Member postings for Marcus Bowman

Charles,

The other reason I redraw is that I work in metric units and use the drawing stage to convert the dimensions. That's an entirely personal preference. My clock gear cutters are all Module rather than DP, my machinery has metric calibrations, and my thought processes work better in metric units. That does have the benefit of forcing me to check dimensions on original imperial drawings actually make sense, and redrawing allows me to alter components so that dimensions end up with convenient metric sizes, and components which can be manufactured as simply as possible, as well as putting my own 'fingerprint' on the design. Ever the tinkerer...

The essential original dimensions should all be available from the drawings, of course, and the components should all work together as drawn, and that is not something which is affected by the measurement system.

Marcus

Charles,

I have been sufficiently interested in this project that I have been collecting the pages and drawings with a view to doing the same as you and creating 3D CAD drawings and an assembly. The project is not top of my list, but I do like to do the preparation at leisure as I find that gives me enough thinking time to spot and solve the problems, as well as to make the odd modification. It also helps me understand more about the mechanism and the project.

I had planned to draw the parts in Fusion 360, but may use the 'community' version of SolidEdge, as that does not suffer from the unfortunate restriction on editable parts imposed by the otherwise excellent Fusion (which I do use a lot for other drawings).

I would be interested to know what challenges lie within the drawings.

Marcus

Some Hewson GWR 57XX info and drawings here, for the new version:

https://modelengineeringwebsite.com/GW_pannier_tank_drawings.html

Marcus

I ended up 3D printing large cones into which I pressed ball bearings. They are then pushed into each side of the central hole in a reel. They are mounted on a rod with screwed ends and sit in an 'A' frame supplied with my printer (but easy enough to make, as I think you have discovered) sitting to one side of the printer, on the bench. That gives a nice smooth naturally curved path into the extruder, and that arrangement has always worked for me. It's the deluxe version of Bazyle's arrangement. If you go this route, print several of the cones, to save having to swap them into the next reel you need to use. I did find one make of reel needs a different size of cone, but its easy to print a size to suit.

I use the same mid-price brand of filament most of the time (SUNLU). Works for me, so I tend to stick to that brand. I have occasionally used other brands, but never the cheap stuff.

Marcus

Welcome, Paul. Always nice to see more folk joining in. Lots to see on this site, and lots of opportunity to pitch in your tuppenceworth.

There's a Forum Topic on bikes; and lots of interest in cars and bikes - as well as just about everything else in engineering.

Regards,

Marcus

This month's issue of the Horological Journal (from the British Horological Institute) contains a multi-page article by Mark Frank outlining some of the thinking behind the design. Stunning photographs, and lots of information about the various modules which form the 'complications' incorporated into the design.

Marcus

You might try www.gaterosplating.co.uk

They sell plating kits, and the nickel plating kit contains a dry powdered acid. They sell replacement packs of chemicals for their kits, so may sell the cleaning acid separately. I have one of their kits.

There are several other suppliers of similar kits and possibly replacement chemicals, such as

www.frost.co.uk

www.classic-plating.co.uk

and Chronos.

Marcus

Nice website/blog, Tom Senior. Useful and informative photos. Thanks.

Marcus

I use, and can thoroughly recommend, the ACCUPRO single-flute solid carbide 'router' cutters for aluminium, sold by MSC Industrial, BUT, they are breathtakingly expensive, and they have plain, metric, shanks. Wickedly sharp, so watch your fingers.

I endorse the comments by Brian Howett 2, re: climb milling, which is essential for the best finish.

Lubricant helps too, but can be neat cutting oil if the stink from WD40 or paraffin is too strong.

The earlier comments about material grade and provenance are spot on.

Run the cutter as fast as you can, and apply a decent feed rate, for a finish as shown by JasonB.

You might find it useful to read the fairly comprehensive advice and study the photos of machining setups in the little book 'Building a Steam Engine from Castings' by Andrew Smith (the modern version has been revised by Pengwern). It's widely available for less than a tenner. Try TEE Publishing, for example.

The previous replies to your questions mention the standard ways of doing the job you are tackling, and these are much more likely to avoid the common pitfalls.

My own inclination would be to order a replacement casting from Stuart Models, and put this one down to experience.

Its a nice engine and a good starter project.

I have had a test rig sitting on my bench for a while. It is a half-second pendulum suspended on a carbon fibre rod, and has a samarium-cobalt magnet attached under the pendulum. It originated with a series in ME by Dick Stephen. I built the rig because here were problems with the timing circuit and I thought I could do the job another way, using a microprocessor. There is a flat coil (no centre iron) which acts both as detector and as impulser (at least that's he theory). The original used two concentric coils, one for sense and the other for impulse, but I think more than one coil is unnecessary.

The pendulum will auto-start if timed pulses are applied to the coil.

The problem is that because the magnetic field is doughnut-shaped, the pendulum will tend to move in a slightly circular or elliptical path. Restraining the pendulum will mean frictional forces probably at the sides of the ball bearing at the top of the pendulum shaft. I am uncertain whether the fore-and-aft tendency is a result of the magnetic field, or simply created by minor random sideways forces - despite careful leveling of the rig, a rigid bench, and a concrete floor.

One of the problems with this kind of system, as Dick Stephen found, is that regular pulses tend to produce over-swinging, taking the pendulum far from any intended isochronous arc. Yes; we are trying to create a stable oscillator, but it must be resonant at the pendulum's natural frequency.

I don't think that a plan to apply regular pulses to the pendulum is necessarily a good way to ensure the pendulum swings at its own natural (resonant) frequency, and my plan is to use a statistical approach to try to identify what that frequency is, then try to maintain it. That means the adjustment of the frequency of swing will be by altering the effective length of the pendulum, which is what you would do on a mechanical clock, rather than attempting to drive the pendulum at a particular frequency to force it to time.

