Nuttall Lathe adjustments.

[slim]

So, hi to everyone and if it all goes to plan I'm sure someone will be able to assist with my question.
This is my first post on MF, but have posted before on the WF.
Sitting in the corner of our workshop is a "NUTTALL CENTRE LATHE" C model 6.5" 40" BC. I think it's an old TAFE machine and has stamped on the Bed. 1967.
We have had it for about 15yrs and use it rarely in our business (to make the odd pin or clean one up etc) We don't have a dedicated operator for it and it's usually left to me if we need something (that doesn't need to be too exact). So what I know about lathes is what I've learned myself on this one and, I seem to be using it more and more these days and while everything on the machine seems to work ok, I have a feeling that it could do with some tweaking with the adjustments etc. So my question(s) is(are).

Does anyone have the same type of lathe and if so, know how to give it an overall adjustment?
Is there some sort of "Machinist's bible" that would give the basics on working with and setting up a lathe (and adjustments)?

Note:
I realise that the Machinist trade, is a very skillful one and I also realise that by reading a book or being told how to use a lathe will not make me too skillful.
It will however lead me in the right direction and possibly make it safer.

Thanks in advance.
Slim

[Michael G]

There is a Hercus turning text book that may help
https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwiGiYXqp_HUAhWIlZQKHZiAA3MQFgg4MAI&url=https%3A%2F%2Ftokentoolroom.com%2Ffiles%2FText%2520book%2520of%2520turning.pdf&usg=AFQjCNEV7mqV3yIXepXmxSM2B-SrQpB2BA
Other than that it is practice and asking questions.

Michael

[slim]

Thanks Michael. Fantastic. Thats my reading for this evening sorted.
Slim

[Retromilling]

There is not that many things that you need to do really .
Two things that will help is make sure the lathe is very level crossways and length ways and put the level on the flats not the v-ways . If the level is too long cross ways build the flats up above the v-ways with some milling parallels and put the level on that . Use a machinists level not a builders level.
Machining a bar between centres and creating two collars on the bar one near the spindle and one down toward the tail stock and taking a fine finishing cut from one collar continuing to the next at the same cross slide setting . Then you measure the two diameters . If they are the same the tail stock is inline if they are not it needs adjustment and re-machining to test .
Safety is a different issue , never wear loose fitting floppy clothing , never wear gloves , never leave the key in the chuck , Never put tools in a rack behind the chuck where you have to reach over the chuck to get them , don't get into a habit of stopping the chuck with your hands after the machine is turned off . I'm sure you already know a lot of this .

[morrisman]

Hi Slim I guess you have seen this Page Title (http://www.lathes.co.uk/nuttall/) I have a Nuttall and it is a solid heavy beast , built like a battleship despite being only moderately larger than a Hercus 9 in its work piece capacity . Interesting seeing Jack Brabham and his Nuttall, apparently he learn't machining informally from a experienced teacher, Jack never did a fitting apprenteship. From all accounts he was brilliant turner and fitter.

[Retromilling]

Jack Brabham did Mechanical engineering at night tech well before he joined the RAAF , became a Pilot but was side tracked into aircraft maintenance due to his engineering skills. Once out of the RAAF he was involved in a small business that had machining as a component . I don't think he needed to be a fitter to understand a lathe being a mechanical engineer and a aircraft mechanic.

[morrisman]

Jack Brabham was never a pilot in the RAAF . I don't thing doing a engineering course means you are automatically a skilled machinist either . This quote from his official website "A retired engineer Bill Armstrong spent a lot of time teaching him how to do general machine work" .http://www.jack-brabham-engines.com/biography.aspx

[slim]

There's no doubt about it, Jack Brabham was a true, world champ and if he 'drove' his Nuttall, like his cars, then I'm sure he was probably pretty good at it.
I asked a friend of mine about my lathe (he has a small machine shop) His first question was, How old is the machine? And the second question was. When did you last change the chuck?
I discarded the first question (being 66 myself) but thought about the second and as per the Nuttall handbook put a piece of round bright bar 45mm x 300mm in the 3 jaw sc chuck (I think it's the original). With the bar in about 50mm I could feel movement and, as my friend pointed out, noticed that the jaws appeared to be 'belled' on the ends. After obtaining some quick advice from youtube I decided my jaws needed grinding and have done this and it appears to have somewhat fixed this problem. So now my measurement on the bright bar, close to the chuck, varies about 5 thou and about 10 thou on the other end. (this is after tapping to get it centered). And, by way, is it normal to have to have to use the dial guage to centre the work each time its put in the jaws? Shouldn't the jaws perfectly centre the work each time? It seems that most of the time I am taking a cut off the work then taking it out to see if it fits the job then putting it back in, measuring, and taking a bit more off etc etc etc.
I haven't even got to the tailstock yet.
Does the headstock need adjusting? My machinist friend seemed to go a little quiet when I mentioned this.
My small project is appearing to show signs of a Ben Hur epic.
Thanks for listening
Slim

[Retromilling]

You could be right he may never have been a Pilot but he did join to be a Pilot . However I am sure a mechanical engineer is quite smart enough to become a self taught skilled machinist . Bill Armstrong may well have taught him but I am sure he was smart enough to work it out himself in time.
No one said it automatically makes him a skilled machinist you are exaggerating what was said but it does make him smart enough to work it all out .

