Member postings for David Littlewood

Bright drawn mild steel (BDMS) - i.e. the normal stuff we buy - often has hoop stresses and can also suffer from bowing if machined asymmetrically. It can be cured by annealing - can't remember the recommended temperature, it's about 700 degrees C - and cooling slowly, before machining.

David

Edited By David Littlewood on 05/01/2013 23:52:43

Kevin,

I'm not familiar with the ML4, but I assume its basic structure is similar to the 7 series - i.e. it has a foot at each end of the bed, with holding down holes at front and back of each foot.

If so, then you need to go through several steps on setting up. The first essential is to know that the bed is not twisted - if it is, then the saddle will not move parallel to the spindle axis, so all turning held in the chuck will be tapered. You will be surprised how easy it is to hold the bed down in such a way that the bed is twisted. The only reliable way to correct this is to chuck a substantial bar - at least 1" diameter and 6" long - with no tailstock support, and turn small bits at remote end and headstock end at the same cross slide/topslide setting (it helps if you relieve the bar slightly between the two ends to remove the need to move the tool when switching between the two). The two lands you turned should be identical in diameter - a couple of tenths out should be acceptable.

If the remote end is larger, that means the bed is tending to move away from the tool point as you move away from the headstock; slacken off the rear bolt of the tailstock foot, and shim it slightly under the foot and re-tighten. Try again, should be better. Repeat until happy. Obviously, if that end is smaller, then shim under the front side of the foot instead.

Some people will tell you that you can do this with an engineer's level. I have an engineer's level, and I've tried it, you can't get the same accuracy (and the levels cost); the way I described is (a) more accurate and (b) free.

Then, when happy the bed is not twisted, check the tailstock is in line with the headstock spinlde axis. The proper way to do this is with a test bar and a DTI, but simply aligning centres in headstock and tailstock is fairly good.

Then you can turn between centres and know that you will get a parallel result. For holding in a chuck you need to be sure your chuck is acceptable. Old 3-jaw s/c chucks are notoriously poor in this respect. You can use a 4-jaw independent, use a collet, buy a Griptru chuck (pricey) and learn to use it, or remedy your old chuck, perhaps by re-turning the register on the backplate (or even providing adjusting screws) and possibly grinding the jaws if they are bell-mouthed.

David

Edited By David Littlewood on 05/01/2013 23:43:20

I started with a metric set, 1 - 5.9 mm. Altohugh over the last 30 years I have acquired most other types (fraction, number etc.) the metric set gets at least 95% of the use. The problem with number drills is that the increments are highly random. Even when working to a drawing in imperial, I find at least for reamed holes I will use a suitably smaller metric drill to follow with a reamer.

Also, consider acquiring stub drills, at least for the hole sizes you use the most. They are substantially stiffer then standard length drills, and thus far less likely to wander.

Tracy Tools currently have a boxed set of standard length metric drills, 1.0-5.9 mm, for £20.

David

Edited By David Littlewood on 05/01/2013 23:20:01

Neil,

I have one of those; its blade can be bent to 90 degrees without any permanent set, quite incredibly well tempered.

David

It's easy to forget the precise mechanics of what happens when you drill with a jobber drill. The chisel edge in the centre of the drill has a huge negative rake and will not cut the metal; it has to gouge it out by plastic deformation. The force needed to do this can become very large indeed as the drill diameter (and hence the size of the chisel edge) increases. Using a pillar drill, the leverage applied by the feed handle is substantial. and one might not realise just how substantial; using a hand-held drill, the force has to be applied by you pushing it.

As you found, a pilot hole (sized about the same as the width of the web on the larger drill) will remove the need to force the chisel edge into the steel and make the job much easier.

David

Edited By David Littlewood on 16/12/2012 19:57:10

Jason,

I too have sent you a PM.

David

Andrew,

I think Machinery's is published by a US company; it's possible that in 1943 no-one over there had heard of BSF threads. The USA has often been, in my experience, very much more inward-looking than we are over here ("War is nature's way of teaching geography to Americans" has some justice in it).

David

Siddley, I did a Google search and saw some similar - possibly identical - ones for about £45. I think, given the effort involved in making one, especially the adjustable legs and the padding, it would scarcely be worth the time spent - but your call, of course.

David

Siddley,

Just taken a couple of photos of one of my stools (they are identical). Hope that gives you a good impression of what they are like.

Martin,

Glad you found it. I looked for the book on Amazon and found TEE there as one of their third party sellers. Among other things, they publish Engineering in Miniature.

David

Edited By David Littlewood on 07/12/2012 16:05:44

Martin,

Just buy the damned book - you won't regret it. I can't understand your comment about Amazon delivery, it's free on virtually everything, unless it comes from a third party. They are currently out of stock, but TEE have it at the same price with £2.80 delivery.

David

Clive, I have seen those straddling seats as well, though I have never tried one. I think they would be OK for desk work, but I'm not sure how they would be for operating machinery. Has anyone tried them for this? In earlier years (bipedal but with very simlar problems from a squashed disc) I very often used to sit on chairs with the back forward and me leaning forward on it. It seemed to ease the discomfort, but caused the occasional funny look at meetings.

