What sort of cut should I be able to take on new Okuma lathe in 6061-AL?

I got a new Okuma Genos L250 lathe some months back and just wondering if I am expecting too much or something may be wrong.

My old LC40 could cut 1/2" DOC with a high positive rake CNMG insert all day without breaking a sweat and sounded smooth as glass. On this new one, it sounds like shit if I try to take anything more than .100 DOC. Same insert, same workholding (5C collet). It seems that can't be right, but maybe I am expecting too much?

I am running 3' bars of extruded 6061 (same as always) and I have a Trusty Cook spindle liner, so the bar ain't whipping around. I also have an ATS A2-5 5C collet chuck, LC40 used an ATS A2-8 5C collet chuck.

If the numbers above don't seem right - what would be the best way to diagnose the problem? Not sure what even to check...

RPM? Feed? Stock diameter? What HP does your machine have?

1/2" DOC -- is that on the diameter or the radius?

Yesterday I was taking .10" per side (.20" on the diameter), 2,000 RPM, 3-3/4" stock, .015" feed per rev. That cut put my 14 HP SL-2B's loadmeter at 105%. Using sharp no-coating Al-specific inserts. It sounded fine, just was pegging the spindle.

Regards.

Mike

I would ASSume its 1/2" off the diameter as 1/2" off the radius on bar in a 5C would leave very little to nothing left

Hi Mike:
I assume you've diagnosed the problem enough to be confident it's not crap aluminum piling up on the tool.
I've been fooled into thinking it was the machine when it turned out to be bubble gum quality material.

Okumas are supposed to be beasts...your new one should theoretically outperform the old one since it's new (and presumably tight)
If it's not the material or something obvious like a loose toolholder then I think it's time for a conversation with the seller.

0.100" DOC is a semi finishing pass for some of you guys.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

I know this sounds basic, but have you adjusted the drawtube pressure? I have the same lathe with live tooling (L200E-MY) and I take .1" per side off of stainless all the time with no issues. What's your feed? What's your spindle load meter reading?

I had a Baldor DC drive acting up on one of my lathes. It seemed like it would occasionally reset its drive parameters. This was due to a loose screw on one of the contacts to the brain of the drive. Anyways, got that resolved finally, and then it would put out its 30hp instead of 15. So go through the drive parameters and make sure they are properly set.

Make sure all the leveling feet are touching the floor.

You can't compare an old LC40 to a new Genos. They are in completely different leagues.
That LC40 would've had 4 different gears to choose from (M41, M42, M43, M44)...actual physical gears....and probably a 35 horsepower motor. Of course it's going to be able to take a bigger cut than a new Genos.
I've never had an LC40 but I do have some LC30s, LC20s, and Genos. Those 30s can take some monster cuts that I wouldn't do on a Genos. There's nothing wrong with a Genos, it just isn't meant to compete with an LC40.

If my Googling serves me right that is a 10 HP machine, of coarse you could take a 1/2" DOC but your feed better not be anywhere near aggressive. I have a 10 HP machine and would go .100 DOC, .020 per rev and about 2000-2500 RPM on 3" 6061 aluminum. That is with good quality material not gummy Chinese crap 6061.