Myford ML7 Operation / Testing

In article , DR_G writes

It's called metamerism, the situation where dyes or pigments have different spectra, but happen to look alike in a particular type of light; in light of different spectral properties they look different, sometimes very much so. Just about every coloured object displays it, unless using chemically identical pigments.

The lathe, BTW, is looking very good.

What difficulty are you having? I'm sure someone here will be able to help.

A bit much. When you get round to it, look at the Hemingway adjustable backplate kit, you should be able to get it down to a tenth of that with one of those and some careful work.

You will always get some detectable movement if you push hard enough; it is a compromise between having the gib strips tight enough to minimise movement, but not so tight as to cause a "sticky" action, which will also make accurate turning difficult.

A very popular start.

Well, everyone will have their own ideas here, but FWIW here is my suggested minimum list:

LH knife Facing tool

45 degree chamfering tool Parting tool (The Q-Cut tool from Greenwood is by orders of magnitude the best parting tool I have used) Round nosed tool (see below) External screwcutting tool Small boring tool (6mm) Larger boring tool (10mm) Between centres boring bar (make your own and use broken centre drills for cutters)

I prefer replaceable tip TC tools, but they are more expensive. If you grind your own you will need a grinder, and you will possibly end up with a large collection of sub-optimum tools (many of us started out that way!).

Later you will want an internal s/c tool. Screwcutting is much less stressful if you use a mandrel handle and turn by hand - again see Hemingway kit.

Profiling tools - wouldn't bother until you need them, you will probably end up making your own as often as not. A round nose tool will do for most of the profiling you do in the average steam engine.

Cutting tools - have you got a vertical slide (or a milling machine)? If not, they will be little use. If you have, a set of mills (slot drills are a little more versatile as they will plunge cut, end mills won't but will cut rebate a little better) will be required. But -and it's a big but - you should *not* try to use them in a drill chuck. A set of ER collets and a holder to fit the Myford nose will be suitable, and nowhere near as pricey as they were when I bought mine....

For turning between centres (or using a between-centres boring bar) you will need a soft dead centre for the headstock, and a hard one for the tailstock. A live centre would be better for the latter. Some kind of catchplate is also required, you may have got one.

Drill chuck with 2MT arbour for tailstock (a good keyless chuck - Albrecht or similar - will be a big advantage) Set of drills 1.0-5.9mm x 0.1mm Set of drills 6.0-10.0 x 0.1mm

Reamers - buy a set, but you could live without for a while. Drill a pilot hole 0.3-0.4mm undersize, then a sharp drill of the required size will probably cut very close to size. Some centre drills would be useful to give the holes a true start, and a magnifying glass to see the hole has started in the right place (if using mill or drilling machine). I prefer stub drills for critical holes, but they are more expensive and hard to find, you can live without them.

For setting up in the 4 jaw you should have a DTI and a centre finder. The best type IMO is a rod with a centre in the rear and a 60 degree pointed spring plunger. In use, hold the back centre with a tailstock centre, with the pointy end in the pop mark, and use the DTI on the rod to get the hole centred.

You will soon find a whole host of other things you can't live without, but to a great extent this will depend on the work you do.

Oh, and do make a tool height setting gauge....

Well, if you really can't lock in position it's pretty useless.

Personally I dislike 4-way toolposts (I assume this is what you have) as they never have the right tolls in them, and the not-in-use tools can be a health hazard. I use a Dickson post, and if you can afford enough holders (I have about 25) the time saving is immense.

David

I understood that to mean that the 4-way has no spring detents at the index positions, since this is quite common and I'm sure it would be obvious that the big locking clamp is vital.

If so .. the detents might save you some time if you're regularly swapping tools with the 4-way. If you trust them to give you the same position. If you even want the tools in the same position. Certainly not essential though - use it and see if gets frustrating.

I've managed for quite a long while with no detents, and never have more than two tools in the 4-way. More just get in the way. If I ever have a lump of money spare it will go on a Dickson or similar, not a better 4-way.

-adrian

Garth Hi,

Lathe is looking very good but I'm a bit distracted by the nice looking MGB (at least the bits I can see) and of course the nose of the E Type?, a very nice collection. David has given you a lot of advice but a few additional comments if they are of any help.

