andypugh

The cheap set of Blacksmiths drills that I got from Screwfix a few years ago have proved to be of surprisingly excellent quality. They are still going strong. Though, with the 10 year gap between my purchase and the present there is no guarantee that they are now from the same supplier.

I met Guy Martin at a motorcycle track day organised by friends of mine (He and another professional racer I have forgotten the name of were using out track day to shake-down their BSB bikes). He seemed entirely genuine to me. He actually sought me out to talk about Diesel particulate filters, having heard that I worked in that area, and because he really is more interested in truck mechanicing than anything else. He also borrowed someone else's AR80 restoration project for a session. Most people would do one lap and come in, but he seemed ot be enjoying himself on the AR80 (top speed 60mph) quite as much as his 200hp BSB race bike, and stayed out for the whole session. So a lot of my friends can truthfully claim to have lapped Guy Martin at a track day. I like him.

I have a vague feeling that we have a Rivetted-on balance weight on the fire engine. You could fill the holes with expanding foam (or balsa wood) to hide them.

I believe it is now 86 years of grime. (Guess who I work for?)

Maybe the burly young apprentice had the job of stamping 'Vehicle" and "Engine" on every chassis, and then Miss Smith, the vehicle records clerk, applied the numbers?

No, but I am really enthusiastic for you to try it and report back :-)

I will try to keep this brief as it is rather off-topic, but as someone who did technical drawing at school in the 70s but never used it, and then went on to do 3D CAD as a job I might have some perspective. Don't think about 3D CAD as making a drawing so much as making the part. In fact it can sometimes be helpful to design the parts exactly as they would be machined. The fundamental operations in 3D CAD are revolve (lathe-like) and extrude (mill-like). Unlike with a real machine tool you have the choice of adding or subtracting material, rather than just removing. Usefully for making foundry patterns you can add a taper to the extrude operations for pattern draught. (The CAD tools also tend to have tools for adding draught to faces for this reason, but these tools might not always be able to "solve" the geometry) With engineering CAD you mainly use a dimensioned / constrained sketch as the basis of the operations (this is not the case in animation or flowing-shape product design). You can constrain lines to be tangent to each other or at right-angles etc, which is nice because the computer does a lot of the "solving" of the shape for you. If I was modelling the spider I would first draw a sketch of half the cross section of the rotationally symmetric part, then revolve it to get a plain funnel. I would then create another sketch plane on the open end, sketch a couple of circles linked by arcs, (dimensioned from the centre of the funnel) and extrude-cut that to make one hole, then pattern that x3 rotationally. The bosses would start from a sketch plane offset from the end of the funnel by the 1" dimension, again a circle dimensioned from the centre, and with a construction line from the previous hole to give an angular constraint. Extrude the correct distance and another rotational pattern. Then run round all the edges with the fillet tools to finish. It's literally 10 minutes work. Probably 45 minutes if you are getting the dimensions from a part rather than a sketch or table.

Onshape seems to be the Solidworks version of Autodesk's "Fusion 360". Both appear to be Cloud-based but free for hobby use. I didn't look in detail at the Onshape conditions, but Fusion is free for Hobby, education of "Startup" which they define as making < $100,000 per year. I actually use Autodesk Inventor in the main, as I get a free home license through my job. But Fusion does seem to have all the features of Inventor that I use, just with the slight inconvenience of having to upload any files not in the native format to the "Cloud" to get then converted into the Fusion native format (You can, however, work offline with native-format files) I switch from Inventor to Fusion when I need fancy CAM (G-code generation for CNC machines). The 3D CAM in Fusion is way ahead of the Free module in Inventor (pretty much equivalent to the Pro module). A nice example is here, engraving text on a cylindrical part using a rotary axis. (Normally a hard thing to do). I imagine that there are similar Onshape tutorials on YouTube.

I think that would make it hard to be sure of the heat-treatment condition. However, it would certainly save some time to have then laser-cut to at least the outline shape.

It's absolutely trivial if using CAD / CAM or 3D printing, you just model it the size you want then scale by 1.02.

Admit it, you are only in this for the painting aren't you? :-)

Is the change to black because the red filament ran out, or to indicate the core print in the conventional way? I can see a use for pattern-coat on other parts, as it goes on like paint but then doesn't shrink on curing/drying like paint does. So would work well for smoothing rusted surfaces too.

Braze repairs are quite common with cast-iron parts, which is why I suggested silver-solder. I don't think that the following is the solution here, but I have also had good results repairing the arm of a mechanical hacksaw using stainless-steel MIG wire. The reason to use stainless is that it won't turn into a super-hard martensite due to carbon migration from the cast iron. I guess that bronze MIG wire might be even better.

Rather than weld on your little lug, it might be easier and stronger to build up a lump with weld and then post-machine that.

I think this is somewhere where silver solder would be the right choice, unless you think it will get hot enough to melt it.

Nice lathe. http://www.lathes.co.uk/boley5lz/ (I am a lathe-spotter)

Wire spark-erosion out of pre-hardened gauge-plate would also have given a very good result. (and without the risk to the heat-treatment or the tapered kerf of laser cutting)

It's very nice. It would fit well in your collection :-)

I might have the wrong impression of the shape. I have only seen it in 2D here as pixels, not 3D in wood. I didn't think that there was a flat face with non re-entrant sides. I might, just possibly, be wrong in this. :-)

Wouldn't you want some radius on the core to avoid sharp corners inside the square hole? It ought to be fairly easy to work in on at least 2 edges. I assume the moulder will have to dig down to the pattern? Making a follow board might be friendly.

I think something has gone wrong. Oddly it is visible in the email notification I was sent.

I would have expected con-rods to be forged rather than cast. What material do you intend to use? Machining from solid might give a better result, for a lot more work. But then I doubt that the rods in an engine of this era were anything very special metallurgically, or that they needed to me. If you know the max revs, the piston mass and the con-rod cross-section it might be worth calculating the peak tensile stress to get a feel for what is required. I understand how to do FEA if you don't know how to do it yourself.

You need one of these: http://www.ebay.co.uk/itm/RECORD-No-311-SHOULDER-REBATE-PLANE-/142514563703?hash=item212e87aa77:g:Rj0AAOSwzx9ZxBBT Or, if feeling flush: https://www.workshopheaven.com/clifton-no-420-shoulder-plane.html

There is a FIAT which last I knew was at Stow Maries (WW1 Aerodrome) but I don't know if it was military. There is a 1916 Fire engine in Kensington, but that's not military.

I am pretty sure that we have an M5 x 0.75 thread tap in the fire engine garage, bought especially for the Zenith on that vehicle.