Member postings for Neil Wyatt

The secret for drilling stainless is lube, speed, never back off on the feed and bit of luck.

I have an ancient and cheap pair of plastic digital calipers. They are ideal as a hack pair for keeping in a pocket to see if bootsale/scrap box bar is 10mm or 3/8", that sort of thing...

Neil

Hi Rik,

What sizes in the pack - is it worth a special journey?

Neil

Andy

> Does anyone actually use a unijunction transistor outside of those demo kits? I'm not sure myself.

Probably not

Transistors are great fun. I have some carefully guarded germanium ones that are destined for a replica 'Fuzz Face', but the best invention for hobby electronics in my lifetime has been the logic-level power FET - switch 30-A with no heatsink

Russell

The reason I suggested the 'choice' is you can make so many things today by just following a circuit and wiring up the bits with no theoretical knowledge at all.

I tend to 'play' with the bits, but occasionally they bond with each other and make something useful. But most of the time my electronic projects are continually evolving prototypes that never get finished.

Neil

With electronics today the big choice is between making things and learning how things work.

For most things you want to make, you can get a custom chip, it's datasheet and build a reference design.

If you want to learn how things work, then the 'Art of Electronics' already mentioned is the way to go. Buy a small breadboard kit from maplins and some 'grab bags' of mixed comonents - or even one of the cheap GCSE learning packs which will entertain for a week or two. I still get pleasure from breadboarding something like a simple relaxation oscillator with a unijunction transistor and 'proving' the waveforms. I even bought a kids 'electronics' set at a boot sale for £1 and enjoyed getting the 'crystal' radio to work. - the forty foot aerial helped

The other area where you can really get drawn in is programming microcontrollers. I'll let you explore the possibilities for yourself.

Neil

Those were the days, when the packaging was better than the contents.

Neil

I went to visit Sir John and pick up a fabricated gear hobber in need of some TLC. I saw the prototype mini-lathe tailstock lever modification and the armature of a very strange squirrel cage motor that had suffered some very strange damage!

I can also testify that the legendary temperature gauge is not exaggerating. It does depend where you are relative to the burner, but near to it I reckon its well over 40 degrees and I had to take my jacket off stood at the far end of the shop!

Neil

&" plus machining allowance should be OK on a mini lathe. This was a nominal 6" x4" block. Pythagorus will tell you that's over 7" across the diagonals and I had to grind a small facet at each corner. (sorry I keep using this pic to convince mini-lathe doubters).

A 1" raising block for mini lathes could be a good project/seller.

There's also "lathing in the mill" - I hope to carry an article on this in MEW soon.

Neil

Welcome aboard Chris,

I'm sure someone will be able to advise, but mean while you have a PM.

Neil

One frustration with Ivan Law's excellent little book is the lack of a formula for teh base circle dimensions.

I'm sure Andrew Johnston won't mind me sharing this gem, which should make trignometric calculation of button sizes much easier:

The diameter of the base circle is defined as the PCD times the cosine of the pressure angle.

Neil

I don't know if Anthony will remember, but several years ago I met him at MMEX and said I loved his designs but they all had 8" flywheels (requiring the gap on a Myford), too big for the 7 1/2" swing of my mini lathe.

So is this all my fault?

Neil

For an entertaining diversion related to this subject, try and track down Last and First Men, by Olaf Stapledon. A classic of early 20th Century science fiction.

Neil

Hello All,

I received an email from Grahame the illustrator today:

"Regarding drawings, if you can send PDF or EPS they’re probably the most reliable formats for me to open – sometimes I can open DWG & DXF but it depends which version of which program was used to create them. I have no problem working from hand drawn scanned images, JPEG’s are fine for those."

Note that images have to be in eps to be used in the magazine, so if the originator (i.e. you) can do the conversion it makes it much easier to avoid errors. I have three programmes (Turbocad, Corel and TotalCAD) that can open DWG and DXF - but all three fall over on some files and I can't always generate a decent PDF.

But YES Grahame is quite happy to work from clear and well-scanned hand drawings.

The one thing we can't be sure of handling are CAD file types, as there seems to be no guarantee of compatibility and most programmes have flaky pdf generation.

Neil

The rebuilding article is in my albums.

As someone who has wanted to build a lathe since reading 'Building a Dead Centre Lathe' in Model Boats/RCM&E or something like that as a teenager, I have an unused pattern in my workshop with an remarkable resemblance to the bed of an Adept.

Steven, if you are serious about model engineering DO look at the other options that are out there.

But DO keep the Adept somewhere, as one day you will have the skills to do something with it, and without it you don't have the option of doing so.

Neil

If you study figure 89 on page 113 of Ivan Law's book, it becomes apparent (after sufficient brain-wrangling) that the centre distance and infeed can be calculated by a certain amount of extra trignometry or by a graphical method (on paper or computer screen).

Darn it, it's easier to do than describe -does this help?

WARNING - INFEED DISTANCE IS WRONG - I SHOULD HAVE DRAWN AN INNER CIRCLE OF RADIUS 1/2pcd-DEDENDUM AND MEASURED FROM THAT!

Otherwise this is correct for 14.5 degree 56 tooth gears at 1DP.

The basic distance between buttons is calculated from knowing the length of the arc between two opposing pitch points either side of a gap. The infeed is calculated along a line that bisects the arc between the pitch points. Much easier to draw than do the trig... just draw a pitch circle and base circle with four radii with angles between them of pitch angle, 180/number of teeth, pitch angle. Using fig89 as a guide draw the circles and measure off the diameter, spacing and infeed.

I know this can be done, as against the odds, I made a 20-degree cutter for 13-tooth 20 DP gears. They needed very slight easing at the base of the tooth spaces, but other than that worked fine with other home made 20DP gears.

For the record my figures were

Cutter No 7.5

Teeth 13

D 4.50"

C 5.65"

E 2.25"

Neil

Hi Dominic,

Obviously a bit late, but...

Most of us mortals don't have the capacity to shear our own plate, especially of that size. Several of the trade suppliers will shear plate for you and their machines leave it pretty much flat.

The ultimate solution is laser cut frames, which don't have the distorted edge of sheared plate.

Neil

John's promised me a write up for the Myford tailstock to run in MEW. I undertstand it's slightly different to the above, but the Myford and mini-lathe tailstocks work in the same way so all that will be different are the dimensions.

Hope to do the mini-lathe mod myself in due course.

Neil

Excellent piece of public art.

A year or two ago I worked with a nice guy called Adrian Moakes. He made us these gates for Moseley Bog (follow the second link if you area Tolkien fan).

He's into some really serious metal fabrication (he bends and welds all the tube himself), and his maquettes of this and other sculptures were such wonderful bits of silver soldered fabrication.

Neil

I have to say, you lot don't have a great deal of imagination. Why not turn it into a lathe?

ME 2408 17 July 1947 pp. 57-60.

Neil

The jackshaft cranks on my shunter are split and clamped to the ends of the shaft and taper pinned for location.

This makes them removable (the bearings are located in holes in the frames and can't be lifted out of hornblocks).

These arrangements are exactly as the prototype.

Neil

Thanks Billy,

I wasn't thinking of clocks, I wonder what it was?

Neil