Help Understanding Turret Alignment

smb44 · Jan 5, 2022

Hey everyone,

I'm working on dialing in a very well used Daewoo Puma 250 from 1998. I got the turret face perpendicular to the Z axis within spec, and test cuts on bar stock over 8 inches show a total taper of .0008. The taper will have to be good enough, because there is no way I can get a breaker bar on 2 of the bolts fastening the headstock.

This brings me to the problem of it cutting above center by about .008. I swept tool holder bores and also did some test facing to determine that value. From what I've been reading, and hopefully understanding, is that the turret is rotational offset to cause the above center cutting. However, when I sweep the stick hold flats on the turret for the tool in the cutting position, the indicator is spot on showing that it is flat to the x axis..... Correct me if I'm wrong, but this means the entire of the turret rotational axis is too high off of the bed/saddle plate, right? How do I deal with that, or am I misunderstanding something (VERY possible!)

If I do have to get into the turret, I know I'll have issues getting the 'locating disc' off of the turret face to get to the fasteners and locating pin holes behind it. Any tricks to getting it out, should I need to go that direction to fix my off-center cutting problem?

Thank you!

Booze Daily · Jan 5, 2022

You could just grind .008 off the bottom of your toolholders.
Are the ID positions the same? Some lathes have a button under the tool block that is actually an eccentric that can be used to adjust the “Y” error.

smb44 · Jan 5, 2022

I'm actually having to shim them, I misspoke. Relative to the tool, they are cutting below center (just above center as an operator looks at it). Shimming isn't a problem of course, but I'd prefer to not have to if at all possible.

The ID holders I checked seemed to be nearly the same, but not identical. I was not aware of the eccentrics, but that makes perfect sense. The turret clearly has spots for them. Thanks for pointing that out!

Booze Daily · Jan 5, 2022

I’d probably just get some plastic shim stock and put it under the seats for your OD ruff/fin turn tools so you don’t leave a tit. The other OD tools are probably not too important unless you do small OD work.

.008 I’d kinda a lot though. Is that actual or TIR?

smb44 · Jan 5, 2022

Booze Daily said:
I’d probably just get some plastic shim stock and put it under the seats for your OD ruff/fin turn tools so you don’t leave a tit. The other OD tools are probably not too important unless you do small OD work.

.008 I’d kinda a lot though. Is that actual or TIR?

Actual, as TIR was right around .020 (my hole finding technique with a dial indicator could use work though, I got too used to 3D tasters on my mill). The tit on facing ops just barely went away with .008 of brass shim stock. It was still present with .006 of shimming. I thought it was a lot as well, hence the desire to 'fix it' properly within the machine. I do have to remind myself that this is a 24 year old machine that was cutting steel in a large production environment with operators who probably weren't at the top of their game...

wmpy · Jan 5, 2022

That's a slant-bed machine, right? Is the spindle mounted on a slant, like the bed? Or is it mounted to a horizontal surface? If it's the latter, then you can get on center by moving the spindle.

smb44 · Jan 5, 2022

wmpy said:
That's a slant-bed machine, right? Is the spindle mounted on a slant, like the bed? Or is it mounted to a horizontal surface? If it's the latter, then you can get on center by moving the spindle.

Yup, it's a slant bed, and mounted on the slant.

smb44 · Jan 6, 2022

I've been pondering this further with a beer in hand, and I'm wondering if the turret is actually eccentric, but still aligned radially. I'll need to take an X reading at every tool index against the ID tool holder block mounting face. If that measurement varies across all tool indexes with consistency, then that would confirm eccentricity. It looks like I'll have something to check tomorrow morning....

Nmbmxer · Jan 6, 2022

The nose radius on the tooling can make a pretty big difference when using the "does it leave a tit" method to determine if the tool is on center. Sometimes if you raise the tool enough so the edge facing the chuck isn't leaving a tit, the contact point when OD turning can end up well over center and it won't cut well. Something to keep in mind.

Mechanola · Jan 6, 2022

I know that shit. There may be chips under the turret base or the screws not tightened correctly or a wrong shim underneath or the indexing pin/bores has/have wear. Have dialed in a number of turrets on Okuma and other bikes, when everything seemed spot on, tool height was not. Best jiffy is tool shims. Make a list of what is needed in which turret port.

