Member postings for Norman Billingham

My VMC mill doesn't have a spindle lock and the ER collet chuck doesn't have spanner flats, so I had difficulty tightening collets especially at the smaller end of their range. The answer was to swap the closer nut for a ball-bearing version (I got mine from Arc Euro). Reduces the tightening torque dramatically and I can get things more than tight enough just by holding the quill pulley with one hand and the c-spanner with the other. I had planned to grind flats on the chuck but there's no need now.

I think the drive for battery powered tools comes mainly from site safety considerations - low voltages and no trailing leads. Mains powered is hands down better for serious drilling and sawing - though I wouldn't be without my cordless drill/driver.

I use the green ones, though not as feeler gauges. The trick I was taught many years ago for setting a milling cutter was to dampen the paper with a bit of oil (or saliva) and stick it to the work then lower the cutter till the paper is dragged off, when you are within 0.001" of the work.

My green ones measure 0.001" + roughly 0.0002, - 0.0000 using a Mitutoyo micrometer.

If you really want to understand cutting fluids in depth, there's a full account in "Metal Cutting Principles" by M C Shaw - the second edition is from OUP in 2005 and chapter 13 is the one to read - though not an easy bedtime story. Its expensive, though there are (probably illegal) download versions on the web and occasional bargain copies on ebay - especially of the first edition.

Apart from the things already discussed there's chemistry involved, though more so at low speeds in things like tapping and broaching - cooling seems to be the most significant thing in high-speed operations like turning and milling, which is why some operations use blown air.

Shaw also discusses in great detail the different cutting mechanisms in brass and steel. Basically steel is ductile and fails by compressive shear, whereas typical "hard" brasses are brittle and fail by repeated cracking ahead of the tool tip - which is why brass "sings" as it is cut and produces tiny spicules of metal. The process in brass is essentially unaffected by cutting fluid.

A lot depends on what your silver solder wire actually is. Silver solders come in lots of grades from "extra easy" (mp 670) up to "hard" (mp 760). The normal braze alloy for model engineering is AG455 which melts at 650. If you use that with EF flux it's pretty much self-indicating - the flux will dehydrate to a white, fluffy powder on heating and turn to a clear liquid when the work is hot enough to melt the braze alloy. So apply flux as paste, heat gently till it dehydrates then as strongly as possible until the flux turns clear, then apply the alloy - use the work not the flame to melt the alloy.

I'd be very cautious about using house bricks for a hearth - they can contain a fair bit of absorbed water which boils and cause bits of brick to come flying off. The compressed vermiculite blocks are good or you can get proper firebricks very cheaply. With half decent insulation, a MAPP torch should have no problem brazing a job like that.

It certainly still exists - the SMEE archive has a copy, but as far as I know it's not online anywhere. It's occasionally played at SMEE on special occasions.

I used to do bits of consultancy work with a company which makes intraocular lenses for cataract operations. They were turned to shape from acrylic plastic using a CNC lathe with diamond tipped cutting tools

We teach students on our basic course at SMEE to make Polly. So far I think we've had about 120 made. We use copper tube to make the boiler and just give it a wash through with hot water to remove flux residues after brazing in the end plates. We've never had a problem. It's actually more important to wash thoroughly when you've used soft solder with Bakers fluid flux as in soldering the firebox to the base - chloride residues from the flux can be corrosive to steel.

Good luck with the build

If you contact SMEE you may be able to get hold of a copy of "100 years of Model Engineering" - a history of the Society published by SMEE in 1998 - many of the people you mention were members.

The Society has also recently published a book by Roger Backhouse on Jim Crebbin - readily available

Edited By Norman Billingham on 17/02/2020 17:06:17

I had the same problem with the steam chest cover on a 10V. Some of the castings Stuart supply are chilled and glass hard. You can return it to Stuarts and they will supply a replacement. If there's enough metal left it's also possible to soften the casting by heating and then cooling slowly - but I'd just get a new one from Stuarts.