The chuck run out at .004" is a little disappointing but not a disaster for you. Have you tried closing the chuck from the different key locations? You will find that one is much better than the rest. Does it always repeat at .004 or is it variable depending on diameter you are gripping? A constant run out would indicate that the chuck jaws are worn or backplate mounting is out, a variable (large variation every 3 jaw will vary a little (.001"ish) each time you remove replace the work) might indicate a worn scroll which is best fixed with a new chuck. When you removed the chuck from the backplate for cleaning did you fit it back in exactly the same position? If it is a three bolt fixing it is possible to rotate the chuck on the backplate. Is the chuck body a tight or loose fit on the backplate register? It is possible sometimes to loosen the chuck mounting bolts and tap the chuck to get it running spot on and then tighten the mounting bolts up again. If someone before you has had a problem and used this method to "fix" it you will need to set it up again. If the jaws show any signs of wear it is possible to re-true the chuck by grinding in situ but I would check the basics first.

The 4 way toolpost is not a problem as long as it can be locked by the top lever at any position. Many people find the indexing system a pain and remove the plunger anyway. As David has said many including me are not keen on the four way toolposts. If you put more than one tool in it look out for a few cuts and scrapes on you hands from the unused tool. I would agree that a QCTP (Dixon/Myford) type would be one of my first purchases for it. The "pattern" ones from Chronos/RDG etc are good and much cheaper than the original Myford ones. You will need at least 5 holders though and the more the merrier.

Tooling, particularly the cutting tools are a bit of an individual choice and I would suggest trying out a couple of individual tools before buying any expensive sets. Simple HSS is a good and very flexible choice for a Myford. You will need a small bench grinder to shape/sharpen them and will need to learn to grind accurate angles etc but that process does not take too long and once mastered you can make all the special shapes and profiling tools you will ever need. If you fancy the TC replaceable tip type and they are very good these days I would suggest trying a CCMT RH type as a start. These can be bought for a few pounds and will let you get the feel for TC tooling. I personally haven't had any success with the cheap brazed Carbide tools that are available in sets very cheaply. Doesn't mean they are no good just they don't work for me.

I see from your photographs that you have a half centre, full centre and a live centre so you are already equipped to turn between centres if necessary. The full centre looks like it has been reground so you might want to have a new one of those but they only cost a couple of pounds from ArcEuroTrade/RDG etc. I can see a rear toolpost with a parting off blade and that system will work very well so although I agree with David that the Q-Cut type is superb you don't actually need one yet. You also have a HSS boring tool but there are a lot of excellent replaceable tip types available in a range of sizes. Once you have sorted out a good tip for the type of work you do then quite often you can choose the same tip in a boring bar which saves on having a large number of tips to buy. Again CCMT is a popular type although DCMT can give more access on occasion. Have a look at the Glanze CCMT RH and LH cutting tools and CCMT boring bars, a couple of them would be a very reasonable place to start IMHO of course. Another excellent tipped tool is the TPUN one available from Mary Poppins bag on E-bay (blatant plug for John Stevenson who is too modest to plug himself these days). You will need to check though that the 12mm type will fit into your 4 way and get low enough to put the tool on center height. Doesn't really matter if it doesn't as you have the normal Myford tool clamp and can use that if necessary.

To shorten a long story (yes please) I would advise using some HSS to start and learn to grind your own tools. Bench grinders are very cheap these days and once learnt it is a skill that will ensure you are never short of the correct cutting tool or a sharp drill again. Then supplement this with a few replaceable tipped tools to do the real hard work. Reamers, Taps, Dies etc are I believe best collected as you need them. If you buy expensive sets there will be many that go unused and a few that wear out quickly. Drills are a problem area as there are numerous cheap sets about that are fairly awful. A basic good quality set from Dormer, Presto (Greenwood had some good offers), Cleveland or Hertel from J&L work well for me as have the very reasonable priced sets from ArcEuroTrade. With drills I'm afraid you get what you pay for in general and good ones are never a waste in my mind.

Best regards

Keith

PS Please feel free to come and clean re-paint my S7 at any time

David, Adrian, Keith,

Thanks for the invaluable advice on all questions (as ever).