This is not a particularly urgent project. It has been maturing on the far end of the bench since 2007, and gets attention as the muse comes upon me.

It will be interesting to see your own results.

Marcus

A handsome job.

I must say I find your last photo, showing the blue hands against the polished brass very attractive indeed.

The case turned out well too.

Marcus

Also +1 for the Sandvick.

I used to use a quality HSS scraper, but pushed the boat out one Christmas and ordered the Sandvick from Greenwood. Much better results than with the HSS scraper. The longer shaft helps, I find, and the blade is wickedly sharp (and has 4 cutting edges). A joy; in frequent use.

Marcus

Gearotic.com

Not free, but well worth a look. Takes a bit of getting into, but very capable indeed.

Marcus

I use the rule:

Up to 8mm diameter hole, drill 0.2mm undersize.

Above 8mm drill 0.3mm undersize.

Dormer recommend the following allowances:

Below 4mm: 0.1mm

Over 4 to 11mm: 0.2mm

Over 11 to 39: 0.3mm

Over 39 to 50: 0.4mm (Good luck with a reamer as large as 50mm)

The larger the drill, the larger the allowance, and I have seen charts suggesting between 2% and 3% undersize.

I agree it is best to drill smaller then bore to the undersized size, then ream, but I seldom bother under 8mm.

I also agree that a floating reamer holder is best. I use one made from the Hemingway kit. Works well.

Lots of neat cutting oil too.

Don't let the flutes get packed, so retract and clean at intervals.

Marcus

Andy,

That's good progress, and its nice to see the dial too, as that, together with the frames, gives a real sense of what the finished clock will look like.

I look forward to reading about, and seeing, progress.

Can I suggest you start a new thread for this clock? I think it would be very useful to have the posts accessible to anyone coming to the forum looking for info on the Strutt, or even just inspiration for a project. That post with the photos would be a good start, perhaps even with a sentence or two about the source of the design. I don't know how you would transfer that post to a new thread, but just starting a new one and re-posting the photos there would do, I think.

Marcus

Ah yes; time. That's an ongoing challenge, I find.
I have a skeleton movement n the bench just now, but it awaits one brass part, which is the little nut (the front collet) at the end of the minute hand shaft. I changed the design of that part of the assembly, so the nut will allow me to test my changes. It's only a very minor change, so I'd be surprised if it doesn't work. I have the base and legs ready, so assembly can begin soon, I hope. Assembly doesn't take long; its the parts for the movement which take the time. I have the drawings for a significantly amended part of the daisy wheel arrangement, so that will be the next stage, for the next movement. That's a bit away yet, though.
The Congreve movement needs the dials finished, and one finial turned. The clock stands on its own feet, but I intend to make a base for it to stand upon, although I have not yet decided on the material. Wood might be traditional, but I'm tempted by stone or even by Corian. I have used Corian (or one of the look-alike materials) for some clock legs, and it can look really good as faux-marble. Thicker sheets need to be built up in layers, though. There were some interesting photos of the Congreves built by the Sydney Clock Club in Australia, in the BHI Journal, some years ago. Their bases were made of Corian, and they looked very attractive.
So there is progress, but, as usual, it has been interrupted a little by other things which seemed more important at the time (and were supposed to be over quickly, but aren't).

Marcus

Andy,

I'm pleased to hear of your progress, and I hope you will be providing updates (and photos?) as you go along. The Strutt is, to my mind, not only an interesting clock but one which will provide a really satisfying project. 'Half way through' means you are close to being nearly there...

I'm glad to hear you joined the BHI, and you will now have access to their new online library of back issues which are an absolute goldmine of good information. Mind you; I do appreciate the monthly physical copies of the Journal; thin but beautifully produced and full of interesting articles.

Marcus

John,

You said:

The sand used was washed silica as used by the building trade. one part sand to 3 parts granite aggregate with a maximum screen of 8mm. and a minimum of dust. These materials are both easy to obtain.

I'm off to mix some cement for a small foundation for a wall, this morning, and I wonder

(a) whether you needed to exclude moisture by using kiln dried sand?

(b) why exclude dust? I have used 'granolithic' as a screed, and that is mostly aggregate, with some cement. The aggregate is described as '6mm to dust' and the dust contributes to the strength, possibly because, like a larger mixed aggregate, the different grain sizes of the sand and aggregate lock well together, and provide strength. Would that not work in the same way with the epoxy mix?

(c) Experience tells me that if I lay a screed on a floor, then work it to a fine flat finish using a float, I need to take care not to over-work the screed, because the more I press it, the greater the tendency for the larger particles to work their way to the top as the smaller particles are forced downwards into the spaces between the larger particles. That can spoil the finish, as well as (I suspect) producing a kind of layering effect, with smaller particles tending to be more concentrated further down the mix. I note that you tamped in layers. Did that help the produce a more uniform distribution of particles? Might be rather difficult to tell, of course, but I shall spend the rest of the day pondering... Perhaps someone has done tests and reported results in one of the many papers on the subject?

Great progress, though. And I agree with your thinking re: concrete reinforcement bars ('rebar' in the UK) and 'inexactly placed' reinforcement.

Marcus

I, too, have had many sites fail to reply to my messages. I took my business elsewhere. I will admit that is sometimes a case of biting off my nose to spite my face, but I resent the time wasted on writing in the first place, then waiting, chasing it all up, etc.

What's worse, though is major suppliers who invite 'reviews' and comments on their products via an automated system on their website. I have found at least one major supplier, which I use quite often, and who is well known to us all, simply ignores any comments or reviews which have any negative comments. So much for "Be first to review this product'. More time wasted trying to give genuine balanced comments.

Marcus