A RETURN TO THE WORKSHOP 
PART 6
BY JOURNEYMAN

Model Engineering in the Styx 6 - Spring

AT LAST the sun has returned to the Styx and since we are south facing we have had one or two shirt sleeve days to make a start on preparing the soil for the veg. crops. Sand and muck have been spread to continue the process of  improving what was very poor ground, and the daffodils are in bloom. The Tamar Valley between Devon and Cornwall used to be a huge market garden, sending millions of early daffs all over the country by rail, and thousands must have dropped off the wagons taking them to the stations as the hedgerows are full of them mingled with the early gorse bloom, a real joy after the hard winter.


Father Christmas

This grand old chap is usually very generous to model engineers, and in the last two or three years he has brought me some super presents. Last year he brought me an immaculate Myford 254 long bed lathe, equipped with camlock spindle nose for the chucks and face plate, a taper turning attachment and fixed and travelling steadies, despite my late father-in-law having to provide a bailout to the Bank of Lapland so that the poor bankers of the frozen North would not have to forego their bonuses.

Although we have two very wide inglenook fireplaces, this year Santa saved himself a lot of trouble by bringing something smaller. There sure enough on the hearth this 25th was a nice heavy parcel, albeit with Parceline tape around it, concealing a digital readout system for my milling machine. This will be a godsend saving me having to do all that plus and minus mental arithmetic, and the in-house computer boffin will be able to help me to tap in all the settings to make it easy for me to use. I’m looking forward to being able to drill a circle of holes without having to set up my rotary table.

I’m currently engaged in attaching the scales and reader heads and this needs a lot patient work to ensure that the scales and heads are free running along their full lengths and don’t collide with any screw heads or other obstacles. The x-axis is done and the y-axis is under way.

It’s been a lot of fun spending a lifetime’s savings, especially as I didn’t even know that I would be returning to the hobby, and my love of machines and tools has always been with me. When I closed the forge business down I sold 12 tons of heavy machinery, including two forging hammers which together weighed 5½ tons, and a huge Mitchell of  Keighley lathe (8 1/2in. x 60in.) weighing 2 tons, all of which have been ‘recycled’ into F.C.’s presents. Of  them all  I most regret parting with the lathe as it was such a super big beast.

I also sold a Kerry AG Mk.2 lathe but it would not have been of much use as it was very worn on all its slideways, and a No. 6 flypress which I have regretted ever since. Doubtless the Kerry could have been restored, but only with a great deal of time and effort, and probably some expense as the bed would have almost certainly have needed regrinding


Boxhill

Progress is slow but steady. I’m continuing work on the reversing gear. The weighshaft and its bearings are in place and I’m working on the reversing and lifting levers. It must be just my lack of knowledge and experience but I find all such parts very complex,  fiddly and time consuming, and always look at award-winning work with awe, wondering  just how such precise and finely finished work is accomplished. However, working out a sequence of operations is part of what I enjoy, and when finished leaves me feeling that training, whilst important, is not all.

I have decided to leave setting the eccentric rod dogleg offsets until I have the expansion links hung from the levers and will then be able to see how the alignments lie. Having close fitting links and die blocks will contribute to a better set-up.

To make the reversing and lifting levers I decided to work off the end of the bar as this would allow for most of the operations to be done while having a solid point of fixing. For  the reversing lever I used 5/8in. square bar and all went well, although it involved quite a number of operations and at times I almost lost track of where I had got to, and at one point thought I had machined away a chunk that should have been left!

For the lifting levers I used ½ x 3/8in. bar and needed to mill the 3/8in. thickness down to 5/16in. before marking out. On looking lengthwise along the bar after machining I noticed that the machined part had taken up a slight curve, reminding me of something I had read in a back number of ME Magazine.

The article was discussing the various metals that we use, pointing out that in the process of cold drawing, stresses are set up in the surfaces layers of the bar which would lead to curving of the bar if one side is machined as the stressed metal is removed. Clever clogs didn’t take enough notice of this little bit of advice and so gave himself a problem. The suggested solution to this in ME was to gently anneal the bar before use.

I have already mentioned my intention to remake the expansion links in gauge steel. My mentor says this gives durable working surfaces without having to harden and since I have no experience of  hardening it makes sense to follow his advice.

I decided to machine them using my 6inch rotary table and had gauge steel bar stock of  ¾ x 3/16in. This meant that the axis of the bar had to be set at right angles to the diameter of the table, and with a radius of curvature of the links slots being 3  7/8in., this meant the link would be beyond the edge of the table.

How to set it up? After various trials with machine vices and considering making the jig designed by Martin Evans for the job, I came up with the arrangement shown. There is a piece of aluminium under the gauge steel to indicate when the milling cutter is right through to avoid cutting into the steel plate. This plate is a piece of  6x 8 x ¼in. black mild steel from the forge. It’s not precision rolled, but after vigorous machine wire brushing and checking for flatness on a surface plate it proved to be adequate for the job, and is bolted down using the t-slots on the table.

All the machining can be done by indexing methods. The die blocks will be done in the same way.


Method and technique 

I’m getting to the end of looking through all those back numbers of ME magazine. The range of topics covered is legion, including doing a particular job in several different ways, and one thing has emerged that has become of great value to me. It’s obvious that whether contributors have had extensive engineering  training and experience or not, they have worked out their own ways of doing things and then given us the benefit of their knowledge, thereby telling those like me who are learning the skills as they go along, that there is no single way to do a job, but you can rely on your own gumption to achieve the desired end.

When milling machines were not common items in people’s workshops, ways to do everything were worked out just for the lathe with suitable attachments. The ‘King of machine tools’ always proved itself capable of doing the job, including making the attachments, of which so many have been featured in ME. A milling machine opens all sorts of possibilities to do jobs in different, and  frequently quicker ways, often because there is less complicated setting up to do, so I am growing in confidence in relying on working out my own ways of doing things.

They may not be the quickest or most efficient ways, but if they get the job done, hopefully first time, then that is all I want. I shall always need my mentor, not least because he can always show me such good methods and techniques, and we can enjoy ‘grumpy old men’ exchanges over those dullards who seek to take away our independence with all their rules and regulations.



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Spring comes to the Styx

Site for ‘See-Saw’ railway

Expansion link. Back outside edge machined

Expansion link. Machining front outside edge

Expansion link. Machining setup

Expansion link. Machining slot

Expansion link. Ready for hand finishing

New DRO being fitted to the milling machine

Model engineering in the Styx -

Part 1    Part 2     Part 3   Part 4   Part 5