[slim]

To Retromilling. l note what you said about making sure the lathe is level. Getting the foundation right is very important.
My lathe is on concrete and in the same position for 15yrs and was only leveled with a builders level.
Other than using a machinists level (which I don't have) what method is there?
Also as Morrisman says, the Nuttall is a 'solid heavy beast'
Slim

[Retromilling]

Your chuck jaws could be worn . When re-chucking work in a 3 jaw I put a whiteout dot on one jaw and a dot on the job so I can align it again even when turning it around it helps . 3 jaw chucks will not perfectly re-centre work all the time but a good one should be very close my 3 jaw centres to .001 . Grinding the jaws off the chuck can still leave some run-out , grinding them still in the chuck is better . This is why I just can't get excited over old second hand lathes some have too many problems and picking a good one is a job for an expert . Don't touch the headstock alignment until all other possibilities are covered. With a well worn lathe the spindle bearings could be sloppy also . If you can feel sideways movement on the bar then that can be the spindle bearings and they can usually be adjusted up tighter but how on a Nuttall I have no clue .
Don't move the head try adjusting the spindle bearings first .
You can only level with what you have keep reversing the level and split the bubble difference. The worst out of level situation is bed twist try and get any out as much as possible.

[slim]

I did grind the jaws in the chuck. I made 3 blocks so that I could put pressure on the jaws in the closing position and then fixed a die grinder to the toolpost. It worked out ok.
On one of my YouTube views I can across one where they changed the position of each jaw in the chuck and each time it was a different measurement. Maybe I'll try that, after checking the spindle bearing adjustment (if there is adjustment)
I'll leave the headstock adjustment alone until all other things are fixed

[Retromilling]

The thing is some older lathes can have bronze bush type spindle bearings and they can't be adjusted like a taper roller bearing system .
I can't find a spindle design schematic for that lathe .

[.RC.]

It will have either tapered rollers or cylindrical roller bearings in the spindle.

[slim]

I think the handbook says it has taper bearings and that they were set at the factory. So maybe they are adjustable. I'll just have to find out how

[Oldneweng]

I did grind the jaws in the chuck. I made 3 blocks so that I could put pressure on the jaws in the closing position and then fixed a die grinder to the toolpost. It worked out ok.
On one of my YouTube views I can across one where they changed the position of each jaw in the chuck and each time it was a different measurement. Maybe I'll try that, after checking the spindle bearing adjustment (if there is adjustment)
I'll leave the headstock adjustment alone until all other things are fixed

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

[morrisman]

The thing is some older lathes can have bronze bush type spindle bearings and they can't be adjusted like a taper roller bearing system . I can't find a spindle design schematic for that lathe . 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 .

[slim]

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.

[slim]

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)

[Oldneweng]

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.

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. :D 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

[slim]

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

[Oldneweng]

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

HaHa. We have a dog each and a rescue dog that we both share. Which half belongs to who, depends on what she has done. When she is barking I own the back half. When she passes wind I own the front half. :D

Dean

[Old Croc]

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
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.

[Oldneweng]

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.

No doubt there are some members tearing their hair out right now. There have been a number of threads where people have written about doing this and the general reply is NO, NO, NO. What have you done! This is a very last resort after everything else has been adjusted. 0.005" over 18 inches can be caused by the bed not being correctly leveled and by that I don't mean with a machinist level, I mean adjusting for the taper. Adjusting the bed (removing the twist) to remove or reduce taper is done a long long time before touching the headstock.

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 "Rollies someones dad".:D

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

[slim]

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

[Retromilling]

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 .

[morrisman]

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.

[Retromilling]

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 .

[.RC.]

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.

[slim]

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.

[pipeclay]

Have you centred the bar at the outer end or just at the chuck end.

If just the chuck end then do it at the outer,then check the chuck end then the outer, you may find that you may have to tap the outer slightly to get it running true without touch the chuck jaws.

Any job hanging out of the chuck of any length will generally require a bit of mucking around to get it running true.

