material handling & bar length

How are you guys handling your bar work?

Haas doesn't recommend hanging a bar out past the end of the spindle, so for one of their three inch machines they recommend three foot long bars, but only as a safety concern.

We've shot brass rods through the walls, sometimes for fun. I'm not concerned about that. What is practical?

Right now we're cutting 2-5/8" stainless into three foot lengths to deliver to our CNC outsource. The bandsaw takes about 15 minutes to cut through that stuff, and right now we're looking at a 10 hour job. does anyone out there have a better method?

No machine tool builder recommends hanging stock past the end of the spindle. This usually ends in a spectacular wreck and possible operator injury. You need to get a bar feed machine. This will allow unattended operation of your CNC. I don't know offhand of one with 3" capacity but I'm sure someone makes one. You can even make a simple one yourself using heavy pipe and air pressure. I can give you more details if you are interested in that route. BTW, I would also pass on a mill that has been broaching. That is a load the mill was never meant to take. I would also pass on a Haas. Their adds about all of their service men and vans show that they need all of that support just to stay running. There are lots of good used machines on the market now but for your first, you should probably buy new so you get maximum factory support. You'll save yourself a lot of lost time and frustration.

Check out the EASYFEED systems. They are new and can handle big dia's safely.

SEE www.manneng.com

I make my own spindle liners and have them come almost back to the barfeed. It is just a simple fact of bar diameter/length sticking past support/RPM. Not much diff than how you would look at sticking a part out the front of the collet and still think that you are going to cut on it.

With 2 5/8 dia SS I would assume that you are NOT spinning that spindle none too fast and 2 5/8 is quite stable in it's own right. Letting it stick out a bit past the support is not going to be the end of the world IMO. Just use your head.

BTW, adding a barfeed unit does NOT help with the support if you are looking at 4' bar loader. A 12'er would I guess. ( I am assuming that you are asking if you can cut it to 4' instead of 3'? )

Think Snow Eh!
Ox

[This message has been edited by Ox (edited 04-20-2003).]

I make my own spindle liners and have them come almost back to the barfeed. It is just a simple fact of bar diameter/length sticking past support/RPM. Not much diff than how you would look at sticking a part out the front of the collet and still think that you are going to cut on it.

With 2 5/8 dia SS I would assume that you are NOT spinning that spindle none too fast and 2 5/8 is quite stable in it's own right. Letting it stick out a bit past the support is not going to be the end of the world IMO. Just use your head.

Think Snow Eh!
Ox

I make my own spindle liners and have them come almost back to the barfeed. It is just a simple fact of bar diameter/length sticking past support/RPM. Not much diff than how you would look at sticking a part out the front of the collet and still think that you are going to cut on it.

With 2 5/8 dia SS I would assume that you are NOT spinning that spindle none too fast and 2 5/8 is quite stable in it's own right. Letting it stick out a bit past the support is not going to be the end of the world IMO. Just use your head.

Think Snow Eh!
Ox

thanks Ox. I think you understand my problem.

our machine is shipping with its own LNS quickload and a collet chuck, too. factory support? I say nothing. I will step into CNC machining with full respect for its capabilities, but I won't fear anything like I fear a screw machine.

by the way, has anyone heard a story or experienced a reason why not to run bars out past the spindle on a CNC lathe machine?

the tech school I went to has an older south bend Magnaturn cnc lathe( which was only a year or 2 old at the time). Most of my first year the machine was down for repairs, replacing guards, the keyboard, the computer screen, and hydraulic lines. It seems one prospective programmer did not limit the rpm on a facing cycle. the 3/4" 12L14 bar at 4000 rpm sticking out about 18" behind the spindle bent 90 degrees and tore h**** out of the machine. as long as it is supported well, you don't have to worry, but long unsupported bar rotating in a lathe is a concern cnc or not. make sure you keep a handle on it during facing cycles when running constant surface speed.

Yea Willie, I also saw a great wreck on a Hardinge lathe. They left about two feet of 1 inch bar sticking out the back of the headstock. It bent the bar about 45 degrees, ruined the collet closer, sheet metal, and headstock bearings. It also broke all of the bed mounting bolts, it looked like a sinking ship. Ox is right about the short bar magazine feeders. They offer very little support. I have seen people make bolt on supports for extended spindle liners. This would let you run 4 foot bars. I would invest in a hydrodynamic type 12 foot barfeeder. That would give you enough support and reduce your waste on bar ends.

Those of you making your own liners. What have you found to be the best material?

For the bigger sizes, I get DOM tubing with the propper ID that I am looking for, and then if needed, I send it to a grinder and have it ground to the propper OD. Make a little donut to weld to the OD for the reciever to grab and your off and running. I don't think you will have supprt issues with that setup! LOL!

Yeah, my T-51 has some battle scars from when the stock tube vibrated away from the machine and left some bar unsupported. Mangled the rear coolant ctacher a bit, and put one heck of a gouge in the Quickload that was slid back to allow the stock tube to pony up to the machine. I was using a Brown and Sharp tube and pulling with the sub. I still like this setup for odd sizes of hex or tubing that you don't run often and/or don't have time to make or order the propper spindle liner for automated feeding. Also saves a lot of ends on the tubing if you can run 20 footers.

I have mounted a B&S tube support to an old axle and tire setup. This doesn't move around on the floor this way, and rolls away to allow the LNS to slide back into position easily. Works good/ cost effective.

BTW: I wouldn't even have the nightmare of expecting the barfeed to help support the loose end of a spinning bar on a short bar type feeder! Go with a stout/longer liner, or shorten your bar length. Those barfeed extensions are made for loading (guiding) a still bar only! NOT for support of a spinning bar!

Think Snow Eh!
Ox

[This message has been edited by Ox (edited 05-20-2003).]