Setting up a Myford ML7

Hi, hope someone can help a neebie before I go meltdown !!.....I bought a
ML7 recently and I'm having loads of trouble setting it up.
I've levelled it up with an engineers level and it now looks spot on. The
chuck is a recon Burnard 3 jaw from Myford....test report = 0.002" rounout
2" from chuck.
The problem is that when I chuck a length of bar it is quite obviously out
of true......I used a DTI...runout is .005" near the chuck and 0.018" at the
end of the 6" bar when rotated by hand.
I've found the mid point at the chuck end and ran the apron to the far end
(without rotating the chuck) and DTI shows no change, therefore I assume the
bed is now straight.
I clocked the nose on the spindle in many positions...no movement apart from
a 0.004" movement right on the end on the vertical surface when rotated and
the DTI horizontal (not on about the endfloat).
There were a few 'bruises' on the spindle threads wheich I gently filed
down...the chuck now goes on a lot easier, whereas it was very stiff
before....the bar shows a slight improvement too.
I tried turning a bar down but it is still wobbling badly on the end of a 6"
bar.....it's as though the bar is bent (which I'm sure it isn't). When it's
turned down it is missing all along the side facing me. I've tried a few
more bars (including a ground test bar)...all clock the same amount. I
have a 4 jaw...would that run true or is there something else wrong?
Any idea's???....Please!!!
Brad.
Reply to
BRAD
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Chucks wear unevenly.
All the reconditioning that anyone can throw at one, can at best, make it relatively accurate for one particular diameter bar. For the other diameters, not so much.
If you can get hold of a couple different diameters of accurate bars, you can get a better idea of what diameters are more accurate.
Look at how the chuck seats on the spindle. A little swarf at the register will result in rather a lot of runout at the chuck face.
Look for damage as well as for solid seating. The burr raised by a trapped chip can cause some difficulty long after the chip was cleared out.
The chuck should thread on smoothly, with little play once the register (the cylindrical area behind the threads) comes into the backplate or the chuck body.
Spend less time with the engineers level, and more time taking test cuts. Stop fiddling with the leg screws when the lathe turns a reasonably parallel cylinder, rather than a cone. Precision levels are pretty much overused, and underutilized. Quite useful if you need every last drop of coolant to run down the drain, but often taken far too much as the final authority when setting a machine up. How it cuts matters rather more than how level it is, though level, or near to it, is a good place to begin. For the most part, a decent carpenters level will do. Look on the net for "Rollie's Dad's Method" for setup and adjusting of feet. Pretty much just a way to read a test cut and understand the cause and effect of adjustments.
Now would be a good time to get used to dialing in a 4 jaw chuck. For whatever reason, the process seems to scare grown men as much as having to cut threads with a singlepoint tool. Both are easy processes that get easier with practice. I like to set my dial up with the stylus on the center of the work, on the back side of the work from me. I can then adjust the jaws on the front side, and see the movement on the dial at the same time. A mag base mount on the cross slide is the goods for that job! Allows you to adjust the position relative to the work, without having to deal with the friction joints of the mount each time.
Also! Don't get too hung up on having to achieve perfection before you can use the lathe. It's supposed to be recreation. If you want a dead nuts perfect lathe as a hobby, you can have one. If you want a lathe that cuts accurately enough, you probably already have one of those, too.
Cheers Trevor Jones
Reply to
Trevor Jones
Brad, Trevor has given you some good advice there. Old 3-jaws aren't really known for their precision, and a 4-jaw or collets are a much better bet here. Or turn between centres.
I had a badly worn Pratt 3-jaw on my Myford for well over a year - 0.012" runout less than 1" from the chuck - but it was not really a major problem as most of the turning in this was done in one hit without having to remove and re-chuck the bar. The turned portions were always concentric with the centre of rotation, if not with the stub held in the jaws.
Run it, use it, get used to it's idiosyncrosies, and a few months and a few jobs down the line review your needs and see if you *really* do need more precision.
Peter
Reply to
Peter Neill
Brad Hi, firstly don't panic this is only the first of the "interesting" issues that using a lathe will throw at you just relax and enjoy the challenge!
