Member postings for Lambton

I wonder if the designer of the engine ever found any M8 x 0.75 cap screws?

I was always taught to check the availability of commercially made fasteners and components before finalising any design. On the odd occasion where difficult components were essential, ensure I had found a supplier prepared to make them at an affordable price. These points are not always appreciated by customers, arty designers or inventors.

Just because there is an ISO standard for a particular fastener, in this case M8 x 0.75, it does not mean that any components are manufactured to it unless there is sufficient general demand. The same applies to BS and other specifications for steel, aluminium etc.

I have a British made Arrand boring head which is excellent. I do not think the company still exists which is a great pity.

Ken,

It is worth getting an original Myford handbook which can be obtained from "new" Myford. Also try the net as there are some PDFs of Myford manuals available for free.

Neil Lickfold describes the exact method used by a long establish gunsmith that I worked for part time for a number of years following my retirement. It is used on shotgun barrels that have brazed or silver soldered ribs (most modern guns) but cannot be used on older traditional “English guns” that have soft soldered ribs because the solder will not withstand the temperature involved. It works very well but the temperature has to be controlled within fine limits if a true black colour is to be achieved. The main snag with this process for gun barrels is that it does not colour brass or silver solder.

"English type" guns with soft soldered ribs have to cold blacked which is along and labour intensive job involving swabbing the barrels with a hell brew containing diluted aqua regia and certain mercy salts. The swabbed barrels immediately gain a fluffy black coating which is left for a few hour before being removed using a soft rotary wire brush. After the fluffy coating is removed the steel will be starting to take a black finish. This process is repeated up to probably ten times until a satisfactory black surface has been established.

Neither process confers much rust resistance and the newly blacked finish has to be protected by bees wax or special oils. Many shot gun barrels that I have blacked were rusted in places due to blood from game contaminating the surface.

The small bottles of blueing of blacking solutions sold by some gunsmiths are only intended to do very minor touching up and not to treat large areas. Similar reasoning to small pots of car touch up paint.

We also applied brown finish to Damascus barrels but this is a work of art and need a lot of experience to produce a professional l job.

There is an excellent book “Firearm Blueing and Browning” by R H Angier dating from 1936 that give full details of the various processes and chemicals used . Copies are available from Amazon. However be warned in 1936 people were not afraid of using all sorts of substances that would make a safety office go “up the wall” today.

I use ball bearing nuts for ER25 and ER30 collet chucks. They require less effort to get the proper grip on the work piece than a plain nut. The ones fro Arc are very good and only about £1.50 more than standard ones.

John, I suggest you try one as I am sure it would be of help to you.

KWIL

Good point but I guess RDG source their cheaper ones from a similar Far Eastern source as Chronos.

Perhaps someone from RDG could confirm?

Grotto,

I am glad you have the original handbook.

Yes the Ian Bradley book is worth having as it often clarifies issues not too well covered in the Myford handbook. For example it clearly explains the bull wheel locking system complete with a very clear drawing. It is also very reasonably priced.

Another useful little book on the ML7 is A Man And His Lathe by L H Sparey as it contains details of lots of simple accessories that can be made to enhance the lathe's capability. Modern reprints are available from TEE Publishing but the original photographs are not very well reproduced.

Buy a handbook!

Jason B is quite correct 8.8 bolts will do fine. What you have to take into consideration are the properties of the material and the design of the item the bolt is being screwed into. There is no point in using ultra high tensile bolts unless the mating material has similar strength or if the action of tightening the bolt tends to spring the tool post open.

I have a 1929 catalogue of Lehmann Archer products. In the preface there is an account of how the British Association Committee, in about 1881, decided on a screw thread system better suited than Whitworth (below 1/4" for instrument applications. This became our familiar BS system.

Mr Lehmann was approached by the Committee to produce the very first BA taps and dies in the range 0 - 16 BA. In order to do this Mr Lehmann had to "invent" machinery capable of generating the necessary, at that time, strange metric pitches.

The BA system came into general use in about 1887 after Her Majesty's Post Office Telegraph Department placed large orders for taps and screw plates.

So Jim you may have no fears about the ancestry of your Lehmann, Archer and Lane taps and dies.

By the way in 1929 a set of BA taps and dies 0 - 10 complete with tap wrench and dies stock contained in a wooden box coat 66 shillings = £3.30

JS's solution to the problem is probably OK for all practical purposes but it will produce threads with small errors of 0.16% & 0.17%. Try it and see if gives the desired result as it is an easy procedure as a 25 tooth change wheel is a standard Myford item.

It may not help much but I think you will find that 12.5 is not a pitch used in the NTP thread series. Do you mean 11.5 which is a standard NTP pitch?

For anyone who want to know all about model engineer's threads, including discussion of metric and BA alternatives I recommend them to refer to Chapter 24 of The Model Engineers Workshop Manual by George Thomas.

Ian SC is quite right - use a suitable high tensile bolt. The steel used for these has exactly the right properties for a chuck key i.e. toughness (rather than hardness) and good resistance to torque. No heat treatment is necessary.

Mild steel would do as a temporary measure but why go to the bother of making a key from a material that is not suited to the application.

James,

I recommend that you buy a copy of Using The Small Lathe by L C Mason quite the best primer for new lathe users that I have seen. Reprints are available from TEE Publishing Ltd.

www.teepublishing.co.uk

Rainbows,

Sound as if John S is offering to make you a new spindle .....

Metal spraying followed by grinding back to size is a much better bet than electroplating. Over the years I have had several shafts (not lathe mandrels) restored very satisfactorily by this method. I used companies in Northampton and another in Luton. Try a web search for your area.

Another good reason for fitting a NVR between the incoming supply and the Dewhurst switch is to relieve the Dewhurst of having to act as the on/off switch and just leaving it to select forward or reverse (with the power off). Dewhurst switches are from a long ago era of electrical engineering and although they were robustly made they are susceptible to contact arcing when used to make and break a circuit driving a motor which eventually causes the contacts to fail due to burning.. Sooner or later they will fail. With a single phase motor this failure often shows when the motor buzzes but fails to rotate because the start winding is not being energised. Over the years I have experience several such failures with Dewhurst switches failing through burnt contacts.

When "fed" via a NVR (or other switch) they will last forever as the contacts will not be subject to arcing.

Lee,

As the centre in the headstock rotates with the work piece it does not need to be hardened mild steel will be OK. In fact MS has the advantage of being capable of being easiiy trued up before use as described by Brian.

When turning between centres watch for the work warming up and expanding along its length requiring the tailstock end to be adjusted accordingly to prevent any distortion, particularly if the work piece is of small diameter.

I am very sorry to learn of this accident to a young lad. I hope it does not put him off using a lathe safely.

We can all learn from this by downloading the link below that was included in the HSE press release. It explains in a very clear way the right and wrong ways to use emery cloth on a lathe. I know that we are perhaps older and wiser however we are sometime tempted to take a short cut.

**LINK**