andypugh

Looking at pictures of "Big Lizzie" I was inspired to speculate on whether anything is still out there running on Dreadnaught wheels (also in some books called the Boydell Endless Railroad) https://en.wikipedia.org/wiki/Dreadnaught_wheel I imagine that the design introduces some NVH concerns. Has anyone ridden on them?

Harrison. It wasn't CNC when it left the factory some time in the 70s. http://www.cnczone.com/forums/vertical-mill-lathe-project-log/109301-cnc.html I might put it into a blog at some point.

It is a CNC universal mill. It takes very little to convert it into a hobbing machine. (and back) Helical gears should be easy enough, but I can't do bevels.

Indeed. And I have such a machine:

If you are making both halves of the pair you could make both at 14.5PA. Is http://www.ebay.co.uk/itm/DP6-PA20-Gear-Hob-Cutter-/271648140579 Cheaper than having gears made?

"Better" is such a subjective word. Do you mean "better" as in "not a totally crazy way to retain a gudgeon pin"? If so, then it is better. But then the whole point of these old vehicles is that they are old and different. It is interesting to ponder if the 60hp should have floating pins and spring clips, interference-pins and compression rings or floating pins with compression rings. It now has floating + buttons, but used to be interference + compression. Maybe there was a misunderstanding at some historical point that led to the (horrible) interference + compression ring arrangement.

A worm has straight-sided teeth, it is just a screw thread with a shallower than normal thread angle. (In fact for a 14.5 degree PA the profile is the same as an Acme thread (14.5 degree half-angle) though the tooth height etc are probably oddly proportioned for the diameter/pitch. It is unlikely that you have a lathe that can single-point your worm using an Acme insert, though. If you have ever wondered why the threading table on your lathe includes MOD and DP pitches, this is why. It is so you can cut a worm thread to suit a standard gear tooth pitch. This assumes a non-enveloping worm and wheel, things get more difficult if the wheel isn't straight-toothed, you need a cutter with the same radius as the worm, or a machine that can generate such a curve. (Ponder, I haven't thought about that before, but my CNC milling machine in hobbing mode can probably generate wheels quite nicely, except that most of my hobs are bigger than any worm I would be using)

No, I think it is semi-steel. https://en.wikipedia.org/wiki/Semi-steel

Thury is 47º30' above size 0 and 53º8' below size 0. It is also rounded about the same amount as Whitworth, so I can imagine that they would be hard to tell apart in the bigger sizes. Having said that, I would be astonished if Dennis used Thury in the teens. I think that you are right, it will probably work for a while, but it will damage the mating gear such that you will need a pair (even if you don't already). 6DP by any chance? If not, what?

It does OK in tension too, up to a point. You would imagine that an axle would be designed with the right amount of metal in the right places. BS 1452 described grades of cast iron by tensile (not compressive) strength, currently the grades are 220, 250 260 etc. 250 is 250N/mm2 tensile strength, or 17 tons/square inch. There are a lot of square inches in an axle casting. It might be better. The Dennis axle appears to be a semi-steel. I re-bored the spring saddles once and it came off in curls rather than normal cast-iron swarf.

How can you be sure they are not Thury -6 ? :-) http://sizes.com/tools/thread_thury.htm

The major loads are contained inside the spring-pad and brake pivot casting. The static loads in the actual diff casting are fairly small. However I wouldn't care to guess the dynamic loads in the axle case when the wheels are busily bouncing about in shell craters. The 1916 Dennis I play with has a rod in the place of the Thorny strap. It isn't especially tight, and I think that they are there as a safety restraint in the event that something unexpected happens to the diff (like landing hard on a rock)

I think a better plan would be for someone to find a pre-war motor launch for Ben to rescue to give the engine a new home. Preferably hidden under a houseboat :-)

I had the rare pleasure of following Gigantic up the hill.. My passengers were complaining about smuts in their eyes (you can see one looking a bit unhappy towards the end) but I wasn't going to curtail the experience. It was great. (I am driving the 1916 Dennis immediately behind)

There were still cars in the carp-ark in October 2014: https://goo.gl/maps/ZuYaS

Is it possible that British manufacturers were quoting "RAC" HP and the US manufacturers were quoting dyno HP?

You can buy it in most major towns: http://www.maplin.co.uk/p/press-and-peel-film-pcb-transfer-system-ab15r

It isn't all that hard to do it yourself. If you can create the artwork in a graphics program then you just need to print it on to Press-and-Peel PCB paper, then etch it with Ferric Chloride. http://www.ebay.com.au/itm/Press-and-Peel-PCB-Etchant-Film-/181754940614?pt=LH_DefaultDomain_15&hash=item2a51704cc6 http://www.ebay.com.au/itm/Ferric-Chloride-Powder-1L-Bottle-/111617956958?pt=LH_DefaultDomain_15&hash=item19fcf2dc5e Here is one I made this way near the bottom here: http://bodgesoc.blogspot.co.uk/2014/11/the-last-bits-and-pieces.html

To harden steel you need to get it to transform to Austenite (which has a higher solubility for carbon) and then transform it quickly back to ferrite. How quickly you do it, and to what temperature, controls how the carbon precipitates out, and what carbides are formed. (Pearlite, Bainite) If you quench very fast you get martensite rather than ferrite, and that is the super-hard but brittle stuff. Martensite is metastable at room temperaure, and warming it back up again converts some of the martensite back to ferrite to bring back some of the toughness at the expense of harness. Austenite is not magnetic, which is how the magnet trick works. However there is a bit of a wrinkle as iron becomes non-magnetic at the Curie temperature too (770C) and at low or high carbon concentrations the Curie temperature is less than the critical temperature. http://www.calphad.com/iron-carbon.html

I am surprised that Ben "two lathes" Hawkins didn't cut the oil groove with a shaper, to show off another tool. :-)

I think it cost about £60 and took an afternoon to assemble, so it might be easier to justify than you think. I built mine for heat-treating gears, mainly.

If you think you might be doing a fair bit of heat-treatment then it isn't all that much work to make a muffle furnace: http://bodgesoc.blogspot.co.uk/2014/11/heat-treatment-furnace.html It's useful for parts that are bigger than a torch can keep hot, though for the 18" seat leaf spring on the Ner-a-Car I had to put two tube furnaces face-to-face.

It might be easier (or less risky) to make one from scratch then. (I think they sell Scratch on Aliexpress :-)

Can the lamps be re-assembled other-handed?

I don't see why one couldn't be wall-mounted, but I have never seen it done. A dual-purpose CNC router / plasma cutter might be a nice thing to have. Maybe your garage needs a mezannine?