Lots of good advice already but a couple of things spring to mind, . 005" on a three jaw chuck is not good but also not unheard of, they are not the most accurate method of workholding. You will get more accurate results with your 4 jaw even over the most accurate three jaw.
However, to try and improve the three jaw; is it mounted on "backplate" or directly threaded? If it has a backplate then loosen the mounting bolts a little and try tapping the chuck to reduce the error, if you can reduce it then retighten the bolts. If the chuck will not move on the backplate then you need to take the chuck off the backplate, fit the backplate on its own and check on the register diameter where the chuck body fits onto it. If there is any movement on this small flat face then you will need to machine the register again whilst fitted to your own machine as well as taking a small cut of the large flat face. If it is directly threaded then correction is almost impossible unless we can find something wrong with the mounting register or thread.
The vertical surface you should be checking is not the one right at the front but the one just behind the smooth portion (register) on the spindle (ie close to the bearings). If the register diameter in the chuck is slightly oversize (very common) then this vertical surface actually positions the chuck when tight, there should be no movement at all. Make sure it is absolutely clean and with no burrs etc. Check the vertical surface within the chuck mounting that fits against it; again it should be absolutely clean as just a speck can throw things out. One thing I have had with some chucks is that the very front of the spindle thread is actually jamming against the chuck body, make sure there is clearance for the very front of the spindle inside the chuck body when mounted on the backplate.
When you mount the work try it by tightening with it held gently against each of the three jaws in turn using different key positions, you will normally find that one is better than the others. This may already be marked with a 0 or a centre punch mark. Look at the inside of each jaw to ensure there is no small burr or swarf trapped between the jaw and work. Most three jaws when older, even if reasonable, will only repeat to about .003" (just in front of the jaws) so don't worry too much if you can't get it absolutely perfect.
Best regards
Keith
Reply to
jontom_1uk
I would start with the test bar, one that fits the spindle internal taper, as this should be the most accurate datum. Then you can set the headstock up for vertical and horizontal alignment with the saddle / bed, using a dial gauge. Of course, the spindle bearing needs to have zero meaureable play first to get accurate / consistent results. Next, put a center in the tailstock end, bar between and use the same method to align the tailstock. Then put the chuck on and see how accurate that is. Of course, the spindle itself will have a runout and coning motion on its internal taper, but this should be very small and there's not much you can do about that anyway.
If you start with a 3 jaw chuck fitted, it just introduces another variable and you don't really know if the spindle or chuck is in error. Chuck jaws wear unevenly, tend to bell mouth and (most relevant here) the error will be different every time you tighten the chuck up.
It's important to get fun out of all this, but I think you have the right approach, especially with a machine received in an unknown state...
Chris
Reply to
ChrisQuayle
Brad, ignore the chuck for a minute. If Myford said 0.002" runout they were probably correct.
Take the chuck off. Stick a block of wood in the gap on the bed then get a broom handle between this and the spindle nose, and see if you can lever up the spindle, and measure any deflection with your clock.
If may be that the spindle has some wear, but this can usually be adjusted out. Underneath the caps that hold the bearings on is a laminated shim - it looks like one piece but is actually a stack of shims, each one 0.002" thick. These can be peeled off using the the point of a scalpel or similar to seperate them, and will take up any clearance caused by wear.
There is a stack on each side of the spindle.
Peter
Reply to
Peter Neill
Many thanks for all replies to my woes of setting up the ML7, all of which were invaluable. The story so far...... I checked the spindle/bearings....no movement detected at all with DTI...so I assume all is well there. I had 0.004" of runout on the vertical surface at the end of the spindle...this was sorted by facing the end very gingerly...DTI now reads bang on now for that....I chucked the bar again and clocked it.....now reading 0.004" near the chuck and 0.010" at the end of the bar.....much improved........but now I've noticed that if I take the bar out and turn it around slightly I get a different reading ! Turn it again and yet another reading !! Tightening the chuck from a different key position produces another set of readings. I'm sure the bar is straight. Finally, I ran the tailstock up to the bar (bar previously centre drilled) tightened the chuck and got some really good readings.....I'm quite confused with all this now !! Incidentally, how do you centre drill a long bar when the bar is too big to fit through the headstock spindle? Do you have use a steady? Brad.