[slim]

I centred it at the chuck end and also tried to centre it at the other end, by tapping and tightening it, but it wouldn't move. I have the, very little used 4 jaw, on. The 3 jaw, which I use most of the time, does allow me to move and tighten. After I had ground the jaws on the 3 jaw I couldn't get the work to move as much, by tapping etc.
If I centre at the end of the work then measure at the chuck end, wouldn't I get the same differential measurements.

[Retromilling]

The full weight pressing on maybe three rollers in the bearing and it's not going to crush even a few thou into the bearing race surface . Could easily cause a slight mark that eventually trashes the bearing some years later .
I do agree that it could damage the whole head stock and or put it out of alignment . Just not a away I ever want my lathe to be lifted .

[Oldneweng]

What exactly are you trying to measure? There are a number of reasons this could happen. If you are measuring how true the lathe is cutting, put a steel bar in the chuck (any chuck), turn the bar down leaving a short section near the chuck and another at the end, just cleaned up with the rest 3mm smaller diam. Do a light cut on these 2 bigger sections in one run without touching anything. Measure them. That is how your lathe is cutting. The bar obviously needs to be big enough to avoid deflection.

Dean

[slim]

I think it was just a coincidence that after centering my peice of 45mm near the chuck with the dialguage on the toolpost, l then wound down to the end and the reading was the same, zero. I was very happy until I turned the chuck 180 degrees and the dialguage read 0.015". When I turn the bar down as you have said shouldn't I get a reading of a touch under 45mm near the chuck and 45mm less whatever it takes to get the concentricity out of the other end.
I also have some bigger chrome bar that I can use 50, 60, 70, or 90. But I'm thinking that the 45 will not flex over that distance.
I will check it tomorrow.
Thanks again

[Oldneweng]

When I turn the bar down as you have said shouldn't I get a reading of a touch under 45mm near the chuck and 45mm less whatever it takes to get the concentricity out of the other end.

What this is doing is taking a cut along a length of bar so you can check measurement at the chuck and further out, so these 2 can be compared. Removing the material between the 2 positions reduces the wear on the cutting tool so you get 2 cuts (one at each end) as close to identical as possible. Both sections should be cut to clean up totally first, then take a light cut to equalise the diameter and then the measurement cut. Cut end to end in one continuous run with power feed. Don't touch the lathe.

As Pipeclay said you need to adjust a long work piece in 2 places to get it to run concentric and this negates any measurement you may wish to take to determine how parallel the lathe is cutting.

Dean

[morrisman]

hi Slim I wish you the best of luck with your Aussie built Nuttall lathe . I am not a lathe expert in any sense but I'm a little confused about what you are trying to measure . If I did a static test like you did i.e. used a 4 jaw chuck and a ground bar and a dial indicator, I would be amazed if I got those results you did, chucks are not the ideal holding method for doing a static test , they are OK for the dynamic tests i.e. turning a bar down at each end and measuring the two diameters for taper .

[slim]

What exactly are you trying to measure? There are a number of reasons this could happen. If you are measuring how true the lathe is cutting, put a steel bar in the chuck (any chuck), turn the bar down leaving a short section near the chuck and another at the end, just cleaned up with the rest 3mm smaller diam. Do a light cut on these 2 bigger sections in one run without touching anything. Measure them. That is how your lathe is cutting. The bar obviously needs to be big enough to avoid deflection.

Dean

368830
So here are the results, 44.420mm at the chuck and 43.985mm at the end (220mm apart). That's 0.435mm
What now? Do I tackle the headstock?
Slim

[Oldneweng]

So here are the results, 44.420mm at the chuck and 43.985mm at the end (220mm apart). That's 0.435mm
What now? Do I tackle the headstock?
Slim

First raise the rear tailstock end floor mount a little. Put a shim under it if you don't have adjusting screws. I would be trying 1mm to start. It is a solid lathe and it may take some time to settle into the new position. If another floor mount lifts off the floor, wait for a day and see what happens. Try doing the cut again. You may need to do this quite a bit. A machinists level will help to tell if the lathe is going to respond to this or not.

I am no expert at this. I have read about it a lot, but I have yet to do it for my lathe. Another job is to make some adjusting screws so I can.

Dean

[morrisman]

Slim, people have heart attacks and mental breakdowns when somebody mentions they are about to move the headstock on a lathe :) If your Nuttall is as bad as your test indicates then you might have to twiddle the adjusting screws . Deans advice is good but the beds on these Nuttall's are very solid with very heavy cross bracing . I don't know if the bed would twist ?

[Old Croc]

No doubt there are some members tearing their hair out right now. There have been a number of threads where people have written about doing this and the general reply is NO, NO, NO. What have you done! This is a very last resort after everything else has been adjusted. 0.005" over 18 inches can be caused by the bed not being correctly leveled and by that I don't mean with a machinist level, I mean adjusting for the taper. Adjusting the bed (removing the twist) to remove or reduce taper is done a long long time before touching the headstock.