David

I must say I hate the double spacing you get from pressing the return key. Since every other program I have ever used is set to give a single line shift on pressing return (i.e. no blank line) I press it twice to get a para spacing, and then have to backspace.

Just one of many naff features of this software.

David

You have my sympathies. I was unfortunate enough to lose a leg about 4 years ago. The occupational therapist was very helpful, and provided me with a pair of perching stools which are ideal for the job. Like bar stools, they are quite tall, but the seat is just slightly angled forward and they have short rails at the sides (to assist atanding up) and at the back (for security). PM me if you would like more details.

Like you, I find it limits the time I can work, especially standing, and it has steered me into doing more light work, such as O gauge loco modelling which I can mostly do sitting down. I can though still work standing up when I need to, but try to restrict it to half an hour or so, then go and have a sit and a cup of coffee (or bunk off and play a comuter game!).

I wish you luck though.

David

Edited By David Littlewood on 07/12/2012 01:08:45

Jason,

He said the Waste Disposal Regulations and the requirement to have a licence to deal in scrap. I was reponding on the latter issue. And once you have boought something that is not "scrap" then it is difficult to see how it is different from anything else you buy.

Oh, and yese, please put me down for at least a couple of feet!

David

Edited By David Littlewood on 06/12/2012 08:43:22

Les,

I also have an FB2, have had it for about 25 years and it has served me well. It too has leaked oil from the quill for many years, but the rate of leakage is so slow that I only have to top up the oil every couple of years or so. The main problem is that if I don't remember to wipe it off after a few days of not using it, I get spattered with oil thrown off by the rotation!

I did speak to the current importers at an exhibition about 4 years ago, and they told me that they did sell replacement seals (but didn't give me any details about where they went). In the end I didn't bother as, for the reasons above, it wasn't bothering me enough to make it a pressing matter.

David

Michael,

Whilst your warning may be a timely one, and one which anyone dealing in metals should give careful thought to, I think you may have become slightly paranoid.

I went to the relevant government website. The 2012 rules amend the Scrap Metals Dealers Act 1964, but it seems the definitions of what constitutes a scrap metal dealer is unchanged. The Interpretation provisions of the latter act state:

9 Interpretation.E+W

(1)For the purposes of this Act a person carries on business as a scrap metal dealer if he carries on a business which consists wholly or partly of buying and selling scrap metal, whether the scrap metal sold is in the form in which it was bought or otherwise, other than a business in the course of which scrap metal is not bought except as materials for the manufacture of other articles and is not sold except as a by-product of such manufacture or as surplus materials bought but not required for such manufacture; and “scrap metal dealer” (where that expression is used in this Act otherwise than in a reference to carrying on business as a scrap metal dealer) means a person who (in accordance with the preceding provisions of this subsection) carries on business as a scrap metal dealer.

Note that this excludes "a business in the course of which scrap metal is not ...bought except as materials for the manufacture of other articles and is not sold except ... as surplus materials bought but not required for such manufacture.

Thus a firm selling surplus bought-in stock is not a scrap metal dealer within the meaning of the act. Interested parties can find the test of the 1964 act at

**LINK**

However, if you are in the metal business and sell metal, you should check for yourself and take advice if in doubt.

David

Edited By David Littlewood on 05/12/2012 22:39:55

Looks like an incredible bargain for somebody! I can't help feeling the seller has not researched the market very well, it should easily sell for at least 1k more. Collecting from Inverness is a bit of a downer, but you could easily find a professional moving firm and still be quids in.

David

I agree. It's not just the bearings (impportant though they are). The S7 has:

Better tailstock
Leadscrew handwheel
Longer cross-slide
Vastly improved topslide mounting
Countershaft clutch

....and probably other things I've forgotten. The ML7R has some, but not all, of these improvements. As for gearboxes, I have the impression (though I've not done a careful check) that the difference in price between S7 and S7B is less than the cost of an add-on gearbox. I certainly wouldn't want to go back to achangewheel machine again, even though you do occasionally have to use changewheels for unusual jobs.

David

Ron,

You don't say which machine you are talking about, or what the motor power is - always give as much info as you can to allow responders to give you the best answer. Also, best to state where you live as if you are outside the UK the suppliers, and the electrical supply position, may differ.

As you suggest you have no great expertise here, it would probably be best to get a motor/VFD package from one of the regular suppliers of these things. I fitted one from Newton Tesla to my Myford S7, and also an inverter from them to my M300 (it already had a 3-phase motor). The S7 package in particular was very much plug-and-play, all the electrical connections were wired up with safe plugs and sockets; the M300 required a bit of wire connecting by me as it was non-standard. I have been completely satisfied with both and have no hesitation in recommending that firm, but there are other suppliers, see magazines. If you tell them what machine you have they will know what motor mount and size will be right for you.

David

Edited By David Littlewood on 26/11/2012 20:00:42