Reply to
BRAD
Brad
What you describe is pretty well what any 3 jaw self chuck does, the only difference between new and old is the size of the variation between tightenings. You need to find the sequence/position that produces the best result and adopt that when fitting work. You will not repeatedly get it pefectly concentric in a three jaw unless you spend a lot of money and buy the "grip-tru" type, even then it will be much better but still not perfect. I am a little confused about which face you machined but the frontmost face of the spindle at the end of the thread should have no affect on chuck mounting whatsoever as it should contact nothing. If you search on "three jaw accuracy" or something like that you will find many discussions on how to "tweak and fettle" to improve them.
The much improved affect you describe by centering with a tailstock centre is standard practise with a longish bar. I might be tempted to have a look at the inner face of each of the jaws where it contacts the work to ensure they are straight and not bell mouthed. If the work is centre drilled then you can always use it to reduce the usual error on fitting into the three jaw. In fact any turning job will be improved if you can support it from the tailstock as well as the chuck. It is just that we are all a bit lazy sometimes and don't always do what's best, just quickest. If you want better concentricity than the three jaw offers then the four jaw or turning between centres will improve things greatly. If you are still unhappy with the performance of your chuck then let us have some figures for what you get on the spindle register (outer surface and front face). Also possibly on the chuck outer body towards the spindle end and let us know how these figures repeat with just removing and refitting the chuck. If these chuck body figures are repeatable then you need to look at different areas of the chuck for the problem. Is the chuck screwed body or backplate fitting?
As you suggest if the bar is too large to fit through the spindle you will need to support with a fixed steady or get a larger lathe (I only add that as if I don't someone will).
Hope you enjoy using the lathe, learning can be frustrating but producing that essential (lowcost?) part is very rewarding.
Best regards
Keith
Reply to
jontom_1uk
Cheers for that, just a few points to hopefully clarify things a little. 1) The surface that I 'faced up' was the vertical surface right in the very end of the spindle, where the threads start, the first bit to enter the chuck ! I did this as the end looked and felt damaged slightly, and as someone pointed out, if the front part of the spindle is damaged it may interfere with the inner part of the chuck. The chuck was very tight before I faced the spindle and cleaned the threads up....now it is a lot better fit altogether with plenty of oil on the threads. 2) I clocked ALL external surfaces on the spindle and all read 0.....and there is no percievable movement in the head stock bearings. 3) The chuck is a Bernerd 3 jaw that was reconditioned at Myfords recently..the test report shows 0.002" run-out nearest the chuck, with no bell mouthing present. The chuck appears to be a screwbody type with 3 hex head bolts on the rear......no backplate! 4) Can't buy a bigger lathe as I've only just bought this one (my first). I'm sure it just needs setting up properly. 5) I have a 4 jaw and will try concentricity on that when I can....can I assume that the 4 jaw will be a little better? Can I also assume that if you clock a bar in the 4 jaw and you go to the free end of the bar, (if all is well) the bar should read similar to near the chuck? 6) We didn't seem to have this problem at school (many, many years ago, on Boxfords|), we just chucked the work and did the turning etc.....so I assume something is amiss with mine......I don't expect perfection, but I thought that a Myford ML7, once set up, should be pretty accurate. Or am I dreaming?? Cheers BRAD.
Reply to
BRAD
Standing back, I think that you are up Sh1ts creek without a paddle!
You are assuming far too much about alignment because you are assuming that your bed is straight in all planes, that your saddle etc etc are in perfect alignment. This is fine in theory but you have a point at about 6" from the business end of the spindle which is worn in at least two planes. In the course of years, this is wher( sorry) the most discernable wear has taken place. So if the wear is only a thou on the top of the bed, you will have another thou at the front shear. Regardless of any other wear points, your lathe will cut four thous or more- or show up on your dial mike on a test bar.. I haven't discussed the added wear of a lathe chuck or the alignment of spindle and tailstock. I am talking about plane geometry. Your straight lines- are not straight lines.
I am not being pedantic or flaming because I didn't invent geometry but I have written on lathe overhaul before. I have two Myfords- a 7 and a Super 7B- and I recently had the top of the 7 blancharded to remove the incipient wear- in one plane but there is no guarantee that the old Lumsden which did the job was true- true. Again, I have to report that the No1 shear had worn hollow and so on and so forth for the rest of the machine.