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 "Rollies someones dad".:D

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
Hi Dean, I am going to politely disagree with you on this. I am an electrician, not a machinist so after I moved the lathe from dad's old shop to mine I got a very respected turner come and set it up and test run it for me. He brought his machinist level and parallel set and after he shimmed it up, we did a test cut and it was cutting a slight taper. He said I needed the experience of adjusting the headstock and believe me it was. He said it was a common problem with
Nuttals.
This may not be Slims problem, but at least he now knows that they are adjustable.
Rgds,
Crocy.

[Oldneweng]

Hi Dean, I am going to politely disagree with you on this. I am an electrician, not a machinist so after I moved the lathe from dad's old shop to mine I got a very respected turner come and set it up and test run it for me. He brought his machinist level and parallel set and after he shimmed it up, we did a test cut and it was cutting a slight taper. He said I needed the experience of adjusting the headstock and believe me it was. He said it was a common problem with
Nuttals.
This may not be Slims problem, but at least he now knows that they are adjustable.
Rgds,
Crocy.

What is it that you disagree about? Are you saying that because it is a Nuttall you should just jump in and adjust the headstock? All I am saying is check first, because if the headstock does not need adjusting then you have just let yourself in for a lot of unecessary trouble. It is far easier to remove a shim that realign a headstock. Did you read Mikes post just before yours.

PS I would like to politely suggest that you check my spelling for Nuttall. :D

Dean

[slim]

I did lift the foot/tailstock end, previously and set a couple of dialguages up on the bar in the chuck. The lathe was off the ground and both dialguages did not measure any movement. I have to agree with old croc, these old Nuttalls are built like the proverbial ****house.
The lathe isn't bolted to the concrete and probably would need to be so that it could be twisted (maybe)
Big job?

[Oldneweng]

The lathe isn't bolted to the concrete and probably would need to be so that it could be twisted (maybe)
Big job?

I have heard that sometimes it is necessary to bolt them down, but you would really need to have a better idea of the level of the bed. If at some previous location the lathe had been sitting in a twisted state then it may have taken a set, so to speak. This would require either bolting or waiting to see if it will return to level over time. The bed would need to be checked for level so you can tell whether this is the case or not. Considering the amount of taper that your lathe is cutting, if the bed is twisted it should be pretty obvious with a level. When I say level, I mean level in a "plane". Using the level to check for twist.

I have owned a Nuttall and I know how solid they are. It is my understanding that even the most solid lathe can twist if sitting unevenly. This is why proper setting up is recommended for all lathes.

Remember I am no expert.

Dean

[Retromilling]

All lathe beds can twist from their own weight the more solid the more weight so that cancels the thickness and bracing somewhat . If they never twisted and never bent slightly then no precision levelling would be required . No one is having any heart attacks over anything . Moving the head at this stage is stupid as the lathe could still be out of level , the chuck or jaws could be the problem a number of things could be out . Is the test bar even straight ?

[slim]

I have watched a video of someone taking the twist out of the bed and each shim made a difference to the dial gauges. When I tried the same exercise on the Nuttall I could not get the bed to twist at all. As I said, I would have to fiix the Headstock end firmly to the concrete and then pack and pull down on the high side at the tail end.
If it is the bed twisting and, in my case the taper is decreasing towards the tail, does that mean that I have to lift up the side closest to the operator?
With the amount of taper (0.435mm) that I am getting over 220mm can I assume that I would be getting something like 2mm over the 40" bed?
The test bar is straight.
Can you tell me the order that all of these measurement checks should proceed. I'm presuming that checking the level is No. 1
1. Check level
2. ?
3. ?
4. ?

[morrisman]

Video of a Nuttall ..seems to run quietly :?

https://www.youtube.com/watch?v=trFshVjTddc

I don't think you can fix the problem easily with shims

[Retromilling]

The hardest thing to level is something that has little flex but is twisted . So it may need to be bolted down to remove that.
I have my lathe on 6 large foot pads and not bolted down. It works because the bed has some flex so all the feet bare some weight but it levels .
A lathe sitting out of level for years may take a set even one as rigid as a Nuttall .

[slim]

Thanks to everyone for listening to me. I'm sure you all have other, more important things, to attend to. I want you all to know though, that I do appreciate your time and patience.
I will spend a bit of time on the bed levelness(?) If I could only get it to twist, I would know which way it needed to go (if it does).

"If it is the bed twisting and, in my case the taper is decreasing towards the tail, does that mean that I have to lift up the side closest to the operator?" At the tail end.

