What did you do Today 2018

Today I repaired a Mills Mk1 1.3 model diesel engine that I picked up for $20 at the recent Aussie Nationals.

It ran quite well until I made a spinner nut with a tight thread that sheared off the cheesy crankshaft. It is threaded 3/16" Whitworth.

To make a new shaft is another day so decided to tap the broken shaft for a stud or screw and picked 4-40 as I have plenty of shcs in this size plus taps and dies. (3mm was the other option)

First problem, how to hold the shaft so made a collet from a scrap of aluminium alloy with a diagonal slit, it worked OK but required lots of tightening of the 4 jaw chuck - next time it will just be in 2 halves.

Once centered it was easy to drill and tap the shaft so decided to make a prop drive washer to fit over the pesky pins that were fashionable in 1947 but ruin a good propeller.

In the end it all worked out so test run in a few days when the neighbours are at work.

* Danny M *

3/16 Whitworth is one of those threads (like the US 10-24 threads) that is really too coarse for its diameter. If it's made in a hardened shaft it's ok. If it's soft, the small core diameter isn't really strong enough.

DAMHIKT!

With your collet, whether cut from square as you have, or from round as I do, after cutting through the side continue about half way through the other side, things get a bit more flexible, not so much heaving on the chuck key.

Ian S C

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... a fact recognised by the British Association for the Advancement of Science.

MichaelG.

I seem to remember that Renault formula 1 cars were fitted with some form of inertia/harmonic damper to their chassis, a few years ago but it was outlawed by the FIA because it gave them an advantage over every other team because none of them had thought about the idea themselves.

Dave W

Dave W, could that have been an "inerter damper"? That was McLaren F1 who tried it, they called it a "J" damper. I believe there work was based on something Oxford uni came up with.

I did some work on an inerter damper before I decided to stop working for a living, must ask if the how its going.

John

Screwcut a coarse thread (About 40mm pitch) on wood.

It did require a modified changewheel setup.

The gear ratio was too high to drive it from the spindle so I had to fit a handle to the input of the gearbox that drives the leadscrew,

Les.

I was involve in some of the trials work for the Harmonic dampers fitted to the Seaking rotorhead. Thats some big dampers!

John mc, yes it is a 900ss, it should be black and gold, but I liked the silver/ blue, not right for the year but so what, I don't have it now as I swapped it for a Harley 45

Les Jones 1, is that a Chester 9 x 20 Lathe? No real reason for asking, I am just curios.

John MC, thanks for the correction, memory not as good as it used to be, I remember it was a formula 1 team but confused with which one, I remember the other teams all complained of unfair advantage so FIA banned it to keep the peace.

Dave W

Hi Ian,
It;s a Chester DB-10G wich I susspect is based on the 9 x 20. It has had quite a few modifications made to it.

Les.

Thanks Ian. You way seems a bit easier than my 'Plan B' which was to drill the block for locating pins and split the thing in half. As it was a one-off job nothing lost and a lesson learned.

The reason for the square collet is simply that I had an off-cut that exceeded the diameter of the crank-web and was of perfect length for the job. With a 4 jaw chuck I thought 'well, why not?'

My biggest mistake was to break the crankshaft in the first place!

* Danny M *

Last week I attended Axminster 5 day Engineering course, met a fantastic bunch of chaps and had a thoroughly enjoyable and productive time

The 6 cylinder IO - 470 Continental aircraft engines that I used to over haul many moons ago had a pair of loose fitting dampers mounted on lugs half way along the crankshaft, the maintenance manual calls them 6th order counterweight assembly.

Today a group of the eown's population gathered at the local War Memorial and there was a short service, 2 minute silence, then the church bell was rung 100 times.

Ian S C

Edited By Ian S C on 11/11/2018 12:56:04

Today I put my newly repaired 1947 Mills 1.3 onto the test stand.

With an ancient 8"x5" laminated wooden propeller and a Cox 0.049 spinner nut it started and ran sweetly within four flicks.

Sweet music.

* Danny M *

I made a quiche using a Staffordshire Oatcake for the base.

A fine piece of culinary engineering.

I needed a nylon bush for the clutch release shaft on the tractor, but had no suitable piece of nylon rod with which to make one. Went online to look for some, tried the local major hardware/homeware chain (Bunnings), no joy, tried the local engineering supplies (Blackwoods) which had a 1m length of 30mm natural white nylon rod for about $40, tried the local bearing suppliers (BSC), they could supply a 1m length of 50mm natural white nylon rod for about $100, but they put me on to a local plastics engineering place. Gave them a call, went over and walked away with a 300mm length of 30mm and a 300mm length of 40mm all for $11.20. Happy chappy. Bush now made, but note to self - avoid turning things out of plastic in the lathe, it makes a bigger mess than metal and it's hard to get a good finish without razor sharp tools. Also found HSS better than carbide tipped tools for what i was doing.

^ in extremis I use nylon rolling pins

Spent a couple of hrs yesterday on my box twin oscillator. Soldered the end blocks on & started cleaning up...

Soldered...

Process of cleaning up...



Lot of elbow grease needed yet.

George.