So have you stripped and checked the bed? Have you then remedially corrected all the lathe bed faults and moved on to overhauling the saddle and its gibs and moved on to the slides and handscraped or surface ground everything in sight?
So now you have to trip off and get Connelly's Machine Tool Reconditioning and a set of carbide scrapers and a machine to hone the blades on a diamond wheel and a set of references to scrape to.
With a hint of humour, Connelly writes on the South Bend of which your Boxford of a bygone age is a fair copy.
So, you have the start- it then gets difficult after this!
Well, someone has to be truthful!
Norm
Reply to
ravensworth2674
Brad, Hi. I'll try once more but to be honest fixing this type of problem is a methodical process where we need to eliminate one potential cause at a time. Without being rude, you cannot assume that because the chuck screws on it is mounting correctly. Or sorry to say that a chuck that tested OK for Myford will fit too your machine in the same way. How big is the bar that you are using to test is it entering the jaws their full length or just the forward part? To give the chuck a fair chance it should be small enough to enter the chuck and allow full jaw length contact.
The questions I asked were to try and see if the chuck was mounting squarely and repeatedly on the spindle, something we still haven't proven. The issue you describe has several elements, the chuck must itself be mounting square and parallel to the spindle and it must also hold the work in the same way. As Norman says the spindle itself must also be parallel with the bed which in turn must be straight and true. All of those things must be correct to replicate your experience at school. With a secondhand lathe you cannot assume any of these is true. But let's start with the chuck. The wobble at the end of the bar could be the chuck not holding the bar correctly or the bar is bent. Your improvement with the tailstock support doesn't eliminate either possibility. Is the bar straight? Does it give the same result if you turn it end for end? Does it give much better figures at say 3" or 4" out of the chuck? What is it like if you hold the bar in the chuck at about the halfway point? These will give you a good idea if and where the bar might be slightly bent.
If you look at the back of the chuck you will see the face that contacts the spindle register, is that flat and undamaged both on the flat face and the internal surface? Have you any measuring equipment to see what the internal register diameter is and what the external spindle register diameter is? Look down the chuck from the back is it clear or is there anything that could be contacting the end of the spindle and throwing things out? Has someone put something in the chuck to stop swarf going through if so is it contacting the spindle end on your machine? How stiff are the threads? One should not need to oil them to get the chuck to screw on; it should screw easily by hand up until the register surfaces contact. Can you feel when the spindle register outside diameter enters the chuck; does it get tight before it stops against the backface? Does it stop suddenly or just get tighter and tighter until you stop? I don't need the answers to these but they will all give you a clue if the thread is causing the problem and not allowing the alignment surfaces to contact correctly. This would mount the chuck off square with the spindle.
Those are all good signs but the only surfaces we are really interested in are the large outer register surface and its flat front face. Are you totally sure that you can detect no movement in the spindle bearings at all? It would be normal to see some very small amount of movement when they are loaded as Peter suggested, it might however be less than the resolution of your DTI.
The jaws of the chuck where they contact the work are they sharp and pointed giving one line of contact per jaw or slightly convex giving two lines per jaw?
I didn't really mean you should just the sense of humour on this forum.
The 4 jaw will hold the work as concentric as you have patience to set it; you adjust the runout by tightening the jaws independently. Unless you have a self centering 4 jaw in which case it might be no better than the three jaw. The readings on the end of the bar even in a four jaw will depend on how straight the test bar is and if the chuck is mounted square to the spindle.
Not dreaming but maybe hoping that your machine is unworn and fully OK. A Myford when set up is as accurate as any other lathe in its class and better than most, which is one reason they are so popular. However, there are a lot of worn or badly set up ones on the secondhand market and they will need to be fully sorted before working correctly. Just approach the checks methodically and you will soon find out if yours is badly set up or worn. Nothing you have said up to now indicates to me anything other than the chuck is not mounting correctly on the spindle. Once we have sorted that problem out or confirmed that it actual is then we can start to worry about some of the things that Norman has identified.
Brad, apologies if you think this is trying to "teach granny" but sorting out a lathe is a question of methodically eliminating problems one at a time until things work. If I am being too simplistic then just ignore these ramblings and I'm sure someone else will come along with a different view.
