machine advice for super good concentricity (cnc lathe)

carbonitetech · Mar 30, 2020

Hi I am looking for a new machine to make round piston-like parts with very good concentricity(.0001") over 3 inches. Looking for a smaller prototype-like machine. I worked at a company where we had a hardinge t42 tuned up to make the parts good, and we bought a new mazak integrix with dual spindle to grab it on both sides which was super nice but not required for me. I am starting my own company and need to buy a machine to build these parts for a prototype. Heavy into CAD/CAM, I mention that as the controller is not that big of a deal to me as I will do everything I can via CAD/CAM and just push a botton at the machine. My budget is $25-35K so obviously I am looking used. Basically want a super rigid, small footprint lathe for small quantities but full cnc. I would prefer not to go older than 2003 or so. thank you for your advice in advance, this forum has been so helpful.

tmt · Mar 30, 2020

carbonitetech said:
Hi I am looking for a new machine to make round piston-like parts with very good concentricity(.0001") over 3 inches. Looking for a smaller prototype-like machine. I worked at a company where we had a hardinge t42 tuned up to make the parts good, and we bought a new mazak integrix with dual spindle to grab it on both sides which was super nice but not required for me. I am starting my own company and need to buy a machine to build these parts for a prototype. Heavy into CAD/CAM, I mention that as the controller is not that big of a deal to me as I will do everything I can via CAD/CAM and just push a botton at the machine. My budget is $25-35K so obviously I am looking used. Basically want a super rigid, small footprint lathe for small quantities but full cnc. I would prefer not to go older than 2003 or so. thank you for your advice in advance, this forum has been so helpful.

Ok, I'll bite! When you find one, I get to be first in a long, long line that want's one as well!!

Comatose · Mar 30, 2020

A used Okuma Genos L250 might get you there, they're only about $55k new and they can definitely hold a tenth concentricity over three inches if you know what you're doing. I'd be interested to know how you're planning to measure it, though.

carbonitetech · Mar 30, 2020

roundness testers are the cheaper way, that or a nice cmm.

carbonitetech · Mar 30, 2020

I first had it at .00035" which is what can live with, maybe I should have left it there.

ChipSplitter · Mar 30, 2020

Comatose said:
A used Okuma Genos L250 might get you there, they're only about $55k new and they can definitely hold a tenth concentricity over three inches if you know what you're doing. I'd be interested to know how you're planning to measure it, though.

They seriously are only $55K new? If that's the case they're cheaper than most Haas machines.
Put me on the list! :willynilly:

Comatose · Mar 30, 2020

CNC | Lathe | GENOS Lathe | GENOS L250II | Affordable Excellence

$54,500 right on the web page

Now, it's Okuma, so you'll overpay by about 3x for every... little... option, and some things that you'd think would be standard aren't. So read carefully. I have the Y axis version and I've been super happy with it.

Maritech · Mar 30, 2020

There is no single right answer to the question you have asked. No used machine will have a guarantee of performance, so you need to be very careful of the answers given here (because your question happens to be too general). You can be pointed in the right direction, but if you are looking at a used machine, you will ultimately have to do your homework (which would require a lot more due diligence than you've done so far). You need to not only take into account the machine selection, but also work-holding and tooling. Most of your "big name" 2-axis, box way machines I'm sure would do fine. Okuma, Mazak, Mori, Doosan, and many other brands.

Good luck.

Dan from Oakland · Mar 30, 2020

Question- are you looking for roundness or concentricity or cylindricity? they are not the same thing, and with that tolerance, you better know the difference. Just sayin.

carbonitetech · Mar 30, 2020

sorry, you are correct. i said concentricity but meant cylindricity.

Murf · Mar 30, 2020

What kind of part diameters?

Murf

mneuro · Mar 30, 2020

Maybe take a step back from the modern age of CNC and get a jig grinder. I have seem them go for very cheap. Put your part on an air bearing and holding that tolerance is no issue at all. Might be the right way to go for prototype work.

Mtndew · Mar 31, 2020

Comatose said:
CNC | Lathe | GENOS Lathe | GENOS L250II | Affordable Excellence

$54,500 right on the web page

Now, it's Okuma, so you'll overpay by about 3x for every... little... option, and some things that you'd think would be standard aren't. So read carefully. I have the Y axis version and I've been super happy with it.

Like what?
Okuma isn't like Haas where the base price only includes the outer shell and casting.

michiganbuck · Mar 31, 2020

It seems most holding devices are best to about .0002. I used to correct the best collets with grinding and mapping, and with not grinding finding their sweet spot and putting a line-up line on the collet and the holding device. Yes removing the holding device or putting it in another spindle would ruin the accuracy.
For lathe or grinder between run centers seems best ..when that is a choice.

Ox · Mar 31, 2020

Cylindricity (sp?) is one of the features that Hardinge (actual Elmyra machines) seems to concern themselves with.

But I don't know if you can expect a 20 yr old lathe to hold those tols?
I've never had reason to check anything like that - so I can't comment on that.

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

Think Snow Eh!
Ox

ChipSplitter · Mar 31, 2020

Comatose said:
CNC | Lathe | GENOS Lathe | GENOS L250II | Affordable Excellence

$54,500 right on the web page

Now, it's Okuma, so you'll overpay by about 3x for every... little... option, and some things that you'd think would be standard aren't. So read carefully. I have the Y axis version and I've been super happy with it.

That's interesting, because I've been prowling around on Haas's website and an ST15 w/ a tailstock, parts catcher, and chip conveyor runs about $70,000 IIRC.
I would rather buy an Okuma for the same money even if I had to pay $15K in options. :cheers:

Ox · Mar 31, 2020

Just so long as y'all understand that that is NOT the same Okuma that was built in 1987.

Those two are likely much more apples/apples than you would like to think.

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

Think Snow Eh!
Ox

ChipSplitter · Mar 31, 2020

Ox said:
Just so long as y'all understand that that is NOT the same Okuma that was built in 1987.

Those two are likely much more apples/apples than you would like to think.

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

Think Snow Eh!
Ox

Hey, I'm interested in hearing the good, bad, and the ugly.

Do you have a newer Okuma? I always thought they were really fast, powerful machines.

Ox · Mar 31, 2020

Nope.

Just what I read here every day.

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

Think Snow Eh!
Ox

ChipSplitter · Mar 31, 2020

Just looked at Okuma's website. Didn't see any prices but I did see that they have a 3 year warranty on the Genos machines. As an OEM, I know a multi-year warranty means you have confidence in your product. Just my $.02

machine advice for super good concentricity (cnc lathe)

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