Thoughts on Cobra lathes

[CNC-Hammer]

Hi guys,

for those of you that run Cobra 42 lathes, what are your thoughts on them compared with other lathes?

I have no specifics about the machines but would just like to know what you guys think of them in general.

I have never touched one but have operated Conquest lathes before, are they similar at all?

[Runner4404spd]

the conquest is a much more rigid machine than a cobra. that being said, i've got a cobra 42 in my shop and i have had no problems holding tolerances and all we cut is stainless steel.

[CNC-Hammer]

Yeah the Hardinge are good for holding tolerances.

So any limitations to the 42's?

[JohnnyTurn]

I have the Cobra 51 (2.0 inch thru bar) 20C collet

It's not a conquest, but if you know what your doing it's a workhorse. The biggest problem is always the operater/machinist/programmer.

An experienced CNC MACHINIST, not someone that has been a button pusher (operator), or someone that 10 years ago "used to be a machinist" (NOT), or someone that has no experience of day after day CNC machining, programming, fixturing, print reading, inspection, quoting etc. etc. You should have no problem with a cobra if you meet those requirements.

a REAL CNC Machinist is someone that can run any cnc mill/lathe from soup to nuts. And produce any job that those machines can handle.

With that diatribe over with. The biggest mistake So-called lathemen make on a slant is: THEY DON'T ORDER ANY LEFT HANDED TOOL HOLDERS FOR OD AND ID ROUGHING!

A slant is a backwards lathe. Therefore running the spindle backwards (M4) turns the workpiece INTO the casting base. Thus, placing all of the cutting pressure down into the mass of the casting. I have turned off the hex in one pass of 303 SST 1-3/4 hex on my Cobra51 with no groaning from the machine. Try that with a right handed tool.... I don't think so! Right hand is ideal for finishing, for the chip falls away from the workpiece and coolant can blast it away.

The Cobra is a straight forward 2 axis lathe that can do much. And it has the Hardinge precision built into it. Is it as powerfull as a 1980's MORI SL series? No.

But is it faster? More reliable, Easier to program? (FUNUC 21i)
Have the best spindle in the business(Collet ready- da Bomb)

Yes to all,

JT out!

[CNC-Hammer]

Thanks JT, but why the diatribe (rant)!

I was looking into buying a small shop and the only CNC's they had was the Cobras and Bridgeport Interact mills. The rest was all old manuals and indexes.

I'd agree with you on the Mori's!

[JohnnyTurn]

Just letting off some steam. This profession can get you hot under the collar! Also people that refer to themselves as "Machinists" and are not even close, burns my hide. I have run into so many of these people thru my 16 years that I could write a good book about it!
Know who are the biggest fools? Machine tool Salesmen! I have had some of them come in my shop and tell me all about the new gear and how THEY have made parts on it!

Yeah, I always say. Let's see you make 500 Pcs. out of 316SST all in spec, without burning up tooling like it's going out of style and also come in every day and run the job until it's complete. Show me a salesman that thinks he is a machinist and I'll show you a complete novice! Oh yeah, don't forget the"Machinists" that can't read G code! Gotta love them too!

JT

[CNC-Hammer]

Hah, I think we have all experienced salesmen telling us to run everything in spec and it will come up roses. I think not!

Back to your rant about 'machinists', I've had the good fortune of being 'led' by a supervisor whose only advice was to put the speed up fed, no matter what I was machining. If I asked him for advice regarding programming he would say 'go and see PED' because he knew he couldn't do it. Best of all he once gave a reamer to a miller and told him to machine a slot with it. Fantastic!

[JohnnyTurn]

You know,

Back to our Cobra conversation. The only thing I don't really like about my 2001 Cobra 52 is the spindle drive. It's a Magnetek! That's were The Hardinge boys skimped. I have learned from my Hardinge tech that if it goes it's not replaceable. You must have hardinge install a Fanuc drive that should have been there in the first place! I think he said it's in the neighborhood of $8,000 installed. The Magnetek is no Fanuc. It's not the smoothest around 2000 RPM. So I avoid that range in my programming. But they all have their quirks.

Like, THE Machine Tool Company. Yeah there good. But my Mori MV40 has morning sickness everyday with the tool changer. You have to cycle the pot in and out a few times until it's in it's happy place. (ZEN)

All in all, The Cobra 51 was THE ONLY machine I ever bought NEW. I will never do that again. Quality, used equipment is the only way to go. Cheaper, sometimes more equiped than new. And that weak one year warrenty you get with machines is over in a heartbeat.

JT