Best regards
Keith
Reply to
jontom_1uk
Perhaps it is time to stop, make a cup of coffee and revise the whole set of objectives of the exercise.
Reading through this thread it seems to me that Brad is chasing a level of perfection that may be impossible to achieve. Particularly in view of his level of experience. So my advice to Brad is to start cutting metal and make something simple and straight forward such as a tool height setting gauge and progress from there. My guess is that it will be a long time before he gets to the point where absolute accuracy of the machine is a limitation. He will know by then that no piece of bar stock taken off the shelf can be expected to be perfectly round or perfectly straight. He will also know a bit more about using the four-jaw, about turning between centres, about using fixed or travelling steadies, etc., and have a whole basket of other tricks to use to overcome machine limitations and achieve results that, I hope, he will find personally satisfying.
Reply to
Mike Hopkins
I cannot ever fault Keith's comments and would congratulate him on his detailed treatise ( send a quid, eh?) No body knows where, what, and when your chuck was at Myfords. Frankly, I dismissed its present accuracy. Until proved accurate now, it is crap. At best, you can only expect concentricity of .0.002 thous and if you know what you are doing, you use the best jaw- always! If you bugger about to true the jaws you will only get them right at that the trued dimension. Again, if you true using a ring round the jaws- you migt bugger the chuck even more. Now, this spindle lark! You have filed the thread but have you checked the spindle register to the chuck register? The chuck thread is not the final arbiter, the mating to the lathe spindle is. To all intents and purposes, the thread on a lot of new chucks is done on a Unified tap when Myford made a bastard BSW spindle. I warned you- my comments are not pretty ones.
Now this alignment business! Keith is dead right( another quid, mate) about the alignment bar. I would set the whole gubbins up with new centres and I would clock them to make sure that they were correct in their respective ends. Quite frankly, I would doubt that the tailstock end is true. the front one- mebbe OK. Here you want old Schlesinger's limits and tests book out of the library or summat similar.
The bed--- let us go back, Eh?
You have in all probability a knackered bed. You read the installation manual which myford g helpfully provides for a NEW lathe which is all bright and shiny having been on a slideways grinder and assembled carefully by skilled staff. You have to make the best of things. Unless you are equally skilled- and I confess that I am not, you are going to have to approximate when levelling up. Strictly you need a minimum of three machinists spirit levels and the ability to go round each bubble in a strange circular fertility dance as each bolt is tightened down and shimmed. You haven't got three ? Quelle surprise- moi, aussie. Got one ancient thing and I have to do this strange evocative dance with bubbles from lesser quality and price.
So Brad, I wasn't joking or being rude. You are somewhere at the beginning of a learning curve- and you owe Keith a quid!
Let us know whether we are right or wrong- enclosing quids or beer tokens.
Norm
Reply to
ravensworth2674
Hi everyone, many thanks for all your replies to my little problem, every one of which were greatly appreciated. I must admit that I am even more confused now than at the beginning, yes maybe I am chasing a dream. I've come to the conclusion from what people are saying, that I bought a heap of s**t, I don't have the skill or money to put it right, and I might as well get rid of it and give up on my life's dream of trying out a little model engineering. That too goes for the mill I bought recently. All I wanted to do is learn but it's probably too late. Cheers to you all. Brad.
Reply to
BRAD
Probably less likely that, than you "bought in" to a legend, that, even when new, was not quite up to it's reputation.
A couple thou run out on a 3 jaw chuck is pretty normal. 10 or 15 is not good, but not uncommon, either. And it can be worked with.
One learns to grab a bar that is a 1/16" or so over the size needed, and to turn as many surfaces concentric as possible, before removal from the chuck. One also learns to plan around the idiosyncrasy's of ones machine.
Money to put it right?
Christ alive, man. Use the damn lathe! Perfection is for guys with too much money to spend.
Guys have been making stuff on new lathes that were nowhere near as accurate as your one is now, for longer that Model Engineer magazine has been in print. If you get a chance to look at some of the "home shop" type lathes that were foisted off on the buying public before the wars, you will see why, exactly, that the Myford got elevated to the near mythical status that it has, as most of the lathes in a price range that a model engineer could afford, were pure trash.