[Michael G]

To visualise what is happening, think in exaggerated terms.
In your case as the part is getting smaller at the tail stock end (making a cone) , if you were making that on a 'perfect' machine, you would have to wind the tool in. Think how you would have to twist the bed to get the same thing (then think of the correction).
My visualised fix is that the tailstock foot furthest away needs to be lifted to reverse the twist.

Michael

[Oldneweng]

He is now turning a bar at 2 points now so it should be concentric.

Dean

[Oldneweng]

To visualise what is happening, think in exaggerated terms.
In your case as the part is getting smaller at the tail stock end (making a cone) , if you were making that on a 'perfect' machine, you would have to wind the tool in. Think how you would have to twist the bed to get the same thing (then think of the correction).
My visualised fix is that the tailstock foot furthest away needs to be lifted to reverse the twist.

Michael

Yes. That is what I said earlier. I am glad you concur Michael. I can't find a wipe the forehead smiley. :D

Dean

[slim]

368871Back again!
In the absence of a precision machinist level I came across this method, on YouTube.
While it doesn't tell me the overall lathe levelness it does a very good job of checking for any twist in the bed. So, the first reading near the chuck was marked at 0. The reading at the other end of the bed showed the plumb bob slightly away from the 0, closer to the back. I then placed a 0.1mm feeler gauge under the rear side and this moved the plumb bob back to the zero. I tried a 0.15mm shim but this was too much.
The place where I took the readings from was the flats. Which is what the handbook says.
I also took readings off the top of the V's and could not read any twist at all.
Is 0.1mm good news?
I took the same readings with a piece of 1/4" plate under the far side tailstock end foot but the readings did not change.
Slim

[slim]

368872368873368874368875
1st pic is near the chuck, plumb bob on the zero.
2nd pic is 40" down the bed.
3rd pic is with 0.1mm shim under
4th pic is with 0.15mm shim
Slim

[.RC.]

On a lathe that old and especially a Nuttall which had soft beds, wouldn't the bed be worn and thus make any exercise in trying to measure twist futile?

[slim]

You could be right but is 0.1mm a big issue, from end to end. I sort of get the feeling that it's never going to be perfect. I just want to get it as close as possible.
Slim

[Oldneweng]

Take the chuck off and see if you can get onto the unworn section right against the headstock, if there is any. The tailstock end where you have it should be good.

Dean

[Jekyll and Hyde]

On a lathe that old and especially a Nuttall which had soft beds, wouldn't the bed be worn and thus make any exercise in trying to measure twist futile?

I'm a little surprised that the whole procedure hasn't had a lot more input from the usual suspects, perhaps they're tired of going over the same arguments with each other over and over.

I expected to start reading comments directly after mention was made of using a piece of bright bar to check runout, given the (lack of) tolerance in off the shelf bright bar... unless the HT bar is much more accurate than I give it credit for?

No disrespect intended to those who ARE in this thread and helping as best they can, but from previous discussions on here (not that I'm exactly experienced in this) aren't we're starting in the middle here? There seems to have been very little discussion on more basic checks, where I'm sure on previous threads there has been a whole procedure laid out to work through from start to finish?

A few things that come to mind.

Could just be the photo creating an illusion, but in the shot with the bar with the two measurements on it, it looks like the gap isn't quite sitting down flush with the rest of the ways? If the gap isn't seated properly, I'd imagine that would have an effect on the diameter closer to the chuck... Likewise, are there any dings on the rest of the ways? Are the chuck and spindle mating faces free of dings and swarf?

If the jaws on the 3 jaw chuck have now been ground, but the lathe is potentially turning a taper, hasn't that taper now been transferred to the chuck jaws? While not relevant currently to the measurements on the bar, I'd imagine if the lathe is indeed turning tapered, the 3 jaw should be reground again once this has been corrected?

Are the gibs adjusted correctly? If so, are there any tighter/looser spots in the carriage travel (which would likely indicate, as .RC. suggested, wear in the bed).

How did you check for play in the spindle bearings exactly? My inclination would be to set a dial indicator up on top of a piece of bar sticking out of the chuck, then attempt to lift the bar by hand, and see how much the indicator moves. I'm sure it's not the best method, but without going back through a number of old threads on this stuff, best I can come up with.

Just a few of the more basic thoughts that I would personally start with, before I even moved to bed twist and test bars and cuts. I'm sure there are some others that could be done before moving to actually adjust something, but again, I'd have to go digging back through a bunch of old topics to find those discussions.

[morrisman]

Maybe you could do the test again but this time use a length of aluminium bar instead of the steel bar. And a sharp tool.

