Lathe - Barber Shop Pole Pattern, Loose Carraige?

I mentioned spindle bearings above because I had a similar problem with my lathe. Tightening the bearings fixed the problem. Since your lathe only has about 10 hours on it, that's about the time it would take the bearings to seat in. It doesn't take much. I set the the bearings so I could just feel some preload when the chuck was rotated.
 
On my lathe, everything's loose, but and I get awesome surface finishes, Atlas 12" it's not so loose that you can detect play by hand but there is bed wear so it's loose at the headstock where all the work is done then it gets tight out right. My spindle bearings are tight tho. I do however sometimes tighten a gib screw for heavy turning on tough steels, but other than that turning the hand cranks is effortless
My bearings are loaded to the point where if I spin the chuck by hand it spins a couple times and stops, I pay close attention to the headstock temp by touching around the bearings
 
coolidge said:
The surface finish is smooth, this pattern is maybe a tenth or something.

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That's actually quite beautiful.
Or would be if that's what you wanted to create.......

-brino
 
If you wanted to get that you would never achieve the pattern like that. I too think its very looking but if you want to make clean cuts start with the headstock has to be the floating of the bearings .
 
Um well ahem yes I 'planned' to machine that pattern look how skilled I am (puffs chest out)
 
It almost looks like the chuck back isn't flat against the adapter plate...could just be the shadows tho
 
if you drag a finger nail gently across the surface if you can barely feel the pattern its about 2 tenths or more, if you can not feel it , less than 2 tenths. Learned that in Forrest Addy's scraping class years ago, thought is was kind of sketchy but has proven out with test indicators.

When I got my Monarch 10ee with over 50K hours on it, I had that problem with certain diameters and speeds and feeds. Been a long time and I had forgotten about it till I read your post today. I solved the problem by using more positive rake in my HSS cutters and smaller radius on carbide inserts and increasing the depth of cut with carbide. As I recall TNMG inserts were the ones that gave me the pattern most frequently. One of the great things about variable speed is you can pretty easily dial that kind of problem out by bumping the speed up or down a bit. I don't pretend to be an expert on worn spindle bearing but I have operated a lathe with them and it gave a surface finish that looked like a poor car paint job, orange peel type of surface from the rumbling of the bearings. Mostly an appearance issue, but finally the shop owner said enough and replaced it.

If you haven't already, I would still look at underside of tool post and see if there is a chip or burr that is keeping the post from sitting perfectly flat. If it isn't that, or bearings, a belt not turning true could do it, or maybe a set screw on a driveline pulley has loosened. Might also check that all the feet of lathe are making good contact with floor, floors change without warning us that it has happened.

michael
 
That looks to be a result of gears meshing or bearings. Are you able to run the lathe from belts only? I know on many gear driven machines there is a slight pattern left that loooks to be harmonic in nature. Check if the gears a aligned and tight on the bango.

I would also suggest setting up your DTI and pushing on the spindle to see if the spindle bearings have loosened up a touch. If the pre-loading is out then you will start to see some strange patterns come out on the finish.

Paul.
 
So I was just looking at some of the scrap pieces I have faced off and seen that same pattern on one of them...I was like what the.... this is after reading this thread. Earlier today while doing some threading internal on cast iron, and I was looking at the lathe setting up the gears and what not, and there it is, my lead screw has a spot about 6inches long where the threads are about a 1/4 of the thickness of the rest of the screws threads (yes near the headstock) I have noticed some lines while OD turning using power feed, you can't feel em. I held a part with those lines up to the lead screw and they are an exact match with the pitch....
 
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