Incidentally the "gold" coating is actually vacuum deposited titanium nitride (TiN) and it can be a mark of very good but also very poor cutters

I think a lot depends on what kind of model you have in mind. On our training course at SMEE, for beginners to the hobby, we build “Polly” the first of Tubal Cain’s models. In many ways this is an ideal beginner’s model because it involves a huge range of techniques, sheet metal work, forming and flanging, brazing and soft soldering, turning, milling, spring winding etc, leaving students well set up for whatever they may want to do next. It’s also built more or less completely from stock materials so that mistakes are cheap – and when finished you have a fully working engine and boiler to show off. On the other hand many modellers only build stationary engines, which may never be run on steam, so that they don’t need, or want, to learn the sheet metal techniques. Many people start with something like the Stuart 10V which is a nice model. Its disadvantage for a beginner is that mistakes are expensive – if you make a mistake with a casting you have to order a new one and wait for delivery before you can move on.

I wouldn’t worry too much about scale. It’s easy enough to build small things with big machines – we’ve seen Pollys built with everything from Cowells to Colchester lathes, and from micro to Bridgeport mills,

I help to run the SMEE Polly course, where we teach the basics of model engineering by building the Polly engine. I'd guess we've seen approaching 150 of them built by students over the years we've run the course. Forming that boiler seam neatly in rolled sheet is pretty tricky and we've always avoided it for beginners by making the boiler from 1 3/4" copper tube. Stronger, and very much easier to get a neat and leak-tight boiler. We supply a piece of the tube to our students, but you can use 42 mm plumbers pipe which is a bit easier to find in short lengths - though you have to change quite a few other dimensions to avoid problems.

Oh dear - I do seem to have started a hare running here with an attempt to be helpful.

To be clear, I wasn't suggesting burning kilos of plastic, or tons in an incinerator. A piece of thin film about 2-3 mm square held on the point of a pin in a small flame is all that's needed and the risk from emissions is non-existent. Before IR spectroscopy became readily accessible, the flame test was a routine starting point for screening plastics. A version of it - the hot needle test is still sometimes used in heritage conservation, though largely superseded by spectroscopic methods for those who have access to them and can get suitable samples.

If you want to be sure, strip a bit of the film and put it in a flame. PVC will char and produce acrid fumes, PE will burn away smelling a bit like a candle and with almost no char. Incidentally the gas released from PVC is not chlorine, it's hydrochloric acid. You can double confirm by putting a bit of ammonia solution nearby - the acid released from PVC will produce clouds of white smoke - though you shouldn't need to do this - the difference is very obvious once seen.

Would one of these generate enough seal and pressure to lubricate a Myford lathe through those ball-seal oil nipples? If so, which model is best?

You could also look for York abrasive blocks - same thing but different maker. Cromwell tools have them for £4.40 including VAT. Other suppliers too.

Not sure if it counts as advertising - in which case i'm sure mods will remove, but there is a recent book by Jorg Hugel called Drill Sharpening. It covers all the details of setting angles for cone and four facet drills in great detail and has a CD of spreadheets which let you see the effects of changing setting parameters for yourself. It's only available from SMEE and all profits go to the Society. Not for the mathematically faint heated. A message to the SMEE secretary via the web site will put you in contact.

If you are able to get to London, you could look at the SMEE model engineering basic training programme which starts in February - details on the Society web site. Part 1 is three Saturday sessions covering setting up a workshop,hand tools, choosing lathe and milling machines, tool sharpening etc etc. Part 2 which runs for six Saturday sessions covers all aspects of building a small steam engine and boiler. Friendly atmosphere and lots of good advice.

I still have copies of Jorg's book available and SMEE can accept payment via BACS or Paypal - we don't do enough trade to warrant e-commerce but we are in the 21st century!

I can be contacted via the meetings address at SMEE (meetings AT SM-EE DOT co DOT uk)

The book is quite densely mathematical but maths methods have also moved on since 1913, with the availability of Excel and Maple

Incidentally if you are close enough to London to visit Marshall House, SMEE also has all back issues of ME 

Edited By Norman Billingham on 09/01/2019 09:53:17

Edited By Norman Billingham on 09/01/2019 09:55:12

I'm no expert on motors but I suspect not as a general rule. If the two motors are connected in series then the same current must flow in each of them. If they always have exactly the same load then that might work, but if the load on one changes then the current it draws must change and that must surely affect the other motor?