Long stock whipping in spindle

at 4' you are going to need more than a spider, you are going to need some kind or support or roller system.

You might want something like the rollers Keith Fenner uses, his personal one can be mounted to a stand to support long stock.

you can see one of them in action in this video around 3:30.
 
Dan_S said:
at 4' you are going to need more than a spider, you are going to need some kind or support or roller system.

You might want something like the rollers Keith Fenner uses, his personal one can be mounted to a stand to support long stock.

you can see one of them in action in this video around 3:30.
Click to expand...

Not questioning your knowledge at all, and you more than likely know more than I do about machining. But if I understood the OP correctly, 20" is sticking out the back, not 4'. A spider at the rear would support the back end of the stock, still leaving 20" sticking out, but supported. As opposed to the entire length being unsupported from the collet chuck.

Would that work? Sure there are safer ways to do it, but it would still work, right? Again, not challenging your knowledge, just trying to get clarification for myself and maybe others.
 
In that situation, I'll admit to just stuffing the spindle around the material with shop towels. It works as long as your speed isn't too high. Pack them in tight and they will keep the stock from whipping. With only 20" hanging out, that's not too bad. If you keep it pretty well centered, the spinning doesn't have as much strength as it does once it gets off to the side, all the way to the spindle ID for instance.
Now if it were a regular thing, it's good to build a spider and or an outboard support. I placed my mill in such a way that I can use the table to mount an outboard support for one of the lathes (3 1/4" spindle hole). I intend to build an actual steady rest of some sort to bolt to the mill someday.......
 
if I read that right it's 20" out the chuck and 4' out the back of the head stock. I've seen a lot of photos of outboard bar stock supports for capstan lathes that look quite simple.

The whipping thing is amazing how quick a piece of bar stock suddenly gets a 90 degree bend in it :) i've only had it happen with very slender steel and also a long bit of nylon, the nylon experience was hilarious but would have been totally not hilarious if it was steel :)

I think someone posted a while back about a machine operator getting taken to the grate machine shop in the sky this way.

Stuart
 
A little off topic here. A place I worked at about 15 years ago. They had a couple of Mazak m5's they ran long bars on. One job they stuck the stock out the back end and had about 4 foot sticking out because they had the rest of it sticking out the front as far as the tailstock would go. Material was about 1-1/2 dia. Anyways day shift operator had it set up and ran it no more than about 600 RPM without it whipping too much. The machine had a 3-jaw chuck on the out board end of the machine just for holding the material steady. Night shift came on started running the parts, decided sometime on his shift to speed it up, 600 RPM wasn't fast enough. Well somewhere between 2000 and 2500 RPM it got away from him. The operator had walked away when he hit cycle start. By the time he got it shut down, that bar had bent 90 degrees and beat the heck out of the back of the machine. Destroyed every piece of sheet metal on that Mazak, dis-lodge the headstock from the bed, beat a hole in the concrete epoxy coated floor, took out ceiling tiles and insulation. When the shaft finally broke off, it flew across the shop into a sheet rock wall about 200 foot away. Wonder nobody was killed. Why is it, that these things happen on night shift?

Enough on my story telling for the night.
 
You really don't want to see it happen. Once on an 8 spindle screw machine only one of the 8 whipped. Those bars were 10 feet long. It took a cutting torch to clear the mess. When the one whipped I doubt I it was 2 or 3 seconds before the tie up occurred.

"Billy G"
 
As boostin53 said
" But if I understood the OP correctly, 20" is sticking out the back, not 4'. A spider at the rear would support the back end of the stock, still leaving 20" sticking out, but supported. As opposed to the entire length being unsupported from the collet chuck. "

This is correct and I used an old ER collet, slid in to the back of the spindle and held in place with tape. But I will make one of those dedicated ones with 3 setscrews.

I was just wondering about a more convenient way of doing it.

I should not have put the word "whipping" in my question as it is only rattling!

Thanks
 
boostin53 said:
Not questioning your knowledge at all, and you more than likely know more than I do about machining. But if I understood the OP correctly, 20" is sticking out the back, not 4'.
Click to expand...

I just miss read the post.

However even at 20" I would seriously start considering some external support, as that's over 30 times the diameter. With that kind of stick-out even if it doesn't bend and become a dangerous wip, just the flexing it will undergo could effect surface finish.
 
Dan_S said:
I just miss read the post.

However even at 20" I would seriously start considering some external support, as that's over 30 times the diameter. With that kind of stick-out even if it doesn't bend and become a dangerous wip, just the flexing it will undergo could effect surface finish.
Click to expand...

And that's why I didn't question your knowledge! I didn't even think of that!
 
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