Member postings for Harold Hall 1

To expand a little on what Graham quotes from the Myford manual. In the section headed "Checking the Levelling" it starts. A final check---- can be carried out by turning a test piece and then explains how final adjustments are done by raising / lowering the appropriate mounting points.

Logic tells me, that Myford are therefore saying, even if you have used precision levels, or the test bar method, you may still be able to improve on the result.

For me, using a spirit level, or a test bar, are only quick methods of getting very close to the best possible mounting. Without them, the test bar only method will just take a little longer.

Harold

I must remember the string method Michael (G) next time I lay out a brand new garden on a hillside, but that is unlikely. Too old now to even contemplate it on the flat.

Sorry to say you final comment leaves me standing, will have to leave it at that.

Joseph. Your translation of Pythagoras's Theorem is new to me, like it. Actually, my wife was only saying this morning that we had not seen the squirrels in our garden for a couple of months, I can now tell here were they have gone.

Harold

Thanks Michael (W) very interesting! Initially, I had a problem making sense of number 4 but eventually it clicked, brain not as agile as it once was.

I think though I will stick with what I call " Workshop Grade Cylindrical Squares"

I am sure most will know, but for those that do not. Builders have in the past used three bars screwed together with distances between the screws probably being 3, 4 and 5 feet. I used the method when setting out walls in a new garden.

For the mathematically minded 5, 12 and 13 also produces a perfect square, but of course much less practical.

Harold

Edited By Harold Hall 1 on 21/02/2013 10:15:53

Thanks Nigel Interesting!

Harold

You have Brian come to the correct conclusion regarding setting up the lathe, Twist is much more important than level.

In the tolerances you quote you state that "all can be zero" and you are theoretically correct, However, no manufacturer would aim for that value as a very small deviation in the wrong direction could at best result in parts having to be reworked, or at worst scrapped.

They will almost certainly aim for somewhere in the middle of the tolerance range as a result a small deviation from perfection is almost inevitable.

Harold

Sorry Nigel but I had not fully taken note of your comments when I posted the above else I would have added the following.

The figures that you quote are interesting and would seem logically, being a means to compensate for the forces existing whilst in use The weight of the chuck, and more so a large workpiece, would compensate for one and the force on the workpiece when being machined would tend to diminish the other.

Incidentally, Myford when machining the top of the bed had a means of slightly lowering it in the centre. When machined and then removed the bed would return to its normal state and would be very slightly high in the middle, left to right that is. The weight of the saddle, cross slide and top slide when eventually fitted would then return it to nominally level, Of course all such measures are compromises as they do not achieve perfection.

Harold

You are correct Michael ( W) that you cannot correct major errors in a lathe by twisting the bed. However, if the lathe bed is set using a precision level the lathe may still not turn parallel due to minute errors in the alignment of the headstock spindle. In this case a very very small twist can be incorporated so as to compensate for such an error. To my knowledge, very few lathes have a built in means of aligning the headstock directly.

It occurs to me that some reading this thread will be unaware why I am making what I call, Workshop Grade Cylindrical Squares. They are for use, normally in pairs, for supporting items on the milling machine. This was originally to make two accurate angle plates, the result being much better than my purchased angle plate.

I use a pair to support one face whilst machining the other, then doing the same with the second face. For the ends I mount the angle plate diagonally between the two squares with one supporting one face and the other supporting the second face and the ends machined. This ensures that all four edges are at right angles with both faces.

Harold

Geir

I cannot totally agree with Andy as making adjustments to the headstock mounting are a very last resort and certainly not for an error of only 0.02mm

For most normal day to day use of the lathe 0.02mm over 100mm is quite good, Even so, to minimise an error of that size the method is to make minor adjustments to the mounting feet, typically, if the test piece is large at the outer end then raise the front foot at the tailstock end and if small the rear foot.

In my book though you will see I was attempting to set up for making a cylindrical square for which 0.002mm would be required, ideally. If your lathe then has jacking screws at each mounting then aiming for 0.002mm is not that extreme as very minor adjustments are easily made. However, if using shims then the task can be tedious and something more like 0.005mm is perhaps more realistic.

I realise that stating 0.002mm in my book is being rather precise as few could measure that difference with certainty. I feel I should have said "with no more than a just noticeable difference with the micrometer readings"

If you want more detail on setting up a lathe to turn parallel then see, as I have said in another thread going at the moment, my website here http://www.homews.co.uk/page309.html

Harold

PS I went for tea half way through writting this should have appeared before Jason's item

Edited By Harold Hall 1 on 17/02/2013 18:27:08

Brian

If you had a precision level then it is a good way of testing that the bed is not twisted, which is the important thing. A slope of say one degree at each end would still indicate that the bed was not twisted but that is difficult to test.

However, even if the lathe is set up using a precision level a test piece would still have to be turned to make the final adjustments. As you do not have a precision level there is no need to go to the expense of purchasing one.

First set up the lathe using a DIY level and then go down the test piece route to finally set the lathe to turn parallel.

If you are not conversant with the method of turning a test piece I have attempted to cover the subject in detail on my web site which you could view. The details are available at **LINK**

It is worth bearing in mind that no lathe is perfect, even a precision one. You may therefore end up placing a very minute twist in the bed to compensate for errors in its manufacture, Hence the reason for turning a test piece even if set up with a precision level

Harold

John

I cannot argue with your first hand experience and am fully aware that H&S can easily go over the top so to speak.

