Lathe finish has gouges and surface is very rough

With HSS you can slow it down, your previous speed would be suitable or maybe a bit faster like 750
The tool makes a lot of difference- carbide tools seem to cause the most trouble for people than any other single thing I've seen
-M
 
Much of getting a good surface finish is the back loading that happens to the slides.
.005 doesn't load the tool or machine at all take a .100 at those same numbers and look at the difference.
 
Much of getting a good surface finish is the back loading that happens to the slides.
.005 doesn't load the tool or machine
 
Is this on your Colchester? Poor finish can result from so many different things. The best a person can do is eliminate any rigidity problems, switch bits, and play with feed speeds and depth of cut until you've figured it out. I think experience plays a big part as well. I don't know your experience level, but I've experienced changing one small variable make all the difference in moments. I think stacking many such experiences up over time is what gets us there in the end.
 
jwmay said:
Is this on your Colchester? Poor finish can result from so many different things. The best a person can do is eliminate any rigidity problems, switch bits, and play with feed speeds and depth of cut until you've figured it out. I think experience plays a big part as well. I don't know your experience level, but I've experienced changing one small variable make all the difference in moments. I think stacking many such experiences up over time is what gets us there in the end.
Click to expand...
Yes, this is the Colchester and I am definitly a novice. I have tried various bits, speeds, and feeds. Using sharp HSS seems to produce better results. There is one remaining question relating to your comment on rigitity problems.

The second picuture shows a pattern in the result that must be related to feed, the photo shows distinct bands. I do not believe these come from the head or spindle, I hope I am not wrong about that. The bands are difinitly visable in the center of the pattern. They are also visable in the cut to the left in this photo. These were all made with a relatively slow feed, .002 to .008 per rev.

The first photo shows 2 bands just to the left of the tool. The first band was manual feed at a very very slow rate, this is actually a pretty clean cut. The second band was auto feed at .002 per rev. It definitly shows banding and a rougher feed. (now I need to sort out if there is a pattern in the spindle or how the feed mechanism could be causing a pattern in the saddle :( .)
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20210725_185516.jpg
 
You might want to consider reading post #104 of the epic lathe tool grinding thread. (You really should read the whole thing, but my link gets you to where mikey gives instructions on making 3 HSS tools.) The tool itself can affect the finish. Check it (under a magnifier) for any chips or defects in the cutting edge.
mikey's epic tool grinding thread post #104
I learned a lot by reading the thread by @mikey
 
It is rare for a professional machinist to take cuts of .002-.009
If you have .200 to remove to be on size then based on your machine and tooling it's one pass at .150-.180 mic the part and dial into the finish size.
A huge part of lathe work is pushing hard enough with the tool to take the spring out of the machine.
There are circumstances that make this more difficult and that is why it takes time and experience to become a good machinist.
Some material you increase the feed and the material flows as it is removed and the finish is beautiful.
Speeds and feeds are important and one thing that makes the difference between a machinist and an operator.
 
I'm not really qualified to give advice on it, because I'm still learning myself. I sure do like the look of those Colchesters. I read they make good stuff. FWIW, I don't think you need to worry about the saddle or feed mechanism being at the heart of this issue. Watch some videos on YouTube about tool grinding, and read the linked post if you're a reader. I did both. It helped. But there is a moment when you get the idea of what you're after, and the grinding gets quite a bit easier after that. Also your lathe is capable of running carbide inserts. When I had a lathe that could do that, faster and deeper was almost always the answer. YMMV
 
Try a cut with different material and maybe work on focusing that camera :)

That banding makes me think there is a problem elsewhere, like in the spindle or bearings
 
The bit you show in your pictures is very poorly done. Your bit should have a radius on the end - not a flat.
 
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