Whats going on with this cut?

[Opie_7afe]

So this is my first time using a center in a lathe and having a weird cut almost like its out of round or the metal is twisted(i know its not.. the metal is 0.656 drill rod, i have 0.002 runout at spindle end, have 0.004 at the tail stock end. Now tail stock was out of alignment, and tried getting it close using two centers and matching the points up, so its most likely off. But i tried moving the alignment a tiny bit to remove that runout and just keeps jumping around.. my main concern is the cut in the pictures, its about a 0.010 cut. Barely cutting at tail stock end and cutting at spindle end.... Have any pointers for me?

In the pictures its that diagonal line you can hardly see. Just a weird twist type of thing going on..

 

[john.k]

I cant tell,but would bet a weeks pay on chatter setting in....(i dont get paid).....you need a travelling steady mounted on the saddle.........you have got a travelling steady?..........chatter is a self excited vibration ,and once set in its hard to completely eliminate,even with a steady........edit......you should also be aware ,if you cut long lengths without coolant,heat expansion will be so forceful,it can bust bearings and centres on little lathes.

 

[Opie_7afe]

Its not chatter at a 0.010 cut...especially in 0.656 01 drill rod at a length of 7" between the centers...drill rod is ground to a fairly tight tolerance so why would i be getting a cut not concentric while twisting at the same time? Im highly doubtful its chatter. Hard to take a picture of what i see..

 

[markba633csi]

When you hold stock between chuck and center you can get strange cutting action if the axis of headstock and tailstock not aligned close enough. Tough hard to cut steels can flex when cutting. Your cutting tool may not be sharp enough or may not be on center. Does it have enough positive rake?
Check the alignment again. Make sure the tailstock and it's quill are locked down. Can you use a faceplate and drive dog instead of 3-jaw?
Mark

 

[markba633csi]

Also check the carriage and compound for loose gibs

 

[john.k]

It may be saddle skewing,always wind the saddle in the same direction for checking.

 

[Opie_7afe]

The tool not being on center could be it, tried to get it close as i can along with the alignment..wish i had a test bar to use as the tailstock was way off went to drill a center in the same piece of rod and noticed it. The compound is "tight" already adjusted the gibs, carriage seems tight as well. Still learning, a mill is much easier to get setup lol.

 

[john.k]

I cant see,but one thing to be careful of is a false edge forming on the tool,this can easily take off a extra few thou on some steels.........otherwise ,it may be simple misalignment of centres....might also be worth putting a dial gauge against the tailstock barrel,and checking its not deflecting.

 

[tq60]

You cannot align the tail stock by sight.

Make a spool for alignment.

Simple to do.

Find some scrap 2 in OD x 3 inches long...anything close in material or size will do.

Place in chuck and face it off, center drill then take finish cut to make it look nice, use power cross feed if you have it.

Flip it and repeat.

Now place in Chuck with about 3/4 length exposed and support with tail stock.

Remove about 1/4 the diameter in the center leaving a coller at each end.

Now place a center in the headstock or place a chunk of your drill rod and make a point, this will be your driving center.

Place the spool between centers and take light cuts as it will slip otherwise.

Cut only enough to make it round .

Measure diameter if each cooler.

If the tail stock end is larger tail stock needs to come forward and if smaller then back.

Make tiny adjustments and insure locked before cutting.

When both are exactly same tail stock is in alignment with headstock.

Now save the spool and NEVER cut again, just place a dial indicator in tool post and measure.

We made ours 20 years ago and is is still primary alignment tool.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Opie_7afe]

Problem is i cant readily get material, have to order it as i work the same time on every day that metal suppliers locally are open..ill figure out something.