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Lathe dog chatter

Dogs for all purposes. Happiness is a good collection of tooling.

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I use new centers, not one from your grand dad's wood box under the lathe. Spindles are checked with a tenth's indicator. Centers are then ground with the tool post grinder. Match marked to the spindle it fits. Every time I place a center in the spindle, I check it with the indicator.

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Centers and drill chucks in wood holders.

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A bar turned with one end chucked in a 3 jaw and with a center in the tailstock will have a lot of induced stress in the material before you turn the switch on!!! Think about this. Combined with a little lathe bed misalignment and it is chatter city. I have turned M98 barrels down to remove the steps, straight taper, with no chatter. Got to have the correct setup and tooling.
 
A bar turned with one end chucked in a 3 jaw and with a center in the tailstock will have a lot of induced stress in the material before you turn the switch on!!!

The center has to run true in the free state and then all is ok.

Or chuck up and center. By the chuck part a groove down to a small diameter. The small diameter flexes but will still drive the part. It may not be perfect but is adequate for most stuff.

No rubber bands, no inner tube pieces, no stretched rawhide. Just the correct feed & speed and a carbide tool bit with a nice chip breaker ground in. 4140 rifle barrel steel. Smoke from the low flash point Rigid Dark cutting oil. Makes the shop smell really good!

Nice! How long and what diameter?

I used to have an enco live center that ran on tapered roller bearings. Quite often it wouldn't chatter when other more expensive centers would.
 
When using 3 jaws chuck and Live center everything goes well, but when I needed an accurate diameter I have to turn between centers.

I'm using hss tool which is doing great, and not passing 250rpm with the minimum feed rate and cutting depth possible.
In the past, when I had to make quill type generator driveshafts, about 12" long x 1.2" dia with a 9" long center section turned to about 0.3" with the end section having an external spline and a 1/4-32 thread. I had some of the same difficulties you've experienced. Ultimately, I chucked the head end with the other end to a live center. Rough to a (chosen) process size, then switch to turning between centers to make round and to size and make concentric. Material was 8620 Rc 28-32.
 
Try chuck and centre if it’s uncontrollable, not ideal but it can get it done, I think centre turning is like tall buildings, once the height to width ratio gets excessive on buildings resonance and wobble or flex makes the building unusable, in turning it seems the length to diameter seems to cause similar problems.
Tie the dog, wrap lead solder round the part, just some of the things I’ve tried that worked.
It can be done, usually folk try to turn etc far too fast, slow it down and be content with very light cuts.
Carbide insert tools are virtually useless on long slender work, HSS is the better, at least in my hands.
There is a lot of trial and error, plus the challenge of expirence, gives the test first and the lesson afterwards.
Welcome to the endless world of metalwork, nice when someone has a go, more the merrier.
Plus consider a fixed steady, imagine a 40’ long 10” shaft ( I tried it) the sag of that is huge, small stuff sags too, actually bows with too much tail pressure, then it gets all whippy!
Mark
 
How big of a center point or center drill are you putting in the work piece?
I'm not sure if I understand what you mean, but the headstock taper is mt4 and I used center drill #4 for it and the tailstock is mt2 and used #2 for it. I drilled 2/3 of the drill tip.
 
I'm not sure if I understand what you mean, but the headstock taper is mt4 and I used center drill #4 for it and the tailstock is mt2 and used #2 for it. I drilled 2/3 of the drill tip.
A no. 2 and 4 center drill is not big enough for 2" OD bar held between centers. A no. 6 center drill in each end should help. Another thing is your centers used in the headstock spindle and tailstock. Need to "blue" them to the taper in the spindle to make sure they fit properly.
 
Up in post #5 he did say there is no problem with chatter when using a chuck.
I did it for a smaller work and it worked well so I assumed it is going to be good on this one but from the comments it's unlikely
Rookie is learning here 😅
 
Umm Smoking!

No rubber bands, no inner tube pieces, no stretched rawhide. Just the correct feed & speed and a carbide tool bit with a nice chip breaker ground in. 4140 rifle barrel steel. Smoke from the low flash point Rigid Dark cutting oil. Makes the shop smell really good!

If you want to see the tool bit profile, it is in Parker Ackley's book.

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This is really great

What is the runout on this setup? Did you grind the tool or it is some sort of carbide inserts?

Not sure if carbide is suitable for the rpm I'm using. Do you think it will help if I use carbide insert for aluminium, I found them to be razor sharp?

Which one of Parker Ackley's books you mean?
 
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