Monthly Archives: June 2017

The Spanner is Vindicated!


A morning at the airfield saw the Spanner used in anger. It worked a treat! We could only get at 4 nuts on the whole engine due to the tightness of space. I think spanner mk II will be slightly different, remade from guage plate so it can be hardened.

Looking at the "Good" engine was hard work. Everything is very tightly packed, like a Chinese puzzle where each part requires removal of the next to get it off. We managed to get a couple of manifolds off and peered inside. The sleeves we could see were rusty, not a good sign. We might only salvage a piston and ball joint, but we’ll see.

Graham has a couple of weeks holiday now, so we have time to remake the Spanner. I might get some alloy so we can start to make the conrod too. Nick is ploughing on with his coreXY plotter robot, and Bob is finalising issue 2 of the design.

I’ll return the nut we borrowed and research the CNC plasma cutter in more detail.

Another engine.


I went back up to Donnington tonight to check out Graham’s other engine. It wasn’t what I expected but it has potential. It also gave me chance to try out the new spanner. (Which fits the nuts but is too big, so a little adjustment is required).

It looks dry and with all the manifolds intact, so the internals may be OK. The manifolds will take a lot of time to remove, which is Saturday’s job. Another trip planned with Bob and Nick then! I’m lucky to have some good friends around to help out!

Making a spanner.


I went round to see my mate Nick today, armed with some 6mm steel plate left over from the workbench. The idea was to make a spanner by cutting the same profile as the prototype in steel.

The issue we had was the cutting depth of the small diameter cutters. We had to cut half way through, then turn the job over and do the same from the other side. We also had to make sure that the two sides lined up perfectly.

Nick made a jig to hold the job between two dowels along the centre line, so when we turned it over everything would line up. It worked perfectly! I’m really seeing the benefit of CNC machining and I think as I tool up that’s the way I’ll go.

Here’s the master at work.

Clever Lad.


So I rang my mate Nick on Saturday morning around 9. We chatted about the project and general stuff, including the possibility of turning my plasma cutter into a CNC plasma cutter – which I’m quite excited about.

Nick was keyed up to make a spanner and I’m taking the nut round tonight, but he asked for some basic measurements. Number of teeth, outside diameter and depth of the teeth. At 11 I received the picture below by email. Looks pretty good doesn’t it? Clever Lad!

So the plan is to make a few mock up spanners in plastic for a trial fit. Once we have the best version it’ll be cut in steel, hardened if necessary and ready to use in anger! A big leap forward for the project, thanks Nick!

Nuts to you sir!


I have in my hand, a very nice Bristol Hercules cylinder nut. Courtesy of Patrick Smart who has a pair of restored Hercules engines he runs up at charity events. I can get this to my friend Nick who recons he can make a spanner on his 3D machine. Thanks Patrick!

Patrick’s mate Pete was kind enough to weigh a piston, rings and gudgeon pin they have and send me the details. I needed these for Bob so he can work out the balance factors.

Two important pieces of the puzzle coming together, thanks very much guys.