However, the safety of many people is not totally in their hands, powers above them expect them to work in less that safe situations. It surely is a case of setting the barrier between legislation and freedom at the correct level.

We have no doubt about your ability in the workshop and with that in mind you are well placed to take the safe route.

Whilst not H&S the following illustrates the limits of some machine operators common sense.

During the time I was editor of MEW I was castigated for publishing a photograph(mine) of a piece of equipment secured to the milling machine using screws, saying it would never have been allowed at his firm. When I enquired why, the reply came back that it was not unknown for someone securing, say a vice, only to find that it was not fully secure. To overcome that a piece of scaffolding was applied to the spanner to get extra torque with the result that the tee slot was broken. No doubt such individuals, with limited common sense, still exist.

Keep up the good work John

By the way, how can you be answering threads at 10 in the morning? Tea break no doubt.

Incidentally, I do always check the length of a screw against the depth of the tee slot before using that method, common sense!

Harold

Edited By Harold Hall 1 on 14/02/2013 10:48:19

Why are you people so anti Health and Safety, hundreds would have died and many more escape serious injury without it, Some of you, like me, may unknowingly be among them.

Harold

I am sorry Alan that you find it surprising I did not give GTH a mention but I am not well read, do not have the time, and did not know of his table.

I cannot say that my offering is totally from my own head but prompted by a photograph I had seen during my time as editor, I now find is was acctually in issue 1 of MEW. And the person who made that was a Tony Daish and I did not give him a mention either.

It is probable that GHT had also been influenced by others offerings.

I have now found the GHT table in the Hemmingway catalogue and can see some long distance similarities. Though I do not see fine adjustments of the stops, 24 hole indexing and, for me, the inbuilt facility to be able to centre workpieces very easy.

It is quite probable that over the years I have produced items that had a noticeable similarity with items designed by others, its inevitable. I can assure you that this is quite coincidental. For me, designing an item is much more satisfying than the making. If I just largely copied others designs most of the satisfaction would be lost.

If eventually Alan you decided to make one please feel free to make contact with me via my web site should you have any questions regarding the areas that you do not find clear. I will do my best to help.

Harold

Dave, you will need an industrial type tool and cutter grinder, or maybe a surface grinder, If you have one then it should be OK, though I have not had any hands on experience with it. Do you need to sharpen enough end mills to warrant the expense

Harold

I was surprised Phil that you had made a rotary table like the one I have produced as it has a number of features that I thought were new, still, I am not well read so I can easily be unaware of such a situation. I like to create designs which I feel are my own, actually, I often get more satisfaction from that than the making.

One such feature that I thought was mine is the method for easily locating, say the bore of a link, precisely on centre and then securing it with a single central screw. It can cope with any size bore and has four fixing screw threads, M3 to M6 for bigger or smaller workpieces.

Two other features that I realised were probably not unique, but I thought not that common, are 24 holes for accurate divisions and fine adjustment on the rotational stops.

Would be nice to know how George Thomas achieves these especially the location of parts.

I agree Rod!

Harold

Edited By Harold Hall 1 on 01/02/2013 09:01:44

Well said Norman!

Harold

If you go to the final page of my Stuart series on the web Berra you will see a picture of the four engines that I have made, only the first one for the fun of it, the others to provide articles for the magazine.

You will see that I have only fitted taps to one off, that being the first, Since then I have omitted them to keep the costs down. Non of them have been run, perhaps one day I will find the time, and the confidence, to make a boiler, but that day never seems to arrive, Shame really.

Fortunately, those who know more about running them appear above to have answered your question.

Harold

Thanks Norman for giving my web site a mention. I am sure you, with others, will realise that even though much of it was taken from my MEW articles there has been lot of work in adding them to the web. Typically, reducing the file size of almost 1000 pictures (twice, page size and large view size)was quite a task. So the more times it gets viewed the more it becomes worthwhile.

Thanks again

Harold

Sandy

The vast majority of the content of ME is provided by the authors as would have been the case during the 40 years you took the magazine. Sadly, by you not taking it, it is mainly you, but also the authors who have lost someone to enjoy their efforts, who are the losers.

Wotsit

A very large proportion (well over half) of the readers of MEW when I was the editor were not at all interested in model making, Many of these would not have taken ME just to have a few pages devoted to their interests.

Also, the magazine was only to be 4 issues a year so was in no way a ploy for selling two sets of magazines so you are very wrong in your interpretation of the reason for this. It was because it became so popular that it was increased to 6 issues and as this was too many for Stan Bray then I took over. During this time many of the readers, not the publishers, were still asking for more issues.

Harold

As Norman has brought us back to Ron making a stationary steam engine perhaps I can give my web pages on making a Stuart 10H or 10V a mention, surely these must be the most common starter engines for the first time model engine maker. The pages are certainly the most viewed on my web site.

Nominally ,they get 6000 page visits a month out of 50000 page visits and equates to 5% of the pages getting 12% of the page visits, so there a quit a few people obviously making them.

There are 27 pages Ron with 81 illustrations, most of machining set ups. It is aimed at the workshop having only a lathe but the milling operations can easily be transferred to the milling machine.

The site is at **LINK**

Harold Hall

Both would be helpful Ron but if it has to be one then I would say MEW. Unfortunately though, magazines only come every few weeks and it may be years before all the topics are covered so I would sugest you include books in your aims to learn the machining methods. I will leave others to suggest any suitable ones, should they agree of course

Harold.