Member postings for ega

Won't a boring tool reach the backplate?

PS I have just remembered that a local engineering shop has a similar one too.

David Clark 1:

I imagine your suggestion was not intended to be taken literally.

Most unlikely to be home made as I have one that looks identical.

Neil Wyatt:

Do you happen to know whether those Power Meters can be used with a VFD? (ie Power Meter in domestic 13A socket and lead to VFD plugged into Power Meter).

I have a similar device from Maplin which I use to keep an eye on the power consumption of my PC.

But can anyone think of instances where the reverse has occurred?

My copy of the 1973 S7 manual shows these "extra" screws numbered K70 and both they and the Wedglok adjusters are M5 which seems quite advanced for the date. My own older machine has 2BA adjusters with lock nuts and two extra setscrews for locking purposes which I think I installed myself years ago. I have never felt the need for additional locking capability but I would agree that the MEW device is likely to be more positive. At the same time, the author's statement that the S7 arrangement does not lend itself to locking seems to be open to question.

Brian John:

"I am still looking at ''dowelling the gib'' but I have to be honest here in that I do not see how it helps. I must be looking at it the wrong way !"

I doubt if I can explain this any better than GHT in the extract I sent you and in any event the question of the geometric accuracy of the slide should be resolved first. I will mention, however, that the dimples in your gib appear to have been drilled normal to the face rather than in line with the adjusters which I think is undesirable and underlines the need to prevent slip-stick being caused by the poor fit of the adjusters to the dimples. In your setup I would install a dowel between two of the adjusters and a locking screw in the other space all as per the GHT extract.

I think it is very positive that you have now dismantled the slide and can actually address the problem - good luck!

IanT:

I was interested to see that you were able to set up a gear train including a 127T gear. These were listed by Myford as late as 2002 at £37.75. My comment was based not so much on the high price of the large gear as on the same point that you make about the gear change cover (and specifically in relation to the S7 with QC gearbox as I have no personal experience of the other models). However, Martin Cleeve (WPS3 p43) seems to confirm that the same problem would apply to the ML7 and he used a physically smaller 127T gear of 30DP.

I have to say that none of the descriptions or photos of his machines that I have seen included a change gear cover and, like you, I would be perfectly happy to cut a thread with the cover open if I had to. On many machines, of course, this would be prevented by an electrical safety switch.

Roderick Jenkins:

Thank you for "doing the math" and for the instructive comparison with the modern mini lathe - no need for four places of decimals there! Myfords clearly came up with a very effective solution to the problem posed by the impracticality of using a 127T gear and I feel it would have paid them to include something like your table in the QC gearbox manual.

naughtyboy:

I have the Mk.II leaflet and price list and would be happy to send them to you. The name then was Town Bent Engineering.

Roderick Jenkins:

Thanks for the helpful explanation and corrected table.

I have the Hoskin letter and notice that you have derived a better suggestion for 2 BA pitch than his 34T/44TPI; I think the 20T is the smallest standard gear which will fit. At the other end of the scale, I have squeezed a 38T in by extending the slot in the quadrant but I don't remember what pitch this was for.

As you say, the original idea whoever had it was simply brilliant and you have to wonder what the thinking was at Myfords when they came up with the expensive metric conversion set which I seem to remember does not quite provide an exact conversion to metric.

Roderick Jenkins:

Many thanks for your excellent table and do please persevere in making it available in accessible form. I have a collection of copy letters to ME and MEW about the use of alternative stud gears to obtain metric pitches on the S7B but have never got round to collating them.

This idea goes back at least as far as MEW no 42 and is I suspect much earlier. Like you, I have not used my (shop-made) metric quadrant for some years - the last occasion may have been turning one of GHT's worms. The practice is so useful that I have wondered how one might "automate" the setup with pre-set stops so that meshing the new stud gear is effected tool-free and without resort to cigarette paper or workshop Esperanto.

KWIL:

Starrett part no 284 certainly, but the picture is presumably of a copy which may not have been "hardened, ground and carefully tested".

John McNamara:

Needless to say, I am of the same mind.

Roderick Jenkins:

I have no doubt that (like me) Bucky would be glad to be corrected on a point of fact. The book I mentioned is a somewhat "popular" exposition of his work co-authored by a friend and admirer and it looks as though whoever wrote the text concerned took his eye off the (Bucky) ball; thanks to you for spotting this.

One of RBF's preoccupations was the use of the world's resources and I found the idea that the US had a bigger tin "mine" above ground than Malaya, etc had below it to be a striking paradox. The discusson about Crobalt makes me wonder how far alloying elements are re-cycled; what happens to those short ends of HSS, etc that are too short for use?

Brian John:

A suitable pulley can be converted into a handwheel with the addition of a handle. There is a photo of one in my album.

Rik Shaw:

Your mention of Kirksite rang a bell as it is mentioned in a book I have here by the late Richard Buckminster Fuller. He used it in the production of his "Dymaxion Dwelling Machine". Apparently it consists chiefly of tin and at the time of writing (1973) the American aircraft industry's stocks of Kirksite dies were reckoned to exceed the known quantity of tin remaining in the ground world-wide. The dies were dressed to size from cast "simply by sandpapering", possibly the same process you mention.

Michael Gilligan:

GHT rules me from his grave! - a great shame that we don't have the benefit of his views on current developments.

I mentioned ball-ended adjusters but a simpler way of achieving the same effect is to centre drill the end of the screw and interpose a steel ball. And an alternative to dowelling as a way of restraining the gib laterally is to install keeps at each end although this would often be more work than the simple dowel which I agree needs to be done correctly.

Brian John:

I don't know the detailed construction of your cross slide, but with the common parallel gib, slip-stick can be caused by the ends of the adjusting screws riding up the side of the dimple in the gib thus effectively increasing the tightness of the slide; coming back the other way the effect is reversed. The answer is either to dowel the gib to prevent relative movement or to use ball-ended adjusting screws.

The late Clifford Bower showed a design for a device similar to Michael Gilligan's link in his invaluable manual Aids to Workshop Practice, with the refinement of a detachable centre plug to control the length of the jaws' grip. He called it a "Chucked-Work End-Stop"; I think I prefer spider!

The creatures of the same name are very plentiful in the garden at the moment. More to the point, naughty boy could have invited his child to look it up - COD has "any object having radiating spokes".

Clive Foster:

In defence of of the home shop guy, the latter gets four times the fun!

The limiting factor seems to be the core size of the nut; I believe GHT managed to cut one as small as 3/8". Can you remember any details of this interesting operation? I imagine that in most cases the tool has the same profile as the thread but I wonder if there might be some advantage in a narrower tool which could cut alternately on leading and trailing flanks.