[slim]

Does it matter if the test bar is not accurate to start with? Isn't it turned down to test?
The gap is flush with the rest of the ways which appear to be in good condition with no dings etc.
I realise that once the taper thing is sorted out I will have to regrind the 3 jaw. They were slightly bell mouthed and the first grinding did fix that.
The carriage seems to run smoothly along the entire bed.
I will check the spindle play as you have suggested.
Is there a way to test for taper without using a chuck? ie.Taking the chuck out of the equation.
Thanks all
Slim

[slim]

Maybe I'm missing something but I don't quite get the need for an accurate test bar before you start.
Is that just for static testing?
Is the aluminium for ease of cutting? It would have to be a decent dia not to deflect? What size?

[Oldneweng]

I'm a little surprised that the whole procedure hasn't had a lot more input from the usual suspects,

My thought too.


No disrespect intended to those who ARE in this thread and helping as best they can, but from previous discussions on here (not that I'm exactly experienced in this) aren't we're starting in the middle here? There seems to have been very little discussion on more basic checks, where I'm sure on previous threads there has been a whole procedure laid out to work through from start to finish?

Good. Someone I can blame for the mistakes. :D Some previous threads would be a useful read, but my attempts at finding threads on here are usually woefully off the mark.


Does it matter if the test bar is not accurate to start with? Isn't it turned down to test?

Maybe I'm missing something but I don't quite get the need for an accurate test bar before you start.

If you machine the bar as I have said it does not matter what it is like before you start. The important thing is to do a light continuous cut all the way along so both sections are as close to the same as possible and that the bar is tight in the chuck and large enough not to flex.


Is that just for static testing?

Yes


Is the aluminium for ease of cutting? It would have to be a decent dia not to deflect? What size?

Yes. That is the idea. Just use a sharp HSS tool.


Is there a way to test for taper without using a chuck? ie.Taking the chuck out of the equation.

No. If you do the machining as above then the bar will be running concentric with the spindle. This is the only way to acheive this with certainty.

Dean

[Jekyll and Hyde]

Does it matter if the test bar is not accurate to start with? Isn't it turned down to test?

It doesn't once you start turning, but I got the impression from the earlier posts that to start off with, you were simply using a dial indicator on the bar as it was? Round bar stock is not necessarily perfectly round.


The carriage seems to run smoothly along the entire bed.

But are the gibs adjusted up?


Is there a way to test for taper without using a chuck? ie.Taking the chuck out of the equation.

Hmmmm... Not sure if I'm imagining this, but I THINK its possible to buy precision ground test bars with various tapers on the end? Which would then insert directly into your spindle (I assume there's a taper inside a Nuttall spindle!). *edit* yes, you can, the first thread linked below should entertain you on that topic :rolleyes:...

As you're working out, lathe alignments are a bit of a rabbit hole... There have been some fairly detailed discussions on these forums in the past about aligning lathes, unfortunately it will take a bit of time reading to catch up on which are which, and find a straightforward procedure for assessing and adjusting the condition of a secondhand lathe.
Below is a nice one to get you warmed up, some of the 'banter' might give a clue as to why you haven't got a lot of interest in your thread over the couple of weeks its been running....

http://metalworkforums.com/f65/t196544-lathe-alignment-bar

Some more discussions here (headstock again, just the first two I came up with):

http://metalworkforums.com/f65/t192493-lathe-alignment

And here's (hopefully) a link to Google with some search results for this forum, reading through some of the results that mention taper, twist, wear should yield some good information...

https://www.google.com.au/search?q=lathe+alignment+site%3Ametalworkforums.com&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=rXJzWfuMH-nc8wez54g4

[Oldneweng]

But are the gibs adjusted up?

What gibs are you talking about? I have never seen gibs on any lathe in relation to the carriage. The carriage runs on a vee.

Dean

[.RC.]

My thought too.






Probably more a case of where do you start?

A brand new three jaw usually has holding tolerances of 0.1mm eccentricity.

A four jaw will probably not hold stock parallel with the spindle (hence why the OP found his bar snaking all over the place)

If the lathe is worn, how would you even measure twist, as you are not going to know. You can put a deliberate twist in to try to compensate for wear, but it is something that will create other issues. Many people forget about the tailstock holding alignment.

If the OP really does not use the tailstock, but does all chuck work, then you might as well just align the headstock to the worn bed, so it turns reasonably parallel.

[Jekyll and Hyde]

What gibs are you talking about? I have never seen gibs on any lathe in relation to the carriage. The carriage runs on a vee.

Dean

http://cdn1.grizzly.com/manuals/g0750g_m.pdf

Page 72 shows the adjustments for the carriage (saddle) gibs on my chinese lathe. I was under the impression all lathes would run them, rather than relying on gravity alone to stop one side of the carriage lifting during cuts?

[Jekyll and Hyde]

Probably more a case of where do you start?

