Len Mason's "Mastiff" - chewed from the solid

[MJM460]

Hi David, those tiny parts really make it start to look near complete.  It is a wonderful build, and I have learned a lot from your methods.

Which part of Melbourne are you in?

MJM460

[deltatango]

Yes, I can now see the time coming when I'll find out if it runs or not. The distributor, plugs, oil lines and carburetor are left to make.

We live in Doncaster, children spread around in Warrandyte, Warragul and Port Melbourne so we get around a bit!

David

[deltatango]

Sorry, clicked "post" too soon on that one. Should have said thanks for the very positive comments. Working out the ways of making bits is a big part of the satisfaction of the work.
Thanks again, David

[gbritnell]

It's been a great journey following along David. The distributor, carb and other small pieces will certainly present it as a complete engine.
I'm restoring one for a friend who got it second-hand and it doesn't look nearly as nice as yours.
Wonderful work.
gbritnell

[deltatango]

Thank you George! Coming from a master craftsman that comment is something I really value. Hope the restoration works out, and runs. I haven't built an IC engine before so when (if??) this one does run I'll be very, very chuffed.

One more tiny bit for the contact breaker wasn't even in the original design, Len Mason used a bit of "varnished drawing paper" to insulate the fixed contact tag from the case but I decided to make a more solid insulator from SRBP (Paxolin etc.). This was milled from a stub of material in the dividing head, first to width to fit the slot under the case:



then spun through 90 degrees to make the groove for the tag and a 3 mm hole drilled for the stem:



then turned again through 180 and, very carefully, milled to thickness:



This material turned out to be tricky stuff to machine, with a tendency to flake off at the slightest provocation, so the bottom bit was left at 0.5 , not 0.3 as I drew it. Maybe paper was a better idea...

Filing buttons were made to round the end:



and the final product looks like:



Paper really would have been easier but it was a nice little part to make.

David

[Ye-Ole Steam Dude]

David your completed engine is a masterpiece and this has been a great build thread to follow.

Have a great day,
Thomas

[gbritnell]

David,
Over here we have a supplier where we can get Teflon sheet in different thicknesses. I use it for just the application you are describing.
gbritnell

[jadge]

Excellent job on tiddly parts! 

In the UK a generic name for SRBP/SRBF is Tufnol. It comes in two forms, resin bonded paper and resin bonded woven cotton fibre. The later has much better mechanical properties and is sometimes better in terms of electrical insulation. I've used the resin bonded fabric version a lot in power converter designs. Although it can chip, it is less prone than the resin bonded paper version.

Andrew

[deltatango]

Thanks Thomas, I'm pleased that you like the build, all and any encouragement helps!

George, I've tried machining Teflon in the past and it hasn't gone well (always ran away from the cutting edge), maybe I need to work out tool angles etc?

Andrew, thanks. Yes I would have been better off using SRBF but the other was what I had. Mostly due to sloth but also influenced by having to pay RS $52.38 for a small sheet of 4 mm thick Carp brand.

One more not quite so small piece is the contact breaker base plate that also serves as the advance/retard lever. The last time I waggled one of these it was on the handle bars of a 1950 Matchless G80...
I printed the outline at 1:1 and used spray adhesive to stick it down to the MS sheet. This in turn was secured to a bit of sacrificial Masonite (hardboard) with double sided tape and the whole lot clamped to the powered rotary table. After aligning the table axis with the axis of the Aciera vertical head the various radii could be cut, starting with the largest:



then the slot for the locking screw:



and the base radius (matches the radius of the case):



Each time the RT software was used to control the angle through which it oscillated. Small depths of cut were in order but the whole job didn't take very long once set up and the results are probably better (and quicker) than I could manage with hacksaw and file. The last cuts were straight ones to define the other edges:



A little bit of free hand filing at the ends and we have:



David

[Roger B]

Still following along and enjoying      Excellent work on the ignition components 

[deltatango]

Thanks Roger!
More ignition bits in this post but no machining. Having finally got the 3D printer (Prusa i3 clone from a kit) working in the summer I went back to use it more recently and had all sorts of troubles. I finally realised that in summer the room temperature was regularly in the low 30s C and so just the right conditions for 3D printing. In June or July it might be 15C, not so good, so I built an enclosure that could be preheated and would keep the drafts off the prints:



Note the high tech preheater... There is also a transparent poly-carbonate sheet cover but having that in place makes photography difficult.

With the printer working properly I decided to try using it for the Mastiff distributor parts. These were already drawn up in Alibre so could be exported as .stl files and the g-code generated using Slic3r. The brass strip in the rotor arm was glued in place then faced smooth in the lathe:



Attached to the engine the bits look like:



David

[MJM460]

Hi David, more excellent progress and great use of the 3-d printer.

We are in the Glen Iris/Ashburton area so you probably pass us un the way to visit your daughter.  It would be great to catch up some time.  Exploring the long paddock again, but later in the year I will send you a pm if you are interested in catching up.

MJM460

[deltatango]

Hi MJM,
Thanks, that's a good idea, I'd like to meet. Please send a PM when you get back from the travels. One of us may have to explain the "long paddock" to some of the readers  .

What I forgot to mention in the previous post was that if anyone building Mastiff wants to have a go at printing the distributor bits then send a PM and I'll send you a link to the .stl files (or the CAD if we can find a common file format). The forum probably doesn't want 114 MB files attached to messages.

Regards, David

[MJM460]

Hi David, OK, sometimes I do get too obtuse in my descriptions.  Perhaps it is a bit paranoid, but I keep wondering what those spiders are doing, that always seem to be trawling around the site.

For those not familiar with the term, I think there are two slightly different meanings.  In the early days of our agricultural industry, cattle were driven from remote stations (ranches in US) to city markets along the roadside, grazing the area between the the road and the fences to keep them going.  So it meant travelling the road road to market.  A paddock, perhaps 20 yards wide but thousands of miles long.

Of course, now days, cattle go to market in road trains.  Think semi-trailer, with up to four additional full length trailers in Northern Territory, but restricted to three trailers or 55 metres in total length as they get closer to the cities.  Truly knuckle whitening experience when they decide to pass you on a narrow road.  One hundred tonnes or more does not stop quickly.

So now, cattle or sheep along the road are more likely farmers trying to find feed for the stock by allowing them to graze along the strip between the road and the fences, particularly during drought, when feed on the farm is severely depleted.  My wife and her sisters spent many an hour tending the stock in the long paddock. 

Travelling as a grey nomad, (retirees in a car with a caravan behind travelling north to find warmer weather when it gets too cold at home), whether following the the traditional droving routes, or just exploring the country, can be described as exploring the long paddock.  I think Hugh Currin calls it snow birding.  Or following the Canada geese!

Our trip last year was about 12,000 km by the time we arrived home.  Will be somewhat less this year.  Had a mob of emu on the road two days ago.  Today, a wild goat with kid, and an echidna (a spiked marsupial) crossed the road ahead of us.  The poor thing chose a time that crossed our path while another truck was passing us.  I think it passed under the other vehicle, but must have given it quite a fright.  They move faster than a tortoise, but probably only walking pace.

Will send a pm as suggested.  Enough diversion, time to get this thread back on track,

MJM460

[zeeprogrammer]

Neat idea on preheating the printer.

What was wrong with the prints?
Do you turn it off once printing starts?

On large prints I sometimes see a corner rise from the table. I'm wondering if this might help.