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Thread: Nuttall Lathe adjustments.
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9th Jul 2017, 09:14 PM #16
You will never get an old chuck to run as good as a new one for 2 reasons I can think of.
When clamping a bar in the jaws it will be held with a force pattern that is impossible to match exactly and still get access to the jaw faces in order to grind them. It will always be a compromise.
The scroll portion of the chuck will have wear which will not be even over its whole length. Think of a chuck that has been used predominantly for a limited range of diameters. This section will have far more wear. When you move to a different section it will behave differently.
I am not sure what you mean by changing the position of the jaws. Moving the jaws around? You can't do that with a SC chuck.
The only reason to adjust the headstock is if it has been moved in some way. It should be set in the factory and not need changing.
Dean
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10th Jul 2017, 07:24 PM #17
That's true re: Jack B and his machining skills . His Formula 1 race team manager said " I'd just give Jack a rough drawing and Jack would have the part finished in no time, he was my best turner " He could also drive a bit as well ! My old Visby lathe has bronze spindle bushes in tapered housings, you adjust them by screwing in/out the flanges on each end it seems to be a effective design .
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10th Jul 2017, 07:47 PM #18Intermediate Member
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All good points Dean. What I mean with moving the jaws around in the chuck, is keeping the sequence ie 123, but moving all 3 around 1 position in chuck. Someone on youtube did it and there was about .010 difference between the best and worst position.
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10th Jul 2017, 07:56 PM #19Intermediate Member
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- Sep 2008
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Checked out the spindle bearings and can't find any movement. I also have a 4 jaw ind chuck, which we have hardly ever used. Should that be more accurate to check out the alignment down the bed. Or am I gasping at straws and should I look for a new 3jaw (what brand)
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10th Jul 2017, 08:41 PM #20
Gotcha. Ya learn something new every day. My chuck is pretty accurate, but the tips are bell mouthed so I want to grind them for that reason.
I had a Nuttall before this one. Both came from my previous employer. The Nuttall was swapped for an even worse one years ago and then they got my current lathe. This resulted from worksite consolidation, when they sold off other sites. The company decided that lathes had to have lead screw covers so maintenance decided it would be a good excuse to get a brand new lathe from H&F. The old one is probably better. The Nuttal had a lot of wear. The cross slide had about 1/8" slop in the screw. I swapped it for half a tractor.
Dean
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10th Jul 2017, 08:50 PM #21Intermediate Member
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Yes, my cross slide has a bit of slop but that was my next thing to tackle.
By the way, which half of the tractor 🚜 did you get?
Slim
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10th Jul 2017, 09:06 PM #22
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12th Jul 2017, 10:33 PM #23Senior Member
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Slim, never say never. I had to adjust mine, it was a very good experience in patience. You need to check if the headstock is in perfect alignment with the bedway. I used a new piece of high tensile bar and centered it in a 4 jaw chuck. Set up a dial indicator on the toolpost and zeroed it on the end of the bar and then wound the carridge back to the chuck and checked the readings. Mine was .005 in over 18 inches. You just loosen the 4 hold down bolts for the headstock and there is a adjuster on the back lefthand side which is a push pull arrangement. Takes a while to get your head around which way to adjust it, but I got it to within .001 inch so I am happy.
Have fun, wonderful old machines and I love the clutch.
Rgds,
Cocy.
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12th Jul 2017, 11:36 PM #24Mine was .005 in over 18 inches. You just loosen the 4 hold down bolts for the headstock and there is a adjuster on the back lefthand side which is a push pull arrangement.
I am not saying not to touch the headstock, but do not encourage people to do this unless they have eliminated every other option. This is a very touchy subject in almost any metalwork forum and don't even think about mentioning "Rolliessomeones dad".
I agree with the clutch being a boon. I swapped the 3hp 3ph motor for a 2hp 1ph motor. If it wasn't for the clutch I would not have been able to do this and the 2 top gears needed to slip the clutch to get the chuck rotating a bit first.
Dean
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14th Jul 2017, 06:35 PM #25Intermediate Member
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- Sep 2008
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Ok, so I have now put the 4 jaw on and have in a piece of bright HT bar, 45mm x 300 with about 250mm out.
I am measuring 0.001" out of ctr at the chuck (that seems as close a I can get it)
When I move along the bed to the end of the piece (240mm) my reading is 0 to 0.015".
If it was the headstock, out of alignment, wouldn't I get a constant reading at the end of the work.
i.e. 0 at the chuck and 0.015 (or whatever) at the tail end. I have taken the piece out of the chuck and replaced it a couple of times but still the same reading.
Once again guys, thanks for your patience.
Slim
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14th Jul 2017, 07:25 PM #26Golden Member
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- Apr 2008
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The thing is that some mad men that move and deliver lathes swing a strap off the chuck !! Full weight of the lathe on the spindle bearings I saw hare and forbes had a picture some place doing it . I was so horrified I refused to let them deliver my lathe and transported it myself , So you never know what has happened to a lathe in the past and the head stock could have moved but leave that until everything else is eliminated .
The .001 runout could be a combination of , the bars natural run-out , the chucks run-out , and the beds out of level or twist .
Machine the bar down until it's cleaned up and then run a very fine cut and see how much it runs out then . Old lathes can have some bed wear near the chuck and there is a kind of taper up to the unworn section .The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.
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14th Jul 2017, 08:09 PM #27
Hi Slim With my little Sheraton 9 lathe, If I am turning a piece and I am needing a accurate diameter over a length ,say 150mm or more , I always turn the piece between centres . I don't know why ( somebody please explain ! ) but I cannot get accurate results with the workpiece held in chuck jaws ( both 3 and 4 jaw ) and the tailstock centre, an unknown force always causes a taper on the piece. I have a short 3MT alignment bar , I know some people reckon they are a waste of time, I love it , it's a quick and convenient tool. And yes I do have a machinist level as well.
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14th Jul 2017, 10:10 PM #28Golden Member
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- Apr 2008
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- NSW
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Work sticking out of the chuck bends away from the cutting tool the more it sticks out and also that can set up vibrations. The unsupported end is the problem. Once it's between centres there is no unsupported end . However diameter and length of the work can still be an issue and thin shafts will deflect more than thick ones . That's why they have travelling steadies . Finishing cuts should be as light as possible and the angle of the tools cutting face should be close to 90 degrees to the job so the cutting force is towards the chuck more not across the lathe centre . This reduces deflection away from the cutting point . It's called Orthogonal cutting .
The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.
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15th Jul 2017, 09:32 AM #29Pink 10EE owner
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Roller spindle bearings as used in the typical lathe can easily handle the weight of the machine being lifted by them. It is more an issue of risking ripping off the headstock if it was a huge lathe, or knocking the headstock out of alignment.
Gold, the colour of choice for the discerning person.
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15th Jul 2017, 11:30 AM #30Intermediate Member
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I set the dialguage on the bar to 0.000 at the chuck, wind down to the end of the bar and get the same reading. Then rotate the chuck 180 and read 0.015 at the end and 0.001 at the chuck. It's like the bar is bent, but it isn't.
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