A brand new three jaw usually has holding tolerances of 0.1mm eccentricity.

A four jaw will probably not hold stock parallel with the spindle (hence why the OP found his bar snaking all over the place)

If the lathe is worn, how would you even measure twist, as you are not going to know. You can put a deliberate twist in to try to compensate for wear, but it is something that will create other issues. Many people forget about the tailstock holding alignment.

If the OP really does not use the tailstock, but does all chuck work, then you might as well just align the headstock to the worn bed, so it turns reasonably parallel.


That was kind of my point, on an old lathe with unknown provenance, I thought there had previously been discussed a sequence to follow which involved assessing and quantifying issues of wear (and adjusting as far as possible), before moving towards aligning it as best as the wear discovered in the previous step would allow.... All of your points are the type of thing I was meaning when i mentioned a lack of basics - particularly relevant in this context is your point about the 4 jaw not necessarily being parallel to the spindle, as its the results from this test that are being used currently as a basis for twisting the bed. My comments about burrs on the chuck mating face and checking spindle bearings were aimed in a similar direction.

Make no mistake, I have no problem with aligning things as needed - however, how it has been determined that whichever particular alignment is needed is where the problem lies. Is the alignment in question the sole factor involved in the inaccuracy being chased, or is there wear/operator error/damage/another alignment etc that could factor into it? Personally, I would want to make damn sure that whatever I was aligning was the answer to my problem, before ending chasing my tail.

Not much point in trying to twist the bed to get two collars the same at 250 mm apart with one next to the chuck, if the lathe has only ever done workpieces at 100mm long, and has a bloody great ditch worn into the ways up near the chuck - it's simply not going to help. However, if that turns out to be the case, armed with that knowledge you could potentially check that the unworn section of bed isn't twisted, and attempt to set up longer jobs there, so that the carriage doesn't drop into the hole...

[.RC.]

This video I took a few years ago shows the folly of trusting even new chucks.

[Oldneweng]

http://cdn1.grizzly.com/manuals/g0750g_m.pdf

Page 72 shows the adjustments for the carriage (saddle) gibs on my chinese lathe. I was under the impression all lathes would run them, rather than relying on gravity alone to stop one side of the carriage lifting during cuts?

Ok, page 73 mentions saddle side gibs, but I would not have called them gibs. Lots of lathes have these and I did mention them before. They only hold the saddle down and do not affect the movement of the carriage like the gibs in the cross slide or compound do unless it is a flat bed lathe.

Richard we are just saying not to play with the headstock alignment until other issues have been checked out.

Dean

[slim]

368912
I now have a 0.05mm taper over the 250mm as opposed to original taper of 0.435mm.
As you can see the taper is now running back to the chuck.
I spoke to someone who has had a couple of these Nuttall lathes.
He suggested to try the headstock alignment as he had done and that it might need a couple of goes. He was right. I did it twice. the first time I went the wrong way (it was getting late) Second time, the result is in the picture. I'm pretty sure that I could get the 0.05mm out, if I adjusted again. But do I need to? Even though it's a fairly easy operation.(on this machine)
Once again I thank you all for the help you have given. In the last couple of weeks my "lathe awareness" along with my "lathe vocabulary" has been vastly improved and that can only be a good thing. I have also learnt that most of time you just have to have a go. (safely)
Slim

[.RC.]

Now you have to check cross slide perpendicularity. :D

[slim]

(Now you have to check cross slide perpendicularity.)

Ok, so whats the best way to check that?
and, is my headstock adjustment to 0.015mm acceptable?

(How did you check for play in the spindle bearings exactly? My inclination would be to set a dial indicator up on top of a piece of bar sticking out of the chuck, then attempt to lift the bar by hand, and see how much the indicator moves. I'm sure it's not the best method, but without going back through a number of old threads on this stuff, best I can come up with.)
I did this test and could not record any movement in the spindle
slim

[slim]

368932
Well, good news I think. I made one more headstock adjustment and am now cutting the 2 collars the same. Yippee! 43.175mm both ends.
Now I am not sure if this is the correct method but I left a small point on the end of the test bar to check the tailstock and, guess what, it appears to be spot on centre now.
Apart from now regrinding the jaws in the 3 jaw, what else should I do?
Slim

[.RC.]

(Now you have to check cross slide perpendicularity.)

Ok, so whats the best way to check that?
and, is my headstock adjustment to 0.015mm acceptable?

(How did you check for play in the spindle bearings exactly? My inclination would be to set a dial indicator up on top of a piece of bar sticking out of the chuck, then attempt to lift the bar by hand, and see how much the indicator moves. I'm sure it's not the best method, but without going back through a number of old threads on this stuff, best I can come up with.)
I did this test and could not record any movement in the spindle
slim

Not that easy to check cross slide perpendicularity. I would not bother as there is nothing you will be able to change it anyway. Other then move the headstock.

