should have done it on the first part too?

The first pass was the only extra deep DOC. If I can get out on the floor today, I will see what happens.

alphonso · Mar 26, 2019

Ran other parts in the "family of parts" just fine. All I can do is watch closely and hope this doesn't happen again.

NodecoMachine · Mar 26, 2019

What’s the code look like? Your hand coding or using CAM?

Fagor 8055T: Unexpected diameter change on second part

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