Demon69 · Jan 6, 2022

Wes did a set of videos about cnc alignment, I thought it was decent, he also talks about what you might find adjustment wise on various machines.
Heres the part on the turret

Good to not go introducing an error to compensate for an existing error you may have missed. Theres an order to things if you have the time.
[video]https://www.youtube.com/playlist?list=PL0dOYq6JmMaKjytv6t6miHAhA4OWqdQeS[/video]

Have fun

Vancbiker · Jan 6, 2022

To start, what is your indicator setup when looking at your turret alignment? I’ve seen plenty of folks slap a mag base on the chuck…….Not good.

angelw · Jan 6, 2022

smb44 said:
I've been pondering this further with a beer in hand, and I'm wondering if the turret is actually eccentric, but still aligned radially. I'll need to take an X reading at every tool index against the ID tool holder block mounting face. If that measurement varies across all tool indexes with consistency, then that would confirm eccentricity. It looks like I'll have something to check tomorrow morning....

Hello smb44,
As mentioned by Kevin, the dial indicator setup is quite important. When clocking the bore of a B/Bar tool holder, if just using a typical magnetic base and dial indicator, the result will invariably show that the bore of the B/Bar Holder is high. Using a magnetic base and dial indicator to check the radial alignment by clocking the flats that support the OD tools should give accurate results due to the magnetic base, dial indicator assembly not moving. The only thing that you have mentioned that corresponds with the turret being above centre line is the pip being left when facing with an OD holder and that by shimming the tool, an improvement is seen.

There is no eccentric device on the turret of the focus machine, so save your time by not looking for one. The height adjustment for the turret when the machine was being built is via a spacer plate between the base of the turret index housing and the X axis carriage. On a machine like yours, its common to see the turret centre line below that of the spindle do to the turcite, used on these machines, or the slide way itself having worn. Its very uncommon to see the turret centre line above that of the spindle (relatively speaking), unless it was like that from the factory.

Regards,

Bill

smb44 · Jan 7, 2022

Vancbiker said:
To start, what is your indicator setup when looking at your turret alignment? I’ve seen plenty of folks slap a mag base on the chuck…….Not good.

Well, at the risk of some embarrassment, that is precisely what I was doing. Now that you say that, I assume it's a bad setup due to gravity acting on the arm, correct?

Those videos by Wes are great. I have watched them a number of times already, and still picking up more each time.

Demon69 · Jan 7, 2022

The best indicator arms can certainly sag. Set it on decent sized bit of stock, put the arm out and set a zero. Then laugh as you watch the clock when you turn it upside down

Demon69 · Jan 8, 2022

In video 3 Wes is checking headstock location.

He uses an adapter in the tool holder as a gauge.

And uses a tight (no long arm stick out) setup on the chuck to indicate.

If you've enough room, you could perhaps turn a spud the same size as the adapter and indicate the difference 'Top and side' from the tailstock, in the same sort of way you'd indicate for tailstock height on a manual lathe. Arm sag isn't a problem this way.

Also, did mention before that theres an order to things, no1 is bed level, then go from there, pita to have redo stuff because an element was missed. Good not to assume too, never know if Bubba has been some place he shouldn't of with his shim pack

timopen · Jan 8, 2022

Strugling with similar problems on my Taiwan made lathe... It's vertical "bed" so little bit different configuration.

But comment from Mechanola below... I did test sweeping turret face with indicator attached to chuck to see if there is problem with tilting of the turret. I think this kind of a test is not usual test because the contact area etc. is kinda limited, but for OP, it can give some more info about aligment.

Mechanola said:
I know that shit. There may be chips under the turret base or the screws not tightened correctly or a wrong shim underneath or the indexing pin/bores has/have wear. Have dialed in a number of turrets on Okuma and other bikes, when everything seemed spot on, tool height was not. Best jiffy is tool shims. Make a list of what is needed in which turret port.

Mr.Q · Aug 28, 2023

Hello, I know this isn't the topic of this forum, but I have a Puma 250 from 1998. Unfortunately, I had an accident with the batteries and lost all the parameters. Would anyone be kind enough to explain how I can obtain them or if someone has them, could they please share? I would be really grateful

Vancbiker · Aug 28, 2023

Mr.Q said:
Hello, I know this isn't the topic of this forum, but I have a Puma 250 from 1998. Unfortunately, I had an accident with the batteries and lost all the parameters. Would anyone be kind enough to explain how I can obtain them or if someone has them, could they please share? I would be really grateful

You have greatly reduced your chance of getting this information by posting a parameter question in a thread about turret alignment. Start a new thread with a title like “Parameter help needed for Daewoo Puma 250”.

rjwalker1973 · Aug 29, 2023

Can you set y centerline in your parameters on that doosan like you can on Haas NGC machines?

Help Understanding Turret Alignment

Plastic

Titanium

Plastic

Titanium

Plastic

Hot Rolled

Plastic

Plastic

Stainless

Stainless

Titanium

Diamond

Diamond

Plastic

Titanium

Titanium

Plastic

Plastic

Diamond

Stainless

Similar threads