Quit bloody well feeling sorry for yourself and go make some chips! Its good therapy! :-)
Cheers Trevor Jones
Reply to
Trevor Jones
Brad, Don't give up that easily, short of it being that knacked that it's condition should be obvious you would be surprised at what can be achieved even on a crap machine, I know I've worked some.
I have a old Myford here that can serve better as a post hole borer but before it got robbed for spares it could still do a reasonable job.
Where are you based ?
Reply to
John Stevenson
In message , BRAD writes
Don't give up before you have started! Try cutting some metal instead.
No matter how badly out your three jaw chuck is, everything that you machine at a single 'chucking' will be self-consistent as far as concentricity is concerned. If the work needs to be removed from the chuck and then replaced then marking the work in relation to jaw number one may be good enough. But better still, once you have had a bit of practice, it will take seconds rather than minutes to chuck something in the four-jaw using a DTI and get it within a small fraction of a thou' without even trying. For very small stuff use collets rather than a chuck.
This from one who had never cut metal in his life until a friend talked him into a project that all the 'wisenheimers' told him he would never finish!
Reply to
Mike Hopkins
OK Brad, 'our' John isn't a fairy Godmother and you will find me a bloody sight older and uglier. I'm in Newcastle upon Tyne if that helps.
Years ago-bugger, I'm 77- I had a Pools lathe which would only turn bananas. I got loads of help from people that I didn't know. Some where professionals giving up what little time they had.
In MEW, I returned the help by writing up how I' restored' a friend's ML7. It cost a mere =A335.and was capable of a 1/2 thou run out at 6" in a week.
People will rally round. As others have said- Don't despair but don't expect miracles. Our John is a grumpy old b. but he took time off at the Harrogate Show to sort a few of my problems. I got the help- John didn't even get a drink till the Show closed. 'Nuff, John?
Norm No, It wasn't going to
Reply to
ravensworth2674
Hi, I'm based near Mansfield, Notts so I'm not that far from Myfords...it's just a pity they are so expensive on bits !!!
I apologise for sounding sorry for myself, but I was overwhelmed by all the advise, quite a lot of which I didn't understand to be fair. I felt low as I thought I'd wasted a load of money on a crap machine.....BUT, I don't think the Myford is in a really bad condition considering it's age (1952) and I'm obviously suffering from lack of experience. Yes, there is a small amount of play in the saddle which I will have a 'go at', but what scares me when I'm told that this that and the other needs doing and I dont even know where to start. I thought I did well trying to level the lathe with a precision level.....I've managed to get it spot on in every way I could. If I need a new chuck, then great, I'll spend my last few farthings on one , as long as I can be assured that the chuck is knackered ! ....despite the very recent Myford report on the one in question. And yes, I was probably expected too much and everything to work properly first time......it's a huge learning curve. Cheers Brad.
Reply to
BRAD
Brad
I think you need to step back a little and think of what has been said and why; several of the posts have said that the runout is not brilliant but a long way from a diasaster. To be blunt it is you that is saying that it does not do what you want; like John and Mike say excellent work can still be produced and has been from far worse machines. The machine will still produce fine work YOU just need to learn how to do it and the best way to do that is to get a piece of bar load it up and make something. The best investment you can make before doing anything else is a copy of the "Amatuers Lathe" or something similar and if possible an hour or two with someone local who will sort you out in very short time. I'm sorry but I'm in south wales or I would help. The machine doesn't need anything doing to it immediately apart from using it to produce a few simple items so that you get used to how it cuts. The other point you need to understand at the start of this learning curve is that the most accurate machine in the world will produce crap work in the wrong hands, spend thousands of pounds on tools and equipment and they mean s***t if you don't know how to use them. For at least the last 60 years and possibly more model engineers have produced superb engineering from lathes that were far worse than yours is or could be, they would see yours as manna from heaven. What they did and do have though is patience and determination and I'm sure you have those qualities as well.
Brad, at the risk of boring you please listen to one piece of advice, the sort of runout you describe is acceptable for an older three jaw and the machine is usable and will produce good work. Use it for 6 months and you will look back and say what was I worried about? True by then you might want to make a few improvements but will have sufficient experience and confidence to make them without spending a fortune.
Good luck
Keith
Reply to
jontom_1uk

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