If you are getting a good surface finish, then the spindle bearings are fine.

Your tailstock might "look" to be spot on, but I know it won't be, but it will probably be good enough for your needs. I used to own a Nuttall like yours and it was worn a lot more then yours is and it still did what I wanted up to a point.

[morrisman]

Slim Turn a piece of short bar to a 60 degree point i.e. in your chuck , the top slide is set to 60 degrees for this job. You have now made a concentric centre at the headstock . If you have a accurate ground bar with centres each end, use the bar between the headstock centre you made and the tailstock centre , run the dial gauge along the test bar and adjust the tailstock until the dial gauge shows minimal movement .

[slim]

Slim Turn a piece of short bar to a 60 degree point i.e. in your chuck , the top slide is set to 60 degrees for this job. You have now made a concentric centre at the headstock . If you have a accurate ground bar with centres each end, use the bar between the headstock centre you made and the tailstock centre , run the dial gauge along the test bar and adjust the tailstock until the dial gauge shows minimal movement .

Back again with an update.
I have adjusted the tailstock as described and all is good.
I was prepared to regrind the 3 jaw but with the short ground bar in the chuck, the dial gauge was showing 0.001" out.
This was after taking the jaws apart and cleaning. I also tried switching each jaw around to the next position. The closest were in the original positions. With the worst at 0.008"
The chuck is a 'Soul' brand. Made in Japan No. 55 DCI body. Is it a good brand?

369047369048
Anyway, thanks again guys for your input and help with the lathe issues. I feel now that I am more on top of the situation (with this lathe anyway)
I still have a few basic questions though, like.
Should I always have the tip of the tool at a height, dead center of the workpiece? Is that a basic rule?
Is it worth investing in a quick change tool post? If so, which one?
What are the general rules relating to RPM of the work? A lot of the steel I have is high tensile.
I'm sure that these questions have been answered somewhere else on this forum.
Thanks again to you all.
Slim

[morrisman]

Hi Slim Yes the tool should be close to centre height 99.99999% of the time ! The quick change tool post . Depends on how often you use the lathe . If you use the lathe once every few months then is it worth the cost of the QCTP ? The QCTP is a great time saver and I think everybody, after using them would not wish to go back to the older style tool posts. RPM's really depends on the diameter of the work and the type of tooling you have and how tough the steel is. It isn't easy to give an answer because of the variables but the old Nuttall is a solid lump . Try experimenting and use plenty of coolant .

[caskwarrior]

Soul chucks are i think the original brand name of teikoku who are now a big manufacturer of hydraulic cnc chucks and are very good, I cant speak of back then when they were the cheap competition to big brands like PB and Cushman but i have never used a bad Japanese machining product yet so i suspect yours will be of decent quality. And as morrisman said, get to turning and youll get a feel for when the feed and surface speed suit the material.

Basic rule of thumb is:
High Speed Steel: slow and steady, low feed rates, shallow depth of cut, especially with no chip breaker ground into your tool, can achive very good finishes on light passes, carbide wont unless using very specific insert/holder geometries.

Brazed Carbide: You can push it a lot harder but on interrupted cuts it tends to chip

Insert tooling: Needs absolutely massive speeds and feeds to get great results but push it really hard for your machine and you should still get good finishes

[Oldneweng]

The quick change tool post . Depends on how often you use the lathe . If you use the lathe once every few months then is it worth the cost of the QCTP ? The QCTP is a great time saver and I think everybody, after using them would not wish to go back to the older style tool posts.

True, I think. I have never used one.

You need to balance the cost against the convenience. Factor in extra tool holders for every tool you are likely to use. If you keep swapping tools in tool holders you may as well stick to the 4 way. It is far easier to adjust centre height with a QCTP.

I have all my tools marked with the spacing required to set at centre height which speeds things up. I use 20mm tooling where possible and all of the 20mm tools I have require the same spacer. I have also made a gauge to measure centre height at the cutting edge which uses a dial indicator and so gives actual measurements of the spacing changes required.

The QCTP that I would use on my lathe is a CA size. I would think your lathe would take a CXA if it is the same as my old Nuttall. I have not bought one because of the cost which I think is way too much just for convenience. It has been suggested that I use a CXA, but 20mm tooling will not quite fit in the 3/4" holders and all these holders will need to be opened up. I find it just a bit strange that CXA holders seem to be designed to fit 16mm tooling, which I think is too light for this size lathe. I have a 25mm parting tool, but it was just over centre height and needed a bit taken off the bottom. It is now on centre without spacer, but it was quite a job to mill it. Tough steel.

Some food for thought.

Dean