Firstly, the chucks. I have a scruffy 3 jaw chuck, and a slightl better 3 jaw chuck, both of which I carefully marked, striped, cleaned lubricated and rebuilt. I then obtained a hardened steel bar from an ol printer, and measured the run-out at about 3" from the chuck. The chuck do not appear to be marked in terms of which key hole to use for bes accuracy. The main spindle (where the chuck fits) does not have an visible run-out at all on my d.t.i. I also have a 4 jaw chuck whic looks in v.g.c. I will re-check in different positions / tightnesse etc and report back.

David, What I mean is the the toolpost has no detents to lock into. I does have a handle and tightens up no problem. The toolholder look home made though. The trouble I had with the gibs was basically knowin what the 'sweet spot' between too much friction and too much play is This particularly applied to the saddle ways (which are worn). Th saddle tightens up at the tailstock, but since I don't know yet wha sizes I will be working in the lathe, I tried to compromise betwee stiffness and taking up play at the headstock end. Someone suggeste scraping the sides of the ways back parallel, but no way would attempt this with no previous experience. It may be that because I hav so little machining experience, everything will be fine for my needs. will soon find out!

All the tooling I got with the lathe is in one of the pictures I poste earlier in the thread. I've got faceplates, centres etc, and yes, vertical slide (the non-rotating one). I only have three tools though a boring bar , parting tool and another standard one. I really need set to play with.

I do have a bench grinder (but would appreciate advice on too refurbishment).

How good are the widely available brass drip-oilers by the way? One o my plastic reservoirs is cracked (my fault I think).

By the way, the MGB is a 1962 model (my Dad's) which I rebuilt in 198

- 1990. The E-Type is a 1964 Coupe, which I bought in 1994 in boxes an spent 8 years rebuilding. The number of times I needed a lathe whil rebuilding those cars - and now I've got one they are both finishe (nearly).

Thanks again for the comments and advice,

Garth

-- DR_

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I found the article at

very useful when I started. I looked at Sparey, and at various other books, but could not get my head around it. Basically the best way to learn is to try. toolbits are not to expensive, so dont worry about messing up, and the angles, whilst important are not critical for general turning. one good tip is to hold the toolbit in a pair of molegrips, helps prevent burnt fingers DAMHIKT. Some of the older books advice about tool grinding is no longer relevent, especially the dunking in water as you progress, iirc HSS should be ground hard and fast, without to much worry about how hot it gets within reason (hence the mole grips) and do not dunk it in cold water, as this causes microcracking of the surface, a bad thing so im told. (cant remember where to atribute that to). The dunking and gental grinding apply to carbon steel tools iirc, as you can easily draw the temper on these. Grinding HSS gently is ok AFAIK, but takes much longer....

Dave

O.K. everyone, next question!

I have started playing with the lathe now (although it's not proper levelled yet). I am goint to try the 'dumbell' machining test first.

Are there any very simple 'projects' that could be made which will giv an indication of the accuracy (for want of a better word) of my lathe Perhaps something like machining a piston to fit a machined or reame hole or something like that? What is the most critical operation tha you can put a lathe through in order to get an idea of how well it i set up?

Last night I tried machining a 1" piece of bar down, measuring it, the taking a 0.001" cut from it (according to the handwheel) an re-measuring it. It seemed ok, but the length was very short because don't have much stock at the moment.

Any suggestions welcome.

Regards,

Garth

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In article , DR_G writes

IMO, the most useful way to test the lathe, and to improve your skills, is to make some items of workshop equipment. If you can make a versatile dividing head to the G H Thomas design, you (and your lathe) will have proved yourselves up to the mark, and you will have a very useful piece of kit.

Maybe you would want to work up to it gradually though, with one or two of the simpler Hemingway kits, or a set of tailstock die holders (see GHT's Workshop Manual).

David

In article , David Littlewood writes

Just been looking round my workshop, looking at what things I found most useful since starting out, and giving this some more careful thought. ISTM that you could do a lot worse than get a copy of the GHT book (The Model Engineers Workshop Manual) and work through chapters 1 to 7, making most of the items in there (I personally would miss out the rear mounted parting tool holder, and get a Q-Cut parting tool from Greenwood instead). The order is quite helpful as some bits get used to make later ones.

Lots of practice in marking out, turning, boring etc. and you end up with quite a few useful tools, with excellent how-to descriptions (and useful asides) from a past master of the subject.

Once you have got that far, you should also have a pretty good idea what other things you want to make (and be ready to make that VDH).

David