large diameters

[sheedy1999]

We have a haas tl3w lathe. Haas says 12" max chuck and the swing is 30" how do we hold bigger diameters without a larger chuck. We are going to turn a piece of steel that is 24 dia X 2 inches any work holding ideas

Thank you

[JWK42]

We have a 15.75 dia 3-jaw with 2 piece top jaws on our TL-3.
It is a Bison brand Set Tru style Model 9903.
I'm not sure if it was a special order, but I can find out if you want to know.
That might hold a 24 inch round with special extended top jaws. I'm not sure how stable that would be.
The other option would be a large face plate mounted on a special A6 adaptor.
We are also going to buy a TL-3W in the next 6 months and we intend to equip it with the same 15.75 3-jaw chuck.
Good luck.
I just found this web site. A6-15.75 is a standard

http://www.workholding.com/BISON-SET...L-ADAPTERS.htm

[HuFlungDung]

I hope your lathe has the poop to turn something at 24" diameter

For odd jobs, I have a sacrificial plate in which I drill and tap various hole patterns. This plate gets held in the normal chucking manner, and then the workpiece gets bolted to the plate.

If you cannot have holes in the part, then welding some tabs on the back side to chuck on may be another option.

Apart from that, you can probably snoop around and find a 24 inch independant 4 jaw chuck. Such a chuck may not be rated for high rpm, so be careful with it.

[sheedy1999]

how can haas build a lathe with a 30 inch swing and only allow a 12 inch chuck. Haas says if you use a bigger chuck and adapter plate you can damage the gear box or spindle and void warranty.

[HuFlungDung]

A lathe is a perverse animal, in that lower rpms at larger effective working radii, require more torque to take the same depth of cut and feed.

This is the exact opposite of what a VFD drive accomplishes with your main motor: typically, the torque is constant up until the main motor reaches its nameplate rpm, and then the torque falls off.

The only solution is a gearbox on the lathe that will permit you to get the motor working in its optimum range, somewhere like +/- 25% of its nameplate rpm.

This is why old manual lathes often have a modest motor hp and a 12 to 24 speed gearbox. A VFD drive simply cannot mimic the full range of torques required for turning from near zero up to the full swing of the machine.

I am not sure what you've got for speed ranges in your Haas. My own older American Tool lathe has two ranges, the low range up to 800 rpm with the 30hp motor turning at about 4000 rpm when the spindle is running 800. I have cut 15" diameters in steel plate on this machine, with a modest .125" DOC and a feedrate of .012" It cuts nice, but its about all the load that the motor will take. Since the spindle is only turning over at 100rpm, I'm not getting 30 horsepower worth of work done, more like 7.5 hp at that speed.

As far as I know, you should not normally 'damage' anything by trying a cut on the larger OD, but make it modest to start with. The overloads on the spindle drive will kick out if there is not enough juice available, there will not be mechanical damage (aside from a broken insert ), because the torque is simply not present to do the work.

[Geof]

Originally Posted by sheedy1999 how can haas build a lathe with a 30 inch swing and only allow a 12 inch chuck. Haas says if you use a bigger chuck and adapter plate you can damage the gear box or spindle and void warranty.

When you say; "Haas says if you use a bigger..." do you mean Haas the factory or your local Haas dealer? It does seem a bit ridiculous to have a 30inch machine that can only work on 12inches.

[sheedy1999]

the local dealer. It also says on the haas website that the TL3W is 12 max

[Geof]

Originally Posted by sheedy1999 the local dealer. It also says on the haas website that the TL3W is 12 max

I looked, yes it says 12" max for the chuck but 30" max for the cut diameter. I think they are limiting the chuck size because the spindle can go faster than a larger chuck would be rated.

[Mazaholic]

Make sure the chuck will fit without interference.
We have a lathe with a 20" swing but is only able to hold a 10" chuck because of the tool eye.
A 24" chuck is alot of mass for a machine to stop,not counting the mass of the part.

[sdopp]

Haas X 24"mass = Crash

[timan]

Originally Posted by Geof I looked, yes it says 12" max for the chuck but 30" max for the cut diameter. I think they are limiting the chuck size because the spindle can go faster than a larger chuck would be rated.

You are exactly right I questioned this at IMTS and that is Haas's answer. There aren't many manual 3 jaw chucks within a decent price range you can spin much faster than 2400 RPM.

[Geof]

Originally Posted by timan You are exactly right I questioned this at IMTS and that is Haas's answer. There aren't many manual 3 jaw chucks within a decent price range you can spin much faster than 2400 RPM.

They need to get sophisticated in their motor control software. Put in an algorithm that monitors the acceleration rate. If the chuck comes up to speed slowly then make the assumption that an oversize chuck is mounted and automatically set a spindle speed cap of 1500 rpm. Then have the software remove the cap when the acceleration goes back to normal once a smaller chuck is mounted.